Chemical cues from honeydew-associated bacteria to enhance parasitism efficacy: from laboratory to field assay

Abstract

Honeydew from Hemipteran insects serves as carbohydrate source to beneficial insects but also to various microorganisms. Microbial volatile organic compounds (mVOCs) may play diverse roles in herbivore-microbe-natural enemy interactions. However, the functional significance of mVOCs from aphid honeydew remains largely unclear. In this study, a total of seven cultivable bacteria from Sitobion miscanthi honeydew have been isolated and identified based on 16S rRNA technique, which included Lysinibacillus fusiformis, Erwinia aphidicola, E. tasmaniensis, Acinetobacter bereziniae, Klebsiella quasipneumoniae subsp. Similipneumoniae, Staphylococcus capitis and Bacillus safensis subsp. safensis. One bacterial strain, L. fusiformis MH1, was found to be most attractive to Aphidius gifuensis parasitic wasp in Y-tube olfactometer. Two compounds, namely 1-ethyl-2-methylbenzene and 2-butyl-1-octanol, were emitted from L. fusiformis MH1 and were attractive to A. gifuensis and identified by using coupled gas chromatography-electroantennography and coupled gas chromatography with mass spectrometry. Application of bacterial and mVOCs formulations in crop field resulted in significant aphid abundance decrease associated with higher parasitism rates compared with control. Our results indicated that some microbes in aphid honeydew could manipulate the herbivore-natural enemy interactions and could be developed as a novel alternative for environmentally friendly biological control of aphids.

Spotted Lanternflies Respond to Natural Pheromone Lures for Mate-Finding and Oviposition

“…Examples include parasitic wasps [ 37 , 38 , 39 ], gall midges [ 40 ], lacewings, and predaceous beetles [ 41 , 42 , 43 ]. The volatiles emitted by the bacterial microbiota found in honeydew can also attract parasitoids [ 44 , 45 ]. However, only a few instances have been reported of honeydew components functioning as a pheromone through which conspecifics communicate their presence to one another.…”