The present study aimed to evaluate the anatomical, histochemical, and phytochemical characteristics of Apeiba tibourbou (Aubl.) leaves, analyzing their possible relationship with herbivory. The anatomical characterization was carried out using histological slides prepared with freehand transverse sections in the middle region of the leaf blade, stained with fuchsin and Astra blue. The presence of secondary metabolites was determined through histochemical analyses using histological sections of the plant material, which were subjected to preestablished histochemical tests. Phytochemical analyses were conducted using alcoholic extracts from the dried and ground plant material, which were subjected to specific tests for group of metabolite of interest. The anatomical description revealed the presence of glandular trichomes and calcium oxalates that could serve a protective function against herbivory. Histochemical and phytochemical analyses of A. tibourbou leaves revealed the presence of phenolic compounds, alkaloids, saponins and sesquiterpene lactones. Based on the results, A. tibourbou may exhibit potential insecticidal activity against herbivorous insects.
Social wasps produce various chemical compounds that play roles in prey capture and colony defense. However, knowledge regarding the variation in the composition of these compounds and the influence of the environment on them remains limited, partly due to challenges related to sampling, analysis, and the complexity of the compounds. Therefore, this study evaluated interspecific variation in the venom composition and the importance of environmental factors on intraspecific variation, and the relationship with the age of Polistinae social wasp workers. To achieve this, colonies of Polistes ferreri, P. lanio and P. versicolor, nesting in different environments were collected and analyzed using Fourier transform infrared-photoacoustic spectroscopy (FTIR-PAS). The absorption spectra of the venom were examined to identify the main absorption peaks, followed by the assessment of the intensities and wavenumber positions of these peaks. We found significant differences between species and among colonies of the same species, based on nesting environment and workers age.
The “pupa ring” formed by the Asian corn borer Ostrinia furnacalis (Guenée) is a fascinating phenomenon discovered during the course of this experiment. The structure consists of approximately 2 to 10 pupae connected by their tails, raising speculation about possible underlying signal communication mechanisms. As a major pest of corn crops, the Asian corn borer has significant agricultural importance. Understanding its behavioral responses to chemical stimuli is crucial for exploring its ecological traits and provides valuable data to support ecological chemical control strategies. In this study, we extracted cuticular volatiles from the larvae and pupae of the Asian corn borer, evaluated their taxis behavior, and investigated the effect of these volatiles on pupa ring formation in fifth instar larvae. The results showed that volatiles from female larvae and pupae were more attractive, and those from female larvae were particularly effective at inducing pupa ring formation. This research seeks to explore the underlying causes of this remarkable behavior and offers plausible hypotheses to explain the formation of the pupa ring.
Leaf metabolites are important drivers of biotic interactions. Leaf metabolic profiles are changing over ontogeny and in response to biotic and abiotic conditions. Additionally, plant species diversity can influence leaf metabolomes. However, it is rarely considered how changes in leaf metabolomes might affect the leaf litter volatiles, which mediate interactions with the decomposer community. We designed an optimized and validated solid-phase microextraction (SPME) method coupled with a gas chromatography-mass spectrometry (GC-MS) analysis to analyze liter volatile organic compound (VOC) emissions. This method was applied to test the hypothesis that sessile oak (Quercus petrea) leaf litter VOC profiles are influenced by surrounding tree diversity. The results showed that plot diversity significantly affected oak litter VOC profiles by increasing the emissions of fatty acids. Tree diversity marginally modulated terpenoid emissions. Particularly, the emission rates of (-)-β-bourbonene and (E)-β-caryophyllene decreased with increasing species diversity. Also, ethanol emissions, likely due to microbial activity, decreased with increasing tree diversity. By detecting diversity- and C: N-related changes in terpenoids, and diversity effects on fatty acids and ethanol emissions of Q. petraea leaf litter, we provide new insights into how biodiversity shapes litter chemistry and potentially restructures decomposer interactions.
Elevated carbon dioxide (eCO2) induces various plant physiological, biochemical and morphological modifications by providing extra carbon and altering tissue nutrient composition and biomass allocation, which can influence ecological processes such as plant-insect interactions. In this study, a literature review was conducted to examine how eCO2 could potentially influence plant-herbivore insect interactions. Studies suggested that eCO2 decreases foliar nitrogen and increases leaf toughness, leaf biomass, and the carbon to-nitrogen ratio in plants. This in turn alters foliar chemistry and can significantly decrease the relative growth rate and consequently pupal or nymphal weight, which could exert an influence on the adult. Hence, the herbivore performance can be decreased. The changes in the plant nutritional quality can also result in compensatory feeding as a result of the reduction of food quality. This consequently leads to an increased defoliation rate, which results in altered leaf chemical composition with enhanced secondary metabolites, including defense compounds and toxins. This increases the risk for larvae in their early instars, whose growth and development are more sensitive to the disruptive effects of toxins, compared to the late-instar larvae. Altogether, these effects may modify the overall abundance of the herbivorous species. An emerging hypothesis is that eCO2 downgrades the nutritional quality more in C3 than in C4 plant species, facilitating herbivorous insect species to escalate their feeding stress on C3 plants by increasing food intake which is considered a behavioral adaptation to compensate for the reduced leaf quality (and protein content) relative to C4 species. However, this hypothesis warrants confirmation and cannot be generalized at present.
