Laboratory experiments on the disruption of mating in the Egyptian cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) by excesses of female pheromones

Abstract

The courtship of Spodoptera littoralis (Boisd.) was studied in closed cages containing an excess of the female sex pheromones (Z,E)-9,11-tetradecadienyl acetate (III) or (Z)-9-tetradecenyl acetate (IIA). High levels of III or IIA were obtained by using polyethylene vials loaded with 5, 1 or 0-1 mg of pheromone. Vials containing 10 or 1 ju.g released low levels of pheromone. Excess pheromone reduced mating; at high levels of III and IIA, only 15% and 42% of pairs, respectively, mated, compared with 92% of control pairs. Some 45% of courtships in control cages did not end in copulation, and in half of these the female rejected the male by giving a rapid flick of the wings. A detailed examination of unsuccessful courtships showed that an excess of III or IIA disrupted female courtship behaviour. At the higher levels of pheromone, no female wing-lifted to show acceptance of the male and only a few rejected the male by wingflicking. Significantly more females took to flight in cages containing III, whilst in cages with IIA females either took to flight or remained still. These changes in behaviour were still apparent in courtships where the female was calling and the male gave a full brush display. It is suggested that both III and IIA block olfactory reception of the male brush pheromone. An excess of either pheromone increased the proportion of male courtships of non-calling females. IIA had no other appreciable effect on male behaviour, but III also significantly reduced full brush displays during courtship, increased the period of flight preceding hovering and increased partial brush extension during flights that did not lead to courtship.

Sexual behaviour and pheromone titre of the Spodoptera littoralis female moth

“…On the other hand, mating of S. littoralis, in closed vessels, was almost completely suppressed by permeation of the atmosphere with synthetic pheromone. Similar results were observed by Ellis et aL (1980). There is no contradiction between the two observations, since the mechanism of disruption of calling is probably very different from that of disrupting copulation.…”

“…The pheromone had no influence on the calling of virgin females, contrary to the situation reported by Ellis et aL (1980). The same phenomenon was observed in the field, where females were found in calling position close to Hercon dispensers used for disruption.…”

Conspecific females promote calling behavior in the noctuid moth, Pseudaletia adultera

“…For example, in the literature some studies used (1) calling conspecifics as the pheromone source, whereas others used synthetic lures; (2) females exposed to conspecific pheromone by caging them together or females held individually but exposed to an airstream with pheromone; and (3) females continuously exposed to the pheromone, whereas in others they were just briefly exposed. Such differences could influence the results obtained, as indicated by studies of autodetection in S. littoralis , which report either no effect (Dunkelblum et al., ; El‐Sayed & Suckling, ), a decrease in female calling (Ellis et al., ), or an increase in calling behavior (Sadek et al., ). In this study, the grouped P. adultera females called at a significantly lower age than females held individually, something that has not been reported in other studies.…”

Fitness Cost of Pheromone Production in Signaling Female Moths

“…Signaling behavior of Adoxophyes sp. and H. magnanima was delayed significantly when the females were exposed to a small amount of their own pheromone under outdoor and laboratory conditions (Noguchi and Tamaki 1985), and Ellis et al (1980) reported a reduction in female signaling events when females were exposed to pheromone in laboratory trials. Reduced oviposition of moths when exposed to an excess of pheromone in the orchard was suggested by Weissling and Knight (1996).…”