Acoustic surveying of subterranean insect populations in citrus groves

Subterranean insect pests cause considerable economic damage but their conc ealment makes detection difficult, A portable acoustic system was developed and tested for it's potential to rate the likelihood that trees in citrus groves were infested with Diaprepes abbreviatus (L.) larvae. The likelihood was rated independently by a computer program and an experienced listener that distinguished insect sounds from background noises. Diaprepes abbrevia tus, Phyllophaga spp., or other pest insects were excavated from all 11 sit es rated at high likelihood of infestation but were absent from 20 of 25 lo w-rated sites. There was a significant regression between the activity rate and the number of pest organisms present at recording sites although the c orrelation was weaker,than between activity rate and likelihood of infestat ion. Although the system is at an early stage of development, the success o f these field tests suggests that it has considerable potential as a tool t o detect and monitor hidden infestations of insects in soil.