Ability of the larval ectoparasitoid Habrobracon hebetor (Say, 1836) (Hymenoptera: Braconidae) to locate the rice moth Corcyra cephalonica (Stainton, 1865) (Lepidoptera: Pyralidae) in bagged and bulk stored rice.

摘要

The potential of using Habrobracon hebetor for the inundative biological control of Corcyra cephalonica in rice stored in jute bags and in bulk was assessed. Host-finding in the situation of bag storage was tested by preparing small jute bags measuring 18x16 cm filled with 5 kg of un-infested rice grains. In the first experiment, 60 larvae of C. cephalonica were released into the bag. The bag was placed in an empty climatized room with an area of 12.3 m2. Sixty H. hebetor adults (sex ratio of 1 male:2 females) were released at a distance of 1.6 m away from the jute bag. The number of H. hebetor adults that entered the jute bag was counted daily for 8 days by opening the bag and counting the parasitoids. Only 3% of the parasitoids entered the jute bag. In a second experiment, 60 C. cephalonica larvae were placed inside a wire gauze cage within the jute bag. Ten H. hebetor adults were released into the jute bag. The bag was sealed. After 1 week the cage was removed, and the number of C. cephalonica as well as F₁ generation of H. hebetor that emerged was recorded. H. hebetor was able to significantly reduce the number of C. cephalonica emerging from the bagged rice; the corrected mortality due to the parasitoid release was 92.13%. The emergence of H. hebetor progeny started on day 9 after the introduction of the parasitoids and continued until day 21. Host-finding in the situation of bulk rice was tested in glass cylinders (50 cm height, O=25 cm) containing caged larvae at horizontal depths of 7 and 14 cm. H. hebetor was able to find its host C. cephalonica in both depths; significantly more F1 H. hebetor adults emerged from hosts placed 7 cm deep. The implications of these results with respect to the suitability of H. hebetor for the biological control of C. cephalonica in bagged and bulk rice are discussed.