Effect of elevated CO2 concentration and temperature on antioxidant capabilities of multiple generations of Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae)

Human Impacts on Insect Chemical Communication in the Anthropocene

The planet is presently undergoing dramatic changes caused by human activities. We are living in the era of the Anthropocene, where our activities directly affect all living organisms on Earth. Insects constitute a major part of the world’s biodiversity and currently, we see dwindling insect biomass but also outbreaks of certain populations. Most insects rely on chemical communication to locate food, mates, and suitable oviposition sites, but also to avoid enemies and detrimental microbes. Emissions of, e.g., CO2, NOx, and ozone can all affect the chemical communication channel, as can a rising temperature. Here, we present a review of the present state of the art in the context of anthropogenic impact on insect chemical communication. We concentrate on present knowledge regarding fruit flies, mosquitoes, moths, and bark beetles, as well as presenting our views on future developments and needs in this emerging field of research. We include insights from chemical, physiological, ethological, and ecological directions and we briefly present a new international research project, the Max Planck Centre for Next Generation Insect Chemical Ecology (nGICE), launched to further increase our understanding of the impact of human activities on insect olfaction and chemical communication.

Effects of elevated CO2 on activities of protective and detoxifying enzymes in Frankliniella occidentalis and F. intonsa under spinetoram stress

BACKGROUND

Elevated CO₂ can directly affect the toxicity of insecticides to insects and the physiological response of insects to insecticides. Frankliniella occidentalis and F. intonsa are highly destructive pests that target horticultural crops. Spinetoram is an effective pesticide against thrips. This study sought to explore the effect of elevated CO₂ on efficacy of spinetoram against F. occidentalis and F. intonsa and effect of the spinetoram on activities of protective and detoxifying enzymes under elevated CO₂ . Notably, these enzymes can be exploited in further studies to develop interventions for thrips resistance management.

RESULTS

Toxicity bioassay showed that the LC₅₀ values of F. occidentalis and F. intonsa exposed to spinetoram at elevated CO₂ (800 μL L^-1 concentration) for 48 h was 0.08 and 0.006 mg L^-1 , respectively, which is 0.62 and 0.75 times of the values at ambient CO₂ (400 μL L^-1 concentration). The findings showed that elevated CO₂ decreased activities of the superoxide dismutase and acetylcholinesterase in thrips, while increasing the activities of carboxylesterase and glutathione S-transferase. However, spinetoram increased activities of protective and detoxifying enzymes in both thrips under the two CO₂ levels. Elevated CO₂ and spinetoram affect the physiological enzyme activity in thrips synergistically, and the activities of analyzed enzymes were generally higher in F. occidentalis than in F. intonsa.

CONCLUSION

Elevated CO₂ amplifies the efficacy of spinetoram on thrips, F. intonsa is more susceptibility to spinetoram than F. occidentalis and the latter showed better adaptation to adverse conditions than the former. © 2021 Society of Chemical Industry.

Time-dependent stress evidence in dynamic allocation of physiological metabolism of Nilaparvata lugens in response to elevated CO2

To assess the time-dependent stress evidence in dynamic allocation of physiological metabolism of Nilaparvata lugens nymphs in response to elevated CO₂, we measured the time-dependent allocation of nutrient compositions and physiological metabolism in the bodies of N. lugens at 1h, 4h and 12h under elevated CO₂. Elevated CO₂ significantly increased the contents of nutrient compositions (protein, glucose and total amino acids) and catalase (CAT) enzyme activity in the body of N. lugens at 12h relative to 1h and 4h (P < 0.05). Significantly higher genes expression levels of acetylcholinesterase (AChE), heat shock protein (HSP70) and vitellogenin gene (vg) were observed in the body of N. lugens compared with those in ambient CO₂ at 4h (P < 0.05). These results showed that there was an instantaneous reaction of N. lugens nymphs to elevated CO₂, which indicated N. lugens may enhance stress defense response to future increasing CO₂ levels.

A Review of the Biology and Control of Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), with Special Reference to Biological Control Using Entomopathogenic Fungi

Simple Summary

The whitefly, Bemisia tabaci, is considered one of the most destructive insect pests of vegetables and ornamental crops globally. Synthetic chemical pesticides are mainly used to control B. tabaci, however, their extensive usage has led to a series of detrimental concerns to human health and environmental contamination. It is therefore of significant interest to develop a safer and eco-friendly alternative for controlling B. tabaci. Here, we review the use of entomopathogenic fungi as a proven, biologically sustainable method to effectively control B. tabaci. The development of entomopathogenic fungi in an integrated pest management strategy against B. tabaci can reduce our reliance on chemical pesticides, and help us to secure food safety while preserving nature.

Abstract

Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), consists of genetically diverse species known to cause significant destruction in several crops around the world. Nymphs and adults of B. tabaci cause damage to plants during feeding, and they can act as a virus vector, thus causing significant yield loss to crops in the tropical and subtropical regions. Chemical pesticides are widely used to control B. tabaci due to their immediate action, but this approach has several drawbacks including food safety issues, insecticide resistance, environmental pollution, and the effect on non-target organisms. A biological control agent using entomopathogenic fungi (EPF) has therefore been developed as an alternative against the conventional use of chemical pesticides in an integrated pest management (IPM) system to effectively control B. tabaci. It is apparent from this review that species of hyphomycetes fungi are the most common EPF used to effectively control B. tabaci, with the second instar being the most susceptible stage of infection. Therefore, this review article focuses specifically on the control of B. tabaci with special emphasis on the use of EPF as biological control agents and their integration in IPM.

Feeding behavior, life history, and virus transmission ability of Bemisia tabaci Mediterranean species (Hemiptera: Aleyrodidae) under elevated CO2

The continuous rise of CO₂ concentrations in the atmosphere is reducing plant nutritional quality for herbivores and indirectly affects their performance. The whitefly (Bemisia tabaci, Gennadius) is a major worldwide pest of agricultural crops causing significant yield losses. This study investigated the plant-mediated indirect effects of elevated CO₂ on the feeding behavior and life history of B. tabaci Mediterranean species. Eggplants were grown under elevated and ambient CO₂ concentrations for 3 weeks after which plants were either used to monitor the feeding behavior of whiteflies using the Electrical Penetration Graph technique or to examine fecundity and fertility of whiteflies. Plant leaf carbon, nitrogen, phenols and protein contents were also analyzed for each treatment. Bemisia tabaci feeding on plants exposed to elevated CO₂ showed a longer phloem ingestion and greater fertility compared to those exposed to ambient CO₂ suggesting that B. tabaci is capable of compensating for the plant nutritional deficit. Additionally, this study looked at the transmission of the virus Tomato yellow leaf curl virus (Begomovirus) by B. tabaci exposing source and receptor tomato plants to ambient or elevated CO₂ levels before or after virus transmission tests. Results indicate that B. tabaci transmitted the virus at the same rate independent of the CO₂ levels and plant treatment. Therefore, we conclude that B. tabaci Mediterranean species prevails over the difficulties that changes in CO₂ concentrations may cause and it is predicted that under future climate change conditions, B. tabaci would continue to be considered a serious threat for agriculture worldwide.