Information about invasive species needs to be spread rapidly across a wide geographic area following an invasion. However, in-person events can be time-consuming and costly for the participants, organizers, and presenters. Online programming like webinars can bridge this gap, but there is limited published data on how best to run these programs. We report on a 10-yr webinar program, Emerald Ash Borer University, and offer suggestions for improving their effectiveness as a communication tool. Webinar participants viewed the webinars positively and undertook recommended management actions. In addition, most of our survey respondents extended the reach of this program by widely sharing the information from the webinars. Posting the webinars on popular streaming platforms greatly extended their reach long after the live viewing event. Despite their longevity, viewers of recorded videos watched them differently than those viewing live events. We suggest modifying the format of future webinar presentations to accommodate these differences to improve information transfer.

Fruit developmental stage affects oviposition responses by tephritid fruit flies, but the role temperature plays in these responses to different fruit stages remains largely unknown. Here, temperature effects on oviposition rates of western cherry fruit fly, Rhagoletis indifferens Curran, in different stages of Bing sweet cherry (Prunus avium L.) were determined in no-choice experiments. Stage 1 (green), stage 2 (green-yellow to orange red), stage 3 (yellow-orange to red), and stage 4 cherries (red to burgundy) were exposed to flies at 15.6, 21.1, 26.7, and 32.2°C for 3 h and oviposition recorded. Oviposition was lower at 15.6°C than at all other test temperatures within all four cherry stages. Regression analysis using the three higher temperatures indicated there were significant cherry stage and temperature effects and a significant cherry stage × temperature interaction. The oviposition–temperature relationship was best explained by linear or curvilinear equations, depending on cherry stage. Oviposition in stage 1 cherries was lowest of the four stages and was not or linearly related to temperature. Oviposition in stage 2 cherries was greater and was related to temperature in a linear or curvilinear response. Oviposition was greatest in stage 3 and 4 cherries, with curvilinear and linear equations, respectively, best explaining oviposition–temperature relationships. Results suggest that temperatures and cherry stage together rather than cherry stage alone may have selected for behaviors leading to oviposition responses in R. indifferens.

A facultative commitment to adult migration in the larval stage can be modified again after adult emergence in some Lepidoptera when influenced by an appropriate environmental cue during a sensitive stage. This phenomenon is termed secondary regulation of migration. The sensitive stage in adult beet webworm, Loxostege sticticalis L. (Lepidoptera: Pyralidae), was determined experimentally by starvation of presumed migrant females reared from gregarious-phase larvae (induced by crowding at 10 larvae per 650-ml jar). When presumed migrant adults were starved for 24 h on either of the first 2 d after emergence, the preoviposition period was shortened. In contrast, preoviposition periods were not significantly shortened for migrants starved on day 3 or when starvation lasted for more than 1 d after emergence. Because the preoviposition period corresponds to the migratory period in beet webworm, the results suggest that the first 2 d of adult life in the beet webworm is the sensitive stage during which presumed migrants can be switched to residents by an appropriate environmental cue. During the sensitive stage or not, starvation did not influence lifetime fecundity, oviposition period, longevity, or hatching rate of eggs laid by the starvation-stressed moths. Starvation on the first day also increased tethered flight performance and accelerated both flight muscle and ovarian development. The results suggest that a pulse of starvation in the sensitive period may inhibit the expected migration by accelerating and compressing the cycle of migratory flight muscle development and degeneration, while accelerating ovarian development, which is normally suppressed until after migration.

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an invasive species to North America and has spread throughout most of the territory. Understanding flight in H. halys is crucial to understanding the dispersal capacity and developing forecasting models for this pest. The purpose of this research was to assess the effects of starvation, age, mating status, sex, and preflight weight on flight parameters of laboratory-reared H. halys using computer-monitored flight mills. The mean flight distance observed over a 24-h period was 266 m and the maximum distance was 7.3 km. Overall, the flight capacity of males and females was similar, even though females weighed more than males. The proportion of H. halys that initiated flight was not affected by starvation, age, or mating status. The number of bouts of individual flights and velocity significantly increased with longer durations of starvation. The number of bouts significantly decreased with increasing age. The total distance flew and total flight time was not affected by starvation, age, or mating status. Although some statistical differences were seen across the experiments, these differences likely represent minimal ecological significance. Therefore, these results suggest that H. halys are remarkably resilient, which may contribute to their success as an invasive species. The findings of this study could help better predict the dispersal potential of H. halys in Minnesota.

Monarch butterfly (Danaus plexippus) populations have declined over the last two decades, attributable in part to declines in its larval host plant, milkweed (Asclepias spp.), across its breeding range. Conservation efforts in the United States call for restoration of 1.3 billion milkweed stems into the Midwestern landscape. Reaching this goal will require habitat establishment in marginal croplands, where there is a high potential for exposure to agrochemicals. Corn and soybean crops may be treated with neonicotinoid insecticides systemically or through foliar applications to provide protection against insect pests. Here, we investigate whether ovipositing monarchs discriminate against milkweed plants exposed to the neonicotinoid insecticide imidacloprid, either systemically or through foliar application. In our first experiment, we placed gravid females in enclosures containing a choice of two cut stems for oviposition: one in 15 ml of a 0.5 mg/ml aqueous solution of imidacloprid and one in 15 ml water. In a second experiment, females were given a choice of milkweed plants whose leaves were treated with 30 µl of a 0.825 mg/ml imidacloprid-surfactant solution or plants treated with surfactant alone. To evaluate oviposition preference, we counted and removed eggs from all plants daily for 3 d. We also collected video data on a subset of butterflies to evaluate landing behavior. Results indicate that neither systemic nor foliar treatment with imidacloprid influenced oviposition behavior in female monarchs. The implications of these findings for monarch conservation practices will be informed by the results of ongoing egg and larval toxicity studies.

Halyomorpha halys (Stål) is an invasive pest in the United States and other countries. In its native range, H. halys eggs are parasitized by a co-evolved parasitoid, Trissolcus japonicus (Ashmead). In the United States, T. japonicus, a classical biological control candidate, is being redistributed in many states where adventive populations exist. To establish if H. halys egg holding conditions affect T. japonicus foraging behavior or successful parasitism, naïve, female parasitoids from an adventive population were allowed to forage in laboratory bioassay arenas with either fresh or frozen (–20 or –80°C) egg masses, the latter held for five durations ranging from 1 h to 112 d. Parasitoid movements were recorded for 1 h. Thereafter, parasitoids were transferred with the same egg mass for 23 h. Additionally, female parasitoids from a quarantine colony were exposed to: 1) pairs of fresh egg masses and egg masses frozen at –40°C (>24 h) or 2) a single fresh egg mass or egg mass frozen at –40°C (<1 h). All exposed egg masses were held to assess progeny emergence. In the foraging bioassay, holding temperature and storage duration appeared to influence host-finding and host quality. Egg masses held at –80°C and fresh egg masses resulted in significantly greater levels of parasitism and progeny emergence compared with eggs held at –20°C. No differences were recorded between egg masses held at –40°C for ≤1 h and fresh egg masses. These results will help refine methods for preparation of egg masses for sentinel monitoring and parasitoid mass rearing protocols.

Whether increased natural enemy density or adding a second natural enemy species will provide superior pest suppression in greenhouse augmentative biological control is unknown for many commercially available natural enemy species. In this study, we use sweetpotato whiteflies, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), on poinsettias, Euphorbia pulcherrima Willd. ex Klotzsch (Malpighiales: Euphorbiaceae), to determine whether adding Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) to Eretmocerus eremicus Rose and Zolnerowich (Hymenoptera: Aphelinidae) is better for B. tabaci suppression compared with either natural enemy alone, both with and without challenges with whitefly immigration or delayed natural enemy releases. The number of whiteflies on caged poinsettias treated with different natural enemy release rates (single or double rate), natural enemy species (one or two species), natural enemy delayed release (weeks 4 and 8), and whitefly immigration treatments (introduced at week 4 or week 8) was censused biweekly for 16 wk. Both species used in combination provided similar or better suppression of whiteflies compared with either natural enemy alone. Both species combined also provided superior suppression of whiteflies when challenged with whitefly immigration or delays in natural enemy releases compared with E. eremicus alone. Whitefly immigration or delays in E. eremicus releases did not increase whitefly populations, suggesting that suppression of whiteflies by E. eremicus alone is relatively robust. This study found no evidence for negative interactions between E. eremicus and A. swirskii for suppressing B. tabaci.

While trapping methods for Drosophila suzukii Matsumura (Diptera: Drosophilidae) have typically relied on fermentation volatiles alone or in association with a visual stimulus, the relative contribution of visual and olfactory stimuli to the food- and host-seeking behavior of D. suzukii is poorly understood. This study quantified the type of response exhibited by male and female D. suzukii to color and the effects that volatiles (fermentation, fresh fruit, and leaf) exert on the outcome. Seven-, four- and two-choice assays were used to quantify interactions between visual and olfactory cues. When no volatiles were present in a seven-choice assay, D. suzukii preferred red, black, and green pigments. Black and red were preferred when yeast odors were present, and black alone was the most attractive color when blueberry odor was present. A strawberry leaf terpenoid, β-cyclocitral, seemed to have overridden the flies' response to color. In four-choice assays, blueberry odor was more likely to interact synergistically with color than yeast or β-cyclocitral. This study demonstrates that D. suzukii modulates the response to multimodal sensory modalities (vision and olfaction) depending, to some extent, on the type of olfactory stimuli. Our findings also provide insight into the relative importance of vision as a function of odor quality in this invasive species.

Cuticular hydrocarbons perform multiple functions in insects such as protecting against desiccation and pathogenic infection, and signaling interactions. Evaluation of cuticular hydrocarbon (CHC) profiles of insects is commonly performed by extraction using a nonpolar solvent such as hexane. Specimens intended for CHC analysis are ideally handled by avoiding contact with solvents such as ethanol. However, insects are frequently stored in ethanol after collection, especially if intended for molecular analysis. To determine if it is possible that chemical compounds in the cuticles of specimens can withstand previous exposure to ethanol, we evaluated the efficiency of CHC extraction from specimens preserved in 95% ethanol. We extracted cuticular compounds from specimens of the social wasp Polybia paulista (Ihering) with no contact with ethanol solvents and compared them with those from specimens stored in 95% ethanol. We analyzed chemical composition from wasps and the 95% ethanol in which they had been stored by a gas chromatograph coupled to a mass spectrometer. In total, 56 compounds were detected: 50 that were classified as hydrocarbons which were mostly branched alkanes, followed by linear alkanes and alkenes. Three compounds were identified as fatty acids, and three compounds were unidentifiable. The ethanol-preserved specimens showed similar chemical profiles to those of specimens that had no contact with ethanol. Thus, we suggest that it is possible to study the chemical profiles of ethanol-preserved specimens.

Tea black tussock moth, Dasychira baibarana (Matsumura) (Lepidoptera: Lymantriidae), is a devastating pest species of the tea plant in China. Here, we evaluated the responses of D. baibarana to tea plant volatiles using gas chromatography coupled electroantennographic detection (GC–EAD), eleclectroantennography (EAG), and a Y-tube olfactometer. In total, 11 of 18 analyzed compounds elicited GC–EAD responses from test insects. GC–EAD bio-active compounds were further investigated using EAG and behavioral responses. In the EAG analysis, male moths had significantly greater responses to four compounds [(Z)-3-hexenyl butyrate, (Z)-3-hexen-1-ol, ocimene and benzyl alcohol] than female moths. For females, maximum EAG amplitudes, were recorded in response to linalool, (Z)-3-hexenyl hexanoate and (Z)-jasmone. In EAG and behavioral bio-assays, the responses of both sexes were dose independent. In behavioral bio-assays male moths responding significantly to (Z)-3-hexen-1-ol, ocimene, (Z)-3-hexenyl butyrate, linalool, benzyl alcohol, and (Z)-jasmone at various concentrations. For females, significant behavioral responses were observed to (Z)-3-hexenyl hexanoate, followed by (Z)-jasmone, linalool, ocimene, and benzyl alcohol. However, neither sex was sensitive to 4 of the 11 tested compounds, phenyethyl alcohol, phenylacetonitrile, (E)-nerolidol, and indole. The present results showed that tea plant volatiles influenced the behavior of D. baibarana moths, which will greatly contribute in developing eco-friendly control strategies for D. baibarana, through the application of a blend of compounds that showed significant EAG and behavioral responses or a blend combined with female-produced sex pheromones.

An increasing body of evidence indicates that cerambycid beetles native to different continents may share pheromone components, suggesting that these compounds arose as pheromone components early in the evolution of the family. Here, we describe the identification and field testing of the pheromone blends of two species in the subfamily Cerambycinae that share 2-nonanone as an important component of their male-produced aggregation-sex pheromones, the South American Stizocera consobrina Gounelle (tribe Elaphidiini) and the North American Heterachthes quadrimaculatus Haldeman (tribe Neoibidionini). Along with 2-nonanone, males of S. consobrina also produce 1-(1H-pyrrol-2-yl)-1,2-propanedione, whereas males of H. quadrimaculatus produce 10-methyldodecanol. Field bioassays conducted in Brazil (targeting S. consobrina) and Illinois (targeting H. quadrimaculatus) demonstrated that adults of both species were attracted only by the blends of both their pheromone components, and not to the individual components. The use of the pyrrole as a critical component for the former species is further evidence that this compound is a common pheromone structure among cerambycines in different biogeographical regions of the world.

Necrophagous insects play an important role in decomposition and nutrient recycling of decomposing vertebrates. Ecological studies of carrion-associated beetles enhance forensic investigations by providing information about community assemblages and predictable patterns of succession. However, lack of standardized protocols that include replication, spatial scale, and phenology reduce detection of patterns and predictions. To address these gaps and examine the influence of habitat (woodlands vs grasslands) and abiotic factors on carrion beetle (Coleoptera: Silphidae) communities, we developed an experimental approach from broad to finer scale located within the Kansas Flint Hills across a full annual cycle (12 contiguous months). In total, 3,333 adult carrion beetles in nine species were collected from pitfall traps baited with rat carrion over thirteen 4-wk collecting periods. PERMANOVA and NMDS demonstrate that the silphid beetle community was significantly different in species composition between grassland and woodland habitats, but communities did not differ significantly in overall mean abundance, mean species richness, or mean species diversity. Two species exhibited strong habitat associations; one associated with grassland habitat (Nicrophorus marginatus F.) and one with woodland habitat (Nicrophorus orbicollis Say). Our results reveal that habitat associations of silphid beetles can be useful in forensic investigations by determining corpse relocation and in ecological studies that explore niche filtering.

Necrophilous insects occupy an ecologically interesting niche because carrion is a highly desirable but ephemeral food source. Dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae and Aphodiinae) within temperate regions are frequently found at carrion, but little is known about their attraction to this resource. Are dung beetles attracted to the carrion itself or are they indirectly attracted due to the exposed gastrointestinal contents? We investigated the association between dung beetles and carrion by examining the distribution of dung beetles on the cranial and caudal end of rat carcasses, delimiting a resource more attractive to necrophagous insects (cranial end) from a resource more attractive to coprophagous insects (caudal end). Dung beetle distribution on rat carcasses was compared with the distribution of carrion beetles (Coleoptera: Silphidae), which serve as a null model of distribution patterns for a taxon known to directly target carrion. Results demonstrated that dung beetles show higher attraction to the cranial end of rat carrion. A similar distribution pattern was found in carrion beetles, suggesting that similar resources were targeted. When dung beetles were grouped by behavioral guilds, rollers and tunnelers also shared this pattern of greater abundance at the cranial end, but dwellers showed no discernible difference.

Nonnative species often transform local communities to the detriment of native species. Much of the existing invasion ecology research focuses on the effects of a few extremely impactful species, and it is less clear how nonnative species which are not causing economic or ecological impacts alter closely related natives at risk of being displaced. Filling these knowledge gaps is critical because consequences of nonnative species are likely to vary depending on taxonomic scale, functional trait, and spatial or temporal niche. We conducted a meta-analysis to evaluate how biodiversity of native Formicidae (ants), Carabidae (ground beetles), and Scolytinae (bark and ambrosia beetles) species changes across a gradient of pressure from nonnative confamilials. We calculated Hill numbers for each group from data presented in literature and correlated native diversity metrics to proportion of nonnative species. Species richness of native ants was significantly negatively correlated with proportions of nonnative ants, whereas bark and ambrosia beetle metrics showed a nonsignificant negative correlation. Nonnative ground beetles had neutral effects on diversity of native ground beetles. Resulting contrasting patterns of invasive species effects on natives suggest complex biotic and abiotic factors driving effects of nonnative species in these groups. Our results suggest that a few extreme examples (e.g., red imported fire ants) drive most of the changes seen in native arthropod communities. To accurately assess impacts of invaders on native arthropod diversity, baseline data are needed, and community analyses must consider diverse functional traits of native taxa and improve the depth and breadth of community sampling.

Five closely related species of greater fritillaries occur in North America east of the Mississippi River: regal fritillary (Speyeria idalia Drury [Lepidoptera: Nymphalidae]), Diana fritillary (Speyeria diana Cramer [Lepidoptera: Nymphalidae]), great spangled fritillary (Speyeria cybele Fabricius [Lepidoptera: Nymphalidae]), Atlantis fritillary (Speyeria atlantis Edwards [Lepidoptera: Nymphalidae]), and Aphrodite fritillary (Speyeria aphrodite Fabricius [Lepidoptera: Nymphalidae]). The regal fritillary and Diana fritillary are species of concern, whereas the great spangled fritillary, Atlantis fritillary, and Aphrodite fritillary are relatively abundant within their respective ranges. However, the Atlantis fritillary and Aphrodite fritillary have experienced severe population declines within the last few decades. We created ecological niche models for these five species by combining each species' known occurrences with climate and environmental variables to identify important response variables and determine the potential distribution of suitable habitat for each species. Important climate variables differed among species, although minimum temperature of the coldest month was important for great spangled, Atlantis, and Aphrodite fritillaries. The regal fritillary responded the most to temperature seasonality, whereas the Diana fritillary responded to maximum temperature of warmest month and the great spangled fritillary responded to annual precipitation. Land use was important for all species except the regal fritillary and average annual relative humidity was important for all species except the great spangled fritillary. This study highlights the different climate and habitat needs for greater fritillary species with important implications for how each species is expected to be impacted by climate change. We also demonstrate the value of citizen science and photo sharing websites for providing important data for evaluating species distributions.

Ants have been suggested as one of many population pressures sea turtles face potentially affecting nesting-beach survival of eggs and hatchlings. However, little is known about the extent to which ants act as incidental or primary mortality factors. Most research has focused on New World fire ants (genus Solenopsis), with confirmed records of other ant species interactions with sea turtle nests in situ being rare. Our study documented the ant species associated with loggerhead sea turtle Caretta caretta (Linnaeus) (Testudines: Cheloniidae) nests in Georgia and determined if ant presence was linked to lower hatching or emergence success. Samples (n = 116) collected from sea turtle nests on eight islands contained 14 ant species including Solenopsis invicta Buren (Hymenoptera: Formicidae), the red imported fire ant, which was the most common ant species encountered. Ant presence was not correlated with lower hatching success, but when other known disturbances were removed, correlated with significantly lower nest emergence success (P < 0.0001). Logistic modeling suggests that proximity of sea turtle nests to the primary dune significantly increases risk of ant predation on hatchling sea turtles. Population managers can reduce this risk by maintaining a 1-m buffer shoreward between dune vegetation and relocated sea turtle nests. Our results suggest that ants may exert a density-dependent pressure on nesting sea turtle populations and call for additional investigations to determine if managing native and invasive ants augments other efforts to improve hatchling survival.

Water conservation is an important factor for production of rice in the United States because of declining aquifer levels, but little research has been done to evaluate insect management in rice systems integrating water conservation practices. Rice water weevil, Lissorhoptrus oryzophilus Kuschel, is an important insect pest of rice in the U.S. Rice water weevil is a semiaquatic species that relies on flooded conditions to complete larval development, so water conservation practices are likely to impact their pest status. The study was conducted across the Mississippi River alluvial floodplain to compare rice water weevil population densities in different zones of a furrow irrigated rice field to a conventionally flooded rice field. All locations were sampled at 3, 4, and 5 wk after the initial irrigation. Larval densities were greatest in the lower end of furrow irrigated fields and in the adjacent flooded rice field compared with the upper and middle sections that did not hold standing water when averaged across three sample dates. Also, rice water weevil densities were greater during week five than week three. In terms of rice yields, the top third of furrow irrigated rice fields, the section that remained mostly dry, produced lower rough rice yields than all other sections and the flooded field. These results suggest that rice water weevil populations can be lower in a furrow irrigated rice system. As a result, more research is needed to determine whether a spatial management plan can be developed based on soil moisture zones in furrow irrigated rice.

We present findings of a general survey of pest wireworms in Alberta, Saskatchewan, and Manitoba conducted from 2004 to 2019; the first such survey of the Canadian Prairie provinces since that published by Glen et al. (1943). Samples were collected from 571 farmland locations where crop damage from wireworms was observed or suspected, and a total of 5,704 specimens (3,548 larvae, 2,156 beetles) were identified. Most specimens (96.9%) were identified as Hypnoidus bicolor (3,278), Selatosomus aeripennis destructor (1,280), Limonius californicus (842), and Aeolus mellillus (125). This suggests that H. bicolor has replaced S. a. destructor as the predominant species and that the relative importance of L. californicus as a pest species has increased since earlier reports. Despite the relatively small number of specimens collected per location (approx. 10), H. bicolor and S. a. destructor, and S. a. destructor and L. californicus were frequently collected at or near the same location (within 1 km). We provide species records and incidence of co-occurrence at different spatial scales, discuss potential reasons for and implications of shifts in species composition, implications of species co-occurrence for managing wireworm pests in crop production, and outline pertinent research needs. A path analysis approach used to correlate incidence of the main species with various soil characteristics indicated that organic matter, cation exchange capacity, and water retention capacity all had a significant species-specific influence on wireworm presence.

Twospotted spider mite (Tetranychus urticae Koch) is a cosmopolitan pest of numerous plants, including hop (Humulus lupulus L.). The most costly damage from the pest on hop results from infestation of cones, which are the harvested product, which can render crops unsalable if cones become discolored.We analyzed 14 yr of historical data from 312 individual experimental plots in western Oregon to identify risk factors associated with visual damage to hop cones from T. urticae. Logistic regression models were fit to estimate the probability of cone damage. The most predictive model was based on T. urticae-days during mid-July to harvest, which correctly predicted occurrence and nonoccurrence of cone damage in 91 and 93% of data sets, respectively, based onYouden's index. A second model based on the ratio of T. urticae to predatory arthropods late in the season correctly predicted cone damage in 92% of data sets and nonoccurrence of damage in 77% of data sets. The model based on T. urticae abundance performed similarly when validated in 23 commercial hop yards, whereas the model based on the predator:prey ratio was relatively conservative and yielded false-positive predictions in 11 of the 23 yards. Antecedents of these risk factors were explored and quantified by structural equation modeling. A simple path diagram was constructed that conceptualizes T. urticae invasion of hop cones as dependent on prior density of the pest on leaves in early spring and summer, which in turn influences the development of predatory arthropods that mediate late-season density of the pest. In summary, the biological insights and models developed here provide guidance to pest managers on the likelihood of visual cone damage from T. urticae that can inform late-season management based on both abundance of the pest and its important predators. This is critically important because a formal economic threshold for T. urticae on hop does not exist and current management efforts may be mistimed to influence the pest when crop damage is most probable. More broadly, this research suggests that current management practices that target T. urticae early in the season may in fact predispose yards to later outbreaks of the pest.

The quinoa pest Copitarsia incommoda (Walker, Lepidoptera: Noctuidae) is a cause of significant damage, and it is thus critical for Andean countries to have access to phenological models to maintain production and food safety. These models are key components in pest control strategies in the context of global warming and in the development of sustainable production integrating agroecological concepts. Phenological models are mainly based on outlining the relationship between temperature and development rate. In this study, we investigated the combined effect of protein content within the diet (artificial diet; artificial diet with –20% protein; artificial diet with +20% protein; natural quinoa diet) and temperature (12, 16.9, 19.5, 22.7, 24.6°C) as drivers of the development rate. Our study supports the literature, since temperature was found to be the main driver of the development rate. It highlights the significant role played by protein content and its interaction with temperature (significant effects of temperature, diet, and diet:temperature on development time using GLMs for all foraging life stages). We discuss the implications of such drivers of the development rate for implementing and applying phenological models that may benefit from including factors other than temperature. While performance curves such as development rate curves obtained from laboratory experiments are still a useful basis for phenological development, we also discuss the need to take into account the heterogeneity of the insect response to environmental factors. This is critical if pest control practices are to be deployed at the optimal time.

Trogoderma granarium Everts, the Khapra beetle, is a major pest of stored products, especially grains. In this study, fumigant toxicity and sublethal effects of Eucalyptus camaldulensis Dehnh. (Myrtaceae) and Mentha piperita L. (Lamiaceae) essential oils (EOs) were investigated against different growth stages of T. granarium. To assess the sublethal effects, insects were exposed to an LC₂₀ or LC₅₀ concentration of each essential oil, and the ability of these oils to deter feeding, oviposition, and damage to wheat seeds and overall mass were surveyed. At LC₅₀ concentrations, M. piperita EO showed higher fumigant toxicity than E. camaldulensis EO against eggs, 2nd instar larvae, 4th instar larvae, and adults of T. granarium. Furthermore, the adults were more sensitive to the tested EOs than immatures. In free-choice tests, both larvae and adults showed a preference for control-treated wheat seeds than for seeds treated with an LC₂₀ or LC₅₀ concentration of EOs from E. camaldulensis or M. piperita. In a no-choice test, adult females exposed to EOs showed lower fecundity and fertility in comparison to control females not exposed to EOs. Treatment of wheat seeds with E. camaldulensis or M. piperita EOs resulted in a dose-specific reduction in the number of damaged seeds and seed weight loss when compared to control. According to our results, both tested EOs, especially EOs extracted from M. piperita, showed good potential for use in integrated pest management strategies against T. granarium.

Insects that hatch in winter and early spring in desert and montane regions are likely to encounter extreme weather events, including precipitous drops in temperature. The susceptibility of insects to exposure to subzero temperatures is predicted to decrease with increasing latitude or elevation. Mormon crickets occur over a broad latitudinal range from southwestern United States to Canada and a broad elevational range from near sea-level to 3,000 m. Population declines have been attributed to late freezing events, but winter hatching suggests they may also be cold tolerant. Lower lethal temperature of high elevation populations in low latitude Arizona (AZ) and high latitude Wyoming (WY) was measured by exposing nymphs and adults to 6 h or 24 h of subzero temperature. From similar latitude, WY was compared with mid-elevation Idaho (ID) and low elevation Oregon (OR) populations. Contrary to the prediction, lethal temperature of third instar nymphs was lower in AZ than in the more northerly populations. Consistently, AZ was more tolerant of cold in early nymphal instars relative to populations from higher latitude. Early hatching at lower latitudes might increase the risk of early instars experiencing a severe cold snap relative to nymphs at high latitudes. Also, contrary to prediction, the lethal temperature of adults increased with elevation, whereas third instar nymphs from mid-elevation ID were the most susceptible to cold exposure. Cold tolerance in immature and mature stages is more likely to be uncoupled when life stages do not coincide, as with Mormon crickets.

The apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera:Tephritidae), is a serious pest of apple in North America that is subject to quarantine measures to prevent its spread to currently pest-free regions, including the tropics. How the fly may survive in warmer climates is unclear. Here, we studied the effects of exposing postchill puparia to simulated temperate and tropical environmental conditions on eclosion of R. pomonella from Washington State, U.S.A. Puparia were chilled for 0–30 wk at 3°C and then held under four postchill conditions: A = 23°C, 16:8 L:D, 40% RH; B = 26°C, 12:12 L:D, 80% RH; C = 26°C, 16:8 L:D, 80% RH; and D = 23°C, 12:12 L:D, 40% RH, with B and D representing tropical conditions and A and C temperate conditions. Within each chill duration, total numbers of flies eclosed were equally high in tropical treatment B and temperate treatment C, while they were lower in treatments A and D. Mean weeks of the first eclosion in treatments B and C were earlier than in treatment D; mean week of peak eclosion and 50% eclosion in treatments A, B, and C were earlier than in treatment D. Eclosion spans in treatments A, B, and D were generally shorter than in treatment C. Results suggest that if introduced into a humid tropical country, R. pomonella puparia from Washington State could produce adult flies, regardless of chill duration or lack of chilling during the pupal stage, but whether flies could establish there would require further study.

Drought events have the potential to mediate tri-trophic interactions. Changes in plant quality influence herbivore performance, which affects prey availability and quality for natural enemies. Parasitoid wasps are particularly vulnerable to these changes since their development is inextricably linked to that of their prey. However, we know little about the indirect effects of plant water limitation on parasitoid performance, especially the consequences of mild water limitation. This study investigated the ability of a parasitoid wasp (Aphidius colemani Viereck (Hymenoptera: Braconidae)) to suppress aphid (Rhopalosiphum padi L. (Hemiptera: Aphididae)) populations on well-watered, mildly stressed, or highly stressed wheat (Triticum aestivum L. (Poales: Poaceae)). We then investigated the role that aphid body size and behavioral interactions might play in wasp acceptance of aphid hosts. We found improved aphid suppression under mild and high-water limitation, but the underlying mechanisms were different. Mild-stress appeared to maximize parasitoid performance, as indicated by the highest mummy production. Aphids were larger when feeding on mildly stressed plants than on any other treatment, which suggests improved aphid quality for parasitoids. Improved aphid suppression under high-stress may have been driven by enhanced nonconsumptive effects. Despite improved aphid suppression, mummy formation was lowest on highly stressed plants. High-stress conditions have been shown to negatively affect aphid performance, so improved aphid suppression may be driven by poor aphid performance exacerbating the cost of interactions with parasitoids, such as stinging. No differences were observed in parasitoid foraging behaviors such as antennation or stinging across any treatments. This study highlights the importance of plant water stress intensity in affecting outcomes of parasitoid–host interactions.

Most commercial citrus varieties are intolerant of salinity stress, but some rootstocks, such as Rangpur lime, tolerate moderately saline irrigation water. Development of salinity-tolerant citrus may allow for citriculture in semiarid and arid regions where salinity stress is problematic. Because salinity stress influences shoot growth in citrus, we compared the behavioral responses of Asian citrus psyllid, Diaphorina citri Kuwayama, to salinity-stressed versus nonstressed Rangpur lime seedlings. The effects of salinity stress on key physiological processes in the seedlings were also examined. Seedlings in the control group were fertilized with a solution having a salinity of 1.7 dS m^–1 while seedlings in the salinity-stressed group were fertilized with a solution having a salinity of 10 dS m^–1. The seedlings were exposed to salinity stress for increasing durations (15, 20, or 60 d). Seedlings presented differential physiological responses 15 d after the imposition of salinity stress, and differences in psyllid settling rate on control versus salinity-stressed seedlings were discernable within 1 h following the imposition of salinity stress. The levels of settling, oviposition, and egg survivorship were significantly lower on salinity-stressed versus control seedlings. Olfactometer tests showed that female psyllids preferred the odor from control seedlings, suggesting that the odors of control and salinity-stressed seedlings were different. The results showed that D. citri avoids salinity-stressed seedlings; this suggests the possibility of using moderate salinity stress as a management strategy to minimize psyllid settlement and reproduction and to reduce the spread of huanglongbing, especially in citrus grown in semiarid and arid areas.

Habitat loss and edge effects resulting from habitat fragmentation are key processes implicated in the decline of bee populations globally. Their effects on wild bees and their pollination services in natural ecosystems are poorly understood, particularly in North American prairies. Our objectives were to determine whether natural habitat loss and edge effects affect bee abundance and pollination services in the Northern Great Plains. We sampled bee abundance and pollination services along transects beginning at road or tree edges in grasslands located in Manitoba, Canada. We measured bee abundance using pan traps, and pollination services using seed-set of Brassica rapa (L.) (Brassicales: Brassicaceae) phytometers. We collected local-scale habitat data by measuring occurrence of flowering species, vegetation type, and vegetation structure, and we measured habitat amount at 1-km radii using GIS analysis of landscape cover. Increasing amounts of habitat loss resulted in declines in bee abundance, and sometimes in pollination services. Results varied with bee life-history: proximity to road edges negatively affected social bees, and litter depth had negative effects on below- ground-nesting bees. Surprisingly, few effects on bees led to corresponding impacts on pollination services. This suggests that conservation of intact natural habitat across the northern Great Plains is important for maintaining resilient and diverse bee communities, but that efforts to conserve bee populations cannot be assumed to also maintain all associated pollination services.

Tarsonemus bakeri Ewing (Acari: Tarsonemidae) is a species of mite commonly associated with citrus in many countries including the United States. A short report in 1942 suggested this species is phytophagous, but it has not been reported as a pest in citrus or any other crop since then. A single survey of 78 orchards in three growing regions in California demonstrated that Tarsonemus spp. mites were only associated with leaf samples that had visible sooty mold. A seasonal population study in one citrus orchard showed that all life stages of Tarsonemus spp. were present year-round on leaves and fruit, with the population on fruit reaching a peak in December (59.7 ± 15.2 mites per fruit). Results from a food suitability study showed that the population declined sharply on both plastic and leaf substrate when the mites were not provided a supplementary food source. When supplementary food was provided in the form of Alternaria, honeydew, molasses, or combinations of these, mites survived and multiplied throughout the 29-d study, irrespective of the substrate. Tarsonemus bakeri were found on excised, decaying leaves collected from an orchard. These studies verify that Tarsonemus spp. are associated only with sooty mold in citrus orchards. T. bakeri populations cannot sustain themselves on leaf tissue alone, indicating that they are nondamaging to citrus and therefore need not be considered a phytosanitary concern by importing countries.