We evaluated the effects of snow cover and debris cover on overwintering success of Aphthona from 2001 to 2004 in southeast North Dakota. Chill degree-days, soil temperature, and duration of soil temperatures were monitored in field plots. Emergence of Aphthona from soil cores collected in October and held in the laboratory under simulated winter conditions did not differ across treatments. Field emergence of Aphthona was significantly reduced compared with emergence of Aphthona in the laboratory under simulated winter. Snow cover protected overwintering of Aphthona during 3 yr. Overwintering success was 77–94% lower in no-snow plots than in snow plots except in 2002. In 2001, when the soil temperature was as low as -4.4°C, 90% of the Aphthona beetles emerged from snow-covered plots. The ranges of winter temperature and winter period for overwintering Aphthona were determined as -5.0–4.5°C and 56–132 d, respectively, by using linear regression. A negative linear relationship between soil temperature and winter period may help predict the minimum needed overwintering period at a given winter temperature. Warmer temperatures during the winter of 2002 caused snow to melt in the snow plots, which led to excessive moisture that seemed to reduce overwintering success of Aphthona in those plots. Overall emergence was too low to conduct statistical procedures in 2003 and 2004 because of temperature extremes and warm periods during the winters that may have caused Aphthona to break diapause prematurely.

Fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), infestations in most of North America arise from annual migrations of populations that overwinter in southern Texas and Florida. Cytochrome oxidase I haplotype profiles within the fall armyworm corn strain, the subgroup that preferentially infests corn (Zea mays L.), can differentiate the Texas and Florida populations. We use this molecular metric to show that fall armyworms in central Pennsylvania originate from Texas, indicating the existence of a migratory pathway from Texas to the northeastern United States. These results were compared with historical trapping data for fall armyworm and another migratory noctuid, corn earworm Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), in the Pennsylvania and Maryland corn-producing areas to better define lepidopteran migratory pathways.

Populations of the gypsy moth, Lymantria dispar (L.), are extensively monitored in the United States through the use of pheromone-baited traps. We report on use of automated pheromone-baited traps that use a recording sensor and data logger to record the unique date-time stamp of males as they enter the trap. We deployed a total of 352 automated traps under field conditions across several U.S. states over a 5-yr period. In many cases, there was general congruence between male moth capture and the number of recorded events. Although it was difficult to decipher an individual recording event because of the tendency for over-recording, the overall distribution of recorded events was useful in assessing male gypsy moth flight behavior and phenology. The time stamp for recorded events corroborated a previous report of crepuscular gypsy moth male flight behavior, because, although most moths were trapped between 12 and 16 h, there was a consistent period of flight activity between 20 and 22 h. The median male flight duration was 24 d (228 DD, base threshold = 10°C), but there were several traps that recorded flight periods >42 d that could not be explained by overcounting given the congruence between moth capture and the number of recorded events. Unusually long flight periods could indicate the introduction of male moths or other life stages that developed under different climatic conditions.

We determined the phenology of the multicolored Asian lady beetle, Harmonia axyridis (Pallas), adults in relation to the phenology of wine grapes (Frontenac and Marechal Foch) in Minnesota and Wisconsin vineyards to establish a management window for H. axyridis infestations in wine grapes. In addition, we also assessed the flight activity of H. axyridis in an agricultural landscape. The phenology of berry development and ripening was determined by recording berry size and sugar content of randomly selected berries. The phenology of H. axyridis was determined by tracking its flight activity with yellow sticky cards in vineyards and with a blacklight trap in an agricultural landscape. Berry development and ripening showed three distinct growth periods or phases. The end of growth period I averaged 9 July (Frontenac) and 11 July (Marechal Foch). Veraison, which marks the end of growth period II, averaged 25 July (Frontenac) and 3 August (Marechal Foch). Harvest, the third growth period averaged 18 September for Frontenac and 17 September for Marechal Foch. A major peak of H. axyridis captures occurred between veraison and harvest (i.e., the grape susceptible stage). A similar peak in the summer was observed in the agricultural landscape ≈10d before the major peak in the vineyards.

A temperature-driven process model was developed to describe the seasonal patterns of populations of onion thrips, Thrips tabaci Lindeman, in onions. The model used daily cohorts (individuals of the same developmental stage and daily age) as the population unit. Stage transitions were modeled as a logistic function of accumulated degree-days to account for variability in development rate among individuals. Daily survival was modeled as a logistic function of daily mean temperature. Parameters for development, survival, and fecundity were estimated from published data. A single invasion event was used to initiate the population process, starting at 1–100 d after onion emergence (DAE) for 10–100 d at the daily rate of 0.001–0.9 adults/plant/d. The model was validated against five observed seasonal patterns of onion thrips populations from two unsprayed sites in the Riverina, New South Wales, Australia, during 2003–2006. Performance of the model was measured by a fit index based on the proportion of variations in observed data explained by the model (R2) and the differences in total thrips-days between observed and predicted populations. Satisfactory matching between simulated and observed seasonal patterns was obtained within the ranges of invasion parameters tested. Model best-fit was obtained at invasion starting dates of 6–98 DAE with a daily invasion rate of 0.002–0.2 adults/plant/d and an invasion duration of 30–100 d. Under the best-fit invasion scenarios, the model closely reproduced the observed seasonal patterns, explaining 73–95% of variability in adult and larval densities during population increase periods. The results showed that small invasions of adult thrips followed by a gradual population build-up of thrips within onion crops were sufficient to bring about the observed seasonal patterns of onion thrips populations in onion. Implications of the model on timing of chemical controls are discussed.

Environmental disturbance may have direct and indirect impacts on organisms. We studied the colonization of ephemeral water bodies by mosquitoes (Diptera: Culicidae) in the Wheatbelt region of southwest Western Australia, an area substantially affected by an expanding anthropogenic salinization. Mosquitoes frequently colonized ephemeral water bodies, responded positively to rainfall, and populated smaller water bodies more densely than larger water bodies. We found that the habitat characteristics of ephemeral water bodies changed in association with salinity. Consequently relationships between salinity and abundance of colonizing mosquitoes were direct (salinity—mosquito) and indirect (salinity—water body characteristics—mosquito). Overall, the structure of mosquito assemblages changed with increasing salinity, favoring an increased regional distribution and abundance of Aedes camptorhynchus Thomson (Diptera: Culicidae), a vector of Ross river virus (RRV; Togoviridae: Alphavirus). We conclude secondary salinization in the Western Australia Wheatbelt results in enhanced vectorial potential for RRV transmission.

Native grasslands are among the most imperiled of the North American ecosystems, but abandoned agricultural areas may provide suitable habitat for animal taxa that are endemic to grasslands. We studied how species diversity of orb-weaving spiders was influenced by secondary succession of a grassland plant community by monitoring the abundance and species diversity in study plots that were cultivated at 6-yr intervals and left uncultivated in the interim. We tested the hypothesis that local abundance and species diversity of spiders would be positively associated with time since cultivation because plant communities in older habitats would be more architecturally complex. Local abundance of spiders in general was not associated with time since cultivation, but abundance of Mangora gibberosa (Hentz) was positively associated with the abundance of perennial plants. Species richness and diversity of spiders also were positively associated with the abundance of perennial plants and reached a threshold a few years after cultivation. Species diversity of orb-weaving spiders seems to be strongly influenced by species composition of the plant community. Therefore, effective restoration of the structure and function of endemic communities of orb-weaving spiders may depend on preserving endemic grassland plant communities.

The pattern of horse fly (Diptera: Tabanidae) distribution and correlations among biodiversity, abundance, abiotic factors, and altitude were determined along a two-sided altitudinal transect. The sampling was carried out on five 3-d periods during tabanid seasonal activity. Linen canopy traps with 1-octen-3-ol as an attractant were used at 20 sampling sites along the transect. The results showed that the qualitative composition of tabanid species can be distinguished by altitude and, especially, between southeastern and northwestern mountain slopes. The peaks of horse fly species richness and abundance were indicated at middle elevations of both slopes, where horse fly distributional groups were overlapping and most rare and infrequent species were sampled. All expected species were sampled according to species accumulation curve. The canonical correlation analysis separated species and sampling sites into three clusters; two were positively correlated with the temperature and the wind but differed in sensitivity toward them, and the third cluster was correlated with the humidity. The horse fly distribution was nonhomogenous, and the distributional patterns were only partially determined by altitude and vegetation. The determining environmental variables were different for each slope: temperature and wind for the southern slope (Mediterranean climatic zone) and humidity for the northern slope (continental climatic zone).

Two hypotheses explain male-biased parasitism. Physiological costs of male sexually selected characteristics can reduce immunocompetence. Alternatively, ecological differences could generate male-biased parasitism. One method of comparing the importance of the two theories is to investigate patterns of phoresy, which are only likely to be generated by ecological rather than immunological differences between the sexes. Here we studied the pattern of phoresy of the mite, Thinoseius fucicola, on two species of seaweed fly hosts, Coelopa frigida and Coelopa pilipes. We found a highly male-biased pattern of phoresy of T. fucicola on both species. These are the first reported instances of sex-biased phoresy in a solely phoretic parasite. We also show the first two cases of size-biased phoresy. We suggest that ecological factors, particularly, male mate searching, generated male biased patterns of phoresy. We highlight the potential importance of studies of phoresy in determining the relative roles of the immunocompetence and ecological theories in generating male-biased parasitism. We suggest that more studies of patterns of phoresy are carried out to allow detailed comparisons with patterns of parasitism.

The social wasp nests were quantified in three different plant physiognomies (forested Caatinga, shrubby Caatinga, and agricultural systems) to analyze the effect of environmental seasonality and plant physiognomy on the richness, nest abundance, and species composition of social wasps in the region of tropical dry forest of Brazil. The forested Caatinga physiognomy had the greatest richness of species (S = 16), followed by shrubby Caatinga (S = 13) and by agricultural system (S = 12). The first axis of detrended correspondence analysis (DCA) explained 67.8% of the variability and shows a gradient of the fauna from agricultural system and shrubby Caatinga to forested Caatinga. In the first axis, wet season scores were much higher than those for the dry season in forested Caatinga. The second axis explained 18.7% of the variability and shows a separation of samples collected during the wet or the dry periods in shrubby Caatinga. This separation was less evident in the agricultural system. Variations in nest abundance were more intense in arbustive caatinga (45% decrease in number of active nests in the dry period), moderate in forested Caatinga (24% decrease in number of active nests in the dry period), and low in agricultural systems (8% decrease in the dry period).

Invasive ants often enter into facultative mutualisms that frequently lead to outbreaks of the hemipteran partner. Native ants may also enter into similar mutualisms but often these do not lead to outbreaks. However, field studies comparing the impact of an invasive and native ant on a honeydew-producing hemipteran are lacking. We monitored numerical changes of the black citrus aphid, Toxoptera aurantii, tended by adjacent colonies of the invasive Argentine ant, Linepithema humile, and the endemic odorous house ant, Tapinoma sessile, during 2005, 2006, and 2007. Ant-tended aphid numbers were higher than those of untended aphids, with L. humile—tended and T. sessile—tended T. aurantii populations being comparable in 2005 and 2007. However, in 2006, a severe storm, with heavy rainfall, reduced T. sessile and aphid populations in areas occupied by T. sessile, whereas L. humile and aphids tended by L. humile were not reduced. This suggested that T. sessile foraging activity and hemipteran-tending was negatively impacted by severe weather. A laboratory experiment simulating rainfall striking the surface of a leaf showed that T. sessile foraging activity declined sharply under severe simulated rainfall conditions, whereas foraging activity of L. humile did not. Maintaining populations of honeydew-producing Hemiptera across broad climatic conditions may be one mechanism by which L. humile gains a competitive advantage over native ants occupying overlapping niches.

Wolbachia species are intracellular symbionts that cause reproductive alterations in arthropods. Transinfection experiments have been performed in many arthropod species to elucidate the interaction between Wolbachia and a new host. To ease transinfection of this bacterium to new arthropod hosts, we introduced two techniques: nymphal injection instead of embryonic injection and the use of a cultured source of Wolbachia instead of direct transfer from donors to recipients. Wolbachia in the small brown planthopper Laodelphax striatellus was cultivated in a cell line and injected into the nymphal body cavity of the brown planthopper Nilaparvata lugens together with the cells. By using these techniques, two transinfected planthopper lines were obtained. In one line, Wolbachia disappeared after several generations; in the other line, Wolbachia was retained for >7 yr. Infection rates in this latter transinfected line were ≈80% in early generations after transinjection but decreased to <10% through 40–60 generations. Subsequent selection for Wolbachia-infected females in this line did not increase the infection rate as a temporary effect. Thus, this transinfected line of N. lugens showed cytoplasmic incompatibility, although the incompatibility level was lower than in L. striatellus, the original host. The method of transinfection presented herein is useful for transmitting intracellular symbionts between small arthropod hosts.

The functional response of two egg parasitoids, Gonatocerus tuberculifemur (Ogloblin) and G. ashmeadi Girault (Hymenoptera: Mymaridae), to varying densities of Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) eggs was studied in the laboratory. G. tuberculifemur showed a type II functional response where parasitism increased at a decreasing rate as host egg density increased from 5 to 40, reaching an asymptote of an upper limit of 9.3 host eggs within the 1-h exposure period. The instantaneous attack rate and handling time as estimated by the random predator equation were 2.28/h and 0.10 h, respectively. In contrast, G. ashmeadi showed a type I functional response where the number of hosts attacked followed a constant linear increase regardless of host density to an upper limit of 11.5 host eggs within the 1-h exposure period. Female G. ashmeadi parasitized on average 4.3 and 3.5 more eggs per hour when presented with 10 and 20 H. vitripennis eggs, respectively, compared with G. tuberculifemur. When 5 or 40 H. vitripennis eggs were offered, there was no significant difference in parasitism rates between parasitoid species. Percentage of female offspring was significantly higher (5%) for G. ashmeadi compared with G. tuberculifemur. Under the experimental conditions used in these evaluations, results suggest that G. tuberculifemur is an inferior parasitoid to G. ashmeadi.

Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae) is a non-native perennial woody plant that is one of the most invasive weeds in Florida, Hawaii, and more recently California and Texas. This plant was introduced into Florida from South America as a landscape ornamental in the late 19th century, eventually escaped cultivation, and now dominates entire ecosystems in south-central Florida. Recent DNA studies have confirmed two separate introductions of S. terebinthifolius in Florida, and there is evidence of hybridization. A thrips, Pseudophifothrips ichini s.l. (Hood) (Thysanoptera: Phlaeothripidae), is commonly found attacking shoots and flowers of S. terebinthifolius in Brazil. Immatures and occasionally adults form large aggregations on young terminal growth (stems and leaves) of the plant. Feeding damage by P. ichini s.l. frequently kills new shoots, which reduces vigor and restricts growth of S. terebinthifolius. Greenhouse and laboratory host range tests with 46 plant species in 18 families and 10 orders were conducted in Parana, Brazil, and Florida. Results of no-choice, paired-choice, and multiple-choice tests indicated that P. ichini s.l. is capable of reproducing only on S. terebinthifolius and possibly Schinus molle L., an ornamental introduced into California from Peru that has escaped cultivation and is considered invasive. Our results showed that P. ichini s.l. posed minimal risk to mature S. molle plants or the Florida native Metopium toxiferum L. Krug and Urb. In May 2007, the federal interagency Technical Advisory Group for Biological Control Agents of Weeds (TAG) concluded P. ichini s.l. was sufficiently host specific to recommend its release from quarantine.

Plant invasions represent ecological opportunities for herbivorous insects able to exploit novel host plants. The availability of new hosts and rapid adaptations may lead to host race formation and ultimately speciation. We studied potential host race formation in the water lily leaf beetle, Galerucella nymphaeae, in response to invasion by water chestnut, Trapa nutans, in eastern North America. This leaf beetle is well suited for such studies because previous work showed that different herbivore populations follow different “evolutionary pathways” and specialize locally in response to differences in habitat preferences and host plant availability. We compared host preference and performance of G. nymphaeae offspring originating from T. nutans and offspring of individuals originating from an ancestral host Nuphar lutea, yellow water lily, on T. natans and three native hosts (N. lutea, Nympheae odorata, and Brasenia schreberi). Regardless of origin (Trapa or Nuphar), adults strongly preferred their native host, N. lutea, over T. natans. Although laboratory survival rates (larva to pupa) were extremely high (80%) regardless of origin or host offered, survival rates in a common garden were greatly reduced, particularly for T. natans (24%) and to a lesser extent on N. lutea (54%), regardless of beetle origin. Larval drowning during more frequent leaf changes when developing on small Trapa leaves seems to be responsible for this difference. Preference of females for N. lutea is beneficial considering the much higher larval survival on the ancestral host. Abundant T. natans where the plant is invasive provides an alternative food source that beetles can use after egg/larval loads on their preferred host reach carrying capacity, but this utilization comes at a cost of high larval mortality.

The development, survivorship, and fecundity of the potato psyllid, Bactericera cockerelli (Sulc), fed on eggplant (Solanum melongena L., variety Special Hibush) and bell pepper (Capsicum annuum L., variety Capsitrano) were studied in the laboratory at 26.7 ± 2°C, 70 ± 5% RH, and at a photoperiod of 14:10 (L:D) h. Immature B. cockerelli developed faster (24.1 d) when fed on eggplant than on bell pepper (26.2 d). Survival rates of immature stages from egg to adult emergence were higher on eggplant (50.2%) than on bell pepper (34.6%). The longevity of B. cockerelli female adults fed on bell pepper was similar to that of females fed on eggplant (62.2 versus 55.0 d), but the male adults fed on eggplant lived shorter lives (39.4 d) than those fed on bell pepper (53.9 d). However, the preoviposition and oviposition periods, fecundity, and sex ratio of B. cockerelli fed on eggplant were not different from those fed on bell pepper. The r_m value and the finite rate of increase (λ) of B. cockerelli were higher on eggplant (0.1099 and 1.116, respectively) than on bell pepper (0.0884 and 1.0924, respectively). Mean generation time and doubling time of B. cockerelli were shorter on eggplant (40.4 and 6.3 d, respectively) than on bell pepper (46.1 and 7.8 d, respectively). In contrast, lifetime fecundity of B. cockerelli was greater on bell pepper (227.3 offspring) than on eggplant (186.5 offspring). Based on these life history parameters, we concluded that B. cockerelli performed better on eggplant than on bell pepper.

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), has killed millions of ash (Fraxinus sp.) trees in North America since its discovery in Michigan in 2002. Efficient methods to detect low-density A. planipennis populations remain a critical priority for regulatory and resource management agencies. We compared the density of adult A. planipennis captured on sticky bands and larval density among ash trees that were girdled for 1 or 2 yr, wounded, exposed to the stress-elicitor methyl jasmonate, baited with Manuka oil lures, or left untreated. Studies were conducted at four sites in 2006 and 2007, where A. planipennis densities on untreated trees ranged from very low to moderate. In 2006, 1-yr girdled trees captured significantly more adult A. planipennis and had higher larval densities than untreated control trees or trees treated with methyl jasmonate or Manuka oil. Open-grown trees captured significantly more A. planipennis beetles than partially or fully shaded trees. In 2007, A. planipennis population levels and captures of adult A. planipennis were substantially higher than in 2006. The density of adults captured on sticky bands did not differ significantly among canopy exposure classes or treatments in 2007. Larval density was significantly higher in untreated, wounded, and 1-yr girdled trees (girdled in 2007) than in 2-yr girdled trees (girdled in 2006), where most phloem was consumed by A. planipennis larvae the previous year. A total of 36 trees (32 in 2006, 4 in 2007) caught no beetles, but 16 of those trees (13 in 2006, 3 in 2007) had A. planipennis larvae. In 2006, there was a positive linear relationship between the density of adults captured on sticky bands and larval density in trees. Our results show that freshly girdled and open grown trees were most attractive to A. planipennis, especially at low-density sites. If girdled trees are used for A. planipennis detection or survey, debarking trees to locate larval galleries is crucial.

Mutualisms may cause coupled population expansion or decline if both partners respond to variation in the other's abundance. Many studies have shown how the abundance of animal mutualists affects plant reproduction, but less is known about how the abundance of plant mutualists affects animal reproduction. Over 2 yr, I compared reproduction of the bumble bee, Bombus appositus, across meadows that varied naturally in flower density, and I compared reproduction between fed colonies and unfed control colonies. Colony reproduction (gyne, worker, and male production) was constant across meadows that varied naturally in flower density. Forager densities per flower did not vary among meadows, and daily nectar depletion was consistently low across meadows, suggesting that bees had ample nectar in all meadows. However, colonies directly fed with supplemental nectar and pollen generally produced over twice as many gynes as control colonies. Feeding did not affect male or worker production. Although colonies may benefit from food supplementation at the nest, it is possible that they may not benefit from additional flowers because they have too few workers to collect extra resources.

Mate finding is a key lifecycle event for the pecan nut casebearer, Acrobasis nuxvorella Neunzig, as it is for virtually all Lepidoptera, many of which rely on long-range, species-specific sex pheromones, regulated largely by circadian clocks. Adult male moths were trapped at discrete time intervals during the first two seasonal flights for 6 yr to determine times of peak activity associated with male response to pheromones. From 1997 to 2002, the Harris-Coble automated clockwork timing trap was used for hourly time-segregated sampling. Analysis of variance with linear contrasts determined that circadian response of A. nuxvorella males to pecan nut casebearer pheromone began at ≈2100 hours, the first hour of total darkness, lasting for 6–7 h. It peaked from midnight to 0400 hours and ended at the onset of morning twilight, ≈0500 hours. The hours of peak activity are hours of minimal bat predation. The study shows that pecan nut casebearer males become responsive to pheromone several hours before females start calling and remain responsive for at least 1 h after they stop. The extended response period conforms to studies of other polygamous Lepidoptera in which a selective advantage is conferred on early responding males in scramble competition for available females.

Flight activities of two sympatric termite species, Macrotermes gilvus (Hagen) and Macrotermes carbonarius (Hagen), were studied in Penang Island, Malaysia. Herein, we present the first documentation of chronological reproductive isolation of M. gilvus and M. carbonarius. Flights of M. gilvus were recorded over a remarkably long 7-mo period from March to September, whereas swarming of M. carbonarius took place from November to January. Swarming events of M. gilvus and M. carbonarius occurred under atmospheric pressures of 1,005–1,011 and 1,006–1,010 hPa, respectively. Most flights of M. gilvus occurred on days with rain, whereas M. carbonarius avoided rain. Flight activity of M. gilvus was correlated significantly with atmospheric pressure and rainfall. The threshold temperature and relative humidity of M. gilvus flights were between 23 and 26°C and 83 and 98% RH, respectively; M. carbonarius swarmed between 25 and 30°C and 72 and 83% RH, respectively. The flight activity of M. gilvus concentrated in the warmer and humid months with a monthly total rainfall of 228 mm. Both species swarmed at distinct times of day during the limited field observations: Flights of M. gilvus began between 0300 and 0430 hours (light intensity <1 Lx), and flights of M. carbonarius lasted for only 4–10 min between 1900 and 1910 hours (at dusk; light intensity: 20–200 Lx). Windless conditions were preferred for the flights of both species.

Insect herbivores typically oviposit on the most suitable hosts, but choices can be modulated by detection of potential competition among conspecifics, especially when eggs are deposited cryptically. Larvae of the wheat stem sawfly, Cephus cinctus Norton, developing within an already infested stem, experience elevated risk when only one will survive because of cannibalism. To increase our understanding of host selection when the choices made by females can lead to severe intraspecific competition, females were presented with either uninfested wheat plants or with plants previously exposed to other females in laboratory choice tests. The oviposition behavior of this insect was described by recording the behavioral sequences that lead to and follow the insertion of the ovipositor in both previously infested and uninfested stems. No significant differences were found in frequencies of specific behaviors or behavioral transitions associated with oviposition. In choice tests, there was no difference in the numbers of eggs laid in infested and uninfested plants. Taller plants received more eggs, irrespective of infestation. Females neither preferred nor avoided previously infested hosts. Other characteristics of the host, such as stem height, may be more important in determining suitability for oviposition. These findings support the use of management tactics relying on the manipulation of oviposition behavior, such as trap cropping. Given that there is no evidence for response to previously infested hosts, the infested plants in a trap crop would remain as suitable as they were when uninfested, which could also lead to an increase in mortality caused by intraspecific competition.

A regression model was developed to predict the flight activity of Acrosternum hilare (Say) using data on the number of adults collected in a single black light trap located in Painter, VA, in the 18-yr period from 1990 to 2007. Eighteen initial weather variables, including cumulative precipitation over different time periods, mean monthly precipitation (PJA) and days below freezing (DFJA) from January to April, and mean monthly temperatures from December to April were tested in developing the regression model. Mixed (backward and forward) stepwise regression analysis showed that a two-variable model using PJA and DFJA was adequate for predicting the seasonal mean weekly number of A. hilare adults in the trap. Validation of the model using five independent black light trap data sets resulted in a strong correlation (r = 0.98) between observed and predicted mean weekly number of A. hilare adults caught in traps. Three peaks in flights of A. hilare adults were observed when mean trap catch was plotted over time for the 18-yr period. Peaks occurred at 319, 892, and 1,331 degree days (DD) from 1 January. Based on known developmental rates, the first peak was attributed to overwintered adults, the second to first-generation adults, and the third to a second generation of adults. This research suggests that A. hilare undergoes two complete generations in Virginia. Cumulative trap catch estimated from the 18-yr mean trap catch showed that 10, 50, and 90% of the total seasonal catch should occur by 153, 501, and 1,066 DD.

The sampling efficiency of pitfall traps and Winkler litter extraction in northern deciduous forests was compared using ants. Both techniques are among the most common methods used to measure the diversity of organisms active on the forest floor. During 2005–2006, 90 Winkler and 180 pitfall trap samples from urban forest fragments in northeastern Ohio obtained 9,203 ants representing 31 species. Winklers captured all 31 species, whereas pitfall traps collected a total of 24 species. Winkler samples accumulated species more rapidly than did pitfall traps and had greater total species richness and higher abundance of ants recorded. Consistent with other studies, Winkler sampling was found to catch a greater number of smaller ants, whereas pitfall trapping caught a greater number of large-bodied ants. According to estimates of expected species richness, the combination of the two sampling techniques allowed for the collection of ≈90% of the ants expected in the surveyed area. Site variation had little effect on the inherent differences in sampling efficacy between the two methods. Either technique adequately collected samples for broad comparisons and documentation of the more typical and representative ant fauna, but Winkler extraction exhibited the advantage of a more complete inventory. The application of both techniques should be considered if the aims of a study require estimation of community properties, such as relative abundance.

Timothy (Phleum pratense L.) is an important forage crop in many Western U.S. states. Marketing of timothy hay is primarily based on esthetics, and green color is an important attribute. The objective of these studies was to determine a relationship between arthropod populations, yield, and esthetic injury in timothy. Economic injury levels (EILs) and economic thresholds were calculated based on these relationships. Thrips (Thripidae) numbers were manipulated with insecticides in small plot studies in 2006, 2007, and 2008, although tetranychid mite levels were incidentally flared by cyfluthrin in some experiments. Arthropod population densities were determined weekly, and yield and esthetic injury were measured at each harvest. Effects of arthropods on timothy were assessed using multilinear regression. Producers were also surveyed to relate economic loss from leaf color to the injury ratings for use in establishing EILs. Thrips population levels were significantly related to yield loss in only one of nine experiments. Thrips population levels were significantly related to injury once before the first annual harvest and twice before the second. Thrips were the most important pest in these experiments, and they were more often related to esthetic injury rather than yield loss. EILs and economic thresholds for thrips population levels were established using esthetic injury data. These results document the first example of a significant relationship between arthropod pest population levels and economic yield and quality losses in timothy.

The male-produced pheromone of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), which is an equal blend of 4-(n-heptyloxy)butan-1-ol and 4-(n-heptyloxy)butanal, was used in laboratory bioassays and in the greenhouse to determine its potential for attracting A. glabripennis adults. In modified “walking wind tunnels,” virgin females were most attracted to the alcohol component, and virgin males were repelled by the pheromone blend at the lowest and highest amounts offered. Y-tube olfactometer bioassays also showed that females were significantly more attracted to the pheromone and its components than males were. However, males were more attracted to plant volatiles than females. Of 12 plant volatiles tested, δ-3-carene and (E)-caryophyllene were highly attractive to males, whereas (Z)-3-hexenyl acetate was repellent to males. Combining the male pheromone blend with (-)-linalool alone or with (Z)-3-hexen-1-ol attracted significantly more males than did the pheromone alone. We tested four trap designs in our quarantine greenhouse with eight different lures. The Intercept Panel traps and the hand-made screen sleeve traps caught more beetles than the Plum Curculio traps and Lindgren funnel traps. Intercept traps worked best when baited with male blend and (Z)-3-hexen-1-ol, whereas screen sleeve traps were most attractive when baited with (-)-linalool. Our findings provide evidence of the attractiveness of the A. glabripennis male-produced pheromone and suggest that it has a role in mate-finding. It is also a first step toward the development of an efficient trap design and lure combination to monitor A. glabripennis infestations in the field.

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an exotic woodborer first detected in 2002 in Michigan and Ontario and is threatening the ash resource in North America. We examined the effects of light exposure and girdling on green ash (Fraxinus pennsylvanica Marsh) volatile production, and effects of light exposure, girdling, and leaf age on emerald ash borer adult feeding preferences and phototaxis. Green ash seedlings grown under higher light exposure had lower amounts of three individual volatile compounds, (Z)-3-hexenol, (E)-β-ocimene, and (Z,E)-α-farnesene, as well as the total amount of six detected volatile compounds. Girdling did not affect the levels of these volatiles. Emerald ash borer females preferred mature leaves, leaves from girdled trees, and leaves grown in the sun over young leaves, leaves from nongirdled trees, and leaves grown in the shade, respectively. These emerald ash borer preferences were most likely because of physical, nutritional, or biochemical changes in leaves in response to the different treatments. Emerald ash borer females and males showed positive phototaxis in laboratory arenas, a response consistent with emerald ash borer preference for host trees growing in sunlight.

The goal of this research was to describe developmental rates, reproductive rates, and infestation patterns of Aphis craccivora Koch on alfalfa (Medicago sativa L.). All studies were conducted on the susceptible cultivar OK08 using aphids reared from collections made in Oklahoma. To determine thermal requirements for growth of A. craccivora, development from birth to adult was recorded at 7.2, 12.8, 18.3, 23.9, and 29.4°C. The same constant temperature treatments (except for 7.2°C being raised to 8.3°C) were used to assess the influence of temperature on reproductive rates. Within-plant distribution patterns were determined by infesting three stems on each of 24 plants and recording numbers of A. craccivora on leaf blades, petioles, and internodal stems sections at 2-d intervals through 10 d after infestation. Aphid counts were analyzed to determine significant differences among node parts (leaf blades, petioles, and stem sections). The developmental threshold temperature for A. craccivora was calculated to be 7.1°C, and the thermal constant for development from the first instar to reproducing adult was 100 DD (°C). The optimal temperature range for reproduction on alfalfa was 18–24°C, with a mean of 82 nymphs produced per female. From the initial infestation of three apterae per stem, numbers increased to a mean of 510 per stem after 10 d. Plant profiles showed that the greatest numbers of aphids were located in middle and lower portions of the plant canopy. On all sampling dates, the proportion of aphids on internodal stem sections was significantly greater (P < 0.05) than on petioles and leaf blades.