For insects that overwinter as adults, winter food resources may affect subsequent spring reproduction and abundance. We tested if provision of food supplements to overwintering adult Hippodamia convergens (Guerin) increased energy reserves, winter survival, and spring reproduction. During 2015–2016, H. convergens adults were placed in field cages in December; adults in each cage received water, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs, bee pollen, wheast protein, sugar, honey, or no food (control). In 2016–2017, treatments were reduced to sugar, bee pollen, A. pisum with E. kuehniella eggs, and no food (control). Adults were sampled to quantify weight, lipid, carbohydrate, and protein content. In 2015–2016, A. pisum and E. kuehniella eggs increased adult weight and protein content, but adult carbohydrate content was reduced by A. pisum and wheast protein treatments. Adults receiving honey and sugar supplementation had higher lipid and carbohydrate content relative to controls. The number of live individuals at the end of the experiment in March 2016 did not differ among treatments. In 2016–2017, winter prey supplements had the greatest effect on protein content, weight, and number of live adults recovered, whereas sugar supplementation increased lipid and carbohydrate content, and number of live adults recovered. Spring reproduction of surviving pairs was evaluated among treatments in March 2017. Prey supplementation in 2016–2017 increased the number of eggs laid and decreased preoviposition period, and food treatment did not affect fertility. Our results indicate that prey and sugar resources improve the overwintering success and spring reproduction of H. convergens.

We characterized the correlation between the occurrences of diamondback moth, Plutella xylostella (L.), larvae and their dominant native parasitoid wasp, Cotesia vestalis (Haliday), in commercial greenhouses in a satoyama area, called Miyama, in Kyoto, Japan. In the three greenhouses used in this study, cruciferous ‘mizuna’ (Brassica rapa var. laciniifolia [Brassicales: Brassicaceae]) crops were grown. Pesticides against diamondback moth were not routinely applied in the greenhouses. We confirmed that populations of diamondback moth and C. vestalis were maintained on the wild crucifer plant Rorippa indica in the surrounding area from March to December. In the greenhouses, we observed several occurrences of diamondback moth larvae that were, in most cases, followed by occurrences of C. vestalis. We found that C. vestalis females were attracted by volatiles emitted from mizuna plants that were lightly infested with second-stadium diamondback moth larvae under laboratory conditions. The synchronous appearance of diamondback moth larvae and C. vestalis could be explained by the latter being attracted by the volatiles emitted from mizuna plants infested by diamondback moth larvae in the greenhouses.

The brown marmorated stink bug, Halyomorpha halys (Stål), is a highly polyphagous species native to Asia that has become a serious invasive agricultural and nuisance pest across North America and Europe. Classical biological control host range evaluations have revealed egg parasitoid Trissolcus japonicus (Ashmead) to be the primary candidate biocontrol agent for field release against H. halys. However, these evaluations only provide us with the physiological host range of T. japonicus. Other Trissolcus species have demonstrated that contact kairomones from different host species elicit varied responses in the parasitoids' host foraging behaviors. To assess T. japonicus response to host kairomones, mated naive females were exposed to leaf surfaces contaminated with adult kairomones from its preferred host, H. halys, or from a native nontarget host, Podisus maculiventris (Say) (Heteroptera: Pentatomidae). Red maple, apple, and soybean were used as plant substrate treatments. The wasp's residence time on the leaf surface, linear walking velocity, and angular walking velocity were observed and measured using Noldus EthoVision XT tracking software. Within each leaf treatment, T. japonicus displayed stronger behavioral responses on leaves contaminated with contact kairomones from H. halys. The parasitoid resided on H. halys contaminated leaves for approximately twice as a long as it did on P. maculiventris contaminated leaves. Further, both species' kairomones elicited significant decreases in parasitoid walking velocity on all tested substrate types. Overall, our study suggests that kairomone-based behavioral studies can be used to further evaluate the host specificity of T. japonicus and can be an invaluable supplement to classical biocontrol host range testing regimes.

The lignocellulosic digestive symbiosis in termites is a dynamic survival adaptation system.While the contribution of hereditary and habitat factors to the development of the symbiotic bacterial community of termites had been confirmed, the manner in which these factors affect functional synergism among different bacterial lineages has still not been fully elucidated. Therefore, the 16S rRNA gene libraries of Odontotermes formosanus Shiraki (Blattodea: Termitidae) and Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae) sampled from sugarcane fields (high sugar) or pine tree forests (no free sugar) were sequenced. The results verify that the prokaryotic community structures of termites could be significantly reshaped by native dietary isolation within a species. Although the most dominant phyla are convergent in all samples, their relative abundances in these two termite species exhibited a reverse variation pattern when the termite hosts were fed on the high-sugar diet. Furthermore, we showed that the taxonomic composition of the dominant phyla at the family or genus level differentiate depending on the diet and the host phylogeny. We hypothesize that the flexible bacterial assemblages at low taxonomic level might exert variable functional collaboration to accommodate to high-sugar diet. In addition, the functional predictions of Tax4Fun suggest a stable metabolic functional structure of the microbial communities of the termites in both different diet habitats and taxonomy. We propose that the symbiotic bacterial community in different host termites developed a different functional synergistic pattern, which may be essential to maintain the stability of the overall metabolic function for the survival of termites.

Strip tillage, in which tillage and seedbed preparation are limited to a narrow band where the subsequent crop is planted, provides many potential agronomic benefits, including reduced fuel and labor costs, reduced erosion, and improved soil tilth. Lower soil disturbance and enhanced water retention associated with strip tillage also may affect density and diversity of predatory arthropods, which have been little studied in sugar beet. We examined the effects of tillage (conventional versus strip) on the predatory epigeal arthropod fauna in sugar beet. Studies were conducted over three growing seasons (2010–2012) in Idaho using both fenced and unfenced pitfall traps to sample arthropods. Unfenced pitfall traps often captured a greater activity density and richness of predators, and showed no bias of higher captures in conventionally tilled plots as has been shown elsewhere. Total density of predators was higher in strip tillage only during 2011. Density and species richness of carabid beetles did not differ between tillage treatments during the course of the study. Density of the other major taxa (staphylinid beetles, spiders, and Opiliones) was higher under strip tillage during some years, especially early in the season, but richness showed little or no relationship with tillage. Predaceous arthropods might be favored by enhanced ground cover, higher humidity, more moderate temperatures, and/or less habitat disturbance associated with strip-tilled plots.The results suggest that certain groups of soil-dwelling predatory arthropods can be favored by strip tillage in sugar beet, which further adds to the benefits of conservation tillage in this system.

Invasive ambrosia beetles are among the most economically important pests of forest and plantation trees worldwide.The development of effective management guidelines for these pests in plantations of high-value hardwood species is hindered by a lack of baseline information regarding their seasonal abundance and dispersal behavior. By analyzing long-term monitoring data from intensively-managed plantations of eastern black walnut (Juglans nigra L.) in north-central Indiana, we identified key spatial and climatic variables that could improve the timing and precision of management actions to reduce ambrosia beetle populations. We also used geospatial analyses to compare species-specific spatial patterns of population density and evaluate the sensitivity of the trap density deployed in our long-term monitoring efforts. Xyleborinus saxesenii Ratzeburg and Xylosandrus crassiusculus Matschulsky (Coleoptera: Curculionidae) were more abundant during the spring in years preceded by a hot, dry growing season, and cold winter. Both species were positively associated with plantation edges during the fall flight period. However, X. saxesenii was less abundant in plantations close to forest corridors, whereas X. crassiusculus was more abundant in plantations closer to woodlots and other walnut plantations. Geospatial analysis revealed X. crassiusculus is active in larger, more spatially continuous patches than X. saxesenii, and that 200-m trap spacing is likely to be sufficient to detect both species in the spring flight period but may be insufficient to detect X. saxesenii during the fall flight period. Our findings underscore the power and utility of long-term monitoring to improve management strategies.

The arrival of spotted wing Drosophila, Drosophila suzukii (Matsumura), to the United States has caused many berry and cherry growers to replace IPM programs with calendar-based broad-spectrum insecticide programs. Alternative management tactics are urgently needed to mitigate the current dependency on chemical control. Postharvest burial is a cultural crop sanitation strategy that has the potential to reduce D. suzukii reproductive habitat and eliminate infested fruit wastes. This study revealed that D. suzukii rarely pupate on the soil's surface or below 1 cm, but are capable of unburying themselves from depths up to 48 cm. Although zero emergence was not obtained in the field, adult emergence decreased exponentially with deeper burial depths. A burial depth of 24 cm reduced D. suzukii emergence by 97%, although soil texture may influence this optimal burial depth. Soils that had a higher concentration of sand had a negative impact on D. suzukii survival at shallower burial depths. The mechanism behind the reduction in adult emergence from differing burial depths remains unclear as the lipid concentration between emerging D. suzukii was the same regardless of burial depth.

Studies on the natural factors contributing to pest regulation are fundamental to developing efficient integrated pest management programs. Chemical control is the main management method used for pests [e.g., Aphis gossypii (Glover)]. The studies of pest management with chemical control provide information that can be incorporated into integrated pest management programs to promote more sustainable pest control approaches. Here, we report the critical stages of A. gossypii and its abiotic and biotic natural mortality factors in cotton crops as a function of plant phenology using a life table. The critical stages of A. gossypii were the first and fourth instars. Together, the abiotic and biotic factors caused 94.31% of the mortality in the A. gossypii populations in cotton crops with plants in the vegetative, flowering, and fruiting stages. The key mortality factors were rainfall and predation. Syrphidae Allograpta exotica (Wiedemann) (Diptera: Syrphidae) and Chrysopidae Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) larvae, many Coccinellidae species Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae), Eriopsis connexa (Germar) (Coleoptera: Coccinellidae), Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), Hippodamia convergens (Guérin-Meneville) (Coleoptera: Coccinellidae), Scymnus rubicundus (Erichson) (Coleoptera: Coccinellidae) and Stethorus punctillum (Weise) (Coleoptera: Coccinellidae), one Anthocoridae species Orius insidiosus (Say) (Hemiptera: Anthocoridae), and individuals from the Araneidae family were responsible for the predation of A. gossypii.The results obtained in this study provide support for the idea that efforts to preserve natural enemies (e.g., predators) and rainfall monitoring should be adapted due to their importance for the regulation of A. gossypii populations in all the phenological stages of cotton in tropical regions.

Tomato chlorotic spot virus (TCSV) is an orthotospovirus that causes a devastating disease in tomato (Lycopersicon esculentum Miller).TCSV emerged recently in South Florida. Studies were conducted in three commercial tomato fields in Miami-Dade County, Florida during the vegetable-growing seasons from October to April in 2015 through 2017. Each year, data were collected at 3, 6, and 9 wk after transplanting at various distances from the edges of each fields. Based on 3 yr total samples, three species of thrips were commonly observed melon thrips, Thrips palmi Karny (62.16 ± 0.79%), being the most abundant species followed by common blossom thrips, Frankliniella schultzei Trybom (21.55 ± 0.66%), and western flower thrips, Frankliniella occidentalis (Pergande) (16.26 ± 0.61%). Abundance of all thrips and TCSV infected plants was high at the edge of a tomato field 3 wk after transplanting with significantly fewer infected plants toward the center of the field.The distribution patterns of thrips and TCSV in various fields were mostly regular and aggregated across the sampling dates during the study period. Abundance of TCSV symptomatic plants and thrips species was high at the edge of the field and increased over time. The number of samples required to accurately determine population density of thrips was calculated by using three precision levels (0.10, 0.20, 0.30) at three predetermined densities of thrips (0.10, 0.20, and 0.40 per sample).This information will provide guidelines to growers, crop protection personnel, agricultural scouts, and researchers to develop a sustainable thrips and tospovirus management program.

Megacopta cribraria (F.) (Hemiptera: Plataspidae) is an invasive pest of soybean that has spread across the southeastern United States since its initial discovery in 2009 in Georgia. Previous studies in the southeastern states have documented both the population dynamics of this pest and host plant resistance (HPR) among soybean varieties, although the specific mechanisms of HPR remain unknown. The objectives of this study were, therefore, to 1) quantify field resistance to M. cribraria in multiple soybean varieties in two states previously affected by severe M. cribraria infestations, North Carolina (NC) and South Carolina (SC); and 2) study the role of soybean trichome density in imparting resistance against M. cribraria. Soybean variety ‘Camp’ was least attractive to M. cribraria, through time and locations, suggesting consistent resistance. Other varieties showed variable performance among the locations and sampling dates. A significant difference in trichome density was evident. However, there was no correlation between trichome density and M. cribraria infestation. Compared to a previously published study in the same location, when M. cribraria adults emerging from overwintering dispersed into soybeans, in our study only first-generation adults dispersed into soybeans. Considering the current trend of significantly lower M. cribraria infestation rates in North and South Carolina, this pest may be finally succumbing to indigenous natural enemies and should be managed by incorporating integrated pest management tactics, such as HPR, that help conserve natural enemy populations.

Insects respond to environmental conditions with a variety of developmental responses which include changing developmental rates, or suppressing development altogether in quiescence or diapause. Such responses have important implications for survival and voltinism. The spruce beetle, Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae), has long been assumed to have an obligatory adult diapause based on field observations that adults always overwinter prior to dispersing and reproducing; however, it has never been experimentally demonstrated and recent evidence suggests that adults in some populations may exhibit facultative tendencies. We examined the emergence of adults at a constant 22°C after exposure to 2°C for 0 (no cold), 25, 50, and 75 d. Our observations of a delayed and extremely protracted emergence period in the absence of a substantive cold period, which could last several months, in combination with rapid, synchronous mass emergence after a substantive cold period, are most consistent with an obligate diapause. Approximately 50% of individuals could complete diapause in 55 d at 2°C, and 75 d of cold was adequate for almost all individuals to complete diapause. Beetles that emerged slowly over time may still have been in diapause; however, additional research would be required to test this hypothesis. Conditions throughout the beetle's range in Canada should facilitate successful completion of diapause. An obligate adult diapause for spruce beetle populations in western Canada would limit the shortest possible life cycle to 1 yr, but would also serve to maintain an adaptive 1-yr life cycle, especially under a changing climate.

An insect species' geographic distribution is probably delimited in part by physiological tolerances of environmental temperatures. Gloomy scale (Melanaspis tenebricosa (Comstock)) is a native insect herbivore in eastern U.S. forests. In eastern U.S. cities, where temperatures are warmer than nearby natural areas, M. tenebricosa is a primary pest of red maple (Acer rubrum L.; Sapindales: Sapindaceae) With warming, M. tenebricosa may spread to new cities or become pestilent in forests. To better understand current and future M. tenebricosa distribution boundaries, we examined M. tenebricosa thermal tolerance under laboratory conditions. We selected five hot and five cold experimental temperatures representative of locations in the known M. tenebricosa distribution. We built models to predict scale mortality based on duration of exposure to warm or cold experimental temperatures. We then used these models to estimate upper and lower lethal durations, i.e., temperature exposure durations that result in 50% mortality. We tested the thermal tolerance for M. tenebricosa populations from northern, mid, and southern locations of the species' known distribution. Scales were more heat and cold tolerant of temperatures representative of the midlatitudes of their distribution where their densities are the greatest. Moreover, the scale population from the northern distribution boundary could tolerate cold temperatures from the northern boundary for twice as long as the population collected near the southern boundary. Our results suggest that as the climate warms the M. tenebricosa distribution may expand poleward, but experience a contraction at its southern boundary.

Effective insect management strategies require a firm understanding of the factors determining host preference, particularly in highly mobile insect herbivores. Host preference studies commonly employ average or first position as a proxy for preference. Yet few studies have explored host preference in relation to transitory attraction and leaving rates, yet these are both components of host plant selection. We investigated the transitory dynamics of preference by the green rice leafhopper, Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae) by conducting experiments on groups of females, males, or mixed-sex leafhoppers, and recording their position over time between low-N and normal-N rice plants. Utilizing a log-linear model and variants of a biostatistical model we used these positional data to extract attraction, leaving and tenure rates to better understand the process of host-plant selection. We found a general preference for normal-N over low-N plants at equilibrium. However, between sexes there was variation in the relative significance of attraction or leaving rates on that preference. Female leafhoppers were more attracted to host plants with higher nitrogen content. Male leafhoppers were less discriminate in their initial attraction to hosts but left low-N hosts at a faster rate. Whereas estimated tenure times on both normal- and low-N plants exceeded transmission times for the leafhopper-transmitted rice dwarf virus, longer tenure on normal-N plants likely increases the likelihood of virus acquisition from these plants. Our findings support previous recommendations that growers can mitigate the risks of leafhopper damage and pathogen transmission by optimizing their application of nitrogenous fertilizers.

Environmental stressors may induce variation in the number of larval instars of holometabolous insects. Host plant quality and ambient temperature can both induce this life history shift in the silver-spotted skipper, Epargyreus clarus (Cramer 1775) (Lepidoptera: Hesperiidae). To better understand this phenomenon, we raised larvae on high-quality (kudzu) or low-quality (wisteria) host plants in growth chambers under three temperature regimes (20, 26, and 32°C) that were either constant or diurnally fluctuating (T ± 5°C), and recorded survival and incidence of supernumerary instars. Larvae feeding on the low-quality host and/or experiencing thermal stress were more likely to show supernumerary development (SD). A subset of treatments yielded a mix of SD and TD (typical development) individuals, allowing for comparisons between phenotypes. Under the most stressful treatment (20 ± 5°C, wisteria), development time was 9 days longer in SD than in TD individuals; by contrast, at typical summer temperatures (26 ± 5°C), also on wisteria, total development time did not differ between these two phenotypes. Head capsules of both second and third instars were smaller in SD individuals. A retrospective logistic regression analysis indicated that third-instar head capsule size could be used to predict expression of the SD phenotype. By the ultimate instar, however, there were no detectable differences in head capsule size, and SD and TD individuals did not differ in pupal mass, strongly suggesting that the SD phenotype functions as a compensatory mechanism allowing E. clarus larvae to achieve the same size at metamorphosis (a strong fitness correlate) asTD larvae.

Laboratory studies were conducted with Dichelops furcatus (F.), Euschistus heros (F.), and Nezara viridula (L.) (Heteroptera: Pentatomidae) aiming to evaluate nymph and adult biology and adult preference for immature reproductive structures of the cultivated plants, soybean, Glycine max (L.) Merrill (Fabaceae), wheat, Triticum aestivum L. (Poaceae), and canola, Brassica napus L. var. oleifera (Brassicaceae). Considering the survivorship for D. furcatus nymphs, it was greater on soybean and wheat, for E. heros nymphs it was greater on soybean compared to canola and wheat, and for N. viridula nymphs the survivorship was greater on soybean and canola. Dichelops furcatus nymphs developed faster on soybean and wheat, and E. heros and N. viridula nymphs developed faster on soybean and canola. Body weight at adult emergency for D. furcatus was greater on soybean and wheat, and for E. heros and N. viridula, it was greater on soybean. Adult survivorship and longevity were similar on soybean/ wheat/canola for D. furcatus and N. viridula, and greater on soybean for E. heros. Reproduction and weight gain of adults were greater on soybean and wheat for D. furcatus, and on soybean for E. heros; N. viridula reproduced only on soybean and tended to gain greater body weight in this food source. As expected, soybean considering its superior nutritional quality was, in general, the best food.These laboratory studies coupled with field observations allow to conclude that the sequence of soybean/wheat/canola crops in the area studied forms a ‘green bridge’ that favor stink bug populations abundance in southern Brazilian neotropics.

Many farmers use manure as an alternative to inorganic fertilizer. Previous research has shown that manure can decrease plant susceptibility to herbivores, but the mechanisms remain unclear. To determine how manure affects herbivore performance in a greenhouse setting, we fertilized corn with stacked cow manure or an equivalent amount of NPK fertilizer and measured caterpillar development, plant nutritional content, and defenses. After 4 wk of growth, we allowed fall armyworm (Spodoptera frugiperda) or black cutworm (Agrotis ipsilon) caterpillars to feed on these plants for 6 d. Compared to inorganic fertilizer, manure reduced mass-gain of black cutworm caterpillars and smaller fall armyworms. We paired this greenhouse experiment with a 3-yr field experiment, which incorporated a wheat cover-crop treatment crossed with the two fertilizer treatments in a 2 × 2 factorial design. We measured plant damage early in the season from naturally occurring herbivores and measured neonate fall armyworm performance on field-collected leaf tissue. In 2017, corn in manure-fertilized plots sustained more herbivore damage, primarily driven by a higher incidence of slug damage. Fall armyworm performance, however, was lower on leaves collected from manure-fertilized plants. In contrast to previous studies, we did not find increased micronutrients or enhanced defenses in manure treated plants. While manure can offer resistance to some herbivores, our results suggest that this resistance can be overshadowed by habitat conditions.

Twelve selected cultivated or wild solanaceae (Solanum dulcamara, Solanum nigrum, Solanum villosum, Solanum lycopersicum, Solanum muricatum, Solanum melongena, Datura innoxia, Datura metel, Physalis spp., Capsicum annuum, Nicotiana alata, and Petunia spp.) (all species Solanales: Solanaceae) were tested as potential alternative host plants against Solanum tuberosum for a local population of the Colorado potato beetle Leptinotarsa decemlineata Say (CPB) in Estonia. Some CPB populations in America and southern Europe accept most of these plants. However, geographically isolated populations of beetles can differ in their acceptance of new host plants. Migrants from the southern Europe supplement Estonian beetle population regularly, so individuals may differ in their host plant preferences. S. melongena and S. dulcamara were well accepted by the beetles, Lycopersicum spp. (Solanales: Solanaceae) and N. alata were intermediate, and S. villosum and S. nigrum were least accepted.The beetles rejected S. muricatum, Physalis spp., C. annuum, Petunia spp., and D. metel. First-instar larvae completed a full life cycle only on S. dulcamara, N. alata, S. lycopesicum, S. melongena, although their development rate was slower, mortality was higher and emerging adults were underweight relative to those that fed on S. tuberosum. The fourth-instar larvae were less sensitive in relation to food. We found that S. dulcamara as a native plant could provide resources for CPB during early and late season. At the same time, the cultivated S. melongena would be suitable plant species for further testing as dead-end crop for integrated pest management.

Neonicotinoid seed treatments are frequently used in cotton (Gossypium hirsutum L. [Malvales: Malvaceae]) production to provide protection against early-season herbivory. However, there is little known about how these applications affect extrafloral nectar (EFN), an important food resource for arthropod natural enemies. Using enzyme-linked immunosorbent assays, we found that neonicotinoids were translocated to the EFN of clothianidin- and imidacloprid-treated, greenhouse-grown cotton plants at concentrations of 77.3 ± 17.3 and 122.6 ± 11.5 ppb, respectively. We did not find differences in the quantity of EFN produced by neonicotinoid-treated cotton plants compared to untreated controls, either constitutively or after mechanical damage. Metabolomic analysis of sugars and amino acids from treated and untreated plants did not detect differences in overall composition of EFN. In bioassays, female Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) parasitoid wasps that fed on EFN from untreated, clothianidin-treated, or imidacloprid-treated plants demonstrated no difference in mortality or parasitization success. We also conducted acute toxicity assays for C. marginiventris fed on honey spiked with clothianidin and imidacloprid and established LC₅₀ values for male and female wasps. Although LC₅₀ values were substantially higher than neonicotinoid concentrations detected in EFN, caution should be used when translating these results to the field where other stressors could alter the effects of neonicotinoids. Moreover, there are a wide range of possible sublethal impacts of neonicotinoids, none of which were explored here. Our results suggest that EFN is a potential route of exposure of neonicotinoids to beneficial insects and that further field-based studies are warranted.

Selenium (Se), as an essential micronutrient, has been demonstrated to play an important role in life activities. In this study, we studied the effects of sucrose solutions containing sodium selenite on Apis mellifera (L.). We obtained the appropriate level of sodium selenite for A. mellifera by determining the life span by lab rearing, and then, we studied the effects of sodium selenite on antioxidant activity, phenol oxidase activity, development of the hypopharyngeal gland, Se content of body tissues and royal jelly (RJ), and related gene transcription levels for a bee colony. The results of lab rearing showed that a concentration of 0.57 mg/liter sodium selenium could extend life. After feeding the colony sodium selenium at concentrations of 0.3 mg/liter and 0.6 mg/liter, the results showed that 0.6 mg/liter sodium selenite could enhance the antioxidant and immune activity of 6-d-old larvae and 1-d-old and 9-d-old worker bees (P < 0.05), increase the Se content of body tissues (P < 0.05) and RJ (P < 0.05), and improve the expression of related genes (P < 0.05).

Ornamental flowers are commonly planted in urban and suburban areas to provide foraging resources for pollinator populations. However, their role in supporting broad pollinator biodiversity is not well established as previous studies have been conducted in urban landscapes with pollinator communities that are distinct from those in natural systems. We observed pollinator visitation patterns to five ornamental annual plant genera and their cultivars over multiple years at two semi-natural sites in Pennsylvania to understand their potential for supporting diverse pollinator communities. There was significant variation in visitor abundance and diversity by season and year for many annual ornamental cultivars. Within some genera, cultivars had similar visitor abundance, diversity, and main visitor taxa, while cultivars in other genera varied greatly in these measures. We observed only polylectic (pollen generalist) bee species visiting annual ornamentals, despite the presence of oligolectic (pollen specialist) bee species in the background population. We conclude that the attractiveness of annual ornamental plants likely depends on both cultivar characteristics and environmental context. While their role in supporting complex pollinator populations is limited both based on the number of and dietary breadth of the species they support, ornamental plants may nonetheless provide long-lasting supplemental foraging resources for the generalist pollinator communities characteristic of urban and suburban environments.

Pollen is the source of protein for most bee species, yet the quality and quantity of pollen is variable across landscapes and growing seasons. Understanding the role of landscapes in providing nutritious forage to bees is important for pollinator health, particularly in areas undergoing significant land-use change such as in the Northern Great Plains (NGP) region of the United States where grasslands are being converted to row crops. We investigated how the quality and quantity of pollen collected by honey bees (Apis mellifera L. [Hymenoptera: Apidae]) changed with land use and across the growing season by sampling bee-collected pollen from apiaries in North Dakota, South Dakota, and Minnesota, USA, throughout the flowering season in 2015–2016. We quantified protein content and quantity of pollen to investigate how they varied temporally and across a land-use gradient of grasslands to row crops. Neither pollen weight nor crude protein content varied linearly across the land-use gradient; however, there were significant interactions between land use and sampling date across the season, particularly in grasslands. Generally, pollen protein peaked mid-July while pollen weight had two maxima in late-June and late-August. Results suggest that while land use itself may not correlate with the quality or quantity of pollen resources collected by honey bees among our study apiaries, the nutritional landscape of the NGP is seasonally dynamic, especially in certain land covers, and may impose seasonal resource limitations for both managed and native bee species. Furthermore, results indicate periods of qualitative and quantitative pollen dearth may not coincide.

Industrial hemp, Cannabis sativa (Cannabaceae), is a newly introduced and rapidly expanding crop in the American agricultural landscape. As an exclusively wind-pollinated crop, hemp lacks nectar but produces an abundance of pollen during a period of floral dearth in agricultural landscapes.These pollen resources are attractive to a range of bee species but the diversity of floral visitors and their use of hemp across a range of agricultural contexts remains unclear. We made repeated sweep net collections of bees visiting hemp flowers on farms in NewYork, which varied in both landscape context and phenotypic traits of hemp varieties. We identified all bee visitors to the species level and found that hemp supported 16 different bee species. Landscape simplification negatively impacted the abundance of bees visiting hemp flowers but did not affect the species richness of the community. Plant height, on the other hand, was strongly correlated with bee species richness and abundance for hemp plots with taller varieties attracting a broader diversity of bee species. Because of its temporally unique flowering phenology, hemp has the potential to provide a critical nutritional resource to a diverse community of bees during a period of floral scarcity and thereby may help to sustain agroecosystem-wide pollination services for other crops in the landscape. As cultivation of hemp increases, growers, land managers, and policy makers should consider its value in supporting bee communities and take its attractiveness to bees into account when developing pest management strategies.

Reliance on the honey bee as a surrogate organism for risk assessment performed on other bees is widely challenged due to differences in phenology, life history, and sensitivity to pesticides between bee species. Consequently, there is a need to develop validated methods for assessing toxicity in non-Apis bees including bumble bees. The usefulness of small-scale, queenless colonies, termed microcolonies, has not been fully investigated for hazard assessment. Using the insect growth regulator diflubenzuron as a reference toxicant, we monitored microcolony development from egg laying to drone emergence using the Eastern bumble bee Bombus impatiens (C.), a non-Apis species native to North America. Microcolonies were monitored following dietary exposure to diflubenzuron (nominal concentrations: 0.1, 1, 10, 100, and 1,000 µg/liter). Microcolony syrup and pollen consumption was significantly reduced by diflubenzuron exposure. Pupal cell production was also significantly decreased at the highest diflubenzuron concentration assessed. Ultimately, diflubenzuron inhibited drone production in a concentration-dependent manner and a 42-d 50% inhibitory concentration (IC₅₀) was determined. None of the dietary concentrations of diflubenzuron tested affected adult worker survival, or average drone weight. These data strengthen the foundation for use of this methodology, and provide valuable information for B. impatiens; however, more work is required to better understand the utility of the bumble bee microcolony model for pesticide hazard assessment.

Prescribed burning is a common silvicultural practice used in the management of longleaf pine (Pinus palustris Mill., Pinales: Pinaceae) savannas to reduce hardwood encroachment and ground cover and to maintain biodiversity. We investigated the response of the native bee community (Hymenoptera: Apoidea: Anthophila) in the Sandhills of North Carolina to prescribed burning on a 3-yr rotation over two consecutive years (2012 and 2013). We deployed bee bowl traps in sites that had been burned the year of sampling, 1 yr before, 2 yr before, and in unburned controls. In total, 2,276 bees of 109 species were captured. Bee abundance declined with time since fire, with 2.3 times more bees captured in the most recently burned sites than in unburned controls. Bee diversity also declined with time since fire, with 2.1 times more species captured in the most recently burned sites than in controls. Bee community composition also responded to fire; we present evidence that this response was mediated in part by the effect of fire on the amount of bare ground and canopy cover. Bees nesting aboveground were unaffected by fire, contrary to our expectation that fire would destroy the wood and stems in which these species nest. Our results indicate that prescribed burning is a silvicultural practice consistent with pollinator conservation in longleaf pine ecosystems of the North Carolina sandhills.

Many bumble bee species (Bombus Latreille) have declined dramatically across North America and the globe, highlighting the need for a greater understanding of the habitat required to sustain or recover populations. Determining bumble bee species' plant selection is important for retaining and promoting high-quality plant resources that will help populations persist. We used nonlethal methods to sample 413 plots within riparian corridors and meadows in the Sierra Nevada of California for bumble bees during two summers following extremely low and normal precipitation years, respectively. We assessed the five most abundant bumble bee species' plant selection by comparing their floral use to availability. Additionally, we described the shift in plant selection between years for the most abundant species, Bombus vosnesenskii Radoszkowski. Bumble bee species richness was constant between years (13 species) but abundance nearly tripled from 2015 to 2016 (from 1243 to 3612 captures), driven largely by a dramatic increase in B. vosnesenskii. We captured bumble bees on 104 plant species or complexes, but only 14 were significantly selected by at least one bumble bee species. Each of the five most frequently captured bumble bee species selected at least one unique plant species. Plant blooming phenology, relative availability of flowers of individual plant species, and plant selection by B. vosnesenkii remained fairly constant between the two study years, suggesting that maintaining, seeding, or planting with these ‘bumble bee plants’ may benefit these five bumble bee species.

Current climate projections for the Great Plains of North America indicate markedly increased air temperatures by the end of the current century. Because the Great Plains contains >80,000 intermittent wetlands that serve as irreplaceable wildlife habitat, this projected warming may have profound effects throughout a continental-scale trophic network. However, little research has been done to determine how projected warming may affect the growth, development, or survival of even common species in this region. We conducted laboratory warming experiments, using an abundant amphibious predatory insect, Enallagma civile (Hagen, 1861), as a model organism, to determine whether projected warming may affect development or survival. Eggs were collected and reared under four water temperature regimes representing current (26°C) and projected future conditions (32, 38, and 41°C). Nymph body size after each molt, development rate, and deaths were recorded. Elevated water temperatures were found to significantly affect the survivorship of E. civile eggs and nymphs as well as adult body size at emergence: an increase in temperature incurred a decrease in survival and size. Nymphs in the two hotter treatments were smaller and had low survivorship whereas individuals in the cooler temperatures generally survived to adulthood and were larger. Nymphs reared at 32°C experienced accelerated ontogenetic development compared with the other temperatures, going from egg to adult in 26 d. Projected elevated temperatures may, thus, be both advantageous and detrimental, causing concern for aquatic invertebrates in this region in the future.

Reproduction in female spruce budworms, Choristoneura fumiferana, entails sedentary oviposition early in life (gravid females with their heavy abdomen full of eggs are unable to sustain flight), followed by short- and long-range dispersal by females that have laid a portion of their eggs. Body size measurements (wing surface area and dry weight) of gravid females, spent females at death (after all eggs are laid), and inflight females captured at light traps were collected at one location (forest stands near Fredericton in New Brunswick) over multiple years, from the outbreak stage (1976–1979: peak budworm abundance) to late declining phase with collapsing populations (1988–1989, following near two-fold magnitude of decline in adult density after 1987). For both demographic phases, females rarely flew until having laid at least 40% of their eggs, in contradiction to the hypothesis that females in defoliated forest stands can fly upon emergence due to their light-weight abdomen. As expected, the weight and fecundity of females in 1988–1989 was significantly lower than early on; in terms of body size (wing surface area), however, females were larger in late outbreak phase.These trends suggest that females have evolved morphological adaptation to further dispersal from deteriorated habitats.

Douglas-fir dominated forests are an integral part of the Pacific Northwest. In the Cedar River Municipal Watershed, Washington, these forests provide erosion control and ecosystem buffering for the Cedar River system that supplies high-quality drinking water to the Seattle area. Mortality of Douglas-fir in the watershed has been increasing in recent years. The Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, as well as fungal pathogens, are key agents of mortality in Douglas-fir dominated forests, but their contributions to the current rates of mortality are unknown. We modeled D. pseudotsugae phenology in western Washington and estimated peak flight of overwintering adults at 344.5 cumulative degree-days (base temperature threshold = 4.3°C). We extended the results from the phenology model when assuming a 1.7°C increase in temperature and estimated that D. pseudotsugae adult flight could be advanced by 21–27 d. We also conducted a field study over 2 yr to quantify the individual and interacting roles of D. pseudotsugae, root rot pathogens, and other abiotic and biotic variables as drivers of Douglas-fir mortality. Study sites with recent high rates of mortality of Douglas-fir (>30%) were generally in lower elevation stands and affected by both D. pseudotsugae and root rot pathogens. Attacks by D. pseudotsugae in 1 yr were significantly associated with the presence of root rot mycelia in the following year, but not vice versa. The development of a D. pseudotsugae phenology model for the region and the identification of variables associated with Douglas-fir mortality facilitates the development of management strategies.

Interspecific competition between agricultural pests may affect the species that can establish, and may also affect food production. Prostephanus truncatus (Horn), the larger grain borer, is endemic to Central America, but invaded Africa with disastrous consequences for maize production. Its main competitor is Sitophilus zeamais Motschulsky, the maize weevil, which is cosmopolitan. These insects co-occur in many regions of the world and both are threats to maize. However, the impact of competition between these two species is not well-understood, nor is its effect on grain quality or potential to limit P. truncatus invasion in new areas. The aims of our study were to evaluate the outcome of interspecific competition between P. truncatus and S. zeamais at four different temperatures on a fixed quantity of grain, and determine effects on progeny production, grain damage, and mold growth. We found that coexistence may be possible at a range of 25–30°C, but mixed colonies experienced a direct competitive cost compared to single-species colonies. Prostephanus truncatus performed better at warmer temperatures, while S. zeamais favored cooler temperatures. The majority of grain damage was the result of P. truncatus activity as opposed to S. zeamais. Finally, mold growth was greater where both species were present, and species of mold that produce aflatoxin were identified. Although there are an increasing number of areas where both of these species occur, our results suggest P. truncatus will be capable of destroying much more maize in a shorter period compared to S. zeamais at temperatures greater than 25°C.