B. F. Nesbitt, P. S. Beevor, D. Hall
May 1, 1980
Citations
1
Influential Citations
51
Citations
Journal
Entomologia Experimentalis et Applicata
Abstract
We recently reported the identification of up to five pheromone components in abdominal tip extracts of female Heliothis armigera and in volatiles emitted by the virgin female moth (Nesbitt et al., 1979). These were (Z)-I 1-hexadecenal (I), the major component previously identified by Piccardi et al. (1977, (Z)-11-hexadecen1-ol (II), (Z)-9-hexadecenal (III), hexadecanal (IV) and 1-hexadecanol (V). The (Z)-9-hexadecenal (III) was only found in some batches of insects from Malawi when it was present in amounts similar to those of (I). Field trapping in Malawi and elsewhere with (Z)-I 1-hexadecenal (I) alone gave low and erratic catches of male H. armigera moths, and addition of components (II), (III) and/or (IV) did not have any consistent effect on the attractiveness. However, there were suggestions from this and other work carried out in Australia (G.H.L. Rothschild, pers. comm.) that the addition of small percentages of (Z)-9-hexadecenal (III) enhanced the attractiveness of the major component (I). It was also reported by Klun et al. (1979) that in H. zea, a New World species closely related to H. armigera, the female moth produces trace amounts of (Z)-7and (Z)-9-hexadecenal and hexadecanal in addition to the major component, (Z)-ll-hexadecenal. The attractiveness of the latter to male moths was synergised by an appropriate mixture of the minor components. These findings prompted us to re-examine the pheromone system of H. armigera. Insects were collected as larvae or pupae in Malawi, India and the Sudan and flown to London. The pupae were sexed and separated, and then maintained on a reversed light/dark cycle (12 hr light at 25 ° and 70% r.h.: 12 hr dark at 20 ° and 80% r.h.). Ovipositor washings were made in carbon disulphide as described by Sower et al. (1973) and Klun et al. (1979) using female moths 2-3 days after emergence and 5-8 hr into the scotophase. The washings were analysed directly by gas chromatography (GC). After preliminary analyses on packed Carbowax 20M, OV 225 and Apiezon L columns (Nesbitt et al., 1979), more detailed analyses were carried out on glass support-coated (SCOT) and wall-coated (WCOT) opentubular columns, and also on a packed liquid crystal column (Lester & Hall, 1980). Ovipositor washings from moths of Indian origin were also examined on SCOT