Host Larval Body Odours AID Host Location Of Apanteles Machaeralis, A Braconid Larval Endoparasitoid of Cucumber Moth Diaphania Indica

Abstract

The parasitoids of phytophagous insects are mainly guided by olfactory cues emanated from their host. Apanteles machaeralis (Wilkinson) parasitizes the larvae of cucumber moth Diaphania indica (Saunders). Our previous studies have shown that larval body odours of D. indica attract adult female of A. machaeralis, however the compounds responsible for this attraction have not been identified. The present study was conducted to identify the odour cues underlying the female A. machaeralis attraction towards its larval host, D. indica. Series of GC-EAD and GC-MS studies carried out revealed that a total of eleven chemical cues (n- decane; (z)-ocimene; allo-ocimene; methyl salicylate; 2,6,11-trimethyl dodecane; octanoic acid 2-methyl propyl ester; n-tridecane; farnesene; 2,6,10-trimethyl tetradecane; n-heptadecane; n-tricosane) from host larval body wash elicited antennal response in female A. machaeralis. Olfactory bioassays with commercially available synthetic chemical compounds of EAD active cues revealed that n-decane (p = 0.004), allo-ocimene (p = 0.005) & (z)-ocimene (p = 0.003) could elicit significant attraction in A. machaeralis. This study revealed that the larval body odour cues namely n-decane, allo-ocimene, (z)-ocimene of D. indica might function as kairomones to attract female A. machaeralis parasitoids to their host.