Stridulations of Melolontha spp. larvae open up new possibilities for species-specific pest monitoring in soils

Abstract

Root-feeding Scarabaeidae larvae can pose a serious threat to agricultural and forest ecosystems, but many details of larval ecology are still unknown. We developed an acoustic data analysis method for gaining new insights into larval ecology. In a laboratory study, third instar larvae of Melolontha melolontha (n=38) and M. hippocastani (n=15) kept in soil-filled containers were acoustically monitored for 5 min each, resulting in the first known stridulation recordings for each species. Subsequent continuous monitoring of three M. hippocastani larvae over several hours showed that a single larva could stridulate more than 70 times per hour, and stridulation rates increased drastically with increasing larval abundance. The new fractal dimension-based data analysis method automatically detected audio sections with stridulations and provided a semi-quantitative estimate of stridulation activity. It is the first data analysis method specifically targeting Scarabaeidae larvae stridulations in soils, enabling for the first time non-invasive species-specific pest monitoring.\n\nKey messageO_LIRoot-feeding scarab beetle larvae, known as white grubs, can be serious agricultural and forest pests.\nC_LIO_LIWhite grub infestation monitoring is difficult due to their cryptic lifestyle, but detailed monitoring data is essential for effective pest control.\nC_LIO_LIWe present the first acoustic data analysis routine targeting stridulations, using Melolontha melolontha and M. hippocastani as model organisms.\nC_LIO_LIThis new method provides for the first time the basis for the development of tools for non-invasive, species-specific, and rapid white grub monitoring in soils.\nC_LI