Species-Specific Effect of Parasitization of Ectoparasitoid, Bracon hebetor (Hymenoptera: Braconidae) on the Larval Haemocyte Counts of Corcyra cephalonica and Ephestia kuehniella (Lepidoptera: Pyralidae)

Özet

Many studies have described post-parasitization physiological changes in insect hosts for koinobiont endoparasitoids. However, not much is known regarding idiobiont ectoparasitoids that how these parasitoids affect their target hosts’ physiology. The present study aimed to determine the effect of parasitization by Bracon hebetor (Hymenoptera: Braconidae), an efficient idiobiont ectoparasitoid of many lepidopterous larvae, on the total haemocyte counts (THCs) of 5th instar larvae of Corcyra cephalonica and Ephestia kuehniella, two important stored product pyralid pests. Results showed that B. hebetor parasitization differentially affected THCs in parasitized E. kuehniella and C. cephalonica larvae. In E. kuehniella larvae, THCs steadily increased till 12th hour observation after a sharp decline in the very first hour of parasitization and then started decreasing from 24th hour post-parasitization. Highest THCs value (2800 ± 300 cells mL-1) was observed at 6th day of parasitization. While on the contrary, C. cephalonica THCs exhibited a boost in first 6 hours of post-parasitization with maximum THCs value (3413 ± 139 cells mL-1) at 6th hour, but then gradually decreased till the end of experiment on 9th day. Average THCs in fresh unparasitized larvae of E. kuehniella and C. cephalonica were 2078 ± 137 and 1474 ± 47 cells mL-1, respectively. These findings indicate that parasitization by idiobiont parasitoids may alter the haemocyte profiles of their hosts and these responses are species-specific. However, future studies on the interaction of post-parasitization changes in haemocyte profiles and immunity mechanisms of host larvae would help in better comprehension of the effects of ectoparasitoids parasitization on their host physiology.