Probabilities for survival of glassy-winged sharpshooter and olive fruit fly pests in urban yard waste piles

Glassy-winged sharpshooter (Homolodisca coagulate) and olive fruit fly (Bactrocera oleae) were introduced into unturned, chipped yard waste piles to evaluate their survival with time and depth within the piles. In all three trials, no pests lasted more than 14 d, and in no trial did pests survive more than 4 d at the 30 and 100 cm depths. No survivors were found after 14 d in any of the treatments at any depth. Neither of the pests survived 100 cm after 2 d. A mathematical model for describing pest survival probabilities is described. The model modifies time according to the Arrhenius equation in order to include heat effects on pest survival and can be used to determine exposure times necessary to eliminate these pests with a determined statistical probability. Model projections suggest that for conditions similar to this study, there is 99% confidence that all glassy-winged sharpshooter eggs would be eliminated from 1000 infected leaves in 6.1 d at 15 cm depth and in 4.8 d at 30 cm or below. Olive fruit fly larvae at these depths would require 4.8 and 4.1 d, respectively, for 1000 infected olive fruits. Projected elimination times at the surface were longer, 6.5 d for sharpshooter eggs and 14.3 d for fruit fly larvae.