Sap Feeders Research Articles

Symbiotic Bacterial Communities of Insects Feeding on the Same Plant Lineage: Distinct Composition but Congruent Function.

The health and diversity of plant-feeding insects are strictly linked to their host plants and mutualistic symbionts. However, the study of bacterial symbionts within different insects on the same plant lineage is very limited. This study aimed to investigate the bacterial diversity in insect samples that exclusively feed on Bambusa, representing three insect orders, Hemiptera, Lepidoptera, and Blattodea, each exhibiting distinct dietary preferences. The bacterial community was predominantly composed of Proteobacteria, Spirochaetota, Cyanobacteria, Firmicutes, and Bacteroidota. The study found significant variations in symbiotic organisms among three insect orders: hemipterans had Buchnera, lepidopterans had Acinetobacter, and blattodean had Treponema. Furthermore, the dietary preferences of these insects played a pivotal role in shaping the symbiotic relationship of insects. Proteobacteria are prevalent in sap feeders, Spirochaetota dominate in stem feeders, and Cyanobacteria are abundant in leaf feeders. Seasonal influences also affect bacterial symbionts in P. bambucicola, with Serratia present exclusively in winter. We also observed that the bacterial composition varies across all samples, but their core functions appear to be consistent. This highlights the complex relationship between host phylogeny and diet, with phylogeny being the primary driver, shaping adaptations to specialized diets.

Bio-efficacy of different doses of noval insecticide against sap feeder insect pests infesting pomegranate

Bio-efficacy of different doses of noval insecticide against sap feeder insect pests infesting pomegranate

Status of defender and offender arthropods in Bt transgenic cotton

The widescale cultivation Bt cottons in India has altered the landscape of pest management, particularly of sap feeders. To have updated understaning field surveys were carried out during kharif 2022-23 and arthropod defenders (spiders, coccinellids and chrysopids) and offenders (sucking pest) in Bt cotton at Dharwad and Haveri districts of Karnataka were noted. Their peak activity was found during flowering stage. In the defenders, spiders exhibit a higher abundance compared to chrysopids and coccinellids. Thrips, conversely emerged as predominant offender. In Dharwad district, seasonal mean of spider was 1.23/plant. Chrysopids displayed a seasonal mean of 0.96 individual 1.48 spiders/ plant were recorded, chrysopids exhibited a seasonal mean of 1.33 individuals/plant and coccinellids 1.36/plant. Offenders displayed specific seasonal incidences, with thrips recorded at 14.97/3 leaves, leaf hoppers at 2.67/3 leaves, aphids at 17.05/3leaves, and whiteflies at 1.27/3 leaves. Notably, offender defender ratios differed, with Dharwad district at 7.5 offender per defender and Haveri district at a slightly lower ratio of 6.5 offender per defender was recorded. Overall higher offender and defender population was observed at Haveri district. Thus it’s important to maintain wider ratio of defender: offenders through selective practices.

Pesticide-induced resurgence a hindrance in sustainable forestry: a case study with whitefly Aleurolobus nandiensis and mealybug Planococcus bendovi infesting Gmelina arborea in Tamil Nadu

Gmelina arborea an indigenous tree species valued for its medicinal and timber properties is often attacked by numerous insect defoliators, miners, borers, sap feeders throughout the year including some major pests namely- Calopepla leayana, Tingis beesoni, Prioptera punctipennis, Alcidodes ludificator, Myllocerus sp. etc. As in agriculture the easiest management measure in forestry also comes in the form of different chemical pesticide treatments when the pest population is high and alarming. This investigation is a case study of such pesticide-induced resurgence among secondary insects of G. arborea in nurseries and plantations of Tamil Nadu. Two rare sap feeding insects Planococcus bendovi and Aleurolobus nandiensis in the nursery condition have been exposed directly and indirectly to the different concentrations of chemical pesticide treatment from 2020-2022 repeatedly. Over time the maximum dose of organophosphate pesticide dimethoate 30% EC (Rogor) failed to reach LC50 during insecticide efficacy (EA) testing against P. bendovi bioassay. Similarly, neonicotinoids thiamethoxam 25% WG (Actara) with maximum dose failed in A. nandiensis bioassay. Resurgence index (EHT) showed the higher abundance of A. nandiensis and P. bendovi in treated nursery beds compared to untreated nursery and field conditions by causing the mortality of 10 to 20 % (average) of planting stocks respectively.

Impact of Biotic and Abiotic Stress on Survival of Lac Insects Kerria lacca Kerr. on Pigeonpea (Cajanus cajan (L.) Millsp)

Cajanus cajan is generally grown in rainfed condition. The crop is also a good annual host plant of lac insect. C. cajan is widely reported to have biotic stress due to insect pests on it. Lac insect is phloem sap feeder and hence imparts biotic stress. The present field study was conducted to evaluate the percent survival of lac insects on C. cajan by adjusting different levels of biotic and abiotic stress on the host plant. The biotic stress due to insect pests on C. cajan was minimised with periodic spray of contact insecticides. The varying level of biotic stress i.e., No, Low, Medium, and High level was maintained on C. cajan plants with lac insects on it. The three levels of abiotic stress in this experiment were considered in terms of soil moisture stress. It was managed through irrigation per plant through drip system, it was considered that creating different levels of moisture stress in soil will impact the host plant. The abiotic stress was of three levels i.e., Low, Medium, and High. The result reveals that survival percent of Lac insect from brood lac inoculation to the harvest of lac crop was highest 37.52 percent on C. cajan with one primary branch and its secondary branches with lac insect (L1- Low biotic stress). It was 32.13 percent (W3- Low soil moisture stress). The study indicates that biotic and abiotic stress play a major role in the survival of K. lacca.

Presence of non-symbiotic yeasts in a symbiont-transferring organ of a stag beetle that lacks yeast symbionts found in other stag beetles

Dispersal from wood to wood is essential for wood-inhabiting fungi and wood-inhabiting insects play an important role in the dispersal success of such fungi. However, it is poorly understood whether wood-inhabiting insects which change the habitats from wood to non-wood environments can contribute to the fungal dispersal. Larvae of most stag beetles (Coleoptera: Lucanidae) are wood feeders, while adults are sap feeders. Female adults of lulcanids possess specialized organs (mycetangia) for transportation of fungal symbionts and harbor specific yeasts (e.g., Scheffersomyces spp.) within. Here, we report that the lucanid Aegus subnitidus harbors non-specific yeasts facultatively in mycetangia. We conducted yeast isolation from mycetangia and hindguts of female adults, in a larval gallery in wood-associated materials, and in female-visiting fermented tree sap using culture-dependent methods. Less than half of the females carried a total of 20 yeast species with small amounts using mycetangia and a female harbored up to five species, suggesting the absence of an intimate association with specific yeasts that are found in other lucanids. Yeast species compositions markedly differed between the larval gallery and sap. Most yeasts from the larval galley exhibited xylose-assimilation abilities, while few yeasts from sap did. Mycetangial yeasts comprised a combination from both sources. In hindguts, most yeasts were found in sap (> 70%) with no yeasts in the larval gallery. Sap-associated yeasts in each female mycetangium were also obtained from the female-visiting sap patch, while mycetangial, larval gallery-associated yeasts were absent from the patch, suggesting the survival success of larval gallery-associated yeasts in mycetangia through sap patches. Therefore, wood-inhabiting insects that possess mycetangia can potentially act as vectors of non-symbiotic wood-inhabiting yeasts dispersing from wood to wood via other environments.

Cicadomorpha Community (Hemiptera: Auchenorrhyncha) in Portuguese Vineyards with Notes of Potential Vectors of Xylella fastidiosa

Cicadomorpha (Hemiptera) insects are currently responsible for a growing negative impact on the agricultural economy due to their ability to directly damage crops or through the capacity to act as vectors for plant pathogens. The phytopathogenic bacterium Xylella fastidiosa, the causal agent of Pierce's disease in vineyards, is exclusively transmitted by insects of this infraorder. Therefore, knowledge of the Cicadomorpha species and understanding their biology and ecology is crucial. In this work, in 2018 and 2019, the canopy and inter-row vegetation of 35 vineyards distributed in mainland Portugal were sampled to investigate species composition, richness, and diversity of the Cicadomorpha community, with a special focus given to vectors and potential vectors of X. fastidiosa. A total of 11,834 individuals were collected, 3003 in 2018 and 8831 in 2019. Of the 81 species/morphospecies identified, only five are considered vectors or potential vectors of this pathogen, namely, Cicadella viridis (Linnaeus, 1758), Philaenus spumarius (Linnaeus, 1758), Neophilaenus campestris (Fallén, 1805), Lepyronia coleoptrata (Linnaeus, 1758), and N. lineatus (Linnaeus, 1758). Cicadella viridis was the most abundant xylem sap feeder, followed by P. spumarius. In addition, Cicadomorpha that cause direct damage to vines and vectors of grapevine yellows' phytoplasmas were also collected and identified in the sampled vineyards. The results suggested that vectors and potential vectors of X. fastidiosa and a large proportion of the population of Cicadomorpha have a positive correction with inter-row vegetation.

Evaluating a decade (2011–2020) of integrated forest pest management in the United States

AbstractTo sustain healthy forests in the United States, the USDA Forest Service, Forest Health Protection and cooperators utilize integrated pest management (IPM) programs to prevent, suppress, and eradicate insect and disease outbreaks affecting trees across all land ownerships. Forest pest management projects supported by federal funding from 2011 to 2020 were assessed to determine the most frequently used project types, IPM strategies and tactics, identify the dominant forest pests and associated hosts managed, and identify the most comprehensive forest IPM programs in practice. Forest pest management projects were obtained primarily from two centralized databases and included 2,416 projects that treated a total of 2,284,624 ha. Two project types accounted for most of the forest pest projects (suppression: 63% and prevention: 30%). Native forest pests were targeted more (79%) than non-native pests (21%) in these projects; however, non-native pests accounted for more treatment areas. Forest pest projects were directed mostly at phloem-feeding insects (70%) and subsequently followed by foliage feeders (10%), sap feeders (6%), and all other pest groups (each < 5%), including diseases. Four IPM control strategies (silvicultural: 32%, semiochemical: 22%, chemical: 21%, and physical/mechanical: 18%) accounted for most of the forest pest projects. Foliage feeders possessed the most comprehensive IPM programs that adopted two or more types of control tactics. Few pest programs incorporated microbial/biopesticide control strategies and this represents an area where research is needed. In addition, better-centralized records are needed for genetic control projects, treatment efficacy, and survey and technical assistance activities.

Global Advances on Insect Pest Management Research in Oil Palm

Here, we review the advances in research on management of key oil palm insect pests globally, including defoliators, leaf/fruit scrapers, borers and sap feeders. The common oil palm pest management methods include synthetic insecticides, biopesticides, semiochemical lures, cultural practices, and integrated approaches. However, effectiveness, affordability, availability and impact of these methods on human and environmental health vary considerably based on the target insect and geographical location. The use of quarantine regulations to prevent the spread of invasive pests has also been applied with remarkable results. There are notable research advances in semiochemicals, bioacoustic detectors, nanotechnology, insect growth regulators, and entomophagy for better management of oil palm pests. We suggest the following research areas for improving effectiveness of oil palm pest management interventions: (i) exploration of semiochemical attractants for the majority of pests with no previous semiochemical work, and their integration in attract-and-kill devices laced with pathogenic microbes; (ii) expanding the application of digital sensing, predictive modeling and nano-technology in pest control strategies; (iii) developing effective technologies for mass trapping of edible insect pests for food or feed, especially among communities with a tradition of entomophagy; and (iv) strengthening regulatory frameworks for the management of quarantine oil palm insect pests.

Predicting parasitoid accumulation by potential Brazilian peppertree biological control agents from assessments in the native and invaded ranges

During their initial releases, classical biological control agents may benefit from enemy-free-space as they are introduced to new habitats with relatively low attack rates by natural enemies. The benefits of classical biological control may be reduced by natural enemies that exploit new agents in the introduced range. Estimates of agent vulnerability to natural enemies prior to release could assist in predicting attack rates and prioritization of proposed agents. Additionally, release of vulnerable biological control agents could have unintended consequences that disrupt native food webs. Our goal was to predict the vulnerability of potential agents to attack by natural enemies by determining parasitism rates in the native range of the weed Brazilian peppertree, Schinus terebinthifolia. Furthermore, we conducted assessments of the rate of attack of ecological analogues in the invaded range in North America, where the agents are to be released, to assist in predicting post release vulnerability. Potential agents and analogues were assigned to four feeding niches, leaf folders, cryptic feeders, thrashers, and sap feeders. Cryptic members were generally most common in the invaded range. However, compared with the other niches, leaf folders were most common in at least one region of the native range. Surveys of potential agents of Brazilian peppertree in their native range of South America indicated parasitism rates were generally <20% for leaf folders (10.5 ± 6.3%; n = 485), cryptic feeders (17.6 ± 3.7%; n = 495), thrashers (12.1 ± 1.2%; n = 381), and sap feeders (2.5% ± 1.1%; n = 200). With exceptions, parasitism rates of the ecological analogues of North America were similar to those from South America for leaf folders (19.2 ± 7.9%; n = 19), cryptic feeders (16.5 ± 5.2%; n = 285), and sap feeders (0.2 ± 0.2%; n = 1247). Thrashers were not included in the analysis as a single parasitoid was found from few (n = 9) hosts recovered in North America. These results suggest that if species of these defoliating leaf folder or cryptic feeder niches are released for biological control in North America they will be parasitized at these same levels. However, if sap feeders are released, these results predict very low parasitism would result. These pre-release assessments of parasitism may assist in the prioritization of potential agent species for biological control of weeds and reduce the likelihood of indirect effects impacting native communities.

Plant-mediated effects of water-deficit stress on the performance of the jujube lace bug, Monosteira alticarinata Ghauri (Hemiptera: Tingidae) on Jujube tree

Drought phenomenon as a consequence of climate change may become a major limiting factor for agricultural systems, and its impacts on plant-insect interactions are only partially understood. Addressing this issue, life-history responses of the jujube lace bug were evaluated on jujube tree under three water treatments (control, moderate and severe drought stress). Performance responses of the jujube lace bug were evaluated under controlled conditions using arenas consisting of jujube leaves inside Petri dishes. Plant biochemical measurements showed that leaf chlorophyll a, b, and total chlorophyll content, were higher in moderate water stress treatment than other treatments while Total Soluble Solids, total carbohydrate, and proline concentrations were increased in drought stress. Also, the lowest amount of carotenoid, phosphorous, sodium content was measured in severe drought stress treatment. The life history responses of Monosteira alticarinata showed that mean oviposition period and life span were statistically higher on moderate water stress than other treatments. The lowest intrinsic rate of increase (r), the finite rate of increase (λ), the net reproductive rate (R0), gross rate reproduction (GRR), total fecundity, and the highest doubling time (DT) were measured on severely drought stress treatment. An increase on the performance of the lace bug can be due to an increase on the chlorophyll, nitrogen, protein and free amino acids in moderate water stressed plants. However in severe stress it do worse. Overall, this study revealed that sap feeders benefit from moderate water stress.

Evaluation of Plant based Aqueous Extracts against the Major Sucking Pests of Brinjal (Solanum melongena L.)

Brinjal holds a distinct place in the domain of vegetables. The production and productivity is extremely lowered by the interference of borers and sap feeders. An experiment was conducted to evaluate the efficacy of different botanicals on the sucking pests of brinjal viz., leaf hoppers (Amrasca biguttula biguttula Ishida), whitefly (Bemisia tabaci Gennadius), mealy bug (Phenacoccus solenopsis Tinsley) and red spider mite (Tetranychus urticae Koch) during March - July, 2021. The results on the evaluation of aqueous extracts revealed that the commercial formulation Azadirachtin 0.003 EC was identified as an effective treatment (46.70% -75.84%) against the infestation of sucking pests. Among the aqueous plant extracts, Neem Seed Kernel Extract (NSKE) 5% showed 63.48% reduction of leaf hoppers, 64.48 % of whitefly, 43.72 % of mealy bug, 42.68 % of red spider mite. Next effective results were obtained from Ginger, Garlic and Green chilli (3G) extract with 61.75 % population decline of leaf hopper, 57.86 % of whitefly, 41.35 % of mealy bug and 36.78 % of red spider mite.

Specialist Aphid Feeding Causes Local Activation of Salicylic and Jasmonic Acid Signaling in Arabidopsis Veins.

Aphids, the phloem sap feeders, probe into leaf tissues and activate a complex network of plant defense responses. Phytohormonal signaling plays a major role in this network; however, the dynamics of the signal spreading is yet to be clarified. Despite the growing knowledge about transcriptomic changes upon infestation, results often differ due to sampling, varying strongly between the tissues collected at the single feeding site, individual leaves, pooled infested leaves, or whole plant rosettes. This study focuses on activation of salicylic acid (SA) and jasmonic acid (JA) signals in Arabidopsis leaves during infestation by cabbage aphid (Brevicoryne brassicae) in high spatio-temporal resolution. We used genetically encoded fluorescent biosensors, histochemistry, and quantitative reverse transcription-PCR to precisely map activation of distinct branches of phytohormonal signaling. We found a rapid induction of SA and JA signaling markers in cells surrounding stylet puncture, colocalizing with callose deposition. For both PR1 and JAZ10, we detected activation at 24 h postinfestation (hpi), increasing and spreading along the veins until 72 hpi and, to a lesser extent, within the epidermal pavement cells. The SA signaling wave appeared in parallel with JA-associated signaling and continued to increase in time. Our results first show a local activation of SA- and JA-related responses after stylet penetration of Arabidopsis leaves and bring a detailed insight into the spatio-temporal complexity of plant defense activation during specialist aphid attack.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Effectiveness of classical weed biological control agents released in Australia

The historical record of releases of 288 species of weed biological control agents in Australia was analysed to examine if considering the damage/host type relationship of agents can offer insights into why some agents and not others have proved to be effective in producing partial or complete control of the target weed. Specifically, the effectiveness of agents released in Australia was examined in relation to their feeding guild and the functional group (growth form) of the target weed. Biotrophic pathogens (rusts/smuts), sap feeders and root/crown feeders were effective in producing control more often than other guilds. Effectiveness of biological control across weed functional groups was somewhat similar, although herbaceous biennials/perennials tended to be more effectively controlled than other functional groups. Significant biological control was recorded for at least one case in each of the 31 of the 37 feeding-guild/weed functional group combinations for which there were data. Possible explanations for the greater success of some guilds are explored, as are caveats with using such inductive approaches to predict effectiveness in classical weed biological control.

Differential expression of gut protein genes and population density of Arsenophonus contributes to sex-biased transmission of Bemisia tabaci vectored Cotton leaf curl virus.

Whitefly, Bemisia tabaci (Gennadius) is an important pest of cotton causing direct damage as sap feeder and vector of Cotton leaf curl virus (CLCuV). Previous few studies suggest that female whiteflies are more efficient vector of begomovirusthan males, however the sex-biased transmission efficiency is still not clearly understood. Present studies with B. tabaci AsiaII-1 haplotype showed higher virus transmission efficiency of females compared to males. This variable begomovirus transmission efficiency has been related to previously identifiedkey factors associated with B. tabaci. The higher density of endosymbiont Arsenophonus and variable expression of some midgut proteins genes i.e. Cyclophilin, Knottin, Hsp40, Hsp70 may be possibly imparting higher vector competency to the females compared to males. The present studies suggest low abundance of Arsenophonus spp. as well as lower expressionof Cyclophilin genein males as compared to females. This is further supplemented by overexpression of Knottin, Hsp40, and Hsp70 genes in males compared to females and thus collectively all these factors might be playing a key role in low virus transmission efficiency of males. The relative density of Arsenophonus spp. and expression of midgut proteins genes in male and female whitefly first time enriches our understanding about sex-biased transmission efficiency of begomovirus.

Identification of Potential Host Plants of Sap-Sucking Insects (Hemiptera: Cicadellidae) Using Anchored Hybrid By-Catch Data.

Simple SummaryPlant–insect interactions are a significant driver of terrestrial biodiversity. Evolutionary studies of such interactions have been hindered by the lack of reliable host plant records, which have primarily been obtained through field observations. More recently, traditional or next-generation sequencing methods have been used successfully to detect host plant DNA in DNA extracted from plant-feeding insects, but most such studies have focused on chewing insects that ingest plant tissues with large quantities of DNA. In this study, next-generation sequencing data were used to determine the feasibility of detecting plant genes in sap-sucking insects, which may ingest very little plant DNA. Although no plant-specific probes were used to generate the sequence data, multiple plant genes were retrieved in the by-catch data. Our results suggest that next-generation sequencing may present a powerful tool for detecting and characterizing potential host plants using DNA extracted from phytophagous insects, including sap feeders.Reliable host plant records are available for only a small fraction of herbivorous insect species, despite their potential agricultural importance. Most available data on insect–plant associations have been obtained through field observations of occurrences of insects on particular plants. Molecular methods have more recently been used to identify potential host plants using DNA extracted from insects, but most prior studies using these methods have focused on chewing insects that ingest tissues expected to contain large quantities of plant DNA. Screening of Illumina data obtained from sap feeders of the hemipteran family Cicadellidae (leafhoppers) using anchored hybrid enrichment indicates that, despite feeding on plant fluids, these insects often contain detectable quantities of plant DNA. Although inclusion of probes for bacterial 16S in the original anchored hybrid probe kit yielded relatively high detection rates for chloroplast 16S, the Illumina short reads also, in some cases, included DNA for various plant barcode genes as “by-catch”. Detection rates were generally only slightly higher for Typhlocybinae, which feed preferentially on parenchyma cell contents, compared to other groups of leafhoppers that feed preferentially on phloem or xylem. These results indicate that next-generation sequencing provides a powerful tool to investigate the specific association between individual insect and plant species.

Seasonal incidence of sap feeders and defoliators in black gram [Vigna mungo (L.) Hepper], at Pajancoa and RI, Karaikal, U.T. OF Puducherry

Seasonal incidence of black gram feeder pests viz., bean aphids, Aphis craccivora and flower thrips, Megalurothrips. usitatus and defoliator pests like striped flea beetle, Phyllotreta. striolata, leaf folder Omiodes indicata and tobacco leaf caterpillar, Spodoptera litura were studied in the entire crop period during Kharif 2019 and Rabi 2019 -2020. The results indicated that the population of sap feeders reached a high peak at 38th and 36th standard week (SW); 12th and 11th SW during Kharif 2019 and Rabi 2019 - 2020. Defoliators reached high peak at 37th and 11th SW in both the seasons and Spodoptera infestation was high during 13th SW. The population of sap feeders and defoliators was recoded positive correlation with morning and evening relative humidity (RH) and rainfall and negative correlation with maximum and minimum temperature during Kharif 2019. During Rabi 2019 -2020, positive correlation was recoded with maximum and minimum temperature and rainfall and negative correlation with morning and evening RH.

Feeding guild determines strength of top-down forces in multitrophic system experiencing bottom-up constraints

Nitrogen (N) and water are crucial in crop production but increasingly scarce environmental resources. Reducing their inputs can affect the whole plant-arthropod community including biocontrol agents. In a multitrophic system, we studied the interaction of the bottom-up effects of moderately reduced N concentration and/or water supply as well as the top-down effects of pests of different feeding guilds on plant nutritional quality (N and carbon concentration), direct defense (alkaloids and phenolics), and indirect defense (plant volatile organic compounds); on herbivore performance and host quality (N and carbon) to parasitoids and the latter's performance. Studied organisms were tomato plants, the sap feeders Macrosiphum euphorbiae and Bemisia tabaci, the leaf chewers Tuta absoluta and Spodoptera littoralis, and the parasitic wasps Aphelinus abdominalis and Necremnus tutae. Resource limitation affected plant quality, triggering bottom-up effects on herbivore and parasitoid performance, except for T. absoluta and N. tutae. Feeding guild had a major influence: bottom-up effects were stronger on sap feeders; N effects were stronger on sap feeders while water effects were stronger with leaf chewers (S. littoralis). Top-down effects of leaf chewer herbivory partly attenuated bottom-up effects and partly suppressed plant defenses. Bottom-up effects weakened when cascading up trophic levels. In summary, the interaction between plants, pests, and beneficial insects was modulated by abiotic factors, affecting insect performance. Simultaneous abiotic and biotic impact shaped plant biochemistry depending on the feeding guild: the biotic top-down effect of leaf chewer herbivory attenuated the bottom-up effects of plant nutrition and hence dominated the plant biochemical profile whereas in sap feeder infested leaves, it corresponded to the abiotic impact. This study highlights the plant's finely tuned regulatory system facilitating response prioritization. It offers perspectives on how smart manipulation of plant nutrient solutions might save resources while maintaining efficient biocontrol in crop production.

Classical biological control against insect pests in Europe, North Africa, and the Middle East: What influences its success?

Many factors can affect the success and failure of classical biological control. However, these factors have mainly been studied independently of each other, which leaves their relative importance within the complexity of classical biological control (CBC) programmes unknown. Therefore, we set out to take a more holistic view on the factors that may impact the outcome of CBC of insect pests by insect predators and parasitoids. To this end, we filtered the BIOCAT catalogue to extract entries for the Greater Western Palearctic ecozone and added 15 new explanatory variables. These mainly concerned traits of released biological control agents, target pests, and host plants of the target, but also included the number of introductions for specific agent-target combinations as a management aspect. We then analysed the data regarding three levels of success: agent establishment, impact on the target population, and complete control of the target. Between 1890 and 2010 a total of 780 introductions of insects for biological control were undertaken in the analysed area, constituting 416 agent-target combinations. Overall success of agent establishment was 32%, successful impact of single agents on their target was 18%, and success of complete control was 11%. The number of factors significantly influencing the outcome of CBC decreased with increasing level of success. Remarkably few agent-related factors influenced the success: insect predators as agents decreased the probability of establishment and using oligophagous parasitoids significantly decreased the chances of complete control. Other significant factors were related to traits of target pests or their host plants. For example, sap feeders and target pests attacking reproductive plant parts were more likely to be successfully controlled. The rate of success increased with the number of introductions of CBC agents, in particular against univoltine target pests. These findings suggest that a focus on agent-related traits to increase the chances of successful CBC is not fully justified and should be complemented with the consideration of lower trophic levels and other aspects of CBC, such as abiotic factors and management.

Low moisture stress influences plant volatile emissions affecting herbivore interactions in tomato, Solanum lycopersicum

1. Frequently changing climatic conditions can cause recurring droughts which often subject plants to tremendous amounts of stress, leaving biologists to wonder about its impact on the associated herbivores and their interactions with host plants.2. The present study was aimed at assessing the impact of low moisture stress on herbivore‐plant interactions using tomato and its associated herbivores (leaf miner, Tuta absoluta and sap feeder, Bemisia tabaci).3. The leaf miner T. absoluta preferred tomato plants exposed to moderate drought stress compared to severely drought stressed or healthy plants while the sap feeder B. tabaci preferred healthy tomato plants that were irrigated regularly over others. Our study uncovers few intriguing aspects of low moisture stress on herbivore‐host interactions and also highlights that this influence may vary depending upon the herbivore feeding guild.4. The volatile profiles of tomato plants were found to differ significantly when subjected to varied degrees of low moisture stress. Such changes in plant's volatile emissions may in turn alter its associated herbivore's behavioural perspective as observed in T. absoluta and B. tabaci.5. Reduced amounts of caryophyllene, humulene, 3‐carene, myristic acid, and γ‐butyl‐γ‐butyrolactone might be what aids T. absoluta and B. tabaci in gauging the drought stress status of a host plant. Further, the presence of chemical cues such as α‐pinene, m‐cymene, and ethyl benzaldehyde might signal T. absoluta moths of severely stressed plants. Similarly, the presence of undecane, ethyl benzaldehyde, n‐hexadecanoic acid might aid whiteflies in identifying plants reeling under low moisture stress.