Laboratory Evaluation of a Diatomaceous Earth and Pyrethrin Insecticide Against DBM Larvae, 1996

Three rates of Organic Solutions 0.2% were compared against a treated check, Xentari, and an untreated check. Test insects were obtained from laboratory colonies initiated from field collected insects. DBM eggs were collected from the colonies and hatched in plastic containers 10 days prior to the start of the bioassay. Larvae were fed fresh cabbage leaves daily and were in the late second to early third instar at the start of the bioassay. The head cabbage variety ‘C-G Hybrid’ was used as the test plant. Seeds were planted in community pots and kept in the greenhouse until ready to use. At the time of the bioassay, the plants were in the 8-10 true leaf stage. A cabbage leaf with a diameter greater than 5 cm was removed and infested with 10 DBM larvae. Each spray mix as agitated vigorously and placed in a spray aerosol apparatus. The leaf containing the larvae was sprayed for 3 seconds or until the leaf was thoroughly coated. The treated leaf and larvae were placed in a ventilated petri dish. Each treatment was replicated 10 times. Mortality was assessed at 24 hour intervals. Larvae were counted as “dead” when there was no movement in the larvae when probed.