Seasonal occurrence and impact of natural enemies of Hypera postica (Coleoptera: Curculionidae) larvae in Iowa
1994
Giles, K.L. | Obrycki, J.J. | Degooyer, T.A. | Orr, C.J.
The entomopathogenic fungus Zoophthora phytonomi (Arthur), (Zygomycetes: Entomophthorales), infected populations of Hypera postica (Gyllenhal), (Coleoptera: Curculionidae), larvae at four sites in central and south-central Iowa in 1990, 1991, and 1992. Six epizootics (> 50% host infection) were observed during this 3-yr study; five were associated with above average rainfall. First occurrence of disease after 1 January 1991, occurred following the accumulation of 168-207 degree days above 9 degrees C. From 30 March to 28 May (1991), rainfall averaged between 3.6-7.0 mm per day, promoting epizootics of disease that reduced total larval populations from 15-61% at four locations in Iowa. In 1992, enzootics (< 50% infection) of Z. phytonomi occurred during late May and early June on declining populations of H. postica larvae at three sites. An epizootic occurred in central Iowa despite below-average rainfall. Parasitization of H. postica larvae by Bathyplectes curculionis Thomson (Hymenoptera: Ichneumonidae) and B. anurus Thomson ranged from 2.2 to 27.6% in 1991 and 1992. B. curculionis parasitization rates at two southern Iowa locations declined during epizootics of Z. phytonomi each year, suggesting a negative effect of Z. phytonomi on this larval parasitoid. B. anurus became the most abundant larval parasitoid at the two locations in southern Iowa after epizootics of Z. phytonomi.
اظهر المزيد [+] اقل [-]الكلمات المفتاحية الخاصة بالمكنز الزراعي (أجروفوك)
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