Search Results (171)

To feed a growing population, humanity will need to see an increased global agricultural output in crop production. One key strategy for achieving this goal is to reduce herbivory by insect pests, which is one of the leading causes of crop loss. Although there have been many strategies for combating insect herbivores, biological control may be the most sustainable in the long term. Birds in particular are potentially powerful biocontrol agents, but how avian predation varies within individual agricultural settings remains largely unknown. Here, we analyzed temporal and spatial variations in putative avian predation potential on insect pests in a small-scale agricultural setting. Our results show that the spatial distribution of predation potential is nearly uniform across a small field, indicating that birds with their vagility may be particularly well suited for applying constant, uniform coverage, at least across smaller landscapes. We also found that predation potential by birds varied significantly between seasons, with the fall showing the highest rate of predation. We discuss the applications of our findings for further studies investigating the biocontrol potential of natural bird populations and for leveraging such avian predation to help improve food production systems. Full article

Neltuma pallida is a multi-purpose tree species of the seasonally dry tropical forests of northern Peru, where it provides essential ecological and socioeconomic functions. However, recurrent defoliation associated with the cecidomyiid gall midge Enallodiplosis discordis may compromise early seedling establishment and the success of forest restoration programs. This study evaluated the effects of larval infestation on foliar integrity and established quantitative damage thresholds in N. pallida seedlings under dry forest conditions. Insects collected from naturally infested plants were identified using an integrative taxonomic approach that combined classical morphological diagnosis with COI-based DNA barcoding obtained by Sanger sequencing. Morphological assessment assigned the defoliating dipteran to E. discordis, while BLASTn v2.17.0. analysis of the 576-bp partial COI sequence showed 92.6% identity and 100% query coverage with Cecidomyiidae records, supporting its taxonomic placement within this family. Field bioassays conducted over a 17-week period, in which 25 individual seedlings were evaluated (N = 25), revealed a strong and significant positive correlation between larval density and foliar damage percentage (r = 0.872; p < 0.001), with moderate damage levels predominating throughout the evaluation period. Despite sustained larval presence, seedlings did not reach severe damage categories, suggesting potential relative tolerance to partial defoliation under the evaluated field conditions. Temperature and relative humidity were not significantly associated with infestation intensity or foliar damage during the study period. Overall, these findings indicate that E. discordis-associated foliar damage represents a relevant, although not necessarily lethal, biotic constraint for the early regeneration of N. pallida under the field conditions assessed. The quantitative thresholds reported here provide useful criteria for dry forest restoration programs, phytosanitary monitoring, and integrated pest management strategies in the Peruvian dry forest. Full article

Beauveria bassiana (Balsamo-Crivelli) Vuillemin can colonize plant tissues as an endophyte, promoting plant growth and defense against pathogens and insect herbivory. Understanding the endophytic behavior of native isolates is important for developing pest management strategies in maize, a crop affected by Spodoptera frugiperda (J. E. Smith). This study aimed to genetically characterize a Mexican B. bassiana isolate (Bb-IIAF1-24) collected in Los Reyes, Michoacán, using the β-tubulin gene. The phylogenetic relationships showed that this isolate formed a well-supported clade with other B. bassiana isolates from different countries; however, a low divergence among them was observed. In a second part of this study, the influence of foliar and soil inoculation (1 × 10⁸ conidia mL⁻¹) of Bb-IIAF1-24 isolate on endophytic colonization in maize plants, as well as the effects on plant growth and herbivory by S. frugiperda were evaluated. This fungus was detected in roots, stems, and leaves, but no significant differences were found between root and stem colonization or between foliar and soil inoculation methods. Beauveria bassiana treatment resulted in increased stem diameter in plants when applied to soil compared to foliar application and the control. In contrast, plants subjected to foliar application were significantly taller than those receiving soil application or the control plants. Plants from both application methods experienced lower leaf damage compared to the control. These findings demonstrate the potential of the Bb-IIAF1-24 isolate as an endophytic fungus to promote maize growth and reduce herbivory by S. frugiperda. Full article

Camptotheca acuminata, the primary botanical source of camptothecin (CPT), employs this monoterpenoid indole alkaloid as a key chemical defense against herbivores in addition to its established clinical pharmaceutical importance. Given that Spodoptera frugiperda infestations pose a severe threat to C. acuminata seedlings, we examined integrated, multi-layered defense mechanisms that combine physical barriers with chemical toxins to bolster plant resistance. Physiological analyses revealed that herbivory induces antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT), alongside broader metabolic reprogramming. These responses are orchestrated by differential activation of jasmonic acid (JA) and salicylic acid (SA) signaling pathways, which together drive complex defense mobilization, including a marked increase in trichome density. Concurrently, insect herbivory activates the MYB-bHLH-WD40 (MBW) transcriptional complex to promote trichome development while upregulating core CPT biosynthetic genes. In particular, two cytochrome P450 genes, Ca32236 and CaCYP81BQ18, mediate the accumulation of 10-hydroxycamptothecin (10-HCPT), a derivative that is sparingly soluble in water, which enables alkaloid transport and sequestration to specialized storage sites, including trichomes. Collectively, these stress-responsive strategies confer potent insecticidal activity against S. frugiperda and provide valuable insights for improving protection in C. acuminata seedling plantations. Full article

Host-finding behavior of insect herbivores is a key determinant of herbivory intensity in agricultural and forest ecosystems, which often drives excessive pesticide application for pest control. While host plant apparency theory explains herbivore host detection, and push–pull strategies manipulate this behavior, both produce inconsistent results and remain mechanistically disconnected. Existing frameworks like the Resource Concentration Hypothesis focus mainly on host density, ignoring the multidimensional, context-dependent nature of apparency. Here, we synthesize forest and agricultural research to develop the first unified framework linking these two concepts. We show that host plant apparency is not intrinsic but shaped by plant morphology, non-host identity, and spatial arrangement. Push–pull strategies exploit this relativity by redesigning the chemical and physical apparency landscape. We argue that: (1) push–pull system success requires reducing main crop apparency while enhancing trap crop apparency; (2) trap crops may fail when their dual functions, olfactory attraction or physical interception, are misinterpreted, with profound implications for spatial design; and (3) this integration resolves field contradictions by framing them within a common bottom-up mechanism. Our framework provides a generalizable principle for sustainable pest management: effective control depends on understanding what makes host plants apparent to target pests in their specific local environment. Full article

Plant genotypes can vary in multiple functional traits due to adaptation to heterogenous environments. However, whether such variation can extrapolate to effects on soils and further on performance of subsequent plants, thus generating a genotypic variation in soil legacy, remains unclear. In this study, we studied how plant genotypic variation impacts soil legacy when exposed to aboveground insect herbivores. We used 11 wild genotypes of woodland strawberry (Fragaria vesca L.) experimentally exposed to leaf beetles (Galerucella tenella) to condition live soil. We then replaced the conditioning plants with naïve plants to examine soil legacy effects on growth and resistance on the subsequent plant genotype (referred to as the focal genotype) against the generalist herbivore Spodoptera littoralis. This allowed us to test the extent to which plant genotypic variation in soil legacy is altered by aboveground herbivory. We found an overall positive soil legacy effect of woodland strawberry, indicated by 69.9% higher belowground biomass of the subsequent focal genotype grown in conditioned soil compared to in unconditioned soil. We also observed a genotype-dependent soil legacy effect on performance of S. littoralis indicated as relative growth rates reduced by 37.9% on the subsequent focal genotype in soil conditioned by the focal genotype itself compared to by other genotypes, though the legacy effect was cancelled out when conditioning genotypes were exposed to G. tenella herbivory. A genotypic variation was further detected in soil legacy on the efficiency of conversion of ingested food by S. littoralis caterpillars feeding on the focal genotype. However, the genotypic variation was only present when the focal genotype was excluded from the conditioning genotypes at the exposure of G. tenella herbivory. Collectively, our study shows a conditional plant genotype-dependent soil legacy effect on herbivore resistance (measured as herbivore performance) rather than on plant growth, and the magnitude of the legacy effects depends on both the identity of the conditioning genotypes and the measures of the herbivore resistance. The findings of this study provide new insights into how plant genotypes or herbivory affects soil feedback on plant growth and herbivore resistance. Full article

A comprehensive annotated checklist of the members of the phytophagous ladybird beetle tribe Epilachnini (Coccinellinae) in China is compiled based on existing published sources and incorporates the latest taxonomic and nomenclatural updates. The checklist documents 176 extant species across 10 genera and provides analyses of regional species richness, distribution, and host plant associations. Regarding regional species richness, Yunnan Province is home to the highest number of species (76), followed by Taiwan (50), Sichuan (48), Guizhou (48), Guangxi (43), Tibet (43), Guangdong (25), Hainan (17), Hubei (17), Hunan (13), Shaanxi (13), Fujian (12), Henan (10), Jiangsu (10), Anhui (7), Shandong (7), Zhejiang (7), Jiangxi (5), Hong Kong (5), Gansu (5), Beijing (4), Hebei (4), Liaoning (3), Shanxi (2), and Chongqing, Jilin, Heilongjiang, Ningxia, and Xinjiang (each with one species). Among the recognized genera, Epilachna Chevrolat, 1837, is currently the most species-rich genera, with 59 species, followed by Afissa Dieke, 1947 (34), Uniparodentata Wang & Cao, 1993 (28), Henosepilachna Li, 1961 (29), Afidentula Kapur, 1958 (10), Diekeana Tomaszewska & Szawaryn, 2015 (9), and Epiverta Dieke, 1947 (4). Additionally, Afidenta Dieke, 1947, Cynegetis Chevrolat, 1837, and Subcoccinella Agassiz & Erichson, 1845 are each represented by a single species. Host plant data are currently available for only 72 species (approximately 41% of the species recorded in China), which are associated with 177 plant species across 34 families. The most frequently recorded host plant families are Solanaceae (43 species), Cucurbitaceae (32), Urticaceae (15), Fabaceae (14), Asteraceae (14), and Poaceae (10), whereas each of the remaining 28 families comprises fewer than 10 host species. For 104 species (59% of the Chinese members of the tribe), host plant associations remain unknown, highlighting a substantial gap in our understanding of their feeding habits. Full article

The damage caused by herbivores is generally measured as the amount of leaf tissue consumed, without accounting for the fate of the leftover tissue. As a result, the plant defense mechanisms that promote resistance to herbivore feeding by photosynthetically acclimating the rest of the plant to the feeding spot leaf area have not been well exploited. Plant-insect interactions are now becoming better defined with the development of visualization methods that permit spatial whole-leaf assessment of photosynthetic efficiency after herbivore attack. The purpose of our study was to evaluate the spatial heterogeneity of photosystem II (PSII) function at the whole-leaf level before and after herbivory by the Colorado potato beetles. Twenty minutes after Colorado potato beetle (Leptinotarsa decemlineata) feeding, the maximum efficiency of PSII photochemistry (Fv/Fm) decreased significantly, suggesting photoinhibition due to reduced efficiency of the oxygen-evolving complex (OEC). The decreased quantum yield of PSII photochemistry (Φ_PSII) after feeding, at the neighboring area of the feeding spot and at the rest of the leaf area, was attributed to the reduced efficiency of the open PSII reaction centers (Fv′/Fm′), since there was no change in the fraction of open PSII reaction centers (qp). Nevertheless, plant defense elicitation was activated by the photoprotective mechanism of non-photochemical quenching (NPQ) that reduced the singlet oxygen (¹O₂) formation in potato plants in the neighboring area of the feeding spot and at the rest of the leaf area. In addition, the increased production of hydrogen peroxide (H₂O₂) triggered by this increase suggests that it acted as a signaling molecule in the biotic stress defense response. Full article

Insect pests are a major limiting factor to producing profitable soybean (Glycine max (L.) Merr.) in South Carolina. Production practices within the soybean industry have drastically evolved over the last few decades, but treatment thresholds for insect pests have stayed the same. Evaluating treatment thresholds for insect pests typically involves simulating injury because it offers a controlled and repeatable way to evaluate an injury–yield relationship. Simulating defoliation injury in soybean typically involves methods such as hand-plucking or cutting leaflets, but these methods are not truly representative of insect feeding injury. This study describes the design, development, and validation of a novel pneumatic leaf puncher created with a 3D printer and used to simulate insect defoliation injury in soybean. The device was engineered to deliver controlled, repeatable leaf tissue removal at varying target levels (5, 15, 30, and 40%) by using interchangeable punching plates. Simulated defoliation treatments were applied to mature leaves on soybean plants at the V6 growth stage in a greenhouse study. The leaf area removed was quantified using LeafByte, a mobile app designed for measuring leaf area, and confirmed against target values. Results showed a high level of correlation between intended and actual defoliation levels, with accuracy ≥ 90%. The pneumatic leaf puncher provides a potential standardized method for administering foliar damage and offers a reliable alternative to manual clipping or herbivory feeding trials in defoliation research. Ongoing field trials at Clemson University will incorporate yield data to refine defoliation thresholds. Due to its adaptability and ease of use, the pneumatic leaf puncher could be implemented regionally, nationally, or internationally to support standardized defoliation studies across diverse cropping systems. Full article

Insects exhibit a range of ecological relationships with plants, including pollination, seed dispersal, parasitism, predation, and herbivory. Interactions between insects and plants are shaped by internal daily timekeeping systems in both sets of organisms termed circadian clocks. This review describes the impact of the circadian clocks of insects and plants on herbivory, which is highly relevant not only to natural ecosystems, but also to agriculture and forest management. Following an introduction to the circadian clocks of plants and insects, we discuss the circadian organization of relevant aspects of plant metabolism and defense. Next, we describe how insect clocks govern herbivory-associated physiology and behavior before exploring how rhythmic processes in plants and insects interact to temporally control herbivory. Finally, we describe how insights from the clock control of herbivory may inform pest management strategies and what future research in this area may contribute. Full article

Green leaf volatiles (GLVs) are significant volatile signals that have been shown to protect plants against biotic and abiotic stresses, including insect herbivory and pathogen infections, as well as drought, cold, and heat stress. Since all these stresses are affected by climate change, GLVs provide an important target for research into their broad activities and their potential applications in agricultural settings. Therefore, to gain further insights into the protective properties of GLVs and their regulation under changing environmental conditions, we investigated whether climate-related changes alter the capacity to produce and the responsiveness to GLVs in Zea mayss, our model plant. Specifically, we studied the effects of limited nutrient supply, drought, and higher temperature. Neither significantly affected the capacity of plants to produce Z-3-hexenal as the first metabolite of the pathway, but elevated temperature increased E-2-hexenal production. We further identified changes in the effectiveness of plants to respond to GLVs under changing abiotic conditions by monitoring glucose levels and typical GLV-responsive genes covering metabolism, direct defense, indirect defense, and water stress. The results provide first evidence that plant responses to GLVs under defined environmentally challenging and stressful conditions are highly context-dependent and can vary substantially. Full article

Sometimes, crop breeding varieties demonstrate high resistance to target insects under laboratory conditions but exhibit significantly low resistance in the field. This research aimed to explain this phenomenon based on inter-species interactions among insects, as herbivory by one insect species can trigger physiological changes in plants that enhance their attraction to other insect species. The striped stem borer (SSB), Chilo suppressalis (Walker), and the brown planthopper (BPH), Nilaparvata lugens (Stål), are pests of rice (Oryza sativa L.) that cause major losses in grain production. In this study, we investigated BPH performance and behavior on the planthopper-resistant rice variety “Mudgo” with pre-feeding of SSB. BPHs showed better growth and development, as well as feeding behavior, on SSB-damaged plants compared to undamaged plants. Then, gene expression and phytohormone analysis revealed that jasmonic acid (JA) biosynthesis was induced by SSB feeding. The JA pathway is a central defense signaling hub in rice responding to chewing herbivores like SSB; however, our findings reveal that its induction can have contrasting ecological consequences, inadvertently reducing resistance to a subsequent piercing-sucking pest (BPH). Finally, we discovered that volatile emissions induced by SSB damage attracted BPH and benefited its development. In summary, we found that JA biosynthesis triggered by SSB herbivory played a vital role in rice defense against BPH. This provides insight into the molecular and biochemical mechanisms underlying BPH preferences for SSB-damaged rice plants. Our study emphasizes the crucial role of inter-species interactions in enhancing host plant resistance to insect pests and evaluating germplasm resistance. These findings can serve as a basis for controlling BPH. Full article

The tea plant (Camellia sinensis) employs inducible chemical defenses against insect herbivores, yet the role of phenylalanine ammonia-lyase (PAL) in this process remains inadequately characterized. This study demonstrates that PAL is essential for tea plant’s direct resistance against the tea geometrid (Ectropis grisescens Warren). Inhibition of PAL activity using 2-Aminoindan-2-phosphonic acid significantly reduced catechins accumulation and promoted larval growth of E. grisescens. Compared to mechanical wounding alone, simulated herbivory feeding (mechanical wounding plus oral secretions) induced higher PAL activity and more pronounced upregulation of CsPAL genes. This response specifically highlighted CsPALb, CsPALd, and CsPALe as core, herbivore-responsive members. Transient silencing of CsPALb in tea leaves led to a significant reduction in the levels of catechin (-)-epigallocatechin and epigallocatechin gallate. Moreover, heterologous overexpression of CsPALb and CsPALd in tobacco (Nicotiana tabacum) enhances resistance to Spodoptera litura. Our results indicate that PAL-mediated phenylpropanoid metabolism is not only critical for herbivore resistance of tea plant, but can also provide valuable gene resources for improving herbivore resistance in other plants. Full article

Plants are naturally exposed to various biotic stresses, including pathogen attacks and insect herbivory, which activate distinct signaling pathways as part of their defense responses. Inoculation with beneficial microorganisms, such as plant growth-promoting rhizobacteria (PGPR), can trigger induced systemic resistance (ISR) in plants, a defense response that resembles the one activated by herbivore attack in terms of signaling pathways and physiological effects. However, these interactions have typically been studied independently, limiting our understanding of their combined effects. In this study, we examined the effects of aphid (Acyrthosiphon pisum) herbivory on Ocimum basilicum plants and assessed how these responses are modulated when the plants are inoculated with the PGPR strain Bacillus amyloliquefaciens GB03, with a particular focus on biochemical and structural defense mechanisms. Aphid herbivory significantly increased total essential oil (EO) content and volatile organic compound (VOC) emission and induced a greater density of glandular trichomes while also modifying the phytohormone profile. In contrast, total phenolic content remained unchanged. When aphid herbivory occurred on GB03-inoculated plants, the effects on defense-related parameters became more pronounced. EO and eugenol contents were further increased compared with inoculated controls, jasmonates remained comparable to levels induced by either factor alone, and SA levels nearly doubled relative to aphid-infested plants. Feeding assays revealed that aphids preferred inoculated plants over controls, a response that may be explained by the increased emission of eugenol in inoculated basil. These results demonstrate that GB03 inoculation modifies several defenses-related responses in O. basilicum upon aphid herbivory, including by hormonal signaling, specialized metabolites accumulation, and structural barriers such as glandular trichomes. These findings suggest that PGPR may contribute to modulating plant responses to herbivory under certain conditions, highlighting their context-dependent influence within plant–microbe–insect interactions. Full article

Maize plants challenged by insect herbivores activate an array of defense measures, all aimed to reduce damage and repel the attacker . Among those are the activation of proteins that interfere with the digestion of consumed plant material in the herbivore (proteinase inhibitors), the production of toxic compounds like benzoxazinoids, and the biosynthesis and emission of herbivore-induced plant volatiles (HIPVs). Among those HIPVs are mainly a variety of terpenoids, green leaf volatiles (GLVs), and indole. While often serving as attractants for natural enemies of the attacking herbivores, many of those volatiles have also been found to induce defense responses in neighboring plants and/or prime them against future menace. Indole is of particular interest since it can be involved in a variety of biosynthetic pathways including those leading to auxin, benzoxazinoids, and tryptophan. Here, we demonstrate that indole emissions in response to simulated insect herbivory by treatment with an insect elicitor (N-linolenoyl glutamine) strongly depend on the developmental status of the affected leaf in maize. Outgrown leaves emit significantly higher amounts of indole compared to the next younger, still growing leaves, distinguishing indole from other HIPVs, which are typically released at higher levels by young leaves. As a central and flexible metabolic intermediate, indole emissions appear to be mediated through variable allocation between growth-related processes and defense-associated outcomes, depending on the developmental stage of the damaged leaf. These findings highlight the importance of considering plants as inherently dynamic organisms. Full article