Factors affecting male probing activity of the red bollworm Diparopsis castanea (Hmps.) in relation to sterility induced by tris(1 ‐aziridinyl) phosphine oxide (tepa)

SUMMARY Assuming that the sex attractant of the female red bollworm, Diparopsis castanea (Hmps.), can be isolated, it might be used at bait stations in combination with chemosterilants for the control of this insect. To ensure success, it is essential that male moths attracted to the bait station should pick up an effective dose of chemosterilant either by brief contact with, or by momentary probing on, chemosterilant‐treated surfaces. In Rhodesia, during the dry season, up to 90 % of the moths tested probed on water after 3 days, while 80% probed on 10 %‐D‐glucose after 2 days. In a laboratory with controlled humidity, 70 % of the moths probed after 18 h at 0–10% R.H.; and 10% probed after 18 h at 40% R.H. The average amount of liquid imbibed by individual moths varied from 15·5 μl after 18 h at 0% R.H. to 7·2 μl after 18 h at 40% R.H. It was estimated, and later confirmed, that thirsted moths probing on a 0·1 % aqueous solution of tris (1‐aziridinyl) phosphine oxide (tepa) would take up the equivalent of a sterilizing dose. The treated moths were consistently sterilized with no adverse effects on mating frequency, longevity or competitiveness. As both sexes were found to be sexually mature on emergence, it is probable that little dispersion of the newly emerged adult population occurs before the first mating.