Submitted to: Arthropod Management Tests
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/1999
Publication Date: N/A
Interpretive Summary: Integrated pest management strategies are being developed to reduce chemical pesticide usage and to slow down the development of chemical pesticide resistance in insect populations. The use of living microbes which infect and kill insect pests (biopesticides) has the potential to be an important component of these integrated pest management strategies. The ecommercial use of biopesticides requires that low-cost production methods be developed which yield stable, infective microbial preparations. Liquid-culture production methods have been developed in our laboratory which yield high concentrations of stable, infective spores of P. fumosoroseus, a disease-causing microbe which infects and kills the silverleaf whitefly. Laboratory bioassays were performed which measured the effectiveness of our liquid culture produced spores in infecting and killing the silverleaf whitefly. These studies showed that low concentrations of liquid culture produced spore preparations which were highly effective in killing whitefly nymphs. The low lethal concentration of spores required suggests that formulations of liquid- culture produced P. fumosoroseus spores have potential as mycoinsecticides for controlling the silverleaf whitefly.
Technical Abstract: Tests evaluating the insecticidal activity of different preparations of liquid-culture produced blastospores and solid-substrate produced conidia of the insecticidal fungus Paecilomyces fumosoroseus were performed using silverleaf whitefly (Bemisia argentifolii) 3rd instar nymphs. All blastospore and conidia preparations infected and killed whitefly nymphs. However, possibly due to the slower germination rate of conidia compared t liquid-culture produced blastospores, aerial conidia produced a lower mortality rate compared to blastospores in these tests. The blastospore preparations, particularly those that had been air-dried, had potency ratios which showed they were much more effective than conidia in killing B. argentifolii. The low lethal concentration (EC50) of the blastospore preparations (7-70 spores/mm**2) suggests that formulations of P. fumosoroseus blastospores have potential as mycoinsecticides for controlling the silverleaf whitefly.