Heterologous expression of a substance which inhibits receptivity and calling in Helicoverpa armigera (Hübner).

Abstract

The accessory glands of male moths secrete several proteins, which are known to affect post-mating behaviour in females such as calling, reduction in receptivity, rate of egg maturation and laying, sperm maintenance and release and formation of mating plug. Helicoverpa armigera (Hübner) is a polyphagous pest of numerous crops and it is widely distributed on the Indian subcontinent where it causes severe economic losses. In the present study, receptivity- and calling-inhibiting substance (RCIS), a peptide secreted from the accessory glands of male H. armigera, was sequenced, cloned and expressed in a prokaryote, Escherichia coli. RCIS is a peptide comprising 58 amino acids and had a theoretical molecular weight of 6.03 kDa. It showed 64% similarity with pheromonostatic peptide 1, identified in Helicoverpa zea (Kingan et al., 1995) but differed regarding deletion of four and one amino acids at positions 14-17 and 44, respectively, and insertion of one and five amino acids at position 38 and the terminal position of RCIS, respectively. H. armigera females injected with recombinant RCIS showed reduced receptivity and calling behaviour (in 70-80% of the treated individuals), and mating frequencies decreased by 80%. Recombinant RCIS may be employed to artificially induce non-receptivity in virgin females in order to prevent reproduction.