Chewing Insects Research Articles

The Impact of Neonicotinoid Pesticides on Reproductive Health.

Neonicotinoids are some of the most widely used insecticides in the world because they broadly target chewing and sucking insects. Neonicotinoids are used in commercial agricultural systems, sold for use in home gardens, and found in veterinary pharmaceuticals in the form of flea and tick preventatives for companion animals. They are also used as crop seed treatments and spread throughout crops as they mature. As a result, humans, wildlife, livestock, and pets are routinely exposed to neonicotinoids through consumption of contaminated food and water as well as through use of some veterinary pharmaceuticals. Although several studies indicate that neonicotinoid exposure causes genotoxicity, neurotoxicity, hepatotoxicity, and immunotoxicity in some non-target species, the impact of neonicotinoid pesticides on the male and female reproductive systems in mammals is largely understudied. This review summarizes current insights on the impact of common neonicotinoid pesticides such as acetamiprid, clothianidin, imidacloprid, and thiacloprid on male and female reproductive health in mammals. The review also summarizes the impacts of exposure to mixtures of neonicotinoids on reproductive endpoints. In addition, this review highlights where gaps in research on neonicotinoid pesticides and reproductive health exist so that future studies can be designed to fill current gaps in knowledge.

Plant Stress in Determining Attack Rates of Herbivorous Chewing Insects

Plant Stress in Determining Attack Rates of Herbivorous Chewing Insects

Transgenic cotton expressing Allium sativum leaf agglutinin exhibits resistance to whiteflies and aphids without negative effects on ladybugs

Cotton (Gossypium hirsutum L.) is of great economic importance as a cultivated crop in many parts of the world. In addition to being a pillar of the textile industry, cotton and its byproducts are used for livestock feed, seed oil, and other products. Bacillus thuringiensis crystal toxin (Bt) expression in cotton provides effective protection against chewing insects but does not defend plants from piercing/sucking insect pests. With the aim to create transgenic plants with resistance against piercing/sucking pests, we used Agrobacterium-mediated genetic transformation of cotton cultivar Coker 312 to express the Allium sativum leaf agglutinin (ASLA) gene from the phloem-specific rolC promoter. The ASLA transgene was stably inherited and showed Mendelian segregation in the T1 generation. Transgenic lines, expressing the ASLA gene, showed explicit resistance against major sap-sucking pests. Green peach aphid (Myzus persicae Sulzer) choice assays showed that 75% of aphids preferred untransformed cotton plants relative to those expressing the ASLA gene. In detached leaf bioassays, plants expressing ASLA caused 82% aphid mortality and 44–53% reduction in fecundity. Clip cage bioassays with whiteflies (Bemisia tabaci Gennadius) showed 74–82% mortality and 44–60% decrease in fecundity due to ASLA gene expression. In whole plant bioassays, whiteflies showed 77% mortality and a 54% decrease in fecundity on ASLA transgenics. Importantly, we did not observe a negative effect of the ASLA gene on ladybugs (Coccinella septempunctata) that consumed these whiteflies. Together, our findings demonstrate the potential of ASLA-transgenic cotton for providing protection against two devastating insect pests, whiteflies and aphids. The ASLA-transgenic cotton appears promising for direct commercial cultivation besides serving as a potential genetic resource in recombination breeding.

A conserved protein family in mirid bug Riptortus pedestris plays dual roles in regulating plant immunity.

The mirid bug (Riptortus pedestris), a major soybean pest, migrates into soybean fields during the pod filling stage and causes staygreen syndrome, which leads to substantial yield losses. The mechanism by which R. pedestris elicits soybean (Glycine max) defenses and counter-defenses remains largely unexplored. In this study, we characterized a protein family from R. pedestris, designated Riptortus pedestris HAMP 1 (RPH1) and its putative paralogs (RPH1L1, 2, 3, 4, and 5), whose members exhibit dual roles in triggering and inhibiting plant immunity. RPH1 and RPH1L1 function as herbivore-associated molecular patterns (HAMPs), activating pattern-triggered immunity (PTI) in tobacco (Nicotiana benthamiana) and G. max. Furthermore, RPH1 stimulates jasmonic acid and ethylene biosynthesis in G. max, thereby enhancing its resistance to R. pedestris feeding. Additionally, RPH1 homologs are universally conserved across various herbivorous species, with many homologs also acting as HAMPs that trigger plant immunity. Interestingly, the remaining RPH1 putative paralogs (RPH1L2-5) serve as effectors that counteract RPH1-induced PTI, likely by disrupting the extracellular perception of RPH1. This research uncovers a HAMP whose homologs are conserved in both chewing and piercing-sucking insects. Moreover, it unveils an extracellular evasion mechanism utilized by herbivores to circumvent plant immunity using functionally differentiated paralogs.

Oral secretions from striped stem borer (Chilo suppressalis) induce defenses in rice.

The striped stem borer (SSB, Chilo suppressalis) is one of the most destructive insect pests on rice. As a chewing insect, SSB larval feeding causes a dramatic increase in rice defense responses. However, the effects of oral secretions (OSs) during SSB feeding on rice defense remain largely unexplored. In this study, based on transcriptome analysis results, treatment with SSB OSs regulated the expression of genes involved in the plant defense-related pathways of calcium, mitogen-activated protein kinases, reactive oxygen species, jasmonic acid (JA), herbivore-induced plant volatiles (HIPVs), and protease inhibitors. Unsurprisingly, treatment with SSB OSs elicited the accumulation of JA and JA-isoleucine in rice. The defense mechanisms activated by the cascade not only induced the expression of trypsin inhibitors, inhibiting the normal growth of SSB larvae but also induced HIPVs emission, rendering rice attractive to a common larval parasitoid. High-throughput proteome sequencing of SSB OSs led to 534 proteins being identified and 343 proteins with two or more unique peptides being detected. The study demonstrates that SSB OSs trigger both direct and indirect defense mechanisms in rice, akin to the effects of SSB feeding. It identifies specific proteins in SSB OSs that may influence the interactions between SSB and rice during feeding, providing valuable insights for effectors research. © 2024 Society of Chemical Industry.

Toxicological assessment of a novel spiro‐derivative, 4‐amino‐1‐azaspiro[4.5]dec‐3‐en‐2‐one for the greater wax moth, Galleria mellonella

AbstractThe greater wax moth, Galleria mellonella L., poses a substantial threat to apiculture, adversely impacting wax quality and potentially acting as a disease vector. There is an urgent need to develop innovative and effective control strategies to address the challenges posed by this pest and ensure the sustainability of the apiculture industry. Spiro‐derivative compounds represent a novel class of environmentally safe compounds with high insecticidal properties. For example, they have demonstrated high efficacy against sap‐sucking insects such as aphids and whiteflies. However, their effect on chewing insects has not yet been well explored. In this study, we hypothesized that 4‐amino‐1‐azaspiro[4.5]dec‐3‐en‐2‐one (4A1AD), a spiro‐derivative compound, would exhibit efficacy against G. mellonella larvae. To test this hypothesis, we conducted dipping and feeding bioassays, incorporating varying concentrations of 4A1AD on fourth instar G. mellonella larvae, and recorded mortality, biochemical parameters including total soluble protein content and enzyme activities, and anatomical abnormalities resulting from treatment. Results revealed a significant increase in larval mortality with increased concentrations and treatment durations across both bioassays. Additionally, a significant decrease in protein content and an increase in phenol‐oxidase activity were observed with alterations in α and β‐esterase activities. Scanning electron microscope findings revealed abnormalities in larval cuticle, spiracular openings and legs. These findings demonstrated the efficacy of 4A1AD, indicating a potential alternative to conventional insecticides in promoting sustainable apiculture practices. Moreover, they provide valuable contributions to the development of novel strategies for effective pest management in apicultural settings.

Foliar phosphorus concentration modulates the defensive mutualism of an endophytic fungus in a perennial host grass

Abstract Grasses hosting Epichloë endophytes are protected against herbivores due to the production of various fungal alkaloids. Previous research has found that high foliar phosphorus concentrations reduce the level of the alkaloid ergovaline, thereby reducing the endophyte‐mediated herbivore resistance. Yet, the impact of phosphorus on ergovaline biosynthesis versus its influence on endophyte growth and synthesis of other fungal alkaloids remains unresolved. Our objective was to elucidate these relationships. We grew endophyte‐symbiotic and non‐symbiotic Festuca arundinacea plants and fertilised them with different doses of phosphorus. Later, half of the plants from each treatment were challenged with larvae of the generalist chewing insect Spodoptera frugiperda. We assessed the relationships between foliar phosphorus levels, fungal mycelium and alkaloid concentrations, as well as their impacts on larvae performance, herbivore‐caused damage and plant biomass. Endophyte mycelial biomass in plant tissue was found to be independent of foliar phosphorus concentration. The alkaloids lolines and peramine showed a linear relationship with mycelial biomass but no correlation with foliar phosphorus. Surprisingly, high ergovaline concentrations were positively associated with an interaction between endophyte mycelial biomass and foliar phosphorus concentration. Although herbivory increased loline concentration, only high concentrations of ergovaline and peramine were related to reduced S. frugiperda larvae weight gain. However, endophyte presence did not reduce herbivory damage on plants. Contrary to expectation, we did not find a negative but a positive association between concentrations of foliar phosphorus and ergovaline alkaloid, through its interaction with endophyte mycelial biomass. Alternatively, our findings suggest that phosphorus plays a crucial role in modulating the Epichloë‐mediated defensive mutualism, primarily through its effects on ergovaline rather than on endophyte concentration or production of other alkaloids. Read the free Plain Language Summary for this article on the Journal blog.

Feeding specialization shapes the bottom‐up effect of arbuscular mycorrhizal fungi across a plant–aphid–parasitoid system

Societal Impact StatementArbuscular mycorrhizal fungi (AMF) impact the relationships between plants, aphids (insects that feed on plant phloem), and their natural enemies (insects that prey on or parasitize aphids). The presence of AMF influences the growth and population of different aphid species and affects the development of aphid‐killing wasps and their attraction to plants. This research has been conducted also considering the insects' feeding strategy and their feeding specialization. This study provides novel perspectives on how these fungi shape interactions in the natural world, offering potential insights for the development of sustainable pest management strategies in agriculture.Summary Arbuscular mycorrhizal fungi (AMF) are major root symbionts regulating plant physiology. Their presence affects the performance of aboveground insect herbivores in relation to their feeding strategy and their feeding specialization. For example, the effect of the arbuscular mycorrhizal (AM) symbiosis on chewing insects, positive for specialists and negative for generalists, has been previously demonstrated. Conversely, the impact of AMF on phloem‐suckers with relatively different levels of specialization remains unexplored. We tested the influence of the AM Funneliformis mosseae on the fitness of the specialist aphid Acyrthosiphon pisum and the generalist aphid Myzus persicae on Vicia faba plants. Further, we investigated the effects of AMF on the higher trophic level, the aphid parasitoids Aphidius ervi (specialist) and Aphidius colemani (generalist), by evaluating plant attractiveness and parasitoid fitness. To support the results of behavioral and biological bioassays we characterized the photosynthetic parameters, the volatilome and the transcriptome of tested plants. Mycorrhizal plants proved unsuitable for the generalist M. persicae but enhanced the fitness of the specialist A. pisum. The AM symbiosis had no effects on the behavioral response of A. colemani and enhanced the attraction and fitness of A. ervi. Volatilome and transcriptome profiling corroborated the results of bioassay highlighting a bottom‐up effect of the AMF across a plant–aphid–parasitoid system.

Developing Oak Buds Produce Volatile Emissions in Response to Herbivory by Freshly Hatched Caterpillars.

Plant responses to damage by insectivorous herbivores are well-documented in mature leaves. The resulting herbivore-induced plant volatiles (HIPVs) protect the plant by attracting carnivorous arthropods and even some insectivorous vertebrates, to parasitize or consume the plant invaders. However, very little is known about plant production of HIPVs in developing buds, particularly when herbivorous insects are too small to be considered a prey item. It is additionally unclear whether plants respond differently to generalist and specialist chewing insects that overlap in distribution. Therefore, we compared HIPV production of Downy oak (Quercus pubescens Willd.) buds infested with freshly hatched caterpillars of Tortrix viridana (specialist) and Operophtera brumata (generalist), against uninfested buds. Of the compounds identified in both years of the experiment, we found that (Z)-hex-3-enyl acetate, (E)-β-ocimene, acetophenone, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), methyl salicylate, α-copaene, α-humulene, (E)-caryophyllene, and (E,E)-α-farnesene appeared to be higher in infested buds compared to controls. We found no difference in HIPV production between the specialist and the generalist herbivores. Production of HIPVs was also associated with leaf damage, with higher HIPV production in more severely attacked buds. Thus, our study shows that oak trees already start responding to insect herbivory before leaves are developed, by producing compounds similar to those found in damaged mature leaves. Future work should focus on how Downy oak may benefit from initiating alarm cues at a time when carnivorous arthropods and insectivorous vertebrates are unable to use herbivorous insects as host or food.

Lethal and Sublethal Effects of Cyantraniliprole on the Biology and Metabolic Enzyme Activities of Two Lepidopteran Pests, Spodoptera littoralis and Agrotis ipsilon, and A Generalist Predator, Chrysoperla carnea (Neuroptera: Chrysopidae).

Cyantraniliprole is a novel anthranilic diamide insecticide registered for controlling chewing and sucking insect pests. Here, the lethal and sublethal effects of this insecticide on two destructive lepidopteran pests, Spodoptera littoralis Boisduval and Agrotis ipsilon Hufnagel, were evaluated. Because the effects of novel insecticides on beneficial and non-target arthropods must be considered, the impact of cyantraniliprole on a generalist biological control agent, Chrysoperla carnea [Stephens 1836], were also examined. Overall, our study revealed that cyantraniliprole was more toxic to A. ipsilon than to S. littoralis. Moreover, the LC15 and LC50 of the insecticide significantly prolonged the duration of the larval and pupal stages and induced enzymatic detoxification activity in both species. Treatment of the second-instar larvae of C. carnea with the recommended concentration of cyantraniliprole (0.75 mg/L) doubled the mortality rates and resulted in a slight negative effect on the biology and detoxification enzymes of C. carnea. Our results indicate that both sublethal and lethal concentrations of cyantraniliprole can successfully suppress S. littoralis and A. ipsilon populations. They also suggest that C. carnea, as a generalist predator, is compatible with cyantraniliprole under the modelled realistic field conditions. In future investigations, insights into the effects of cyantraniliprole on S. littoralis, A. ipsilon, and C. carnea under field conditions will be required to appropriately validate our results.

Genome-Wide Transcriptomic and Metabolomic Analyses Unveiling the Defence Mechanisms of Populus tremula against Sucking and Chewing Insect Herbivores.

Plants and insects coevolved as an evolutionarily successful and enduring association. The molecular arms race led to evolutionary novelties regarding unique mechanisms of defence and detoxification in plants and insects. While insects adopt mechanisms to conquer host defence, trees develop well-orchestrated and species-specific defence strategies against insect herbivory. However, current knowledge on the molecular underpinnings of fine-tuned tree defence responses against different herbivore insects is still restricted. In the current study, using a multi-omics approach, we unveiled the defence response of Populus tremula against aphids (Chaitophorus populialbae) and spongy moths (Lymantria dispar) herbivory. Comparative differential gene expression (DGE) analyses revealed that around 272 and 1203 transcripts were differentially regulated in P. tremula after moth and aphid herbivory compared to uninfested controls. Interestingly, 5716 transcripts were differentially regulated in P. tremula between aphids and moth infestation. Further investigation showed that defence-related stress hormones and their lipid precursors, transcription factors, and signalling molecules were over-expressed, whereas the growth-related counterparts were suppressed in P. tremula after aphid and moth herbivory. Metabolomics analysis documented that around 37% of all significantly abundant metabolites were associated with biochemical pathways related to tree growth and defence. However, the metabolic profiles of aphid and moth-fed trees were quite distinct, indicating species-specific response optimization. After identifying the suitable reference genes in P. tremula, the omics data were further validated using RT-qPCR. Nevertheless, our findings documented species-specific fine-tuning of the defence response of P. tremula, showing conservation on resource allocation for defence overgrowth under aphid and moth herbivory. Such findings can be exploited to enhance our current understanding of molecular orchestration of tree responses against herbivory and aid in developing insect pest resistance P. tremula varieties.

Biochemical Responses in Populus tremula: Defending against Sucking and Leaf-Chewing Insect Herbivores.

The main biochemical traits were estimated in poplar leaves under biotic attack (aphids and spongy moth infestation). Changes in the abundance of bioactive compounds in genetically uniform individuals of European aspen (Populus tremula), such as proline, polyphenolic compounds, chlorophylls a and b, and volatile compounds, were determined between leaves damaged by sucking insects (aphid-Chaitophorus nassonowi) and chewing insects (spongy moth-Lymantria dispar) compared to uninfected leaves. Among the nine analyzed phenolic compounds, only catechin and procyanidin showed significant differences between the control leaves and leaves affected by spongy moths or aphids. GC-TOF-MS volatile metabolome analysis showed the clear separation of the control versus aphids-infested and moth-infested leaves. In total, the compounds that proved to have the highest explanatory power for aphid-infested leaves were 3-hexenal and 5-methyl-2-furanone, and for moth-infested leaves, trans-α-farnesene and 4-cyanocyclohexane. The aphid-infested leaves contained around half the amount of chlorophylls and twice the amount of proline compared to uninfected leaves, and these results evidenced that aphids influence plant physiology more than chewing insects.

Defense strategies and associated phytohormonal regulation in Brassica plants in response to chewing and sap-sucking insects.

Plants have evolved distinct defense strategies in response to a diverse range of chewing and sucking insect herbivory. While chewing insect herbivores, exemplified by caterpillars and beetles, cause visible tissue damage and induce jasmonic acid (JA)-mediated defense responses, sucking insects, such as aphids and whiteflies, delicately tap into the phloem sap and elicit salicylic acid (SA)-mediated defense responses. This review aims to highlight the specificity of defense strategies in Brassica plants and associated underlying molecular mechanisms when challenged by herbivorous insects from different feeding guilds (i.e., chewing and sucking insects). To establish such an understanding in Brassica plants, the typical defense responses were categorized into physical, chemical, and metabolic adjustments. Further, the impact of contrasting feeding patterns on Brassica is discussed in context to unique biochemical and molecular modus operandi that governs the resistance against chewing and sucking insect pests. Grasping these interactions is crucial to developing innovative and targeted pest management approaches to ensure ecosystem sustainability and Brassica productivity.

Duplicated Copy Number Variant of the Maize 9-Lipoxygenase ZmLOX5 Improves 9,10-KODA-Mediated Resistance to Fall Armyworms.

Extensive genome structure variations, such as copy number variations (CNVs) and presence/absence variations, are the basis for the remarkable genetic diversity of maize; however, the effect of CNVs on maize herbivory defense remains largely underexplored. Here, we report that the naturally occurring duplication of the maize 9-lipoxygenase gene ZmLOX5 leads to increased resistance of maize to herbivory by fall armyworms (FAWs). Previously, we showed that ZmLOX5-derived oxylipins are required for defense against chewing insect herbivores and identified several inbred lines, including Yu796, that contained duplicated CNVs of ZmLOX5, referred to as Yu796-2×LOX5. To test whether introgression of the Yu796-2×LOX5 locus into a herbivore-susceptible B73 background that contains a single ZmLOX5 gene is a feasible approach to increase resistance, we generated a series of near-isogenic lines that contained either two, one, or zero copies of the Yu796-2×LOX5 locus in the B73 background via six backcrosses (BC6). Droplet digital PCR (ddPCR) confirmed the successful introgression of the Yu796-2×LOX5 locus in B73. The resulting B73-2×LOX5 inbred line displayed increased resistance against FAW, associated with increased expression of ZmLOX5, increased wound-induced production of its primary oxylipin product, the α-ketol, 9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid (9,10-KODA), and the downstream defense hormones regulated by this molecule, 12-oxo-phytodienoic acid (12-OPDA) and abscisic acid (ABA). Surprisingly, wound-induced JA-Ile production was not increased in B73-2×LOX5, resulting from the increased JA catabolism. Furthermore, B73-2×LOX5 displayed reduced water loss in response to drought stress, likely due to increased ABA and 12-OPDA content. Taken together, this study revealed that the duplicated CNV of ZmLOX5 quantitively contributes to maize antiherbivore defense and presents proof-of-concept evidence that the introgression of naturally occurring duplicated CNVs of a defensive gene into productive but susceptible crop varieties is a feasible breeding approach for enhancing plant resistance to herbivory and tolerance to abiotic stress.

Beyond Bites: Differential Role of Fall Armyworm Oral Secretions and Saliva in Modulating Sorghum Defenses.

Flavonoids are major plant secondary metabolites that provide defense against several insect pests. Previously, it has been shown that sorghum (Sorghum bicolor) flavonoids are required for providing resistance to fall armyworm (FAW; Spodoptera frugiperda), which is an important chewing insect pest on several crops. We demonstrate here the role of FAW oral cues in modulating sorghum flavonoid defenses. While feeding, chewing insects release two kinds of oral cues: oral secretions (OS)/regurgitant and saliva. Our results indicate that FAW OS induced the expression of genes related to flavonoid biosynthesis and total flavonoids, thereby enhancing sorghum's defense against FAW larvae. Conversely, FAW saliva suppressed the flavonoid-based defenses and promoted FAW caterpillar growth, independent of the FAW salivary component, glucose oxidase (GOX). Thus, we infer that different oral cues in FAW may have contrasting roles in altering sorghum defenses. These findings expand our understanding of the precise modes of action of caterpillar oral cues in modulating plant defenses and help in designing novel pest management strategies against FAW in this vital cereal crop. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Insecticide mixtures-uses, benefits and considerations.

Insecticides remain an important tool for the control of many insect pests. There has long been an interest in insecticide mixtures (in-can and tank-mix) as a means to provide the needed efficacy and/or spectrum to control many insect public health, crop pests or crop pest complexes. This aspect has become more important since insecticides developed in the last 30 years tend to be narrower in spectrum with many primarily focused on either sap-feeding or chewing insect pests. Insecticide mixtures are also seen as an important approach to insect resistance management (IRM) with certain requirements for optimal implementation. Additionally, insecticide mixtures can also address certain agronomic, commercial and intellectual property needs and opportunities. This perspective will review some of the drivers and considerations for insecticide mixtures and their potential uses. © 2024 Society of Chemical Industry.

Synthesis and insecticidal activity of N-(5-phenylpyrazin-2-yl)-benzamide derivatives: Elucidation of mode of action on chitin biosynthesis through symptomology and genetic studies

Among the six-membered heterocycles, the pyrazine ring is poorly explored in crop protection and does not feature in any product listed in the current IRAC MoA classification. In an effort to identify new leads for internal research, we synthesized a series of N-(5-phenylpyrazin-2-yl)-benzamide derivatives and evaluated them for their insecticidal activity. N-(5-phenylpyrazin-2-yl)-benzamide derivatives 3 were prepared using an automated two-step synthesis protocol. These compounds were tested for their initial biological activity against a wide range of sucking and chewing insect pests and found to be active against lepidopterans only. More detailed experiments, including symptomology studies on the diamondback moth, Plutella xylostella (L.) and the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval) showed that analog 3q causes severe abnormalities in the lepidopteran cuticle leading to larval mortality. Compound 3q shows strong potency against both P. xylostella and S. littoralis, whereas analog 3i shows better potency against S. littoralis causing also impaired cuticular structure and death of the larvae. Additionally, P. xylostella genetic studies showed that compound 3q resistance is linked to Chitin Synthase 1. Our studies show that N-(5-phenylpyrazin-2-yl)-benzamide derivatives 3, and in particular analogs 3i and 3q, act as insect growth modulator insecticides. Conformational similarities with lufenuron are discussed.

Magnetically treated water for removal of surface contamination by Malathion on Chinese Kale (Brassica oleracea L.).

Malathion® is a persistent organophosphate pesticide used against biting and chewing insects on vegetables. It is a difficult-to-remove surface contaminant of vegetables and contaminates surface and ground water and soils. Malathion® is only partially water soluble, but use of detergent carriers makes adhering Malathion® residues difficult to subsequently remove. Magnetically treated water (MTW) successfully removed Malathion® from Chinese Kale (Brassica oleracea L.), meeting Maximum Residue Load (MRL) standards. Samples were soaked in MTW for 30 min prior to detection with GC/MS/MS, 98.5±3.02% of Malathion® was removed after washing by MTW. Removal by simple washing was only ≈42±1.2% which was not nearly sufficient to meet MRL criteria.

Impact of vereda dryness on the insect herbivore diversity in adjacent cerrado areas in Brazilian Protected Areas

Unravelling the factors that influence plant-insect interactions remains a fundamental concern in terrestrial ecology. In the present study, we evaluated the impact of varying degrees of drying on cerrado areas adjacent to veredas on the species richness, abundance and composition of the insect herbivore fauna. Additionally, we examined differences in these impacts between various guilds (chewing and sucker insects) and developmental stages (adult and immature insects). The research has been performed in study areas located in three Protected Areas in Brazil. In total, we recorded 106 species of herbivorous insects across five orders (Coleoptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera). Hemiptera and Coleoptera stood out as the orders with the highest species diversity and individual numbers. Among the families, Cicadellidae and Curculionidae exhibited the highest richness in species and abundance of individuals. We found that richness of herbivorous insects was higher in wet zones (20.2 ± 6.5) of the veredas compared to dry zones (12.3 ± 7.5), as well as the abundance of herbivorous insects was higher in wet zones (49.4 ± 25.5) than in the dry zones (15.8 ± 7.9). Whithin insect guilds, the abundance of chewing insects was higher in wet zones (34.0 ± 13.6) than in dry zones (16.3 ± 14.8), but this difference was not observed for the diversity of sucking insects. Regarding developmental stage, immature insects exhibited higher species richness in wet zones (10.4 ± 5.0) compared to dry zones (5.3 ± 2.1), while adult insect diversity did not show differences between the studied zones. Furthermore, the species composition of herbivorous insects, various trophic guilds (chewers and suckers) and developmental stages (adults and immature insect) did not significantly differ among the zones studied within the veredas. According to our findings, herbivorous insects exhibit a preference for wet environments, which provide better conditions and higher-quality food resources for development and reproduction.

Distribution pattern of arthropods and their ecological interactions on the leaf surfaces of Terminalia argentea saplings.

Terminalia argentea tree, native to Brazil, is widely used in landscaping, recovering degraded areas, its wood, coal production, and the bark or leaf extracts has medicinal use. Despite of its importance, the arthropod fauna associated to this plant and its interspecific relationships still needs further studies. The objectives of this study were to evaluate the arthropods, their ecological indices and the distribution in the leaf faces on T. argentea saplings. The numbers of phytophagous insects (e.g., Cephalocoema sp.), pollinators (e.g., Tetragonisca angustula), and natural enemies (e.g., Oxyopidae), and their ecological indices (e.g., species richness), were higher on the adaxial leaf faces on T. argentea saplings. Aggregated distribution of phytophagous insects (e.g., Aphis spiraecola), pollinators (e.g., Trigona spinipes), and natural enemies (e.g., Camponotus sp.) on T. argentea saplings was observed. Abundance, diversity, and species richness of natural enemies correlated, positively, with those of phytophagous and pollinators insects. Predators and tending ants followed their prey and sucking insects, respectively. Tending ants protected sucking insects against predators, and reduced chewing insects. The high number of Cephalocoema sp. on T. argentea saplings is a problem, because this insect can feed on leaves of this plant, but its preference for the adaxial leaf face favors its control. The aggregation behavior of arthropods on T. argentea saplings favors the control of potential pests of this plant. There seems to be competition between tending ants for space and food resources on T. argentea saplings.