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Title: Mapping of soil insect infestations sampled by excavation and acoustic methods

item Mankin, Richard

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2001
Publication Date: 12/1/2001
Citation: Brandhorst-Hubbar, J.L., Flanders, K.L., Mankin, R.W., Guertal, E.A., Crocker, R.L. 2001. Mapping of soil insect infestations sampled by excavation and acoustic methods. Journal of Economic Entomology. 94:1452-1458.

Interpretive Summary: USDA, ARS, scientists at the Center for Medical, Agricultural,& Veterinary Entomology in Gainesville, FL, Auburn University, and the Texas Agricultural Experiment Station have cooperated in testing the efficacy of portable acoustic technology to detect hidden infestations of insects in soil. Such insects include white grubs, citrus root weevils and black vine weevils that feed on roots underground. This report describes a test of the system under harsh field conditions and identifies improvements needed to ensure reliable interpretation of acoustic signals recorded outside the laboratory. The use of acoustic detection and analysis reduces the amount of time and labor associated with the detection and sampling of these insects and can lead to cost- reductions in integrated pest management programs.

Technical Abstract: Geostatistical analysis was used to map traditionally and acoustically sampled populations of soil invertebrates at two different times in a hayfield at Grove Hill, AL, and once in an Auburn, AL hayfield. The distributions of nearly all the soil invertebrates and their sounds were nonrandom in all 3 mapping studies. The maps constructed by traditional and acoustic sampling methods were compared by correlating the estimated (kriged) soil invertebrate counts with the estimated (kriged) counts of sounds per minute (pulse rate). The 2 maps were positively correlated (P<0.05) in the Auburn study. Kriged estimates for green June beetle grub counts overlapped significantly with kriged estimates of sound pulse rate (R2=0.47, P<0.001). Overlap between sounds increased slightly when other soil organisms were counted along with green June beetle grubs: estimates of sound pulse rates were significantly correlated (P<0.0001) with counts of all white grubs (R2=0.50), earthworms combined with white grubs (R2=0.52), earthworms with white grubs with earwigs (R2=0.59), and total invertebrates (R2=0.58). Low insect numbers and high background noise levels hampered interpretation of the Grove Hill data. These results suggest that acoustic technology is a promising tool for detecting insects in soil, but that further study and additional analysis are needed to improve interpretation of acoustic data obtained in the field.