Anais da Sociedade Entomológica do Brasil (1999) 28, 661-673

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A.L.M. Mesquita, L.A. Lacey, C.S. Ceianu and R. Debire (1999)
Predatory and parasitic activity of Aphelinus asychis (Hymenoptera: Aphelinidae) following exposure to the entomopathogenic fungus Paecilomyces fumosoroseus (Deuteromycotina: Hyphomycetes) under different humidity regimes
Anais da Sociedade Entomológica do Brasil 28 (4), 661-673
Abstract: The effect of the hyphomycete Paecilomyces fumosoroseus (Wise) Brown and Smith on the predatory and parasitic activity of Aphelinus asychis Walker, a common parasitoid of the Russian wheat aphid, Diuraphis noxia (Mordvilko), was investigated under three different humidities. Three cohorts of 20 females of A. asychis were treated with 5.2 x 104 spores/cm2 (twice the LD95 for D. noxia). Each female was then individually maintained in a ventilated Petri dish into which three barley leaves were placed and together with 20 third-instar D. noxia. Cohorts of 20 treated females were each held at one of the following relative humidities along with an equal number of untreated control insects: 67-73%, 85-89%, and 94-98%. Every 24 hours over a period of one week, the surviving parasitoids were transferred into a new Petri dish provided with fresh leaves and 20 aphids. After each 24-hour period of exposure and for each parasitoid, dead aphids were counted and the leaves with live aphids were transferred to barley plants to permit the re-establishment of the aphids. Nine days after the transfer of aphids, the mummies were counted. The total number of aphids consumed and mummies originated from the treated parasitoids incubated at 94-98% RH was significantly lower than in the control group. There was a significant decline in predation and parasitism per treated female per day and a progressive reduction in the number of treated parasitoids surviving each day. The death of all treated parasitoids incubated for 7 days at 94-98% RH after treatment and the high level of mycosis in cadavers demonstrate the susceptibility of adult A. asychis to P. fumosoroseus at high relative humidity. However, the reduced suceptibility of parasitoids at lower humidities means that it may still be possible to develop an integrated program of pest management using parasitoids and pathogens.
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Database assignments for author(s): Lawrence A. Lacey

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation


Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.


Cordyceps fumosorosea (entomopathogen)
Aphelinus asychis (parasitoid)