INFLUENCE OF ENTOMOPATHOGENIC FUNGI ON SERANGIUM-PARCESETOSUM (COLEOPTERA, COCCINELLIDAE), AN IMPORTANT PREDATOR OF WHITEFLIES (HOMOPTERA, ALEYRODIDAE)

The lethal and sublethal effects of the entomopathogenic fungi Beauver ia bassiana (Balsamo) Vuillemin and Paecilomyces fumosoroseus (Wize) B rown & Smith against the coccinellid predator Serangium parcesetosum S icard were studied in the laboratory. We also tested if the ingestion of whiteflies contaminated with B. bassiana affected predator survivor ship in 3 tests: (1) S. parcesetosum larvae were fed contaminated whit eflies for a 10-d period; (2) larvae were fed 1 time-only prey contami nated 24-, 48-, 72-, or 96-h previously; and (3) larvae were fed prey after the conidia were washed off the leaves and prey cuticles. The pr edator had significantly lower survivorship when sprayed with B. bassi ana than with P. fumosoroseus. However, survivorship was not affected by the dosage rates for each pathogen. Survivorship curves for P. fumo soroseus treatments also did not differ significantly from blank and c arrier controls. Mean larval duration was longest (approximate to 22.5 d) in S. parcesetosum sprayed at the medium and high dosages of B. ba ssiana, intermediate (approximate to 20 d) for the low dosage of B. ba ssiana, and lowest (approximate to 18 d) for the blank and carrier con trols and the P. fumosoroseus treatments. The pupal stages averaged 6. 6-8.0 d. Mean adult body weights ranged from 0.97 mg (B. bassiana low dosage) to 1.54 mg (P. fumosoroseus medium dosage),but were not signif icantly different. Analysis of cumulative predation showed that predic tors sprayed with P. fumosoroseus consumed prey at a rate similar to t hat of the controls (approximate to 130 prey daily per predator), whic h was significantly higher than that of predators sprayed with B. bass iana (approximate to 60 prey daily per predator). Again, dosage was no t a significant factor. Feeding on B, bassiana-contaminated prey cause d approximate to 86% mortality in S. parcesetosum immatures, compared with approximate to 13% in the controls. Prey contaminated 24-, 48-, 7 2-, and 96-h previously induced mortalities of 92.5, 71.4, 71.4, and 4 4.4%, respectively. Washing conidia off the leaves and the cuticle of whiteflies did not result in lowered mortality of the predator relativ e to the other treatments.