INFLUENCE OF ENTOMOPATHOGENIC FUNGI ON SERANGIUM-PARCESETOSUM (COLEOPTERA, COCCINELLIDAE), AN IMPORTANT PREDATOR OF WHITEFLIES (HOMOPTERA, ALEYRODIDAE)
Tj. Poprawski et al., INFLUENCE OF ENTOMOPATHOGENIC FUNGI ON SERANGIUM-PARCESETOSUM (COLEOPTERA, COCCINELLIDAE), AN IMPORTANT PREDATOR OF WHITEFLIES (HOMOPTERA, ALEYRODIDAE), Environmental entomology, 27(3), 1998, pp. 785-795
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.