Functional response of six indigenous trichogrammatid egg parasitoids (Hymenoptera: Trichogrammatidae) in Kenya: influence of temperature and relative humidity

Laboratory tests were conducted to evaluate the functional responses of six species/strains of native Kenyan trichogrammatids using the factitious pyralid host, Corcyra cephalonica, under different temperature and relative humidity regimes. The objective was to identify promising species/strains for...

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Bibliographic Details
Published in:Biological control 2005, Vol.32 (1), p.164-171
Main Authors: Kalyebi, Andrew, Overholt, W.A., Schulthess, F., Mueke, J.M., Hassan, S.A., Sithanantham, S.
Format: Article
Language:English
Subjects:
biological control agents
Corcyra cephalonica
Functional response
host density
host-parasite relationships
Kenya
parasitism
parasitoids
population density
Relative humidity
strain differences
Temperature
Trichogramma
Trichogrammatids
Trichogrammatoidea
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Summary:Laboratory tests were conducted to evaluate the functional responses of six species/strains of native Kenyan trichogrammatids using the factitious pyralid host, Corcyra cephalonica, under different temperature and relative humidity regimes. The objective was to identify promising species/strains for controlling the noctuid Helicoverpa armigera, a serious pest of vegetables in Kenya. The six species/strains of Trichogramma and Trichogrammatoidea represented collections from low (1200 m) altitude locations. They were compared for parasitisation rates at six temperatures (10, 15, 20, 25, 30 and 35 °C) and two relative humidity levels (40–50% and 70–80%), at five host egg densities (6, 12, 18, 24, and 30 per adult female). Temperature affected parasitisation rates while relative humidity did not. Trichogrammatoidea sp. nr. lutea from a high altitude location, Trichogramma sp. nr. mwanzai from a low altitude site, Trichogramma sp. nr. mwanzai from a mid-altitude location and Trichogrammatoidea. sp. nr. lutea from medium altitude showed higher parasitism across a wider temperature range compared to the other strains. There was no relationship between source (altitude, climate) and performance of the strains at the temperatures and host densities tested. The implications of these results for deploying the strains for inundative biocontrol of H. armigera in agroecosystems in Kenya are discussed.
ISSN:1049-9644
1090-2112
DOI:10.1016/j.biocontrol.2004.09.006