Egg predation and integration pest management of white grubs (Coleoptera: Scarabaeidae) in turfgrass and maize

Field experiments were conducted to identify predators and to measure their predation on white grub eggs in the soil. Identification of turfgrass damaging white grub, southern masked chafer (SMC), Cyclocephala lurida, and Japanese beetle, Popillia japonica Newman, egg predators was determined by direct observation through buried Plexiglas plates. Predation rates of Japanese beetle eggs in turfgrass was further measured using buried bait stations filled with eggs. Up to 73% of white grub eggs in the soil were taken within a 72 hour period and ants were found to be the predominant predator. One species of ant, Solenopsis molesta (Say), proved to be the primary ant predator of white grub eggs in turfgrass. The effects of four commonly used turfgrass insecticides on ant predators of white grub eggs were also measured using buried bait stations. Isofenphos and diazinon significantly reduced ant numbers as well as egg predation, while imidacloprid and halofenozide did not significantly impact either measurement. The identification and relative abundance of white grub (Phyllophaga sp.) egg predators were observed and predation measured through buried Plexiglas plates and pitfall traps in no-till and conventional-till maize in Honduras. Significantly more ants, ant species and egg predation were found in no-till than in conventionally tilled fields. To more accurately synchronize pesticide application timing with southern masked chafer egg hatch, degree-day estimates for the SMC egg stadium were calculated. Egg development rates at six constant temperatures were measured under laboratory conditions. The duration of the egg stadium was calculated to be 185 $\pm$ 2.3 degree-days, or approximately 12 calendar days if the average soil temperature is 27$\sp\circ$C, typical during the month of July in the midwest