Potential lethal effects of commonly applied turfgrass fungicides on the larvae of Popillia japonica (Coleoptera: Scarabaeidae)

Larvae of Popillia japonica Newman (Coleoptera: Scarabaeidae) are common insect pests in turfgrass systems where they reside in the soil and feed on plant roots. Larvae are commonly found in golf course roughs and fairways, but are rarely in neighboring putting greens. We hypothesize that this phenomenon may best be explained by the frequent application of fungicides to golf course putting greens. Putting greens receive more fungicide applications compared to other areas on the golf course, and it is possible that these fungicides adversely affect larvae of P. japonica.

Second and third instar larvae were treated with two different fungicides (propiconazole and chlorothalonil) and an insecticide (trichlorfon) in the laboratory. Products were applied at maximum-labeled rates, and larvae were assessed as ‘alive’ or ‘dead’ over a 20-day period. Trichlorfon exhibited 100% control of second and third instar larvae.  Propiconazole provided 50% mortality of second instar larvae compared to the untreated control, but did not result in any significant mortality of third instar larvae.  Chlorothalonil did not result in significant mortality of second or third instar larvae.