The brown planthopper, Nilaparvata lugens (Stål), is one of the most serious and destructive pests of rice in Asia. Climate warming in tropical regions and extreme-high- or low-temperature events may become limiting factors affecting the survival and distribution of N. lugens.The effects of continuous high temperature (CHT), discontinuous high temperature (DHT), and abnormal low temperature in summer (ALT) on the growth and development of N. lugens were studied under lab conditions. High temperatures and ALT decreased the survival rate of nymphs (in fourth-instar nymphs, CHT, DHT, ALT, and control survival was 46.67% ± 1.67, 31.67% ± 1.67, 48.33% ± 4.41, and 60.00% ± 2.89, respectively, P < 0.05). ALT also prolonged the development of N. lugens nymphs (in fourth-instar nymphs, ALT and control survival was 6.09 ± 0.193 d and 5.39 ± 0.082 d, respectively, P < 0.05). In fifth-instar nymphs, CHT (2.36 ± 0.064 d, P < 0.05) and DHT (2.34 ± 0.048 d, P < 0.05) had little influence on nymphal development compared with the control (2.25 ± 0.012 d, P < 0.05). The three temperature treatments (CHT, DHT, and ALT) decreased the number of eggs produced (61.33 ± 0.067, 62.67 ± 0.882, and 34.00 ± 0.577, respectively, P < 0.05) compared with the control (68.00 ± 1.000, P < 0.05).The female sex ratio decreased after nymphs were subjected to CHT (65.82% ± 0.771, P < 0.05, in fifth-instar nymphs) and ALT (76.01% ± 1.362, P < 0.05) compared with the control (81.63% ± 1.007, P < 0.05). Adults in CHT (25.30 ± 0.182, P < 0.05) and DHT (14.64 ± 0.238, P < 0.05) consumed significantly more food than the control (11.54 ± 0.181, P < 0.05), but adults in ALT (6.54 ± 0.196, P < 0.05) fed significantly less than the control (11.54 ± 0.181, P < 0.05). Hatching rates of eggs under the three temperature treatments (CHT, DHT, and ALT were 69.57% ± 0.215, 71.29% ± 0.529, and 43.13% ± 0.508, respectively, and were significantly lower (P < 0.05) than the control (78.95% ± 1.000, P < 0.05).These experiments revealed that extreme temperatures can influence the growth and development of N. lugens and may affect its distribution. As such, N. lugens remains a serious pest of rice.

Both ecosystem function and agricultural productivity depend on services provided by bees; these services are at risk from bee declines which have been linked to land use change, pesticide exposure, and pathogens. Although these stressors often co-occur in agroecosystems, a majority of pollinator health studies have focused on these factors in isolation, therefore limiting our ability to make informed policy and management decisions. Here, we investigate the combined impact of altered landscape composition and fungicide exposure on the prevalence of chalkbrood disease, caused by fungi in the genus Ascosphaera Olive and Spiltoir 1955 (Ascosphaeraceae: Onygenales), in the introduced solitary bee, Osmia cornifrons (Radoszkowski 1887) (Megachilidae: Hymenoptera). We used both field studies and laboratory assays to evaluate the potential for interactions between altered landscape composition, fungicide exposure, and Ascosphaera on O. cornifrons mortality. Chalkbrood incidence in larval O. cornifrons decreased with high open natural habitat cover, whereas Ascosphaera prevalence in adults decreased with high urban habitat cover. Conversely, high fungicide concentration and high forest cover increased chalkbrood incidence in larval O. cornifrons and decreased Ascosphaera incidence in adults. Our laboratory assay revealed an additive effect of fungicides and fungal pathogen exposure on the mortality of a common solitary bee. Additionally, we utilized phylogenetic methods and identified four species of Ascosphaera with O. cornifrons, both confirming previous reports and shedding light on new associates. Our findings highlight the impact of fungicides on bee health and underscore the importance of studying interactions among factors associated with bee decline.

Scirtothrips dorsalis Hood infest strawberry (Fragaria x ananassa Duchesne, Rosaceae) fields from nearby crop fields and surrounding vegetation and cause injury to plants by feeding on young leaf tissues. Greenhouse and field studies were conducted to determine the short-range movement of S. dorsalis to assess the risk of an early S. dorsalis population to spread to adjacent plants. In a greenhouse, 25 potted strawberry plants were arranged in two concentric rows around a central plant, where plants in inner rows were 20 cm, and those in the outer rows were 40 cm from the central plant. In the field, 20 strawberry plants were arranged in two beds (90 cm apart), ten in each bed, and five plants in each row, with plants 30 cm apart. White sticky cards were placed at 60–120 cm from the central plant. Fifty S. dorsalis adults were released on a centrally located plant, and the numbers of S. dorsalis adults and larvae and feeding injury were recorded for 9–17 d on adjacent plants and sticky cards. Results showed that significantly more S. dorsalis adults and larvae remained on the initially infested plant compared to adjacent plants, although few adults were found up to 120 cm on sticky cards.The rate of spread of feeding injury was low with slight bronzing injury (<10% injury) on adjacent plants by 14–17 d. Since most S. dorsalis remained on initially infested plants for at least 2 wk, it is feasible to delay management actions and ‘rescue’ plants around a plant with minor injury symptoms.

The mushroom phorid fly, Megaselia halterata (Wood), is a common pest of mushroom production in many parts of the world. Due to the reduced availability of conventional insecticides for mushroom production, M. halterata has recently developed into a major pest in the top mushroom-producing county in the United States (Chester County, PA). Mushrooms are grown entirely indoors, and though larval development of M. halterata occurs in the mushroom-growing substrate, adult flies have been captured both inside and outside of the facilities. Here, we investigated three factors that might contribute to their growth and development. 1) The effects of ambient temperature (15–30°C) and relative humidity (RH; 21–98%) on adult M. halterata lifespan, 2) the effect of spawned compost stage (freshly inoculated with spawn vs 14-d spawned compost) on reproductive output, and 3) the effect of population density on reproductive output.The longevity of adult M. halterata increased under cooler temperatures and more humid conditions (>75% RH), which reflect the conditions inside mushroom-growing facilities. Similar numbers of flies emerged from freshly inoculated and 14-d spawned compost, but flies emerged earlier from 14-d spawned compost. The higher the parental fly density, the more offspring emerged from spawned compost, but the positive relationship reached a plateau beyond 40 parental mating pairs per 100 g of compost. Our findings highlight relevant abiotic and biotic factors that may contribute to M. halterata population dynamics.

The red sunflower seed weevil, Smicronyx fulvus L., is a univoltine seed-feeding pest of cultivated sunflower, Helianthus annuus L. Artificial infestations of S. fulvus onto sunflowers with traditional (<25% oleic acid), mid-oleic (55–75%), or high oleic (>80%) fatty acid profiles were used to test if fatty acids could be used as natural markers to estimate the proportion of weevils developing on oilseed sunflowers rather than wild Helianthus spp. and confection (non-oil) types. Oleic acid (%) in S. fulvus confirmed the fatty acid compositions of mature larvae and weevil adults reflected their diets, making primary (oleic or linoleic) fatty acids feasible as natural markers for this crop-insect combination. Oleic acid in wild S. fulvus populations in North Dakota suggests at least 84 and 90% of adults originated from mid-oleic or high oleic sunflower hybrids in 2017 and 2018, respectively. Surveys in 2017 (n = 156 fields) and 2019 (n = 120 fields) extended information provided by S. fulvus fatty acid data; no significant spatial patterns of S. fulvus damage were detected in samples, damage to oilseed sunflowers was greater than confection (non-oil) types, and the majority of damage occurred in ≈10% of surveyed fields. Combined, data suggest a few unmanaged or mismanaged oilseed sunflower fields are responsible for producing most S. fulvus in an area. Improved management seems possible with a combination of grower education and expanded use of non-insecticidal tactics, including cultural practices and S. fulvus-resistant hybrids.

Seven entomopathogenic fungi strains (M1–7) were isolated from field-obtained dead coconut hispine beetles Brontispa longissima (Gestro), identified to species, and bioassayed for their pathogenicity. According to ITS sequences, all isolates belong in the genus Metarhizium, mainly M. flavoviride and M. anisopliae. Measured median lethal times (LT₅₀) of 1×10⁷ conidia/ml of M1–7 against fourth-instar B. longissima larvae within 15 d following exposure were, respectively: 5.43, 10.64, 11.26, 10.93, 6.62, 4.73, and 5.95 d. The isolate M6 yielded the highest mortality to fourth-instar larvae, and was thus selected to be tested against other larval instars and adults of B. longissima, after Time–Dose–Mortality (TDM) models. M6 proved more pathogenic against larvae than adults. The obtained bioassays data produced a good fit to theTDM models, yielding estimated LC₅₀ and LT₅₀ for each of the tested developmental stages of B. longissima. Both the obtained dose (β) and time effect (ri) parameters from TDM models suggest that first-instar larvae are the most susceptible life stage of the pest insect, while adults are more resistant to M6 infection. Calculated LC₅₀ values were, respectively, 1.23×10³ and 1.15×10⁶ conidia/ml for first-instar larvae and adults, on the 15th day following M6 inoculation. Estimated LT₅₀ were 3.3 and 5.9 d for first-instar larvae and adults, respectively, at 1×10⁸ conidia/ml. Taken together, these results would suggest Metarhizium M6 as an option for the biological control of B. longissima in the field.

As the mean temperature and the duration of the growing season decline with elevation, growth of immature insects should initiate at a lower temperature, but it should also be faster to complete development prior to season's end. Although flightless, Mormon crickets migrate in large aggregations across broad spatial and elevational distances that might limit adaptations to local environments. In addition, selection to be active at cooler temperatures might limit selection to maximize growth rate. I measured growth rate in controlled environments for nymphs from three populations that vary in altitude (87–2,688 m) but are similar in latitude (43.2–45.7°N). Growth rate increased significantly with mean rearing temperature between 22 and 30°C. The intercept of the regression of growth rate on temperature increased with elevation, whereas the slope did not change significantly. For any given rearing temperature, growth rate increased with elevation, which suggests that selection to initiate growth at cooler temperatures did not compromise growth rate. Body mass did not differ between the two lower elevations, whereas the highest elevation population had smaller hatchlings and adults. Critical thermal minimum (base temperature) declined with elevation (0.7°C per 1,000 m), and the degree days were 509 across all elevations. For pest management, a base temperature from midelevation of 15.3°C (60°F) and growing degree days of 509 (equivalent to 916 Fahrenheit-based degree days) are reasonable estimates for applications from sea level to 2,700 m.

Graphical Abstract

Closely related phytophagous insects that specialize on different host plants may have divergent responses to environmental factors. Rhagoletis pomonella (Walsh) and Rhagoletis zephyria Snow (Diptera: Tephritidae) are sibling, sympatric fly species found in western North America that attack and mate on plants of Rosaceae (∼60 taxa) and Caprifoliaceae (three taxa), respectively, likely contributing to partial reproductive isolation. Rhagoletis zephyria evolved from R. pomonella and is native to western North America, whereas R. pomonella was introduced there. Given that key features of the flies' ecology, breeding compatibility, and evolution differ, we predicted that adult eclosion patterns of the two flies from Washington State, USA are also distinct. When puparia were chilled, eclosion of apple- and black hawthorn-origin R. pomonella was significantly more dispersed, with less pronounced peaks, than of snowberry-origin R. zephyria within sympatric and nonsympatric site comparisons. Percentages of chilled puparia that produced adults were ≥67% for both species. However, when puparia were not chilled, from 13.5 to 21.9% of apple-origin R. pomonella versus only 1.2% to 1.9% of R. zephyria eclosed.The distinct differences in eclosion traits of R. pomonella and R. zephyria could be due to greater genetic variation in R. pomonella, associated with its use of a wider range of host plants than R. zephyria.

Lycorma delicatula (White), an invasive planthopper originally from Asia, is an emerging pest in North America. It is important to understand its phenology in order to determine its potential range in the United States. Lycorma delicatula nymphs were reared on Ailanthus altissima (Miller) (Sapindales: Simaroubaceae) at each of the following constant temperatures: 5, 10, 15, 20, 25, 30, 35, and 40°C. The time spent in each instar and survival was recorded. Developmental rate increased with temperature from 15 to 30°C for all instars, then declined again at higher temperatures. Nymphal survival was lower at 35°C than between 15 and 30°C for all instars, and first instars placed at 5, 10, and 40°C all died without molting. This suggests that L. delicatula survival and development may be affected in the Southern United States by high temperatures and developmental delays will occur under cool spring conditions. The lower developmental threshold was found to be 13.00 ± 0.42°C for first instars, 12.43 ± 2.09°C for second instars, 8.48 ± 2.99°C for third instars, and 6.29 ± 2.12°C for fourth instars. The degree-day (DD) requirement for nymphs in the previous instar to complete development to reach the second instar, third instar, fourth instar, and adult was 166.61, 208.75, 410.49, and 620.07 DD (base varied), respectively. These results provide key data to support the development of phenology models and help identify the potential range of L. delicatula in North America.

Carpenter ants (genus Camponotus) are considered to be predominantly omnivorous, mixing several feeding habits that include predation, scavenging of animal matter, and plant-derived resources. Nitrogen acquisition is crucial for the nutritional ecology of ant colonies because growing larvae require sustainable protein provisioning. Here, we investigate the foraging ecology and the spatial nesting structure of the carpenter ant, Camponotus leydigi Forel, in Brazilian cerrado savanna. By marking workers from different nests with distinct colors, we revealed that C. leydigi occupies physically separated but socially connected nests (up to 30 m apart), a phenomenon known as polydomy. Observational data on aboveground internest movements in C. leydigi corroborate cooperative exchanges between nest units and confirm several types of social connections, including internest transfer of liquid and solid food, transport of colony members (brood, workers), movement of solitary workers, and internest recruitment. Polydomous C. leydigi allocate foragers throughout 1,700 m², feeding mostly on termites and plant-derived exudates. Influx of exudates is threefold higher compared with solid food. Uric acid pellets excreted by lizards comprise 20% of the solid diet in C. leydigi, a rare quantitative assessment of this peculiar type of nitrogen complementation in ants. Based on video recordings, we hypothesize that nest decentralization in C. leydigi may reduce foraging constraints caused by overt interference by the aggressive ant, Ectatomma brunneum Smith, F. (Hymenoptera: Formicidae), which regularly blocks nest entrances. Our field study enhances the importance of natural history data to clarify selective pressures underlying the evolution of particular behavioral patterns (nutritional and nesting habits) in ants.

The effects of rearing temperature and host stage parasitized on the development of three parasitoid species; Encarsia noyesi Hayat (Hymenoptera: Aphelinidae), Idioporus affinis LaSalle & Polaszek (Hymenoptera: Pteromalidae), and Entedononecremnus krauteri Zolnerowich & Rose (Hymenoptera: Eulophidae) were investigated. These parasitoids are part of the biological control program for the giant whitefly Aleurodicus dugesii Cockerell (Hemiptera: Aleyrodidae) in the United States. Temperature and host-dependent development was assessed for each species using the nonlinear Brière-1 model and simple linear regression to obtain critical thermal parameters. All three parasitoids successfully developed at constant temperatures ranging from 15°C to 30°C, which was narrower to their predicted thermal limits due to thermal constraints of A. dugesii. There were significant effects of both temperature and A. dugesii nymphal stage parasitized on immature parasitoid development times. All three parasitoid species' development time decreased as nymphal stage age increased. Thermal tolerance limits and development times varied by parasitoid species. The results of these findings in the context of biological control potential are discussed.

Determining the host range of an invasive insect in a new environment is a key step in the development of management strategies. As the brown marmorated stink bug, Halyomorpha halys Stål, expands into agricultural regions of North America, efforts to elucidate its dietary habits on a landscape scale rely on intensive sampling of potential host plants. Although this approach yields useful information, results can be biased toward common and easily sampled plant species; important hosts can be missed if sampling them is impractical or limited in scope. Here we lay the groundwork for the application of gut content analysis to the feeding ecology of H. halys by investigating the persistence of host plant DNA in the digestive tracts of insects with known feeding histories. Adult H. halys were fed bean seedlings (Phaseolus lunatus L.) for 7 d, followed by a forced host switch to carrot (Daucus carota L.). Insect guts were dissected out at 0, 1, 3, 7, and 14 d following the switch, and host plant chloroplast genes (trnF and trnL) were amplified via polymerase chain reaction. Amplicons were identified using high-throughput sequencing and analyzed for Phaseolus DNA. The original host remained detectable at 3 d (trnF) and 14 d (trnL) in substantial quantities.The proportion of total reads identified as Phaseolus rapidly decreased with time; a concomitant increase in Daucus reads was observed. Our results indicate that high-throughput sequencing of gut contents has great potential for exploring the dietary histories of field-caught H. halys and other phytophagous insects.

Pollinator declines have been documented globally, but little information is available about native bee ecology in Midwestern U.S. agriculture. This project seeks to optimize pollinator support and weed suppression in a 3-yr crop rotation with a fallow growing season. During fallow, one of five cover crop treatments (T1: crimson, red, and ladino clover and Bob oats [Fabales: Fabaceae - Trifolium incarnatum L., Trifolium pratense L., Trifolium repens L., and Cyperales: Poaceae - Avena sativa]; T2: crimson clover and oats; T3: red clover and oats; T4: ladino clover and oats; T5: no cover crop;T6/control: winter wheat [Cyperales: Poaceae - Triticum aestivum] L.) was seeded in one-half of 25 agricultural fields, whereas wheat was left unharvested in the other half as a comparison. Treatments that provide season-long floral resources support the greatest bee diversity and abundance (T1), and treatments with red clover support declining (Hymenoptera: Apidae) Bombus species (T1 and T3). Late-season floral resources may be important, yet limited (T1 and T4), and some species of agricultural weeds provide floral resources. Floral diversity may be less important than flower abundance or timing for pollinator diversity (T1–T4). Weed diversity was greatest in the no cover crop treatment (T5), least in winter wheat (T6), and intermediate in cover crop treatments (T1–T4) with no differences in weeds of economic concern. Wheat suppresses weeds but does not provide floral resources for pollinators. These results may also be applicable to marginal lands taken out of cultivation or field margin pollinator plantings in a typical corn–soybean rotation. Floral resource availability across the landscape is critical to maintain pollinator diversity.

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is historically a pest of both corn (Zea mays L. (Poales: Poaceae)) and dry beans (Phaseolus sp. L. (Fabales: Fabaceae)) in the western Great Plains. However, it has recently undergone an eastward range expansion establishing itself across the Corn Belt in 25 states and 4 Canadian provinces.To mitigate the effects of infestation in Michigan, foliar insecticides are used in dry beans, whereas management of the pest in corn relies more heavily on the use of Bt-expressing hybrids. In this study stable carbon isotope analysis was used to determine what crop adult moths developed on as larvae with analysis showing that very few of the adult moths developed on dry beans.These results suggest that beans and corn are not suitable as co-refuges and that mainly adults which developed on corn are contributing to the next generation of western bean cutworm in Michigan.

Successful conservation and management of protected wildlife populations require reliable population abundance data. Traditional capture-mark-recapture methods can be costly, time-consuming, and invasive. Photographic mark-recapture (PMR) is a cost-effective, minimally invasive way to study population dynamics in species with distinct markings or color patterns. We tested the feasibility and the application of PMR using the software Hotspotter to identify Nicrophorus spp. from digital images of naturally occurring spot patterns on their elytra. We conducted a laboratory study evaluating the identification success of Hotspotter on Nicrophorus americanus (Olivier, 1790) and Nicrophorus orbicollis (Say, 1825) before implementation of a mark-recapture study in situ. We compared the performance of Hotspotter using both ‘high-quality' and ‘low-quality’ photographs. For high-quality photographs, Hotspotter had a false rejection rate of 2.7–3.0% for laboratory-reared individuals and 3.9% for wild-caught individuals. For low-quality photographs, the false rejection rate was much higher, 48.8–53.3% for laboratory-reared individuals and 28.3% for wild-caught individuals. We subsequently analyzed encounter histories of wild-caught individuals with closed population models in Program MARK to estimate population abundance. In our study, we demonstrated the utility of using PMR in estimating population abundance for Nicrophorus spp. based on elytral spot patterns.

The globe skimmer dragonfly, Pantala flavescens Fabricius (Odonata: Libellulidae), is a long-distance migrant, well adapted to exploiting ephemeral waterbodies. This species occurs in Japan every summer, but overwintering has only been recorded on subtropical Ishigaki Island. It is not known from where the summer immigrants originate, nor what proportion of the globe skimmers seen in Japan are of local origin. We analyzed stable hydrogen isotope (δ²H) composition of wings of 189 P. flavescens captured at six sites in Japan from August to September in 2016 (n = 57) and from April to November in 2017 (n = 132). We determined that the majority of individuals were immigrants. Individuals of probable Japanese origin occurred only later in the year and were of lower mass on average than immigrants. Immigrants potentially originated from a broad area as far west as northern India and the Tibetan Plateau and, especially late in the season, as near as northcentral China and the Korean peninsula. However, for April samples, the most parsimonious interpretation suggested southern origins, in northern Myanmar to southern China, or possibly Borneo-Sulawesi. Our investigation underlines the power of combining stable isotope data with other information such as wind speed and direction, arrival dates, and body mass to estimate origins and to understand the life history of this and other insects.

In arable agroecosystems, arthropod communities often have a reduced abundance and diversity, which represents a challenge for sampling techniques needed to detect small differences among these simplified communities. We evaluated the suitability of pitfall traps for comparing the effects of cropping systems on arthropod communities. In a field experiment, we compared the effects of two pitfall trap diameters, the type of preserving fluid and the sampling effort on three metrics (activity density, taxonomic richness, and community weighted mean [CWM] of body size) for carabids and spiders. Trap size affected the observed composition of communities, with large traps yielding a higher proportion of spiders, and a higher richness and CWM body size for both taxa. The type of preserving fluid had a weaker effect. Simulations with various sampling efforts showed that only very different communities could be distinguished with less than 10 traps per field or less than 30 field replicates. Fewer traps were required to find differences between cropping systems for body size than for other metrics. Carabid activity density and body size, and spider genus richness, were the variables better distinguishing between cropping systems with the smallest sampling effort. A high sampling effort was required for comparing activity density and richness across cropping systems. Selection of the most appropriate trap design, metrics, and crops are the main factors for optimizing the trade-off between sampling effort and the ability to detect arthropod community responses to habitat management.

To support efforts to manage and contain spotted lanternfly (SLF), Lycorma delicatula White (Hemiptera: Fulgoridae), research is being conducted to develop classical biological control methods.To date, two potential biocontrol agents from China have been identified: an egg parasitoid, Anastatus orientalis, and a nymphal parasitoid, Dryinus sinicus Olmi (Hymenoptera: Dryinidae). The research detailed here focuses on investigating the biology and rearing of A. orientalis to assess its potential efficacy in a biocontrol program and optimize its rearing. Female wasps lived significantly longer than male wasps (68 and 23 d, respectively) and females produced an average of 94 total progeny that successfully emerged as adults, with most progeny produced between weeks one and four of the females' lives. The sex ratio of the progeny, with no re-mating, was initially highly female-biased but became progressively more male-biased, likely due to sperm depletion. There was no evidence of additional mortality to SLF eggs from wasp host feeding, but the data were highly variable and the sample size was small. There was high parasitoid emergence when oviposition conditions mimicked mid-September Beijing temperature and photoperiod; however, there was little emergence under 25°C and long-day conditions because most progeny entered a diapause. Storage of parasitized eggs in 5°C chill lowered parasitoid emergence rates. Lastly, there was no evidence that storing field-collected SLF egg masses in 5°C for 10 mo prior to parasitization affected parasitism rates. These findings inform our rearing protocol for A. orientalis and facilitate our testing of this species as a potential biological control agent for SLF.

An invasive population of spotted lanternfly (SLF), Lycorma delicatula White, was first noted in North America in Pennsylvania in 2014, and by September 2020 populations had spread to six additional states. To develop a biocontrol program to aid in the management of the pest, exploratory surveys for SLF natural enemies in its native range were carried out in 27 provinces and other administrative regions of China from 2015 to 2019. Naturally laid egg masses were collected and sentinel SLF egg masses were deployed to attract egg parasitoids, and yellow sticky traps were used to collect SLF nymphs to discover and determine the parasitism rates of nymphal parasitoids. Results show that SLF is widely distributed in China (22 provinces and regions) and that the population densities in northeast China are higher than in southern and western China. An egg parasitoid, Anastatus orientalis Yang (Hymenoptera: Eupelmidae), and a nymphal parasitoid, Dryinus sinicus Olmi (Hymenoptera: Dryinidae), were collected. Anastatus orientalis was reared from SLF eggs in seven provinces in China with parasitoid emergence rates ranging from 4.0 to 15.5% (or 17.6 to 37.3% if including only egg masses that had at least some parasitism). There were significant differences in parasitoid emergence rates between sites associated with factors including habitat and host plants. Dryinus sinicus was discovered in eight cities across six provinces. The percentage of SLF nymphs parasitized by D. sinicus were 31.1, 23.3, and 0% in Tai'an, Shandong Province, Beijing City, and Yan'an, Shaanxi Province, respectively. These two parasitoids are promising natural enemies that are being considered as potential biocontrol agents of invasive populations of SLF.

Graphical Abstract

Because it keeps land in production, conservation programs that focus on in-field habitat manipulations may help farmers better support predators than by building predator habitat around fields.We investigated two in-field habitat manipulations that benefit producers and soil quality: fertilizing with dry-stack cow manure and planting a wheat cover crop. We hypothesized that, compared with inorganic fertilizer and fallow plots, both treatments augment habitat and residue and support more small arthropods that can serve as alternative prey for larger predators. As a result, we expected manure and the cover crop to increase ground-active predators. In turn, these predators could provide biological control of pests. Each year in a 3-yr field experiment, we applied manure and in 2 yr planted a wheat cover crop. We found that both planting a cover crop and applying dry-stack manure increased the plant cover in May. In the last year, this translated to greater soil mite (Acari) density. At the end of the experiment, however, neither manure nor the wheat cover crop had increased residue on the soil surface. As a result, our treatments had inconsistent effects on predator activity-density, especially for carabids and spiders. We observed strong edge effects from neighboring grass alleys on carabid activity-density. Regardless of treatment, we observed high predation of sentinel prey. We conclude that even without cover crops or organic fertilizer, the stability of no-till maize and increased weeds in fallow treatments generate sufficient habitat complexity and alternative prey to support robust predator communities.

Bagrada hilaris (Burmeister) is a serious pest on brassica crops in many regions throughout the world. As part of our efforts to enhance biological control, we have been studying an egg parasitoid that was collected from B. hilaris eggs found on brassica plant debris in Pakistan. This species has recently been described as Ooencyrtus mirusTriapitsyn & Power. A major component of rearing biological control agents is understanding the relationship among host egg age, parasitoid age, and reproductive success.To this end, we used a factorial design to evaluate all combinations of host egg ages 0–5 d and parasitoid ages 0–11 d. The results showed that the best combinations are 0- to 1-d-old host eggs with 3- to 10-d-old parasitoids. A further study using frozen host eggs showed that O. mirus can reproduce as successfully on frozen B. hilaris eggs as on fresh ones.

Graphical Abstract

The convergent lady beetle, Hippodamia convergens Guerin-Meneville, is a specialized predator of cereal aphids on the High Plains, completing its first generation each year in winter wheat, the resulting adults dispersing into summer crops and producing additional generations, contingent on the availability of aphids. In the present study, we tested the collective value of supplementary plant resources (sugars, pollen, and seedling wheat leaves), and small amounts of alternative prey, eggs of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae), all provided together, for improving beetle life history and reproductive success even when suitable prey, Schizaphis graminum (Rondani) (Hemiptera: Aphididae), were provided ad libitum. Although a monotypic diet of S. graminum yielded slightly faster larval development and heavier adults than the omnivorous diet, preoviposition periods were extended and 21-d fecundities greatly reduced when this diet was continued through adult life, largely due to fewer oviposition days, although egg fertility was unaffected. The results highlight the critical importance of plant-derived resources even when suitable prey are not limiting. However, monotypic diet beetles that diapaused for 21 d in the presence of supplementary plant resources, plus moth eggs, achieved the same reproductive success as those reared on the omnivorous diet, with or without diapause, demonstrating that access to these resources post-emergence was sufficient to compensate for their absence during development. The diapause treatment itself had no impact on the fitness of beetles reared on the omnivorous diet, likely because neither its duration, nor the caloric restriction imposed, were sufficient to diminish reproductive effort.

Trypodendron retusum (LeConte) (Coleoptera: Curculionidae: Scolytinae) females excised from newly attacked trembling aspen, Populus tremuloides Michaux (Salicaceae), were shown for the first time to produce the aggregation pheromone (+)-lineatin. Coupled gas chromatographic-electroantennographic detection analysis (GC-EAD) disclosed that the antennae of T. retusum, as well as the antennae of three sympatric species, native T. lineatum (Olivier) and T. rufitarsus (Kirby) and exotic T. domesticum (L.), respond to synthetic (+)-lineatin, but not the (–) enantiomer. In contrast, the antennae of T. betulae Swaine responded to SR- and RR-linalool oxide pyranoid and did not detect lineatin. GC-EAD analysis of volatiles from host and nonhost tree species revealed that conifer-produced α-pinene and angiosperm-produced conophthorin and salicylaldehyde were perceived by the antennae of all three native lineatin-perceiving species, suggesting behavioral activity. Field trapping experiments showed that salicylaldehyde synergized the response of coastal, but not interior, T. retusum to lineatin and inhibited the response of T. lineatum and T. rufitarsus. In the absence of salicylaldehyde, α-pinene appeared to inhibit the response of interior T. retusum to lineatin, while for T. lineatum and T. rufitarsus it had an apparent positive additive or synergistic effect. No behavioral response occurred to conophthorin. The results provide evidence for semiochemical-based reproductive isolation between T. retusum and T. betulae, and between these two angiosperm-infesting species and the two conifer-infesting species. They do not explain how isolation could be maintained between T. lineatum and T. rufitarsus.

Ants represent a highly diverse and ecologically important group of insects found in almost all terrestrial ecosystems. A subset of ant species have been widely transported around the globe and invade many natural ecosystems, often out-competing native counterparts and causing varying impacts on recipient ecosystems. Decisions to control nonnative ant populations require an understanding of their interactions and related impacts on native communities. We employed stable isotope analysis and metabarcoding techniques to identify potential dietary niche overlap and identify gut contents of 10 ant species found in natural ecosystems in Aotearoa New Zealand. Additionally, we looked at co-occurrence to identify potential competitive interactions among native and non-native ant species. Ants fed mainly across two trophic levels, with high dietary overlap. Relative to other ant species sampled, two nonnative ant species, Linepithema humile and Technomyrmex jocosus, were found to feed at the lowest trophic level. The largest isotopic niche overlap was observed between the native Monomorium antarcticum and the invasive Ochetellus glaber, with analyses revealing a negative co-occurrence pattern. Sequence data of ant gut content identified 51 molecular operational taxonomic units, representing 22 orders and 34 families, and primarily consisting of arthropod DNA. Although we generally found high dietary overlap among species, negative occurrence between a dominant, non-native species and a ubiquitous native species indicates that species-specific interactions could be negatively impacting native ecosystems. Our research progresses and informs the currently limited knowledge around establishing protocols for metabarcoding to investigate ant diet and interactions between native and nonnative ant species.

The decline and disappearance of seminatural grasslands in Japan have caused a reduction in plant and animal species inhabiting such grasslands. We aimed to understand the assemblage structure, species diversity, and distribution of carabid beetles in traditionally managed seminatural grasslands, by comparing with the adjacent old beech forest. We investigated the carabid beetle assemblages in a seminatural grassland maintained by prescribed burning and annual mowing, and the adjacent old beech forest inYamagata Prefecture, northeast Japan.We recorded several forest species along with open habitat species and habitat generalists in the grassland, suggesting that forest species may utilize the adjacent grasslands as temporary habitats. Cluster analysis showed that the assemblage structure of carabid beetles in the grassland differed from that in the beech forest.There were no clear differences in the carabid assemblages between the burned grassland sites and the grassland sites mowed in July after burning. This suggests that the annual mowing had little influence on the response of grassland carabid species in parts of the grassland.We recorded Harpalus roninus (Coleoptera: Carabidae), a rare carabid species in Japan, indicating that this beetle can be a characteristic of the studied grassland. Redundancy analysis showed that the eight abundant grassland species were associated with canopy openness, grass height, and understory vegetation cover, whereas the five most common species recorded from the beech forest were associated with litter depth and soil moisture.