Abstract Entomopathogenic fungi (EPF) can suppress aphid populations through biological control, but whether EPF‐associated volatile cues influence aphid behaviour remains poorly understood. We investigated the olfactory response of apterous Myzus persicae to Beauveria bassiana and to conspecifics infected with B. bassiana . Aphid responses were assessed using four‐arm olfactometer assays. In the first assay, aphids were exposed to B. bassiana ‐colonised agar, sterile agar and two blank‐air controls. In the second, aphids were exposed to odours from EPF‐infected conspecifics, healthy conspecifics, an agar control and a blank‐air control. Time spent within each odour field was converted to compositional proportions and analysed following centred log‐ratio transformation. Aphids showed no detectable olfactory response to B. bassiana ‐colonised agar alone. In contrast, aphids responded positively to odours associated with infected conspecifics, spending significantly more time in this odour field than in those containing healthy aphids, agar or blank air. These findings demonstrate that the behavioural response of M. persicae to EPF‐associated cues is context dependent, with cues generated during host infection appearing more salient than fungal odours presented in isolation. The results extend our understanding of pathogen‐mediated chemical communication in aphids and suggest that EPF infection may influence host–pathogen interactions and potentially pathogen transmission in ways that are not predicted by repellency‐based models alone.
Abstract Food availability directly influences predatory behaviour and the efficiency of natural enemies in agroecosystems. This study evaluated the effect of food scarcity on the foraging dynamics of the lady beetle Eriopis connexa (Coleoptera: Cocinellidae) preying on Myzus persicae (Hemiptera: Aphididae). Adult females were subjected to four starvation periods (0, 24, 48 and 72 h). After starvation, individuals were transferred to Petri dishes containing 40 M. persicae , and predation was recorded every 15 min for three consecutive hours. In a second experiment, beetles were exposed to different prey densities (3–90 aphids), and predation was recorded after 6 and 24 h. Kaplan–Meier survival analysis revealed a significant reduction in aphid survival probability with increasing starvation duration, with the 72‐h treatment showing the highest predation intensity. The functional response of E. connexa fitted a type II model across all treatments, characterized by a high initial attack rate and saturation at higher prey densities. The generalized linear mixed‐effects model confirmed that both starvation duration and exposure time significantly affected predation rates, with no significant interaction between factors. Although handling time remained stable across treatments, attack rates increased after prolonged food deprivation, indicating intensified search and capture activity. These results demonstrate that food scarcity modulates the predatory behaviour of E. connexa , promoting compensatory responses that sustain its consumption efficiency. The ability to enhance predation under starvation conditions reinforces the potential of this species as a biological control agent in agricultural systems with fluctuating prey availability.
Emerald ash borer (EAB; Agrilus planipennis Fairmaire) has caused mortality of hundreds of millions of ash (Fraxinus spp.), leaving an 'orphaned' cohort of immature ash seedlings and saplings in forests. As immature ash grow and become susceptible to EAB, their long-term persistence in natural forests is unknown. This study leveraged long-term research sites established during the early stages of ash mortality near the epicentre of invasion to investigate the extent and severity of ash loss after two decades with a focus on the regenerating cohort of ash. We found ash remained abundant in the understory of post-outbreak forests, but their abundance and size class varied based on soil hydrology, with higher densities of larger, susceptible ash in wetland forests than in upland and riparian forests. While many ash of susceptible size (>= 2.5 cm dbh) showed symptoms consistent with EAB infestation, the majority of larger ash (>= 5 cm dbh) had healthy canopies. We found that silver maple (Acer saccharinum) has become dominant in the overstory in wetland forests and that populations of tamarack (Larix laricina) were associated with black ash regeneration. These findings suggest ash regeneration has occurred differently among forest habitats. Ash in wetland forests have responded quickly to changes following EAB-induced ash mortality and are closer to reaching the sizes required to become reproductively mature. However, EAB populations are present in low densities, and the persistence of ash in natural forests will depend on improved ash recruitment and the efficacy of introduced natural enemies.
The use of neonicotinoid insecticides in seed treatments in the United States has increased drastically since the mid-2000s, but it is difficult for farmers to directly evaluate their efficacy because of the lack of availability of untreated seed. We observed plants from both treated and untreated seeds of a commercial soybean variety over 12 site-years (4 sites & times; 3 years) in the University of Maryland Soybean Variety Trial. Sites ranged from the foothills of the Appalachian mountains to the Atlantic coastal plain, covering much of the physiographic and climatic variation of the mid-Atlantic region. Neonicotinoid seed treatments (NST) did not provide consistent reduction in insect feeding damage (chewing or stippling) throughout the experiment. Furthermore, treated seeds showed no increase in soybean yield compared to untreated seeds. Our results show no benefits from NST to Maryland soy production. This lack of benefits, along with the conflict between preventative pesticide use and the principles of integrated pest management (IPM), adds to a large body of evidence that NST should be avoided to minimize health risks for humans and the environment.
Abstract Soil‐borne pathogens of the Fusarium oxysporum species complex (FOSC) reduce soybean production, yet their mechanisms of dispersal in the field conditions remain insufficiently understood. Diabrotica speciosa is a widespread pest in South America, but its potential role in disseminating soil‐borne fungi needs further research. This study evaluated the carriage and contribution of D. speciosa to disperse FOSC members in soybean fields. Larvae and adults of D. speciosa were collected from two commercial areas and dissected and fungi associated with their cuticle, mouthparts, digestive tract and prothorax were isolated. Seven fungal genera were recovered and a FOSC member was consistently detected in all larval body parts and in multiple regions of adults of D. speciosa . Morphological and phylogenetic analyses confirmed its placement within FOSC and it induced characteristic root rot symptoms in soybean in pathogenicity assays. This is the first characterisation of the fungal microbiota associated with distinct body regions of D. speciosa and also the evidence of an interaction between this insect and a FOSC member. These findings revealed an unrecognised pathway for FOSC dissemination in soybean systems with new insights into the epidemiology of soybean root rot, with implications to develop more effective management strategies.
Bark beetle outbreaks are often triggered by abiotic disturbances (e.g., storms and drought), but the mechanisms underlying outbreak initiation remain poorly understood. Moreover, the mechanisms that maintain populations at endemic levels remain poorly understood. During the endemic phase, secondary bark beetles compete with both conspecifics and other secondary species for weakened or dead trees, leading to reduced reproductive success. This interspecific competition may be influenced by host quality, such as phloem moisture. However, the combined effects of interspecific competition and phloem moisture remain unclear. We conducted field experiments in Hokkaido, Japan, using experimental logs to evaluate how the reproductive success of Polygraphus proximus Blandford (Coleoptera: Curculionidae: Scolytinae) is affected by intraspecific competition, interspecific competition with the sympatric bark beetle species and host phloem moisture. Our results showed that at high and mean phloem moisture levels, P. proximus reproductive success declined significantly with increasing presence of Cryphalus laricis. In contrast, when phloem moisture was low, C. laricis presence had no significant effect. Intraspecific competition had no significant effect. These findings indicate that the effects of interspecific competition are mediated by phloem moisture. Additionally, adult offspring density of P. proximus declined significantly with increasing presence of C. laricis across a range of phloem moisture. Our study suggests that both interspecific competition and low phloem moisture can contribute to maintaining low population levels of P. proximus during the endemic phase. Cutting weakened or dead trees into shorter pieces may promote desiccation, reduce the quality of breeding material and suppress future outbreaks.
Elm trees (Ulmus spp.) are common ornamentals in urban green spaces and are frequently affected by insect pests and diseases. The elm leaf beetle, Xanthogaleruca luteola (M & uuml;ller) (Coleoptera: Chrysomelidae), is one of the most significant pests of elm trees in Iran and worldwide, causing substantial damage to urban greenery each year. This pest injures trees by feeding on their leaves during both larval and adult stages. The present study aimed to investigate the effects of seven constant temperatures (15, 17, 20, 25, 30, 32, and 35 degrees C) on the life-table parameters of X. luteola and to determine its temperature thresholds under laboratory conditions. The results revealed that the mean duration of the egg stage ranged from 4 to 15 days, depending on temperature. The duration of the adult stage was longest at 17 degrees C (114.93 +/- 2.87 days) and shortest at 32 degrees C (11.81 +/- 0.62 days). At 15 and 35 degrees C, the beetles failed to complete development and did not reach adulthood. The intrinsic rate of increase (r) was lowest at 17 degrees C (0.027 +/- 0.004 days-1) and highest at 25 degrees C (0.106 +/- 0.003 days-1). The highest net reproductive rate (R0) was observed at 20 degrees C (341.59 +/- 41.18 offspring/individual), while the shortest generation time (T) occurred at 32 degrees C (30.41 +/- 0.62 days). The temperature requirements of this pest were estimated using two linear regression models and 17 nonlinear regression models. Among the linear models, the Ikemoto & Takai model demonstrated higher accuracy, as indicated by a higher R2 value. Among the nonlinear models, the Bieri 1 model was identified as the most suitable for describing the pre-adult developmental period, based on statistical fit and accurate estimation of biological parameters. The findings of this study provided an empirical foundation for the development of integrated management programs for the elm leaf beetle.
Beetles of the subfamily Bruchinae (bruchine) can increase the speed of seed germination by breaking physical dormancy. However, the larval feeding also consumes part of the endosperm, resulting in a loss of reserves and creating doubts about the seedlings' ability to survive. Consequently, the increase in germination speed may lead to misguided conclusions that bruchines can also favour seedling survival. Because the bruchine Acanthoscelides macrophthalmus increases the germination speed of Leucaena leucocephala seeds, we tested the hypotheses that the speed of seedling emergence of L. leucocephala increases when the seeds are infested with A. macrophthalmus as well as that seedlings from the infested seeds do not have long-term survival Leucaena leucocephala seeds were subjected to three treatments: (1) scarified intact seeds; (2) non-scarified intact seeds (intact seeds); and (3) infested seeds. All seeds were individually sowed in seedling tubes filled with soil, which were kept in an acclimatised room at 25 +/- 3.0 degrees C and 24 h light. The number of emerging seedlings and those that died after emergence was recorded for 121 days. We found that seedlings from the infested seeds emerged faster than those from the intact seeds; 94.1% of the seedlings emerged within the first 10 days of sowing, and all seedlings from the intact seeds emerged after this time period. However, most seedlings from infested seeds survived less than 30 days. We showed that although seedling emergence increases when seeds are infested, they do not survive, suggesting that A. macrophthalmus acts as a predator of L. leucocephala seeds.
Pollination in apple orchards depends on insect activity during a short and weather-sensitive bloom period. Flower-visiting insect assemblages may vary across orchard gradients in microclimate, bloom development and habitat structure, but fine-scale spatial and seasonal patterns during apple bloom remain poorly understood. We examined how flower-visiting insects in a Lake Ontario apple orchard varied with distance from the lakeshore, trap height and apple flowering phenology. With blue vane traps placed at approximately 10 cm and 1 m above the soil surface across transects spanning 23-1140 m from the lakeshore, we collected >14,000 insects during 11 weeks, of which 12% belonged to bee and fly genera classified as likely flower visitors. Temperature loggers were placed 10 cm belowground and at 1 m height. Aboveground temperatures were consistently warmer than belowground, and inland warming was more evident at 1 m. Flies declined more steeply than bees with increasing distance from the lake and increased more rapidly through the season; both groups were more abundant and taxonomically richer in elevated traps. Among common genera, Lasioglossum, Agapostemon, Andrena and Apis corresponded most closely with apple bloom timing. Potential pollinator assemblages were spatially and seasonally structured, with common bee genera tracking blooms more closely than flies. These results suggest that pollinator availability during apple bloom depends not only on the presence of flower-visiting taxa in orchards, but also on their seasonal timing, flight height and spatial distribution during the narrow pollination window.
Abstract Insects are fundamental to global ecosystem health, providing essential services including pollination, decomposition and biological control. The global economic value of insect pollination alone is estimated at USD 235–577 billion annually, underscoring its critical role in food security and human nutrition. Without pollinators one‐third of flowering plants would produce no seeds. Although studies have examined climate‐driven pollinator declines or pest expansions separately, these are not independent crises—yet a synthesis integrating them as linked, mutually reinforcing outcomes remains underdeveloped. Here I discuss that climate change simultaneously restructures insect communities unevenly—accelerating pollinator decline while expanding agricultural pests—threatening both food security and ecological networks. I argue this dual crisis arises from climate change acting as a selective ecological filter, favouring opportunistic, r‐selected pests while disadvantaging specialist, K‐selected pollinators. Synthesized evidence indicates that for every degree of warming, documented bee species richness has declined by approximately 25% since the 1990s, while pest‐induced crop losses increase by 10%–25%. These disruptions are severe across multiple biomes but are especially concerning in tropical regions, where extreme heatwaves cause catastrophic mortality in stingless bees and monitoring remains critically sparse. I review the physiological, phenological and distributional mechanisms driving these changes, including phenological mismatches that decouple flowering from pollinator emergence. To address these challenges, I advocate for a network‐centric approach encompassing climate‐responsive integrated pest management, landscape‐scale habitat restoration and community‐based monitoring. Systematic monitoring and further research into species‐specific and network‐level responses are essential to guide effective policy and safeguard insect biodiversity in a rapidly changing climate.
Tuta absoluta is a major pest of tomato that first invaded Japan in 2021. However, the mechanism of its invasion remains unclear. We tested the hypothesis that this species migrates from overseas to Japan by analysing the strontium radiogenic isotope ratio 87Sr/86Sr of individuals trapped in Japan and tracing their backward migration trajectories. In southern and western Japan, individuals with higher 87Sr/86Sr ratios than those of host plants in the Japanese trapping areas were captured simultaneously at multiple sites during periods of strong westerly winds blowing from the East Asian continent, suggesting that they had arrived from outside the study area. The endpoints of the backward trajectories for these captures were distributed across the continental regions where T. absoluta likely occurred. The results suggest the possibility of overseas migration, thereby supporting our hypothesis. Although further studies, such as the investigation of potential source regions, are needed, this study provides an important ecological perspective for establishing effective pest management strategies for this species.
This study evaluated pruning practices and slash management on ambrosia beetle attacks in a Khaya grandifoliola C. DC. plantation in S & atilde;o Roque de Minas, Brazil (March-May 2018). Three treatments comprised of non-pruned controls, pruned trees with slash removal and pruned trees with slash retention; attack intensity on standing trees was assessed via weekly visual inspections counting holes-evidence of beetle boring into trunks-with frass or gum. Slash retention significantly increased beetle activity, likely by providing breeding substrate that may contribute to local population build-up and subsequent colonization of nearby trees. No attacks occurred in slash-removal plot, confirming residue removal prevents ambrosia beetle attacks. Attacked trees exuded gum, demonstrating K. grandifoliola's effective defence that killed pioneer beetles. Prompt slash removal constitutes essential integrated pest management for sustainable African mahogany plantations.
While being one of the most destructive agricultural pests globally, aphids are also important components of herbivory networks in forest and woodland habitats. They are predicted to be among the few insect herbivore 'winners' under future elevated CO2 (eCO2) scenarios, but additional field experiments are needed to determine species-specific responses, including impacts on fecundity and mortality at the population level. The impact of eCO2 on populations of aphids on common sycamore, Acer pseudoplatanus, was investigated within a temperate woodland at the Birmingham Institute for Forest Research (BIFoR) Free-Air CO2 Enrichment (FACE) facility. A survey of the aphid species, Drepanosiphum platanoidis, Periphyllus testudinaceus and P. acericola, showed an increase in the abundance and population density of all three species under eCO2 (150 ppm above ambient), although differences were only significant for D. platanoidis. The number of nymphs produced by individual D. platanoidis alates isolated in clip cages was not significantly affected by the eCO2. These results suggest that D. platanoidis could be a species of aphid that may increase in abundance under eCO2, but that population-level responses are not driven by improved individual performance. Further experiments are needed to determine the relative contribution of competition and attack by natural enemies as drivers of population-level effects on aphid populations under climate change.
Ambrosia beetles (Coleoptera: Curculionidae, Scolytinae and Platypodinae) constitute a group of wood-boring insects relying on symbiotic fungi to exploit weakened trees. Some invasive species can also colonise healthy hosts, posing risks to forests. We investigated how environmental drivers may affect the ambrosia beetle community in two valleys in NW Italy. Over a two-year monitoring period (2024-2025), 48 ethanol-baited traps were placed in sites with chestnut as the dominant species: cultivated and managed chestnut orchards and mixed environments with assorted tree composition. In total, 118,286 individuals were collected representing six species, with Xyleborinus saxesenii (Ratzeburg) dominating the assemblage. Three non-native species were found, namely Anisandrus maiche (Kurentsov), Xylosandrus crassiusculus (Motschulsky) and Xylosandrus germanus (Blandford). The geographic structure of the two valleys and their climatic context were the main factors shaping the beetle assemblage, while local drivers acted as secondary elements. The Pesio Valley exhibited higher alpha diversity and more invasive species, likely linked to the high presence of 'bridge hosts' and a more humid climate. Moreover, a specific association between chestnut-dominant environments and invasive species, such as X. germanus and A. maiche, was found. This study suggested that while chestnut orchards serve as important ecological refuges, their vulnerability to biological invasions may be mediated by specific local conditions. Further investigations are needed over a longer period to evaluate how local habitat conditions may act as a hint of the seasonal population trend of the beetle community, also in a climate change perspective.
The intensification and simplification of complex vineyard landscapes have a negative impact on the abundance of natural enemies of crop pests. Semi-natural areas with non-crop plants, like hedgerows and woody margins, can act as sources for these organisms that frequently spill over to nearby vines. To assess their impact on beneficial arthropods, we sampled parasitoid wasps, spiders and Phytoseiidae mites in common native Mediterranean tree and shrub species and herbaceous ground cover in semi-natural areas around vineyards. We then assessed whether the distance to the periphery or periphery composition affected the abundance of these natural enemy groups in the vineyard. While distance did not affect the abundance of the sampled groups, vineyard location and cultivar did. Populations of phytoseiids were significantly higher in vineyard plots next to biodiverse margins than in plots surrounded by other vineyards. Also, vineyard plots with more parasitoids had lower spider numbers, and vice versa. Plants of Tamarix africana harboured high numbers of both spiders and parasitoids in May and August, as did Pistacia lentiscus in August, while Rubus ulmifolius, Rosmarinus officinalis and Rosa canina hosted large spider populations in more than one season. Herbaceous plants also proved important winter hosts for parasitoids and spiders. However, the number of phytoseiids was overall low in marginal plants. Our results underline the impact of marginal habitats on the populations of beneficial arthropods in vineyards and the potential of particular Mediterranean plant species to host these groups throughout the year.
Ants are highly abundant insects that occur in almost every environment and exhibit diverse foraging and nesting behaviours. Despite their known ecological roles and ant-plant associations, the potential of ants as pollinators remains relatively unknown, especially in agroecosystems. This study investigated the potential of ants as pollinators of commercial raspberry (Rubus idaeus. (Rosales: Rosaceae)) crops. To determine the importance of ants as raspberry pollinators, we conducted visitation surveys and measured pollen loads and fruit set in the presence and absence of ants across six commercial blocks located within a single growing region near Coffs Harbour, New South Wales, Australia. Blocks were spaced 15-3500 m apart and selected to ensure uniform cultivar and flowering stage; replication was limited by the availability of suitable blocks. Ants were the most abundant flower visitor of raspberry, followed by European honey bees (Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae)), endemic Australian stingless bees (Tetragonula carbonaria Smith, 1854 (Hymenoptera: Apidae)) and then flies. Temporal flower visitation activity differed across insect groups, with ants more active before midday and honey bees in the afternoon. The three most frequently collected ant species (Iridomyrmex mjobergi Forel, 1915 (Hymenoptera: Formicidae); Iridomyrmex suchieri Forel, 1907 (Hymenoptera: Formicidae) and Nylanderia obscura (Mayr, 1862) (Hymenoptera: Formicidae)) all carried raspberry pollen on their bodies. Ant-mediated pollination resulted in heavier and higher-quality fruit compared to bagged (non-pollinated) flowers, though open pollination yielded the best results. The findings show that ants support fruit development and quality, emphasising that integrating diverse insect visitors into crop and habitat management can improve pollination efficiency and agricultural outcomes.
The invasive apricot aphid, Myzus mumecola (Hemiptera: Aphididae) is native to Eastern Asia and was first detected in Europe in 2016. Within a decade, it has spread from Italy to several other European countries. Despite the potential threat to apricot cultivation, little is known about the biology of M. mumecola. It is known to shift from apricot trees to one or more alternative hosts. However, information on its feeding pattern and particularly on the summer hosts in the invaded region is limited. To investigate plants visited for probing during migration, we performed a molecular gut content analysis and a bioassay on the biological performance of the aphid on different plant species. Plant DNA from several genera such as Robinia, Prunus, Carpinus, Malus, Salix and Fraxinus was detected from autumnal morphs that migrate to apricot, indicating that M. mumecola acquired plant sap from these species during its migration. From the tested Prunus spp., only apricot resulted as a suitable host, confirming the host specificity of M. mumecola, whereas hop was identified as a suitable summer host for this pest. This study provides new insights into the feeding and reproductive host plants of M. mumecola in Europe and highlights the importance of combining molecular and ecological approaches to investigate the feeding behaviour of emerging pests.
The invasive bumblebee Bombus terrestris has established widespread populations across northern Japan since its introduction in 1991 and has become dominant in some agricultural regions. This dominance has raised concerns about ecological impacts on native pollinators; however, the consequences of its removal for crop pollination and yield remain poorly understood. We conducted a field-based case study in squash (Cucurbita maxima) fields to examine differences in pollination dynamics between a year without queen removal (2022) and a year with intensive queen removal (2024). We quantified floral visitation, stigmatic pollen deposition, fruit set, fruit weight and seed production. Queen abundance was also monitored in 2025 to document population reappearance following the removal period. The abundance of B. terrestris workers during flowering was markedly lower in 2024 than in 2022. Although native bumblebees and alternative visitors such as Vespula were observed, their visitation did not compensate for pollen transfer and fruit and seed production were reduced relative to the non-removal year. In 2025, B. terrestris queens were again recorded, indicating recolonisation from surrounding areas. These results indicate that B. terrestris currently plays a dominant functional role in pollination at the study site and that its removal may be associated with reduced pollination services and crop production. Management of invasive pollinators in agroecosystems should therefore consider potential trade-offs between biodiversity conservation and pollination services and integrate control efforts with measures that support native pollinator communities.
Invasive species pose major threats to agriculture, biodiversity and livelihoods. However, risk assessments are often reactive rather than predictive. The melon thrip (Thrips palmi Karny) is a regulated quarantine pest native to Southeast Asia that has established in over 50 countries, but its global potential distribution under current and future environmental scenarios remains insufficiently characterized. Using 86 georeferenced occurrence records and six WorldClim bioclimatic variables, we developed and validated a Maxent model to estimate current and future (2081-2100) global habitat suitability for T. palmi. Model performance was strong (Area Under Curve = 0.81, True Skill Statistic = 0.53, Continuous Boyce Index = 0.63). The most influential predictors were precipitation of the wettest month (37.7%), precipitation of the driest month (36.7%) and annual mean temperature (9.7%). Suitable habitat for T. palmi is projected to increase from 4.1% of current global land area to 7.82% by 2081-2100, a 92.8% expansion. The greatest increases are expected to occur in West and East Africa, South and Southeast Asia, and Central and South America, alongside poleward expansion into temperate regions of Europe and North America. Our study supports proactive surveillance, phytosanitary regulation and integrated pest management for T. palmi in vulnerable agricultural regions.
