The phenology of the stem-mining weevil Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae) as adults attacking Dalmatian toadflax, Linaria dalmatica (L.) Miller (Plantaginaceae), was studied in 2014-2015 at two low elevation sites in northern Utah. The seasonal pattern of adult weevil abundance on the host plant at the two sites was most similar between years when described by degree-day accumulation, versus calendar date. Repeated censusing over the growing season revealed that males appeared first and subsequently peaked in abundance on the host plant earlier than females did, such that the adult population was dominated by males early in the season and by females late in the season. Peak female abundance on the host plant occurred at the time when Dalmatian toadflax stems reached their maximum height and density and when they began flowering widely. Maximum toadflax stem heights and densities, and flowering activity, were markedly reduced in 2015 compared to 2014. In contrast to these host plant parameters that vary between years, degree-day accumulation can be used readily for timing collection and survey efforts for adult weevils and female adult weevils in particular. Use of degree-day accumulation can thereby facilitate implementation of redistribution and monitoring programs for M. janthiniformis as a biological control agent of Dalmatian toadflax.

Sogatella furcifera (Horváth) is a migratory rice pest that periodically erupts across Asia, and early immigration is an important cause of its outbreak. The early immigration of S. furcifera into southern China shows evident annual fluctuations. In the spring of 2012, the huge size of the immigrant population and the large number of immigration peaks were at levels rarely seen prior to that year. However, little research has been done on the entire process of round-trip migration to clarify the development of the population, the long-distance migration and the final eruption. In this study, the light-trap data for S. furcifera in southern China and Vietnam in 2011–2016 were collected, and the trajectory modeling showed that the early immigrants to southern China came from the northern and central Vietnam, Laos, and northeastern Thailand. Analysis of the development of the population, the migration process and meteorological factors revealed the reasons for the huge size of the early immigration: 1) the expansion of the source area could be seen as a precondition; 2) the large size of the returned population in the last autumn and the warm temperature of southern Vietnam and Laos in the last winter increased the initial populations; 3) the sustained strong southwest winds were conducive to the northward migration of the population during the major immigration period in early May. Therefore, the large-scale immigration of S. furcifera to southern China in the spring of 2012 resulted from the combined effects of several factors involved in the process of round-trip migration.

Spatial synchrony and cycles are common features of forest insect pests, but are often studied as separate phenomenon. Using time series of timber damage caused by Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae) (southern pine beetle) in 10 states within the southern United States, this study examines synchrony in D. frontalis abundance, the synchronizing effects of temperature extremes, and the evidence for shared cycles among state populations. Cross-correlation and cluster analyses are used to quantify synchrony across a range of geographic distances and to identify groups of states with synchronous dynamics. Similar techniques are used to quantify spatial synchrony in temperature extremes and to examine their relationship to D. frontalis fluctuations. Cross-wavelet analysis is then used to examine pairs of time series for shared cycles. These analyses suggest there is substantial synchrony among states in D. frontalis fluctuations, and there are regional groups of states with similar dynamics. Synchrony in D. frontalis fluctuations also appears related to spatial synchrony in summer and winter temperature extremes. The cross-wavelet results suggest that D. frontalis dynamics may differ among regions and are not stationary. Significant oscillations were present in some states over certain time intervals, suggesting an endogenous feedback mechanism. Management of D. frontalis outbreaks could potentially benefit from a multistate regional approach because populations are synchronous on this level. Extreme summer temperatures are likely to become the most important synchronizing agent due to climate change.

Recent decades have witnessed an intensified expansion of thermophilic organisms from southern into northern Europe. Argiope bruennichi, an orb-weaver spider species, is extending its range relatively fast and gradually becoming a common species in Europe. The aim of this study was to investigate how this relatively newly-come taxon is affecting another orb-weaver spider species and whether it demonstrates features of an invasive species. Interactions were examined between this species and another dominant species with similar body and web size, Araneus quadratus. The study areas were located in two adjacent regions in northeast Poland: the warmer Mazury Lake District and the colder Suwalki Lake District. The areas differed in both population density of the studied species as well as in climatic conditions. Six study sites were selected in each region. In the Mazury Lake District, A. bruennichi was more frequent than A. quadratus; this relationship was reversed in the Suwalki Lake District. We measured the height of the web hub above the ground and the height of the plants to which webs were fixed. Web location height was chosen as an indicator of the interaction. The results indicate that A. quadratus located its webs higher than A. bruennichi, regardless of species abundance and region. A. bruennichi does not exert a significant negative impact on A. quadratus web placement. The two species clearly prefer different heights, which in turn may determine the kind of prey they catch.

Natural enemies are valuable components of agroecosystems as they provide biological control services to help regulate pest populations. Promoting biocontrol services can improve sustainability by decreasing pesticide usage, which is a major challenge for the blueberry industry. Our research is the first to compare natural enemy populations in managed (conventional and organic) and unmanaged blueberry systems, in addition to the effects of non-crop habitat. We conducted our study in 10 blueberry orchards during the growing season across the major blueberry producing counties in Georgia, United States. To estimate the spatial distribution of natural enemies, we conducted suction sampling at three locations in each orchard: within the forested border, along the edge of blueberry orchard adjacent to forested border, and within the interior of the blueberry orchard. Natural enemies maintained higher abundance over the season in unmanaged areas when compared with organic or conventional production systems. In the conventional orchards, natural enemies were more abundant in the surrounding non-crop area compared with the interior of the orchard. Populations were more evenly distributed in less intensive systems (organic and unmanaged). Our results indicate spatial structure in natural enemy populations is related to management practice, and less intensive management can retain higher abundance of natural enemies in blueberry systems. Considerations must be made towards promoting ecologically based management practices to sustain natural enemy populations and potentially increase the delivery of biological control services.

Tetropium fuscum (Fabricius) (Coleoptera: Cerambycidae), a phloem-feeding and wood-boring beetle introduced from Eurasia, attacks spruce in eastern Canada alongside its native congener Tetropium cinnamopterum Kirby. We reared phloem- and wood-feeding insects (and their predators) from bolts of red and Norway spruce (Picea rubens and Picea abies) in Nova Scotia, comparing insect communities between bolts with added eggs of T. fuscum or T. cinnamopterum and bolts without added Tetropium (controls). We tested for impacts of each Tetropium on insect community structure (Simpson's diversity, richness, and evenness). We also asked whether, consistent with Darwin's Naturalization Hypothesis, Tetropium spp. would have greater impacts on emergence of its closer relatives (which might be most likely to compete and/or share natural enemies). Addition of Tetropium eggs (either species) to bolts lowered insect diversity in both host trees. Both richness and evenness components of diversity were always lower in +Tetropium treatments, although different components reached statistical significance in different Tetropium species × host combinations. Addition of Tetropium spp. significantly reduced emergence of some species: Evodinus monticola (Randall) (Coleoptera: Cerambycidae) was reduced by T. fuscum on both hosts and by T. cinnamopterum on Norway spruce; Hylobius congener Dalla Torre, Schenkling, and Marshall was reduced by T. fuscum on red spruce; and Xylophagus sp. (Diptera: Xylophagidae) was reduced by T. cinnamopterum on Norway spruce. However, there was no relationship between Tetropium's impact on a community member and their phylogenetic relatedness, and the overall impacts of Tetropium presence were not very different between T. fuscum and T. cinnamopterum.

Dung beetles are globally used in ecological research and are useful for assessing the effects of anthropic and natural changes in environment on biodiversity. Here we investigate how the choice of baits (human feces, cattle dung, carrion or a combination of all three) and sampling season influence the taxonomic and functional diversity of insects captured in traps in Brazilian pastures. We sampled dung beetles in July 2011 (dry season) and January 2012 (rainy season) in eight areas: four pastures with native grasses (e.g., Andropogon spp. and Axonopus spp.) and four pastures with introduced grasses (Urochloa spp.) in Aquidauana, Mato Grosso do Sul, Brazil. To collect the insects, we used pitfall traps baited with carrion, cattle dung and human feces. A total of 7,086 dung beetles of 32 species were captured. In both pasture types, only traps baited with human feces captured similar abundance, species richness, and functional diversity compared with the sum total of beetles captured by the three bait types. The species richness and functional diversity were higher in the rainy season in both pasture types. Our results demonstrate that using human feces alone as bait and sampling dung beetles in the rainy season are potentially sufficient to ensure the greatest number of functional traits, species, and individuals in both pasture types. Thus, the best sampling method observed in this study may be useful for studies focused on dung beetle fauna survey and rigorous comparison among studies on these insects in Brazilian pastures.

Neonicotinoids are highly toxic to insects and may systemically translocate to nectar and pollen of plants where foraging bees may become exposed. Exposure to neonicotinoids can induce detrimental sublethal effects on individual and colonies of bees and may have long-term impacts, such as impaired foraging, reduced longevity, and reduced brood care or production. Less well-studied are the potential effects on queen bumble bees that may become exposed while foraging in the spring during colony initiation. This study assessed queen survival and nest founding in caged bumble bees [Bombus impatiens (Cresson) (Hymenoptera: Apidae)] after chronic (18-d) dietary exposure of imidacloprid in syrup (1, 5, 10, and 25 ppb) and pollen (0.3, 1.7, 3.3, and 8.3 ppb), paired respectively. Here we show some mortality in queens exposed at all doses even as low as 1 ppb, and, compared with untreated queens, significantly reduced survival of treated queens at the two highest doses. Queens that survived initial imidacloprid exposure commenced nest initiation; however, they exhibited dose-dependent delay in egg-laying and emergence of worker brood. Furthermore, imidacloprid treatment affected other parameters such as nest and queen weight. This study is the first to show direct impacts of imidacloprid at field-relevant levels on individual B. impatiens queen survival and nest founding, indicating that bumble bee queens are particularly sensitive to neonicotinoids when directly exposed. This study also helps focus pesticide risk mitigation efforts and highlights the importance of reducing exposure rates in the early spring when bumble bee queens, and other wild bees are foraging and initiating nests.

Agricultural expansion and intensification negatively affect pollinator populations and has led to reductions in pollination services across multiple cropping systems. As a result, growers and researchers have utilized the restoration of local and landscape habitat diversity to support pollinators, and wild bees in particular. Although a majority of studies to date have focussed on effects in pollinator-dependent crops such as almond, tomato, sunflower, and watermelon, supporting wild bees in self-pollinated crops, such as grapes, can contribute to broader conservation goals as well as provide other indirect benefits to growers. This study evaluates the influence of summer flowering cover crops and landscape diversity on the abundance and diversity of vineyard bee populations. We showed that diversity and abundance of wild bees were increased on the flowering cover crop, but were unaffected by changes in landscape diversity. These findings indicate that summer flowering cover crops can be used to support wild bees and this could be a useful strategy for grape growers interested in pollinator conservation as part of a broader farmscape sustainability agenda.

Gregarious nesting behavior occurs in a broad diversity of solitary bees and wasps. Despite the prevalence of aggregative nesting, the underlying drivers and fitness consequences of this behavior remain unclear. I investigated the effect of two key characteristics of nesting aggregations (cavity availability and progeny density) on reproduction and brood parasitism rates in the blue orchard bee (Osmia lignaria Say) (Hymenoptera: Megachilidae), a solitary species that nests gregariously and appears to be attracted to nesting conspecifics. To do so, I experimentally manipulated nest cavity availability in a region of northern Utah with naturally occurring populations of O. lignaria. Nest cavity availability had a negative effect on cuckoo bee (Stelis montana Cresson) (Hymenoptera: Megachilidae) parasitism rates, with lower parasitism rates occurring in nest blocks with more available cavities. For both S. montana and the cleptoparasitic blister beetle Tricrania stansburyi Haldeman (Coleoptera: Meloidae), brood parasitism rate was negatively correlated with log-transformed O. lignaria progeny density. Finally, cavity availability had a positive effect on male O. lignaria body weight, with the heaviest male progeny produced in nest blocks with the most cavities. These results suggest that cavity availability and progeny density can have substantial effects on brood parasitism risk and reproduction in this solitary bee species.

Plants and herbivorous (or parasitic) insects form the majority of macroscopic life. The specificity of interaction between host plant and parasitic insect depends on the adaptations of both the host and the parasite. Over time, these interactions evolve and change as a result of an ‘arms race’ between host and parasite, and the resulting species-specific adaptations may be maintained, perpetuating these interactions across speciation events. This can lead to specialisation between species or clades. With speciation and species sorting over time, complex interactions evolve. Here, we elucidate a three-tier method to test these interactions using the aphids (Hemiptera: Aphididae) and plants of Churchill (Manitoba, Canada) as a model system. We analyzed these interactions by testing for three patterns in host specificity: monophagy, phylogenetic clustering, and cophylogeny. We defined monophagy strictly as one species feeding exclusively upon a single host plant species (an association likely driven by arms races in morphology, chemical resistance/tolerance, and visual appearance) and observed this in 7 of 22 aphid species. In all the remaining ‘polyphagous’ cases, there was a strong trend toward monophagy (80% of individuals were found on a single host plant species). Second, we observed two separate examples of phylogenetic clustering where groups of closely related aphid species fed upon individual plant species. Finally, we found no support for cophylogenetic relationships where both aphids and plants cospeciate to form congruent phylogenetic trees (evidence of coadaptation through an ongoing arms race). One explanation for uncovering species-specific interactions in a recently deglaciated, subarctic locality is that the species involved in the associations moved north together. Testing different levels of specificity in the most predominant species–species interactions on the planet will allow us to elucidate these patterns accurately and gives us insight into where to direct future research.

The importation and establishment of Coccinella septempunctata L. (Coleoptera: Coccinellidae) in North America purportedly caused the displacement and local extirpation of the native ninespotted lady beetle, Coccinella novemnotata Herbst (Coleoptera: Coccinellidae), across most of its former range, and several reports have shown that C. septempunctata maintains competitive advantages over C. novemnotata. We investigated the role of aphid density on the retention time of these two species on fava bean plants, and the effect of con- versus heterospecific pairings of adult beetles on the foraging behavior of C. novemnotata. We found that aphid density did not affect C. novemnotata's retention time, but did affect the retention time of C. septempunctata, which left plants without aphids significantly faster than C. novemnotata. Additionally, C. septempunctata females left plants significantly faster than their male counterparts, whereas we observed no difference between the two sexes for C. novemnotata. Our test of pairs of beetles showed that C. novemnotata were together on plants more frequently than conspecific pairs of C. septempunctata and heterospecific pairs of beetles, and that all beetles were more likely to be found together on the aphid-infested plant versus the non-infested plant regardless of the pairs' composition. These results show that C. novemnotata spend more time foraging for aphids when aphids are scarce compared with C. septempunctata, and that C. novemnotata is less tolerant of occupying plants inhabited by C. septempunctata versus a conspecific beetle, adding additional mechanisms whereby C. septempunctata could outcompete C. novemnotata in the field.

The pea leaf weevil (PLW), Sitona lineatus L., is a pest of field pea (Pisum sativum L.) and faba bean (Vicia faba L.) that recently invaded the Canadian Prairie Provinces. Although most damage is done by larvae that feed on root nodules, adults are easier to monitor than larvae. Both male and female weevils respond to a male-produced aggregation pheromone and to volatiles released by host plants. The current study tests the attractiveness of synthetic aggregation pheromone, 4-methyl-3,5-heptanedione, and host plant volatiles linalool, (Z)-3-hexenol, and (Z)-3-hexenyl acetate to PLWs in spring when weevils are reproductively active and in fall when weevils seek overwintering sites. Different combinations of semiochemical lures at various doses, released from a variety of devices were tested in pitfall traps. Semiochemical-baited traps captured both male and female weevils in both seasons but the sex ratio varied with season. Weevils did not respond in a dose-dependent manner to pheromone, as all pheromone lures were equally attractive. Pheromone release rate was determined by the release device and not the pheromone dose in the lure. The addition of plant volatiles sometimes increased weevil captures but plant volatiles alone were not attractive to PLW adults. An additional study tested the effect of trap type on weevil capture. Of the 12 different trap types tested, pheromone-baited pitfall traps were most successful in attracting and retaining weevils. Bycatch of other Sitona species was limited to a few specimens of the sweet clover weevil, Sitona cylindricollis Fahraeus.

Delta- and bucket-style (Universal or Unitrap) traps baited with 1 standard survey lure and 1/3 and 3 lures were compared for their attractiveness and trapping efficiencies for gypsy moth, Lymantria dispar L. (Lepidoptera: Erebidae), males. With bucket traps, the numbers of males attracted to within 2 m of traps and the proportion of these actually captured were identical among the three doses although the percentage of attracted males actually captured in bucket traps was low, less than 15%. A three-lure delta trap attracted about 70% more males than traps with the two lower doses. Capture efficiencies were above 80% for 1/3- and one-lure traps and about 60% for traps baited with three lures. The number of males captured in delta traps was equivalent for the three doses although our observations also suggest that a delta trap baited with three lures drew males from a wider range than lower dose lures and therefore would be a more sensitive trap for detecting incipient populations. We also noted that males tended to arrive in clusters, suggesting that attraction over moderate distances requires periods when the wind direction is fairly constant. This observation coupled with the great variability in the direction of male arrival to the traps also suggests that important changes in the area of influence of the plume are driven in such forested areas by slower but greater changes in wind direction compared with open habitats.

Nine herbivore-induced plant volatiles (HIPVs) and one methyl jasmonate were field-tested for their attractiveness to the main predators in cotton fields of North China in 2 yr. The main predators including ladybird beetles (Propylaea japonica (Thunberg), Harmonia axyridis (Pallas)), green lacewings (Chrysoplera sinica (Tjeder), Chrysopa spp.), predatory bugs (Geocoris pallidipennis (Costa), Orius spp., Nabis spp.) and spiders (Misumenops tricuspidatus (Fabricius), Erigonidium graminicolum (Sundevall)) were investigated. Two-way ANOVA indicated that the volatile compound, year, and the volatile compound × year interaction affected the behavioral responses of predators. It was found that indole significantly attracted the ladybird beetle P. japonica, H. axyridis. Linalool could attract P. japonica. Green lacewing C. sinica was significantly attracted by α-pinene and β-pinene, whereas indole significantly attracted Chrysopa spp. Methyl jasmonate and α-pinene showed significant attraction to small-flower bug Orius spp. In addition, the attraction of α-humulene to C. sinica, attractiveness of β-pinene to Orius spp. and Chrysopa spp., were observed only in one of the two years. However, the big-eyed bug G. pallidipennis, damsel bug Nabis spp., spiders M. tricuspiata and E. graminicolum did not respond to any of the tested HIPVs. These results are discussed with respect to possible applications of a synthetic attractant for main predators in cotton fields.

Emerald ash borer (EAB) (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), an invasive phloem-feeding buprestid, has killed hundreds of millions of ash (Fraxinus spp.) trees in the United States and two Canadian provinces. We evaluated EAB persistence in post-invasion sites and compared EAB adult captures and larval densities in 24 forested sites across an east–west gradient in southern Michigan representing the Core (postinvasion), Crest (high EAB populations), and Cusp (recently infested areas) of the EAB invasion wave. Condition of green ash (Fraxinus pennsylvanica Marsh) trees were recorded in fixed radius plots and linear transects in each site. Ash mortality was highest in Core sites in the southeast, moderate in Crest sites in central southern Michigan, and low in Cusp sites in the southwest. Traps and trap trees in Crest sites accounted for 75 and 60% of all EAB beetles captured in 2010 and 2011, respectively. Populations of EAB were present in all Core sites and traps in these sites captured 13% of all beetles each year. Beetle captures and larval densities at Cusp sites roughly doubled between 2010 and 2011, reflecting the increasing EAB populations. Sticky bands on girdled trees captured the highest density of EAB beetles per m² of area, while baited double-decker traps had the highest detection rates and captured the most beetles. Larval densities were higher on girdled ash than on similar ungirdled trees and small planted trees. Woodpecker predation and a native larval parasitoid were present in all three invasion regions but had minor effects on ash survival and EAB densities.

The redbanded stink bug Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae) is an invasive stink bug species in the United States. First documented as a soybean pest in Louisiana in the year 2000, this species continues to spread in the Mid-South region of the United States. We designed laboratory and field studies to investigate supercooling points, lethal exposure time (LT), critical thermal minimum (CT_min), and winter mortality of this species. The mean supercooling points (SCP) ± SE of adult field collected P. guildinii ranged from −8.3 ± 0.2°C (highest) in March to −11.0 ± 0.2°C (lowest) in January. Significant differences in SCP occurred over the months and between sexes with significant interactions between month and sex. The CT_min was significantly different between adults and nymphs (third, fourth, and fifth instars combined). LT₅₀ and LT₉₀ were evaluated at subzero temperatures of 0°C, −2°C, and −5°C. There were significant differences in LT₅₀ and LT₉₀ among the temperature treatments. Winter survival significantly differed between the two study years and decreased with progression of winter months.

The application of ultraviolet-B (UVB) radiation to control spider mites is challenging as a key technology for integrated pest management (IPM) in greenhouse strawberries in Japan. To address this, concurrent use of phytoseiid mites and reduced UVB irradiance is desirable to ensure control effects in areas shaded from UVB radiation and to minimize the sunscald in winter, respectively. We designed experiments reproducing the UVB dose on the lower leaf surfaces in strawberry and evaluated the effects of intermittent UVB irradiation at midnight for practical application in the greenhouse and low temperature on the survival of the spider mite Tetranychus urticae Koch (Acari: Tetranychidae) and damage to the phytoseiid mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). The midnight intermittent UVB irradiation effectively suppressed egg hatching and development of larvae of T. urticae, and the control effect was reinforced at 20°C (no eggs hatched at 0.13 kJ m⁻² d⁻¹) rather than, at 25°C (70.8% eggs hatched). In contrast, the hatchability of N. californicus eggs was unaffected by intermittent UVB irradiation at 0.27 kJ m⁻² d⁻¹ at 25°C and 20°C. However, residual effects of UVB irradiation to N. californicus eggs on survival of hatched larvae were seen, so that reducing the UVB dose is also advantageous for this phytoseiid mite. N. californicus showed a photoreactivation capacity, whereas their UVB tolerance was improved by prey species, suggesting the possibility of the improvement of phytoseiid mites by diet. The reduction of UVB dose and concurrent use of phytoseiid mites increase reliability of the UVB method in IPM strategies in strawberry greenhouse.

The bamboo mosquito, Tripteroides bambusa (Yamada) (Diptera: Culicidae), is a common insect across forested landscapes in Japan. Several studies have reported its overwintering as larvae and eggs, in both natural and artificial water containers. Nevertheless, it is unclear how sensitive this mosquito species is to changes in weather patterns associated with global warming. The El Niño event of 2015 through 2016 was one of the strongest on record and provided an ideal scenario for observations on the overwintering of the bamboo mosquito during a winter predicted to be unusually warm. Thus, we set oviposition traps in mid October 2015 and made weekly observations, from December 2015 to May 2016, on bamboo mosquito larval recruitment and pupation in Nagasaki, Japan. We found that larvae were pupating as late as the first week of January (prior records from the study site indicated mosquito pupation ended by mid-late October) and that pupation resumed in mid April (one month earlier than previous records at the study site). We also found that fourth instar larvae were able to survive in frozen oviposition traps following an extremely unusual snowstorm and cold spell and that recruitment of larvae from eggs happened after this unusual event. Our analysis suggested that overwintering and metamorphosis of the bamboo mosquito is sensitive to average and extreme temperatures, the latter measured by temperature kurtosis. Our results highlight the need to better understand changes in overwintering strategies in insects, and associated trade-offs and impacts on population dynamics, in light of climate change.

Edible insects have become a recognized alternative and sustainable source of high-quality proteins and fats for livestock or human consumption. In the production process of black soldier fly (BSF), (Hermetia illucens L. [Diptera: Stratiomyidae]), initial substrate pH is a critical parameter to ensure the best value of insect biomass, life history traits, and quality bio-fertilizer. This study examined the impact of initial pH values on BSF larvae production, development time, and adult longevity. The BSF were reared on artificial diet with initial pH of 2.0, 4.0, 6.0, 8.0, and 10.0; the control was set at 7.0. Final BSF larval weight was significantly greater in substrates having initial pH 6.0 (0.21 g), control 7.0 (0.20 g), and 10.0 (0.20 g) with no significant difference among them, whereas larval weight reared with initial pH 2.0 and 4.0 were lowest at 0.16 g (−23%). Prepupal weight was greatest when larvae were reared on substrates with initial pH 6.0 (0.18 g), control 7.0 (0.19 g), 8.0 (0.18 g), and 10.0 (0.18 g). In contrast, the prepupal weight of larvae reared on diets with initial pH 2.0 was lowest at 0.15 g (−22%). Larval development time was 21.19 d at pH 8.0, about 3 d (12.5%) shorter than that of those reared on diets with initial pH 6.0, 7.0 control, and 10.0. In all treatments, pH shifted to 5.7 after 3–4 d and 8.5 after 16–17 d except for two groups (2.0 and 4.0) where the pH remained slightly acidic 5.0 and 6.5, respectively.

Drosophila suzukii (Matsumura; Diptera: Drosophilidae) is a key pest of sweet cherry and small fruits worldwide. The present studies were designed to describe the reproductive physiology in both sexes, through dissections of their reproductive organs. We extensively dissected female D. suzukii throughout the season from 2013 to 2016 and classified the reproductive status flies based on five recognizable ovarian maturation stages: 1) no ovaries; 2) unripe ovaries 3) ripening eggs in ovarioles; 4) mature eggs in ovarioles; and 5) mature eggs in the abdomen. Development was examined as a function of calendar days as well as degree-days (DD). Results obtained from winter collections revealed that females collected from November to March contained a lower percentage of mature eggs than females collected from April to September. These data suggest that environmental conditions during the dormant period induce reproductive diapause. Oogenesis likely increased with an increase in mean monthly temperatures and DD. The first overwintered females with mature eggs were dissected as early as 21 February 2014 in Trento (7 DD). Additionally, we found that a low proportion of males (less than 50%) had sperm in their testes between January and March, yet during the same period females already have sperm stored in their spermathecal. Ivy berries was an alternative but unfavorable non-crop host during the late dormant period, as evidenced by emergence of smaller adults when compared to individuals emerging from cherry fruits. This study showed that D. suzukii females have great potential for oviposition early in the season, posing a risk to early season maturing crop hosts.

Dormancy strategies, including diapause and quiescence, enable insects to evade adverse conditions and ensure seasonally appropriate life stages. A mechanistic understanding of a species' dormancy is necessary to predict population response in a changing climate. Climate change is influencing distribution patterns and population success of many species, including Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), the most important mortality agent of pines in western North America. Diapause is considered absent in D. ponderosae, and quiescence in the final larval stage prior to pupation (i.e., prepupal) is considered the main dormancy strategy. We evaluated if a facultative diapause in the prepupal stage, rather than a pupation threshold ∼15°C (i.e., quiescence), could describe pupation patterns in two latitudinally separated D. ponderosae populations in the western United States. We hypothesized that if pupation occurs at lower temperatures than previously described, and if significant prepupal developmental delays occur, diapause is a likely physiological mechanism. Although there was considerable variation within and between populations, pupation occurred below the previously established threshold suggesting a prepupal facultative diapause that is induced when late instars experience cool temperatures. Individuals that pupated at temperatures below 15°C also had developmental delays, relative to development at warmer temperatures, consistent with diapause development. Pupation patterns differed between populations wherein diapause was induced at cooler temperatures and diapause development was shorter in southern compared with northern D. ponderosae. Recognition of a facultative diapause that varies among and between populations is critical for making predictions about future population response and range expansion in a changing climate.

Coevolution is a major driver of speciation in many host-associated symbionts. In the termite-protist digestive symbiosis, the protists are vertically inherited by anal feeding among nest mates. Lower termites (all termite families except Termitidae) and their symbionts have broadly co-diversified over ∼170 million yr. However, this inference is based mainly on the restricted distribution of certain protist genera to certain termite families. With the exception of one study, which demonstrated congruent phylogenies for the protist Pseudotrichonympha and its Rhinotermitidae hosts, coevolution in this symbiosis has not been investigated with molecular methods. Here we have characterized the hindgut symbiotic protists (Phylum Parabasalia) across the genus Zootermopsis (Archotermopsidae) using single cell isolation, molecular phylogenetics, and high-throughput amplicon sequencing. We report that the deepest divergence in the Zootermopsis phylogeny (Zootermopsis laticeps [Banks; Isoptera: Termopsidae]) corresponds with a divergence in three of the hindgut protist species. However, the crown Zootermopsis taxa (Zootermopsis angusticollis [Hagen; Isoptera: Termopsidae], Z. nevadensis nevadensis [Hagen; Isoptera: Termopsidae], and Z. nevadensis nuttingi [Haverty & Thorne; Isoptera: Termopsidae]) share the same protist species, with no evidence of co-speciation under our methods. We interpret this pattern as incomplete co-cladogenesis, though the possibility of symbiont exchange cannot be entirely ruled out. This is the first molecular evidence that identical communities of termite-associated protist species can inhabit multiple distinct host species.

Glutathione S-transferases (GSTs) in insects are widely known for their role in the detoxification of both endogenous and xenobiotic compounds. Grape phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera: Phylloxeridae) is a serious grape pest, which causes great economic damage in vineyards, and has currently spread throughout the world. In this study, eight putative GST genes were identified by analyzing the transcriptomes of grape phylloxera. Phylogenetic analyses showed that there are seven cytosolic DviGSTs and one microsomal DviGST. These cytosolic DviGSTs are clustered into four different classes including two delta genes, one omega gene, one theta gene, and three sigma genes. Among candidate cytosolic DviGSTs, a conserved N-terminal domain and a less conserved C-terminal domain were identified. For the candidate microsomal DviGST, three transmembrane regions were predicted. Multiple sequence alignment analysis of the candidate microsomal DviGST was conducted with other insect microsomal GSTs and the result showed that there is a conserved sequence pattern. Semiquantitative polymerase chain reaction was used to examine the tissue expression of these transcripts, and the results revealed that DviGSTs were ubiquitously expressed in the head and the body, but DviGSTd1, DviGSTd2, DviGSTs2, and DviGSTs3 were abundantly expressed in the head and body. This is the first study of the molecular characteristics of GST genes in grape phylloxera. Our results will provide a molecular basis for future studies of the detoxification mechanisms in grape phylloxera.

Anthropogenic climate change and global warming are expected to alter the geographic distribution and abundance of many ectothermic species, which will increase the invasion of new areas by exotic species. To survive in variable or fluctuating temperature conditions, insects require sensitive thermal sensory mechanisms to detect external thermal stimuli and induce the appropriate behavioral and physiological responses. TRPA, a thermal-activated transient receptor potential (TRP) family ion channel, is essential for thermotaxis in insects. Here, we investigated the potential role of BtTRPA in short-term and long-term thermal stress in Bemisia tabaci Mediterranean (Gennadius; Hemiptera: Aleyrodidae). We found that BtTRPA was mainly expressed in the head, where the antennae are located. Under short-term thermal stress, the BtTRPA gene was robustly expressed after exposure to acute low or high temperatures, BtTRPA expression reached the highest levels after exposure to 0°C for 3 h and 40°C for 5 h, but was relatively low after exposure to milder stimuli (12 and 35°C). These results demonstrated that BtTRPA could discriminate between innocuous and noxious temperature stimuli. Under long-term thermal stress, the highest expression level of BtTRPA occurred at G1 exposed to mild innocuous temperature of 21 and 31°C, along with BtTRPA sharply increased and peaked in adult females, implying that mild innocuous long-term thermal exposure could cause transgenerational expression effects to enhance the ability of offspring to cope with the same stress. This study demonstrates that the channel BtTRPA is important in temperature sensing and provides a molecular basis for thermosensation regulation in response to varied environmental temperature in B. tabaci Mediterranean.

In this review, we evaluate the intentional mixing or blending of insecticidal seed with refuge seed for managing resistance by insects to insecticidal corn (Zea mays). We first describe the pest biology and farming practices that will contribute to weighing trade-offs between using block refuges and blended refuges. Case studies are presented to demonstrate how the trade-offs will differ in different systems. We compare biological aspects of several abstract models to guide the reader through the history of modeling, which has played a key role in the promotion or denigration of blending in various scientific debates about insect resistance management for insecticidal crops. We conclude that the use of blended refuge should be considered on a case-by-case basis after evaluation of insect biology, environment, and farmer behavior. For Diabrotica virgifera virgifera, Ostrinia nubilalis, and Helicoverpa zea in the United States, blended refuge provides similar, if not longer, delays in the evolution of resistance compared to separate block refuges.