Receiver Operating Characteristic curve analysis determines association of individual potato foliage volatiles with onion thrips preference, cultivar and plant age

Potato leaf senescence affects the olfactory and feeding preferences of the green peach aphid, Myzus persicae

BACKGROUND

Foliar senescence is a physiological process involving the degradation of chlorophyll and proteins, with nitrogen compounds, especially amino acids, mobilised to other parts of the plant. This process enriches the phloem, and improves its nutritional quality for phloem sucking insects like aphids. This study investigated how natural and induced leaf senescence affect the feeding and olfactory behaviour of the green peach aphid (Myzus persicae Sulzer) in potato (Solanum tuberusom L.). Two phenological stages were examined: young plants where senescence was induced in the basal leaves by covering them with a gas-permeable, light-blocking cloth, and mature plants with naturally senescent basal leaves. Chlorophyll and protein levels were quantified to confirm senescence, and volatile organic compounds (VOCs) were identified using gas chromatography-mass spectrometry (GC-MS).

RESULTS

Senescence, both natural or induced, reduced chlorophyll and protein levels. In young plants, the induction of leaf senescence tended to increase aphid feeding and olfactory preference. In contrast, in mature plants, aphids consistently preferred non-senescent apical leaves over senescent basal leaves sin both olfactory and feeding assays. Additionally, non-senescent apical leaves of mature plants released significantly higher levels of β-caryophyllene compared to senescent leaves, likely reflecting an overall increase in volatiles emission.

CONCLUSION

The results suggest that senescence induction, rather than natural senescence, enhances the nutritional quality of the leaves, allowing aphid propagation. Insights into aphid host preference can be used in future control strategies by promoting agricultural practices that minimise senescence induction caused by factors such as shading due to high sowing density, or nutrient imbalance. © 2025 Society of Chemical Industry.

Untargeted Volatile Profiling Identifies Key Compounds Driving the Attraction of Western Flower Thrips to Alstroemeria Cultivars

Western flower thrips (WFTs) are significant pests affecting various crops globally. Developing sustainable strategies for managing WFTs is essential for improving thrips management. Ethological control methods, particularly those employing volatile organic compounds (VOCs) emitted by plants to influence insect behavior, have emerged as a promising avenue for pest management. Natural hosts such as Alstroemeria provide an intriguing yet underexplored opportunity for developing attractants tailored to WFT management. This study examined the behavioral preferences of WFTs towards flowers of four commercial Alstroemeria cultivars, focusing on variations in VOC profiles. Using headspace solid-phase microextraction (HS-SPME), VOCs were captured in vivo from cultivars with contrasting levels of WFT infestation. Gas chromatography coupled with mass spectrometry (GC-MS) was employed to analyze the VOCs, with linear retention indices aiding compound identification. An untargeted volatile profiling-based comparative analysis revealed key VOCs that differed among cultivars, shedding light on their potential correlation with WFT behavior. Behavioral assays identified three specific VOCs-butyl butyrate, 1-methylnaphthalene, and citronellyl acetate-as influential in attracting WFTs. Attraction responses were concentration-dependent, with two tested concentrations eliciting significant behavioral effects. These findings highlight the potential of these active VOCs as components of novel attractants for WFT management. The results direct future research and the development of tools to integrate ethological strategies into sustainable pest management practices for crops.

Thrips as the Transmission Bottleneck for Mixed Infection of Two Orthotospoviruses

Mixed infections provide opportunities for viruses to increase genetic diversity by facilitating genomic reassortment or recombination, and they may lead to the emergence of new virus species. Mixed infections of two economically important orthotospoviruses, Tomato spotted wilt orthotospovirus (TSWV) and Impatiens necrotic spot orthotospovirus (INSV), were found in recent years, but no natural reassortants between INSV and TSWV were ever reported. The goal of this study was to establish how vector preferences and the ability to transmit INSV and TSWV influence transmission and establishment of mixed infections. Our results demonstrate that thrips prefer to oviposit on TSWV and INSV mixed-infected plants over singly infected or healthy plants, providing young nymphs with the opportunity to acquire both viruses. Conversely, we observed that thrips served as a bottleneck during transmission and favored transmission of one of the two viruses over the second one, or over transmission of both viruses simultaneously. This constraint was relaxed in plants, when transmission of TSWV and INSV occurred sequentially, demonstrating that plants serve as orthotospovirus permissive hosts, while thrips serve as a bottleneck. Viral fitness, as measured by virus replication, transmission, and competition with other viral strains, is not well studied in mixed infection. Our study looks at the success of transmission during mixed infection of orthotopoviruses, enhancing the understanding of orthotospovirus epidemiology and evolution.