In the face of environmental contamination to copper, mainly resulting from frequent copper-based fungicide applications, it is crucial to understand the side effects of these pesticides on non-target organisms to favor sustainable pest management. Pest natural enemies are indeed severely exposed to copper fungicides through external physical contact and by ingestion. In this study, we assessed the effects of Bordeaux mixture applications on the longevity of the biological control agent Trichogramma cordubensis (Vargas and Cabello, 1985) (Hymenoptera: Trichogrammatidae). The first set of experiments aimed to evaluate the effective doses of Bordeaux mixture contamination by using eight doses from 0 g.L-1 to 160 g.L-1. When ingesting honey contaminated with Bordeaux mixture the longevity of T. cordubensis was strongly reduced. Conversely, cuticular contact with Bordeaux mixture, without ingestion, had no effect on T. cordubensis longevity. The second set of experiments examined how the effects of Bordeaux mixture on T. cordubensis longevity were modulated by global warming conditions, under two fluctuating climatic regimes simulating current and future conditions in Burgundy, France. These experiments used effective doses obtained after the first experiments. Similarly to the first experiments, Bordeaux mixture ingestion led to strongly reduced longevity, whereas cuticular contact had no effects on T. cordubensis longevity. Warming conditions reduced T. cordubensis longevity by 36% after both ingestion and cuticular contact with Bordeaux mixture, with no statistical interaction with Bordeaux mixture. Ingesting Bordeaux mixture was considered to be slightly to moderately harmful, significantly reducing the longevity from 40% to 81% with increasing concentrations, whereas cuticular contact with Bordeaux mixture was harmless to T. cordubensis. This study sheds new light on the side effects of metal-based fungicides on natural enemies and their subsequent effects on biocontrol programs. It suggests that increasing temperatures should have deleterious effects on Trichogramma species, regardless of fungicide contamination by Bordeaux mixture.

The increasing use of pesticides is recognized as a threat to pest natural enemies. We investigated the effects of Bordeaux mixture, a fungicide widely used in viticulture, on Trichogramma cordubensis, a biological control agent used against the major vineyard pest Lobesia botrana. The lethal and sublethal effects of 20 g.L- 1 Bordeaux mixture on T. cordubensis were studied. To assess the potential persistence of Bordeaux mixture, each experiment was conducted at four different time scales after pesticide application. A first experiment aimed to assess the effects of surface contaminations to Bordeaux mixture on the longevity of T. cordubensis, which was reduced by 26 % when exposed to the fungicide. A second experiment aimed to assess the oviposition dynamics of T. cordubensis during the three first days after its emergence in contaminated or unexposed environments. No differences in oviposition were observed when T. cordubensis was exposed to Bordeaux mixture. A third experiment aimed to assess the oviposition choices of T. cordubensis between hosts on either contaminated or unexposed surfaces. No evidence of an oviposition deterrence was detected. Overall, surface contact with Bordeaux mixture was found harmless on T. cordubensis life parameters. Time after fungicide applications did not differently impact our results on longevity and behavior. However, time after both control and pesticide applications may have led to altered micro-environmental conditions affecting T. cordubensis' development. This study suggests that T. cordubensis inability to discriminate against a copper contaminated environment is a crucial factor in enhancing its effectiveness as a biological control agent.

Understanding how multiple stressors interact is essential for predicting insect performance under global change. Although pesticide toxicity is well-established to be temperature-dependent, the physiological mechanisms underlying these interactions remain poorly understood. Insects often display stage- and sex-specific sensitivities to environmental pressures, suggesting complex energetic trade-offs across their life cycles. Copper-based fungicides, such as Bordeaux mixture, are widely used to control fungal diseases but can stress non-target insects. Here, we experimentally examined how Bordeaux mixture exposure interacts with projected late 21st-century climatic conditions by measuring growth rate, energy reserves, standard metabolic rate (SMR), and Hsp70 concentrations across larval instars (3rd and 5th) and adult sexes in the insect pest Lobesia botrana. Our results show that larvae underwent substantial physiological adjustments to fungicide exposure (increased Hsp70 concentrations, reduced SMR and glycogen), suggesting reallocation of energy from maintenance to stress protection. Future climatic conditions strongly modulated larval responses to the fungicide, shifting the timing of metabolic adjustments across development and interacting with Hsp70 production. Adults displayed sex-specific sensitivity to fungicide exposure, without major interaction with climatic conditions. Females exposed to the fungicide emerged with depleted reserves but unchanged SMR, consistent with energy allocation to reproduction. For males, Hsp70 concentrations were increased by fungicide exposure without major energy reserve loss, suggesting preservation of flight and mate-searching performance. Thus, stress responses are not simply additive but mediated through shared physiological pathways linking Hsp70 concentrations, metabolic regulation, and energy reserve mobilization. This study provides a mechanistic framework for understanding how interacting stressors reshape insect life-history strategies.

Climate change-induced temperature increases are likely to promote the spread of insect pests into new regions, requiring adaptations in pest management strategies. Copper-based fungicides are widely used in viticulture to manage fungal diseases, but may also impact non-target insect pests. This study investigated the effects of Bordeaux mixture on the oviposition behavior and egg survival of the grapevine pest Lobesia botrana, under simulated current (2002-2021) and future (2081-2100) climatic scenarios. Laboratory choice and no-choice experiments were conducted to assess oviposition preferences, potential deterrent effects of Bordeaux mixture, and its toxicity to eggs. In the choice experiment, L. botrana females showed significant preference for untreated grapes under both climatic conditions. However, in the no-choice experiment, Bordeaux mixture neither significantly deterred oviposition nor affected egg hatching rate in either scenario. While Bordeaux mixture had minimal influence on oviposition behavior, future climatic conditions significantly reduced female longevity and fecundity. This reduction in reproductive output may suggest lower pest pressure, but accelerated generation turnover and increased voltinism under warmer conditions could amplify pest pressure in the long term. This study provides insights on the collateral effects of Bordeaux mixture on L. botrana under a future climatic scenario and emphasizes the need for further research on its potential impacts on other key life history traits (e.g., development, reproduction). These findings highlight the importance of integrating climate change projections into pest management strategies to ensure sustainable viticultural practices.

While climate change and pesticide use expose insect pests to multiple stressors, their combined effects remain poorly studied. Rising temperatures can accelerate insect life cycles and alter reproductive behaviours, while pesticides can impair physiological functions, reproduction, and survival. Understanding how global warming and pesticide exposure interact is crucial for predicting pest population dynamics and their impact on agroecosystems. As mating behaviour, including mate choice, plays a fundamental role in population growth, studying how these combined environmental stressors influence reproduction is critical. This study investigated how Bordeaux mixture fungicide affects the development, mating behaviour of Lobesia botrana under current (2002–2021) and projected (2081–2100) climatic scenarios. Larvae were reared with two fungicide concentrations and under two climatic conditions. Larval mortality, development time, and adult longevity were monitored. Mating behaviour was assessed using no-choice and choice experiments, measuring pre-mating latency, mating success and duration, fecundity and fertility. Key life parameters (R₀, T, Dₜ, rₘ, and λ) were estimated to investigate population dynamics. Results show that fungicide exposure negatively affected the development and survival of larvae until emergence, but these effects were modulated by climatic conditions. While Bordeaux mixture exposure prolonged development time, future climatic conditions shortened development time compared to current conditions. Choice experiments revealed that under future conditions, moths preferred unexposed partners, whereas no preference was observed under current conditions. These findings emphasize the importance of integrating climate change effects into pesticide risk assessments, as their interactions may have unexpected consequences for pest populations and sustainable management strategies in agroecosystems.

Entomopathogenic fungi are commonly used as biological control agents. Recently, a strain of Metarhizium robertsii (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) collected in France was identified as a good candidate for controlling invasive populations of the yellow-legged hornet, Vespa velutina nigrithorax (Buysson, 1905) (Hymenoptera: Vespidae) in Europe. Since M. robertsii is a generalist parasite, its usage as bioagent could be damaging for non-targeted species. Here we compared the lethal effects of three concentrations of this M. robertsii strain on V. v. nigrithorax and two non-target species commonly found in Europe, the common wasp Vespula vulgaris (Linnaeus, 1758) (Hymenoptera: Vespidae) and the buff-tailed bumblebee Bombus terrestris (Linnaeus, 1758) (Hymenoptera: Apidae). Exposure to M. robertsii spores altered the survival of all three species but at different degrees. Hornets had a consistently lower survival, even under low spore concentrations, when compared to wasps and bumblebees. The low susceptibility of the beneficial hymenopterans is encouraging in the perspectives of using M. robertsii as a biocontrol agent against invasive hornets.

The contamination of non-target organisms and ecosystems by pesticides can adversely affect biodiversity and key ecosystem services such as pollination or natural pest control. In this study, we used honey bee colonies as sentinels of environmental contamination in four distinct habitats -urban, suburban, forest, and vineyard- and collected bees every three weeks from May to November. Pesticide residues were extracted using an adapted QuEChERS method and analyzed by LC-MS/MS, while inorganic elements were measured by ICP-MS and ICP-AES. Our results show that land-use and seasonal changes shape contaminant patterns in bees. Vineyards left the strongest chemical footprint on bees, as indicated by the wide diversity of contaminants detected in this environment. This reflects multiple exposure to both current and historical pesticide inputs -such as copper- which can accumulate over time to potentially harmful levels. Pollinators like honey bees provide effective indicators of environmental risk, as their health and contaminant loads can reveal broader ecological impacts. Overall, environmental exposure and local contaminant inputs determine the pollutant burdens in pollinators, which may affect honey bee health and the ecosystem services they provide. ### Competing Interest Statement The authors have declared no competing interest. LABEX Cote, ANR 22000698, 2019 IDEX University of Bordeaux, ANR 22001283, 2020 French Office for Biodiversity, ANR 22001730, 2023

The use of copper-based fungicides in agroecosystems has resulted in copper accumulation in soils, increasing its uptake by plants and its transfer along the trophic chain. While fungicides are effective to control fungal diseases, they can also impact non-target organisms such as insect pests that feed on copper-contaminated vegetation. This copper exposure can impair developmental and reproductive processes. In addition, global warming alters the functioning of agroecosystems through rising temperatures and shifting precipitation patterns, and by influencing the distribution and abundance of insect pests, as well as their sensitivity to contaminants. Elevated temperatures may mitigate some of adverse effects of copper by enhancing pest survival. However, the influence of temperature on copper bioaccumulation in insects remain poorly investigated, complicating predictions of pest population dynamics. This study investigates copper accumulation in the vineyard pest Lobesia botrana across developmental stages and increasing copper exposure concentrations under current and projected climate conditions. We evaluated the combined effects of copper and climate warming on development time, larval mass, and head-capsule width. Our results showed that insect copper concentrations increased in response to rising external copper levels, but declined over time through life stages, suggesting internal regulation. High copper concentrations combined with warming increased copper accumulation. Copper exposure delayed development and reduced head-capsule width, while warming accelerated growth and increased larval mass. Overall, global warming may enhance larval performance while promoting copper accumulation in L. botrana, potentially affecting copper transfer across trophic levels and undermining biological control in vineyards.

The timing of adult emergence is often closely associated with individual condition and reproductive success across a wide range of taxa. In insects, emergence timing can reflect both intrinsic developmental differences and environmental conditions experienced during earlier life stages and is often correlated with key fitness traits. Individuals also have to synchronise their emergence with fluctuating resource availability, and the population benefits when individuals emerge at different times, by reducing the chance that a single adverse event will affect all offspring in one season. This balance is particularly evident in insects, where synchronising life stages with optimal environmental conditions, such as the phenological stages of host plants, is essential. In this study, we described associations between adult emergence timing and multiple components of individual quality in a wild population of the grapevine moth Lobesia botrana (a major pest of grapevines) according to their host plant. Our findings revealed a reduction in pupal mass and adult longevity with later emergence. Later emergence also impacted mating (decreased mating success, increased mating latency and mating duration) and reproductive‐related traits (reduction in spermatophore volume, fecundity and fertility). Additionally, the impact of emergence timing is more pronounced in individuals originating from Mourvedre compared to Syrah, two distinct grape varieties. This suggested that the quality of larval host is closely tied to the timing of emergence, indicating a complex interplay between emergence timing and host plant quality.

Group-living animals commonly use social information to better locate and exploit resources. In many insects, birds, fish and mammals, this can lead to collective foraging decisions by which animals share a single food source among alternatives of equal qualities. Here, we report collective foraging decisions in a social wasp, the yellow-legged hornet Vespa velutina nigrithorax, a major predator of bees and other terrestrial invertebrates invasive across Asia, Europe and North America. When given a choice between two identical liquid food sources (feeders or traps containing sugar solutions), wild hornets distributed asymmetrically on the two options, and this phenomenon was more frequent as group size increased. Priming one of the food sources with dead hornets predictably biased the collective choices towards this particular option, irrespective of whether the dead insects were conspecifics or hornets from a closely related species. Inter-attraction in yellow-legged hornets is thus a passive and non-specific mechanism, possibly mediated by visual or chemical cues displayed by dead hornets. This collective behaviour may provide important foraging advantages to hornets invading new territories and bring new perspectives for population control. ### Competing Interest Statement The authors have declared no competing interest. European Research Council, https://ror.org/0472cxd90, 101002644 Agence de la transition écologique, https://ror.org/05rth8x13, LOTAPIS

Invasive species pose a threat to the ecological balance of the ecosystems they invade by altering local host-pathogen dynamics. To investigate these relationships and their potential consequences, we examined the prevalence and genetic diversity patterns of Trypanosomatidae, Lipotrophidae, and Nosematidae in a collection of sympatric isolates of the invasive hornet Vespa velutina and local Hymenoptera from two recently colonized areas: Europe and South Korea. Data were gathered through PCR amplification and massive parallel sequencing, and analyses were conducted using population genetics tools. Parasite prevalences showed substantial variation depending on (i) the parasite family (Trypanosomatidae and Nosematidae were the most and less prevalent, respectively), (ii) location (e.g. Galicia displayed the highest pooled values), (iii) the season (highest in spring for Trypanosomatidae and Lipotrophidae), and (iv) the host. V. velutina exhibited significantly lower parasite occurrence than native Hymenoptera across all parasite families (consistent with the enemy release hypothesis), although this difference was less pronounced during the periods of heightened predatory activity, suggestive of trophic transmission. Parasite species displayed significant genetic differentiation between European and South Korean isolates, yet no differentiation was observed across hosts, suggesting that all Hymenoptera are exposed to a common local pathogen population. There was no indication that V. velutina acted as a carrier of foreign parasites to the invaded territories.

AbstractEntomopathogenic fungi are commonly used as biological control agents. Recently, a strain ofMetarhizium robertsii(Sorokin, 1883) (Hypocreales: Clavicipitaceae) collected in France was identified as a good candidate for controlling invasive populations of yellow-legged hornet,Vespa velutina nigrithorax(Buysson, 1905) (Hymenoptera: Vespidae) in Europe. SinceM. robertsiiis generalist, its use as bioagent could be damaging for non-targeted species. Here, we compared the lethal effects of three concentrations of thisM. robertsiistrain on the invasive hornet and two non-targeted species commonly found in Europe, the common waspVespa vulgaris(Linnaeus, 1758) (Hymenoptera: Vespidae) and the buff-tailed bumblebeeBombus terrestris(Linnaeus, 1758) (Hymenoptera: Apidae). Exposure toM. robertsiispores altered the survival of all three species but at different degrees. Hornets had consistently lower survival, even under low concentrations of spores, when compared to wasps and bumblebees. Such lower susceptibility of beneficial Hymenoptera is encouraging in the perspectives of usingM. robertsiias biocontrol agent against invasive hornets.

Global change is affecting plant-insect interactions in agroecosystems and can have dramatic consequences on yields when causing non-targeted pest outbreaks and threatening the use of pest natural enemies for biocontrol. The vineyard agroecosystem is an interesting system to study multi-stress conditions: on the one hand, agricultural intensification comes with high inputs of copper-based fungicides and, on the other hand, temperatures are rising due to climate change. We investigated interactive and bottom-up effects of both temperature increase and copper-based fungicides exposure on the important Lepidopteran vineyard pest Lobesia botrana and its natural enemy, the oophagous parasitoid Trichogramma oleae. We exposed L. botrana larvae to three increasing copper sulfate concentrations under two fluctuating thermal regimes, one current and one future. Eggs produced by L. botrana were then exposed to T. oleae. Our results showed that the survival of L. botrana, was only reduced by the highest copper sulfate concentration and improved under the warmer regime. The development time of L. botrana was strongly reduced by the warmer regime but increased with increasing copper sulfate concentrations, whereas pupal mass was reduced by both thermal regime and copper sulfate. T. oleae F1 emergence rate was reduced and their development time increased by combined effects of the warmer regime and increasing copper sulfate concentrations. Size, longevity and fecundity of T. oleae F1 decreased with high copper sulfate concentrations. These effects on the moth pest and its natural enemy are probably the result of trade-offs between the survival and the development of L. botrana facing multi-stress conditions and implicate potential consequences for future biological pest control. Our study supplies valuable data on how the interaction between pests and biological control agents is affected by multi-stress conditions.

Reproduction is known to be energetically and physiologically costly. Consequently, individuals in good condition are assumed to invest substantial resources in reproduction, while those in poor condition are unable to do so. This is particularly relevant in insects, where reproduction is a nutrient-limited process for males and females and is largely related to their energy reserves. Lepidopteran phytophagous insects are an ideal model to evaluate how larval nutrition affects adult reproductive strategies, because larval host plant is considered a key determinant of the adult phenotype and the performance of both males and females. We studied a capital breeder moth species, the European grapevine moth (Lobesia botrana), to investigate how male energy reserves, body condition and reproductive traits might influence female reproductive output, using different host plants as a means of obtaining different male qufality. We found that the host cultivar for the larvae strongly influenced the energy reserves of male adult moths, affecting their body condition and ultimately their reproductive potential through the content of spermatophores they transfer to females at mating. Moreover, males having different levels of energy reserves may alter the allocation of energy between their body condition and spermatophore size and composition, supporting the idea that organisms can buffer the effect of nutritional constraints by changing allocation to different fitness-related traits. Females also seem to be able to adjust latency to oviposition accordingly. These results have important implications for understanding the population dynamics of this moth species.

During reproduction, females may boost their fitness by being selective based on direct material benefits provided by the males, such as nuptial gifts. In Lepidoptera, male provides a spermatophore containing nutrients. However, virgin males produce a bigger spermatophore, containing spermatozoa and nutrients, allowing higher female fertility. Lepidoptera females that could detect the sexual status of males may thus prefer a male without previous mating experience (i.e. a virgin male). This mate selection could be achieved by the use of chemical indices, such as sexual pheromones and cuticular compounds, known to be possibly exchanged during reproduction, and which can be indicators of a previous mating experience and known to be possibly sources of information exchanged. In this study, we experimentally presented Lobesia botrana virgin males with females in order for them to be exposed to females' natural sexual pheromones or cuticular compounds. 12 or 48 h after the exposure of males to either females' sexual pheromones or cuticular compounds, these males were confronted to naïve females, which have a choice between them or a virgin non-exposed males. We highlighted that, despite producing a spermatophore of similar volume, all exposed virgin males were less likely to mate with females 12 h after exposure, while after 48 h of exposure this is only the case for virgin males exposed to sexual pheromones. L. botrana females may thus discriminate male sexual experience based on chemical cues (either from cues transferred directly from females to males, or from changes in the cuticular or pheromone males' profile) indicating past mating experiences. Mating duration was longer for males exposed to sexual pheromones after 12 h only, and for males exposed to cuticular compounds after 48 h only. Pheromones signal might be more persistent over time and seems to more easily gather information for males. The physiological reasoning behind this result still needs to be investigated.

Native to the Nearctic region, Scaphoideus titanus Ball (Hemiptera: Cicadellidae) has become a major threat for grapevine production after being unintentionally introduced into Europe, where it became the main vector of flavescence dor & eacute;e phytoplasma, being mainly associated with the genus Vitis. Scaphoideus titanus is a highly efficient vector of the most important phytoplasma affecting grapevine. For this reason, compulsory insecticide treatments have been introduced against this pest in many European countries. Moreover, the continuous expansion of its geographical distribution makes this leafhopper a serious threat for several non-European Countries. In this article, we review the current knowledge about its taxonomy, morphology, biology, ecology, and its role as a vector. Finally, we point out the main challenges for research aimed at reducing S. titanus and flavescence dor & eacute;e expansion across Europe and avoiding spread of the disease outside the Old World.

BACKGROUND:Bordeaux mixture is a copper-based fungicide commonly used in vineyards to prevent fungal and bacterial infections in grapevines. However, this fungicide may adversely affect the entomological component, including insect pests. Understanding the impacts of Bordeaux mixture on the vineyard pest Lobesia botrana is an increasing concern in the viticultural production. RESULTS:Bordeaux mixture had detrimental effects on the development and reproductive performance of L. botrana. Several physiological traits were adversely affected by copper-based fungicide exposure, including a decrease in larval survival and a delayed larval development to moth emergence, as well as a reduced reproductive performance through a decrease in female fecundity and fertility and male sperm quality. However, we did not detect any effect of Bordeaux mixture on the measured reproductive behaviors (mating success, pre-mating latency and mating duration). CONCLUSION:Ingestion by larvae of food contaminated with Bordeaux mixture had a negative effect on the reproductive performance of the pest L. botrana, which could affect its population dynamics in vineyards. Although this study highlighted collateral damage of Bordeaux mixture on L. botrana, the potential impact of copper-based fungicides on vineyard diversity, including natural predators is discussed and needs to be taken in consideration in integrated pest management. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Scaphoideus titanus Ball (Hemiptera: Cicadellidae) is a major pest for European viticulture due to its high efficiency in the transmission of one of the most destructive pathogens for grapevine, namely flavescence dor & eacute;e phytoplasmas. Although it plays a major role in spreading this disease, S. titanus is part of a complex epidemiological cycle involving several alternative vectors with variable relevance for phytoplasma spread. Here we provide an updated review on S. titanus monitoring and modelling, as well as the available tools for management of this pest and for limiting phytoplasma transmission and, thus, also spread. Insecticide-based control is examined; additional emphasis is placed on innovative and low-impact control approaches, such as vibrational mating disruption, biocontrol, and methods to reduce vector competence. We also discuss the main emerging challenges to the implementation of effective and sustainable control programs against S. titanus. .

Arthropods represent an entry point for pesticide transfers in terrestrial food webs, and pesticide accumulation in upper chain organisms, such as predators can have cascading consequences on ecosystems. However, the mechanisms driving pesticide transfer and bioaccumulation in food webs remain poorly understood. Here we review the literature on pesticide transfers mediated by terrestrial arthropods in food webs. The transfer of pesticides and their potential for bioaccumulation and biomagnification are related to the chemical properties and toxicokinetic of the substances, the resistance and detoxification abilities of the contaminated organisms, as well as by their effects on organisms’ life history traits. We further identify four critical areas in which knowledge gain would improve future predictions of pesticides impacts on terrestrial food webs. First, efforts should be made regarding the effects of co-formulants and pesticides mixtures that are currently understudied. Second, progress in the sensitivity of analytical methods would allow the detection of low concentrations of pesticides in small individual arthropods. Quantifying pesticides in arthropods preys, their predators, and arthropods or vertebrates at higher trophic level would bring crucial insights into the bioaccumulation and biomagnification potential of pesticides in real-world terrestrial food webs. Finally, quantifying the influence of the trophic structure and complexity of communities on the transfer of pesticides could address several important sources of variability in bioaccumulation and biomagnification across species and food webs. This narrative review will inspire future studies aiming to quantify pesticide transfers in terrestrial food webs to better capture their ecological consequences in natural and cultivated landscapes.