The foxglove aphid, Aulacorthum solani (Kaltenbach), is a major economic pest in Asian soybean fields. Previous studies on its life parameters often used detached soybean leaves, which may not accurately reflect development and reproduction due to disrupted nutrient flow. This study compared survival, development, and reproduction of A. solani on living versus detached leaves at 19, 22, 25, 28, 31, and 34 °C. Between 19 and 28 °C, aphids developed and reproduced successfully on both leaf types. At 31 °C, nymphs failed to mature on detached leaves but reached adulthood on living leaves, though no nymphs were produced. At 19, 22, and 25 °C, fecundity and net reproductive rate were overestimated on detached leaves. At 28 and 31 °C, adult longevity, total longevity, oviposition day, fecundity, intrinsic and finite rates of increase, and net reproductive rate were underestimated on detached leaves. The mean developmental rate (y, reciprocal of nymph duration) on living leaves in relation to temperature (x) follows the equation y = 0.0088 x-0.0717. The lower developmental threshold is 8.15 °C, and the effective cumulative temperature required for nymph-to-adult development is 113.64 degree-days. On detached leaves, the equation y = 0.0055 x + 0.0043 yields an invalid threshold of -0.78 °C and 181.82 degree-days. These findings underscore the necessity of using living soybean leaves for accurate life table studies of A. solani, critical for predicting field populations and improving control strategies.
Insects represent a major component of terrestrial biodiversity and ecosystem function, yet the environmental drivers of occurrence and detection remain poorly understood for many ground-dwelling taxa. Environmental gradients can influence both whether insect taxa occupy habitats and how frequently they are detected during sampling. Rhaphidophoridae (cave crickets) are moisture-dependent, ground-dwelling orthopterans associated with caves, rock crevices, and forest-floor refuges. Here, we used occupancy models that account for imperfect detection to examine how habitat structure and elevation influence detection and occupancy probabilities of Rhaphidophoridae across 75 sites, each measuring 1 hectare, in Hidalgo, Mexico. Rhaphidophoridae were present in 33 of 75 sites. The best supported model indicated that detection probability increased with forest-associated habitat structure (tree and shrub cover, deep leaf litter, refuge availability, and low disturbance), whereas occupancy probability increased with elevation. Herbaceous cover did not predict occupancy but was negatively associated with detection. These findings suggest that broad environmental gradients constrain occurrence, whereas detectability is associated with forest structure and lower human disturbance. Our study provides new ecological data on Rhaphidophoridae in Mexico and demonstrates how distinguishing between drivers of occupancy and detection can improve ecological inference from field surveys.
Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae) is an invasive wood-boring beetle that primarily infests Acer rubrum L. (Sapindales: Sapindaceae) in North America. The first signs of infestation in a host tree are oviposition pits indicating female beetles have attempted to place eggs in the phloem; however, the presence of oviposition pits does not always guarantee the presence and survival of eggs or larvae, and little is known about the relative success of beetle oviposition. To better understand A. glabripennis oviposition and early larval survival, we infested A. rubrum in a common garden environment. We conducted daily observations and destructively harvested these trees to analyze oviposition pit occupation, egg viability, and early larval survival, and compared patterns of oviposition success and survival with field-collected material from naturally infested host trees in the surrounding environment. Oviposition pits on field-collected material were also examined to explore potential links between host tree characteristics and A. glabripennis oviposition success. Our results support previous findings that fecundity is highly variable among individuals, that A. glabripennis oviposition pits were most commonly observed on host material with intermediate sized diameters (6 to 15 cm) and textured bark, and oviposition pits were often chewed without depositing an egg. Oviposition pit occupation, egg viability, and early larval survival were significantly lower on host trees in the common garden environment relative to naturally infested field material. Understanding oviposition and early survival and how host tree characteristics can impact fecundity can help improve detection and more efficiently utilize resources dedicated to invasive species management.
Drosophila suzukii (Matsumura), known as spotted-wing drosophila, is an invasive fruit fly that lays their eggs in soft-skinned fruits with its serrated ovipositor. In this study, we evaluated the effects of oviposition and residence behavior of D. suzukii by two saturated fatty acids (FAs): palmitic acid (C16:0) and stearic acid (C18:0). Both FAs were identified from a novel D. suzukii attractant, Decoy Attract and Kill, using gas chromatography-mass spectrometry and liquid chromatography-high resolution mass spectrometry. The FAs were then tested for their potential to alter oviposition in laboratory trials on blueberry with different concentrations and ratios to determine the optimal behavioral effects. We examined whether exposure to these FAs increased post-contact residence time and altered oviposition behavior. Exposure to 6.62 mg/L C16:0 and 3.61 mg/L C18:0 showed the strongest contact-mediated arrestment, resulting in increased oviposition on FA-treated blueberries. Females exposed to a 2:1 ratio of C16:0:C18:0 showed the greatest contact-dependent arrestment, followed by the 1:1 ratio, C16:0, and C18:0 alone. Additionally, we confirmed that both FAs act in a contact-dependent manner, increasing oviposition behavior after landing. Both C16:0 and C18:0 are effective contact-based arrestants that have the potential to protect soft-skinned fruits from D. suzukii oviposition damage.
Agricultural intensification and an associated reduction of in-field plant diversity have reduced the availability of essential resources needed by beneficial arthropods. Consequently, this has contributed to declines in insect abundance, diversity, and biological control services while shifting the balance in favor of insect pests. Field studies were conducted to investigate the influence of conservation tillage in concert with an interplanted living mulch and/or cover crop residue on arthropod natural enemy abundance and biological control services in sweet corn (Zea mays L.). Treatments included 1 conventional tillage treatment (1) and 3 no-till treatments with different cover crops (2 to 4): (2) cover crop residue, (3) living mulch + cover crop residue, and (4) living mulch + winter-killed residue. All cover crop diversified sweet corn contained a greater abundance of arthropods than conventional till (bare-ground). However, beneficial arthropod numbers varied according to arthropod community and sampling method. For illustration, a greater number of beneficial arthropods were detected on sticky cards in the living mulch + winter-killed residue treatment compared to the no-till with cover crop residue. Within the epigeal community, more beneficials were captured in pitfall traps within the living mulch + cover crop residue treatment compared to conventional till. Still, herbivore damage to sweet corn ears was similar among treatments each study year. Overall, the living mulch treatments tended to attract a greater abundance of beneficial insects, though this did not result in a reduction in ear-feeding damage by herbivorous pest insects.
Loss of floral resources and pesticide exposure are key drivers of wild pollinator declines. Synergistic interactions between pesticides and poor nutrition may exacerbate individual effects, but how these anthropogenic stressors interact remains poorly understood, particularly across understudied life phases. Queen bumblebees in temperate regions emerge from hibernation in spring and attempt to initiate a colony. In agricultural environments, queens typically emerge during (i) a carbohydrate "hunger gap," whereby nectar demand is higher than supply and (ii) during a time of year in which pesticide use is high. Here, we assessed the impact of carbohydrate limitation and exposure to the novel insecticide flupyradifurone on colony initiation of wild-caught bumblebee (Bombus terrestris) queens. Using a fully crossed experimental design, queens were exposed to a field-realistic concentration of flupyradifurone (1.6 ppm) at high (50% (w/w)) or low (15% (w/w)) sucrose concentrations. We found that bees provided with low-sucrose concentrations produced no eggs or larvae compared with 31.6% in the high concentration groups. Queens fed a lower concentration of sucrose also developed smaller ovaries and performed less nest initiation behaviors. We also found that exposure to flupyradifurone increased the activity of bumblebee queens, and that carbohydrate limitation and flupyradifurone synergistically reduced the likelihood of nest initiation behavior. These results demonstrate the importance of carbohydrate intake during the spring when queens are founding colonies, highlighting the need to consider not only floral diversity within environmental land management schemes but also floral quality.
Ants engage in both antagonistic and mutualistic interactions with honeydew-producing Sternorrhynchan insects, depending on the species involved and the ecological context. Ant foraging can also influence the abundance of insect herbivores and their associated natural enemies. A 2-yr field experiment (2023-2024) was conducted to evaluate the effects of ant exclusion on pecan aphids (yellow pecan aphid complex and black pecan aphid) and their associated natural enemies (lady beetles, lacewings, and long-legged flies) at 3 canopy heights (upper, middle, and lower). Seasonal trends in aphid abundance were generally similar between treatments across both years, and on most sampling dates; no treatment effects were detected for aphids or aphidophagous predators. However, on specific sampling dates, aphid abundance was lower in ant-excluded trees, and peak ant activity coincided with the aphid activity, suggesting that the strength of ant-aphid interactions varies with aphid population density. In contrast, parasitized aphid mummies were significantly more abundant on control trees in 2023. It was found that lady beetle and lacewing activity was higher and coincided with the peak activity during July and August. Additionally, long-legged flies were more abundant in ant-excluded trees during 2023 and were influenced by canopy height in both years. Collectively, these results indicate that ant exclusion can influence aphid-natural enemy interactions in pecan orchards, but these effects are episodic, natural enemy-specific, and variable by growing season.
The sorghum aphid, Melanaphis sorghi (Theobald) (Hemiptera: Aphididae), is an economically important pest of grain sorghum, Sorghum bicolor (L.), in the Southern and Central US Great Plains where biological control by natural enemies may be an important contributor to its management. We measured M. sorghi population growth rate (rt-to) on a M. sorghi susceptible (KS-585) and a resistant (DKS37-07) sorghum hybrid in replicated natural enemy exclusion cages during three growing seasons from 2019 to 2021. In a second experiment, we modeled rt-to against natural enemy population intensity data obtained from fields of KS-585 across 3 seasons 2021 to 2023. In the exclusion cage experiment, the rt-to was significantly greater on sorghum plants in complete exclusion cages than in partial exclusion cages and on uncaged plants in 2019 and 2021 but not in 2020. For the second experiment, linear regression models for groupings of natural enemies were not significant except the model for adult coccinellids, where the slope was -43.72, indicating a reduction in M. sorghi population growth rate with increasing adult coccinellid population intensity. Results are discussed in terms of mechanisms that might explain M. sorghi population suppression by natural enemies in grain sorghum.
Coreidae (Hemiptera: Heteroptera) are an important component of phytophagous insect communities in tropical forests, particularly in tropical deciduous forest (TDF) ecosystems. These forests are characterized by high environmental heterogeneity, limited ecological knowledge, and high susceptibility to disturbance. In this study, we analyzed Coreidae communities collected over 3 yr in 3 localities with TDF within the Biosphere Reserve Sierra de Huautla, Morelos, Mexico. We evaluated whether (i) alpha and beta diversity varied among localities, (ii) spatial beta diversity between sites was associated with woody plant beta diversity, and (iii) temporal beta diversity was related to precipitation and temperature. A total of 2,344 individuals belonging to 58 species were recorded. Five species accounted for 70% of the total abundance and were present during most of the year across the 3 localities. Alpha diversity differed among localities and was associated with precipitation levels. Spatial beta diversity was explained by species turnover and showed no relationship with woody plant beta diversity. Temporal variation in climatic conditions, particularly precipitation, was associated with changes in Coreidae diversity. These results highlight the importance of spatial and seasonal environmental variation in shaping Coreidae community composition in TDFs. These findings emphasize the ecological importance of habitat complexity and seasonal variation in maintaining Coreidae diversity in these forests.
Hybridization, or interbreeding between 2 previously diverged populations, is increasing due to human influences on the environment through creating new niches and enhancing hybrid fitness. Rates of hybridization might be increasing particularly quickly among urban species, especially those that are known to be sensitive to environmental disturbances. Butterflies are one such taxa, as some species are commonly found in urban areas, despite being sensitive indicators of environmental variation. For example, Colias philodice Godart and C. eurytheme Boisduval (Lepidoptera: Pieridae) hybridize when their ranges are in contact or overlap and are commonly found in large cities throughout North America. However, it is an open question how variation in urbanization might affect variation in hybridization. Using wild Colias across a gradient of urbanization in Toronto, Ontario, we tested how the variation in Colias color, as an indicator of hybridization, relates to human disturbance and urbanization. We created an objective numeric classification for both C. eurytheme and C. philodice, against which we categorized Colias samples. We found that some of the metrics, including distance to road, ordinal date, and number of pedestrians affect the variation in Colias color, suggesting that urbanization affects Colias coloration, and potentially rates of hybridization, in Toronto. This means that human disturbance of the environment could be affecting Colias rates of hybridization.
Invasive ants often exert strong negative effects on native ant assemblages and other invertebrates through strong resource monopolization and chemical defense. Removal of an invasive ant may therefore promote recovery of local biodiversity. However, evidence for such effects is mixed, and often taxon-specific. In this study, we experimentally removed Pheidole megacephala (Hymenoptera: Formicidae) from 2 secondary forest sites at located at Taiping (TP) (herein referred to as TP1 and TP2) and examined the taxon-specific responses of native ants, beetles, and spiders under field conditions. Removal of P. megacephala had limited effects on ant species richness and Shannon diversity. In contrast, beetle family richness at TP1 increased significantly during the first year of posttreatment compared with pretreatment levels. Several native ant species (eg Carebara diversa, Recurvidris recurvispinosa, and Solenopsis indagatrix) and predatory beetle taxa (Harpalinae, Cetoniinae, Paederinae, and Staphylininae) that were absent before treatment were detected following P. megacephala removal. Spider family richness declined during the second year of posttreatment at TP2, whereas the activity density of hunting spiders, particularly Ctenidae, Oonopidae, and Salticidae, increased approximately 2-fold at TP1 after removal. These native ants, predatory beetles, and hunting spiders that responded positively to removal share similar food resources or overlapping nesting and foraging habitats with P. megacephala. Our results suggest that removal of this invasive ant may have facilitated partial recovery of the local invertebrate community, particularly taxa that are ecologically and behaviorally similar to P. megacephala, likely by releasing food and spatial resources.
Xyleborus monographus (Fabricius, 1792), the Mediterranean oak borer, is an ambrosia beetle native to the Euro-Mediterranean region, western Asia, and North Africa. Its recent establishments in California (2017) and Oregon (2019), United States, have been linked to rapid mortality of seemingly healthy, mature Quercus species, raising concern for oak-dominated ecosystems in North America. Despite the potential implications of this emerging threat, X. monographus remains poorly studied. The only in-depth account of its biology and ecology dates to 1964. Beyond that, references are scattered across gray literature, regional journals, and diverse linguistic sources, leaving researchers and land managers without a centralized foundation from which to respond to its spread in North America. Here, we synthesize 124 primary and secondary sources spanning more than 140 yr, including translated works, recent regional detections, and observations from active infestations. We consolidate all available information on X. monographus, including taxonomy, distribution, microbiome, life history, host associations, and ecological impacts. Across the literature, X. monographus emerges as a species likely adapted to detecting and exploiting weakened hosts in patchy landscapes with few tested management options. We highlight areas of consensus, identify knowledge gaps, and contextualize challenges for interpreting existing data. As land managers and researchers begin to confront the consequences of this invasion, this review provides the foundation for future research, monitoring, and management of X. monographus in North America.
Pathogen spread is a major driver of wild and managed bee decline, with shared floral resources often serving as transmission hubs. However, the abundance of floral resources changes throughout the season, potentially altering bee visitation rate per flower. This could affect pathogen transmission by influencing both the likelihood of pathogen deposition on flowers and of new hosts encountering pathogens. We assessed the effect of peak bloom timing on transmission of a bumble bee (Bombus impatiens Cresson) (Hymenoptera: Apidae) pathogen (Crithidia bombi Lipa & Triggiani) in a 2-wk tent experiment. We manipulated floral abundance using Monarda fistulosa L to provide more flowers either in the first week (early peak bloom) or second week (late peak bloom). Each tent received 1 infected (donor) and 1 uninfected (recipient) microcolony. We recorded floral visitation, and after 2 wk, assessed infection prevalence and intensity in both microcolonies. We found that peak bloom timing affected donor bee infection, but not transmission to recipient bees. Donor infection intensity was lower when bees had more flowers available early than late in the experiment. However, peak bloom timing did not affect the probability of infection in donor or recipient microcolonies, or the intensity of infection of recipient microcolonies. Furthermore, donor probability of infection and recipient infection intensity were positively related to inflorescence visitation rates in the second week. These results suggest that peak bloom timing could influence bee-pathogen dynamics by altering visitation rates per flower, highlighting the importance of phenological changes in plant-pollinator interactions for pollinator health.
Bacterial endosymbionts are ubiquitous in insects and play a critical role in host ecology, including adaptability to thermal extremes. The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is a major agricultural pest in China that harbours diverse microbial symbionts. However, the contribution of Arsenophonus, a key secondary symbiont in A. gossypii, to the host's thermal tolerance remains poorly understood. In this study, we used antibiotics to eliminate Arsenophonus from A. gossypii and evaluated the effects on host thermal tolerance by comparing the life-history traits of an Arsenophonus-infected line (A-infected) and an antibiotic-cured, Arsenophonus-deleted line (A-deleted) across a temperature gradient (26-35 °C). Our results revealed that while host performance declined for both lines as temperatures increased, the magnitude of these fitness costs was significantly modulated by infection status. No significant differences in fitness parameters were observed at 26 °C or 29 °C. Furthermore, at 32 °C, the A-infected line exhibited significantly extended adult longevity compared with the A-deleted line. Under extreme heat stress (35 °C), the infected line surpassed the cured line in both longevity and fecundity. These results confirm the dependency of A. gossypii on Arsenophonus for a conditional fitness advantage at high temperatures, effectively broadening its thermal niche. Ultimately, this symbiont-mediated heat tolerance provides new insight regarding the ecological resilience and population stability of this pest in warming agricultural environments.
The work reported here summarizes research on the seasonal and diel activity periods of adult males of 3 click beetle species native to North America. Seasonal activity was assessed using panel traps baited with synthesized attractants that captured 50 males of Gambrinus griseus (Palisot de Beauvois), 397 males of its congener G. rudis (Brown) (tribe Dendrometrinae), and 131 males of Melanotus similis (Kirby) (Elaterinae). Flight periods of all 3 species were generally unimodal and confined to the summer months. Diel activity periods were assessed with attractant-baited panel traps fitted with collection jars that rotated at intervals of 1 to 2 h. These timer traps captured 38 male G. griseus, 355 male G. rudis, and 67 male M. similis. Males of G. griseus and M. similis were primarily nocturnal, with most flying between 6 PM and 12 AM. In contrast, the diel flight period of G. rudis appeared bimodal, with males being trapped late at night, and from dawn to late morning. Incomplete field data for another 2 elaterid species revealed that adults of Agriotes insanus Candèze (Agriotini) (N = 99) flew earlier than all the previous species, with all 99 specimens trapped during April, and males of Melanotus sagittarius (LeConte) were nocturnal, being trapped between 10 PM and 12 AM (N = 26).
Amauromyza karli Hendel (Diptera: Agromyzidae) has recently emerged as a damaging stem-boring pest of quinoa in Colorado and other quinoa-producing regions of the United States. Severe infestations have been associated with substantial yield losses, highlighting the need for improved understanding of the pest's seasonal dynamics to support integrated pest management (IPM) strategies. The objective of this study was to characterize the seasonal phenology of A. karli in quinoa production systems in the San Luis Valley of Colorado. Adult flight activity was monitored using yellow sticky traps over 4 growing seasons, and larval incidence and stem exit holes were quantified across 2 years. Our results indicated that larval densities peaked in early June with infestations reaching over 90% by mid-July. An ordinal-day, 2-parameter logistic model based on cumulative trap captures was the most parsimonious model and predicted that 50% of adult activity occurred around late June. In addition, a negative binomial mixed-effects model showed no significant association between quinoa field size and adult captures, suggesting that variation in pest pressure is driven by field-level heterogeneity and temporal factors. These findings provide a framework for improving monitoring and management of A. karli. Aligning the timing of biological or chemical control measures with periods of peak adult activity, as well as adjusting planting dates to reduce exposure of vulnerable crop stages, may help mitigate damage caused by this pest. Overall, this study contributes foundational phenological information that can be used to inform IPM decision-making and reduce economic losses in quinoa production.
Herbicides, including glyphosate, have negative impacts on honey bees (Hymenoptera: Apidae, Apis mellifera, Linnaeus, 1758) and bumble bees (Bombus spp., Hymenoptera: Apidae, Latreille, 1802), but no study has addressed effects on wild, ground-nesting bees in a field setting. Over a 3-yr study, we identified pairs of wild bee nest aggregations and applied a topical spray glyphosate treatment to 1 member of each pair. We excavated nests, collected bees, and performed mortality and mass comparisons between the glyphosate-treated and untreated aggregations. We collected overwintered adults to assess the effects of developmental glyphosate exposure on adult mass and body size, and we reared excavated larvae to monitor survival to adulthood and measure body mass. We recovered several species of adult Andrena (Hymenoptera: Andrenidae, Fabricius, 1775), Colletes (Hymenoptera: Colletidae, Latreille, 1802), Lasioglossum (Hymenoptera: Halictidae, Curtis, 1833), Nomada (Hymenoptera: Apidae, Scopoli, 1770), and Halictus (Hymenoptera: Apidae, Latreille, 1804), and we found no significant effects of glyphosate exposure on larval survival or the overall number of bees recovered from an aggregation. We found that adult Andrena from glyphosate-treated aggregations were larger and had greater mass than those from untreated aggregations, but found no differences in larval mass as a function of treatment. Our results suggest that developing ground-nesting bees are not at risk of mortality or loss of mass due to surface applications of glyphosate, but increased site replication, and studies at larger spatial scales, are necessary to fully understand these risks.
Aphelinus certus Yasnosh is a primary parasitoid of the soybean aphid (Aphis glycines Matsumura), an invasive pest of soybeans in North America. Although Ap. certus has displayed the capacity to suppress aphid infestations below pesticide spray thresholds, control levels are variable. Previous research has found hyperparasitoids attacking Ap. certus in the field, but the impact of hyperparasitism on the control of aphid populations remains unclear. This laboratory study investigates some key life history attributes of Alloxysta brevis (Thomson), an aphid hyperparasitoid in North America, and its impact on Ap. certus and soybean aphid populations. First, we dissected Al. brevis adults to show that females emerge with an average of 10 mature eggs, continue to produce eggs after adult eclosion, and can hold over 20 mature eggs at a time. We then investigated hyperparasitism across different Ap. certus larval instars and demonstrated that the highest proportion of Al. brevis adults emerges from first-instar larvae. These results provided context for a mesocosm cage study evaluating the population dynamics between soybean aphid, Ap. certus, and Al. brevis. Hyperparasitism by Al. brevis significantly reduced Ap. certus abundance but did not eliminate its ability to suppress aphid populations in a caged setting, indicating that even under high hyperparasitism pressure Ap. certus can still provide substantial biological control of soybean aphid. Results of the cage study suggest that hyperparasitism could have a stabilizing effect on the Ap. certus population, highlighting the need for further investigation into the impact of hyperparasitoids on pest suppression by primary parasitoids.
Accurate identification of insect flower visitors is fundamental for understanding crop pollination systems and supporting sustainable production. In Western Australia, avocado (Persea americana Mill.) production relies heavily on insect visitation, yet the taxonomic identity of native flower-visiting taxa remains poorly resolved. This study provides the first integrative identification of insects associated with avocado flowering in Western Australia using a combination of morphological examination and mitochondrial cytochrome c oxidase subunit I (COI) DNA barcoding. Insects were collected from commercial avocado orchards in Carabooda and Pemberton during the flowering seasons of 2019-2021. Besides honeybees, morphological assessment identified 5 dominant native bee taxa, primarily within Lasioglossum (Halictidae), and 3 hoverfly taxa (Syrphidae). DNA barcoding confirmed species-level identities for Lasioglossum lanarium (Smith), L. castor (Smith), and the syrphids Simosyrphus grandicornis (Macquart) and Eristalis tenax (Lannaeus) (≥99% to 100% sequence similarity). In contrast, COI sequences from 3 additional Lasioglossum lineages showed lower similarity to available reference records (eg 96%, 91%, and 94%) and are therefore treated conservatively as Lasioglossum sp. 3 to 5 (morphospecies) rather than assigned species-level names. Overall, 73% of putative avocado flower-visitor taxa were shared between regions, indicating a broadly consistent core assemblage across contrasting climatic zones. By clarifying the taxonomic identity and reporting confidence of key avocado-associated taxa, this study provides a baseline for future work evaluating visitation dynamics, pollen transfer, and management strategies in Australian avocado orchards.
