Willow Leaf Beetle Plagiodera Versicolora Research Articles

Relish involved in immunity and larval survival in the willow leaf beetle Plagiodera versicolora.

Insects mainly rely on innate immunity against pathogen infection. Plagiodera versicolora (Coleoptera: Chrysomelidae), is a worldwide leaf-eating forest pest in salicaceous trees. However, the mechanisms behind the immunodeficiency pathway (IMD) remain poorly understood. In this study, we obtained a Relish gene from transcriptome analysis. Tissue and instar expression profiles were subsequently obtained using quantitative real-time polymerase chain reaction analysis. The results showed that Relish has high expression levels in eggs, larvae and adults, and especially in fat bodies. Transcripts of the tested antimicrobial peptides (AMPs), defensin1, defensin2 and attacin2 were downregulated by dsRelish. Knockdown of Relish led to greater mortality in larvae after Staphylococcus aureus infection. In addition, we performed bacterial 16S ribosomal RNA-based high-throughput sequencing. The results showed that the relative abundance of some gut bacteria was significantly altered after dsRelish ingestion. This study provides a greater understanding of the IMD signaling pathway, facilitating functional studies of Relish in P. versicolora. Moreover, a genetic pest management technique might be developed using Relish as a lethal gene to control the pest P. versicolora. © 2024 Society of Chemical Industry.

Greater impact of host plant species on oviposition of a willow leaf beetle Plagiodera versicolora Laicharting (Coleoptera: Chrysomelidae) during the adult stage than in developing larval stage

In some herbivorous insects, such as Coleoptera and aphids, not only the host species of larvae, but also those of adults should be considered as key determinants of potential fecundity because oviposition is affected by the quality of host species during both larval and adult stages. This study examined the relatively greater impact on host species of the larval or adult stage on oviposition of the willow leaf beetle Plagiodera versicolora Laicharting (Coleoptera: Chrysomelidae). We conducted an experiment using a 2 × 2 experimental design, in which either of two different host plant species was fed in larval and adult stages. Females fed on a locally unavailable host Salix eriocarpa in the adult stage did not lay any eggs, but those fed on the locally available host S. babylonica laid 67–75 eggs on average, irrespective of larval host species. Such reproductively inactive females fed S. eriocarpa as an adult host recovered reproductive activity within 3 weeks after changing the host species to S. babylonica. This result indicated that the host species fed in the adult stage had a greater impact on oviposition than in the larval stage.

Do adult leaf beetles (Plagiodera versicolora) discriminate between odors from intact and leaf-beetle-infested willow shoots?

We investigated how adults of willow leaf beetle Plagiodera versicolora find shoots with new leaves that were suitable food resources for them by focusing on shoot odor. Female and male beetles (starved and satiated) preferred the odor from intact shoots of Salix eriocarpa to clean air. Starved females preferred odor from shoots with leaves infested by conspecifics to odor from intact shoots. However, satiated females as well as starved and satiated males showed no significant discrimination between the two odors. Pooling of the preference data revealed that starved individuals of females and males preferred odor from infested shoots to an extent that was significantly different from satiated individuals, while the distribution of starved and satiated females was not significantly different from that of males. These olfactory responses would provide an explanation for the host plant finding behavior of this specialist herbivore in the field.

Factors contributing to the seasonal occurrence of the willow leaf beetle Plagiodera versicolora

AbstractWe conducted a 3‐year study of a natural population of the willow leaf beetle Plagiodera versicolora (Coleoptera: Chrysomelidae) on a river bank of the Inukami River, Shiga, central Japan, where four willow species (Salix chaenomeloides, S. eriocarpa, S. integra, and S. serissaefolia) occur sympatrically. Our survey showed that: (1) at the study site, the abundance of P. versicolora greatly varied among years and among willow species; (2) adult abundance changed seasonally with species‐specific patterns on different willow species; and (3) the dispersal‐settlement of adults had the most pronounced effects on the seasonal population growth rate of P. versicolora. Factors affecting these results were discussed.

Does Rust Infection of Willow Affect Feeding and Oviposition Behavior of Willow Leaf Beetles?

Willows are often attacked by both herbivorous insects and rust fungi. Little is known about interactions between these two willow enemies. We studied whether feeding and oviposition behavior of the willow leaf beetle Plagiodera versicolora upon the willow hybrid Salix x cuspidata is affected when the rust fungus Melampsora allii-fragilis has attacked the plant. Laboratory bioassays revealed that adult willow leaf beetles significantly avoided feeding and oviposition on rust-infected leaves when compared to healthy leaves. Further bioassays aimed to elucidate the temporal and spatial scale of effects of rust infection on feeding behavior of adults. While infected parts of leaves were avoided at all times past infection tested (8, 12, and 16 days), symptom-free parts of infected leaves were only avoided 16 days past infection. Systemic effects extended only one leaf position up and two leaf positions down from the infection site.

Herbivores and pathogens on willow: do they affect each other?

Abstract 1 Willows often need to cope with attack by both rust fungi and herbivores. We studied whether rust infection on willow affects the herbivore, and vice versa, whether herbivore feeding affects the fungal infection. The system investigated by laboratory bioassays and greenhouse experiments consisted of the willow hybrid Salix × cuspidata, the rust Melampsora allii‐fragilis and the willow leaf beetle Plagiodera versicolora. Effects were studied both on a local scale (rust infection and feeding on the same leaf) and systemically (rust infection and feeding on different, but adjacent leaves).2 Rust infection was not affected by herbivore feeding on a local scale. Systemically, however, the willow's susceptibility towards rust infection was increased by herbivore feeding, as indicated by a higher number of rust sori on leaves adjacent to feeding‐damaged leaves. The herbivore's performance was detrimentally affected by rust infection: increase of mortality (systemically), decrease of larval weight (locally and systemically) and prolonging of developmental time (locally and systemically).3 Previous rust infection enhanced systemically the willow's susceptibility towards subsequent fungal infection. Previous herbivore feeding on the willow had no effects on the herbivore's developmental time and mortality. However, feeding upon previously feeding‐damaged willow leaves significantly reduced larval weight.