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Analysis of ovipositor washings from virgin femaleHelicoverpa assulta (Guenée) (Lepidoptere: Noctuidae) from Korea by gas chromatography (GC) linked to electroantennography and GC linked to mass spectrometry resulted in the identification of nine compounds, hexadecanal, (Z)-9-hexadecenal, (Z)-11-hexadecenal, hexadecyl acetate, (Z)-9-hexadecenyl acetate, (Z)-11-hexadecenyl acetate, hexadecan-l-ol, (Z)-9-hexadecen-l-ol, and (Z)-11-hexadecen-1-ol. However, ovipositor washings from females from Thailand contained mainly the 16-carbon aldehydes with very small amounts of (Z)-9-hexadecenyl acetate. Field tests conducted in Korea, China, and Thailand indicated that a binary blend of (Z)-9-hexadecenal and (Z)-11-hexadecenal was sufficient for attraction, although the most attractive ratio of compounds varied with location. In Korea a 20∶1 blend of compounds was the most attractive, while in Thailand a 7.5∶1 blend was most attractive. In China both blends of hexadecenal isomers were equally attractive. Addition of the hexadecenyl acetates to the 20∶1 blend of hexadecenals in the ratio of 1∶3.3 increased the trap catch of maleH. assulta compared to lures containing the aldehydes alone in Korea but reduced trap catch in China. Addition of the hexadecenyl acetates to the 7.5∶1 blend of hexadecenals had no significant effect on trap catch in Thailand or China compared to the aldehydes alone. The addition of the 16-carbon alcohols to the aldehydes had a significantly inhibitory effect in all three countries, suggesting they are not pheromone components. Taken together these results indicate thatH. assulta is polymorphic with at least two populations responding to different sex pheromones.

The mechanisms adopted to ensure mating success, fertility and fecundity of S. littoralis were studied. The male moths usually mate only once a night but they mate repeatedly during most of their life span, and practically all their spermatophores ate equally efficient for inseminating a female. Although females are also multiple maters, one spermatophore is sufficient for a female to lay fertile eggs throughout her life with no reduction in potential fecundity. While a male may mate 5.3 times, on the average, a female may mate only 2.3 times. Asa pronounced decrease in pheromone release occurs after mating,a repeat mating by a femate will occur only after most neighboring competitive vkgin females have been inseminated. A male may mate therefore with 5.3 different females, all of which will be thoroughly inseminated.The female moth is ready to matejust after emergence andat any time throughout her life. If mating is delayed the preoviposition period is greatly prolonged and eggs ate saved to be laid later, after mating, as fertile eggs. Delay in egg laying due to delayed insemination does not result in reduced fecundity as ir is compensated for by prolonged longevity. Even ir mating is greatly delayed and occurs after egg laying has already begun, the potential reduction in reproduction is not very great, due to the low daity egg-laying rate and the increased longevity of unmated females.It appears unreasonable to expect any tendency toward reduction of egg production with a decrease in the ratio of adult males in a population; for this purpose the control of males must be essentially complete. Therefore, a behavioral control program by mass trapping of S. littoralis males is unlikely to be economically feasible.

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(Z)‐11‐hexadecenal and (Z)‐9‐hexadecenal were ineffective lures for H. armigera males unless combined. Attraction depended upon perception of a 90%–99% combination of (Z)‐11‐hexadecenal with 1%–10% (Z)‐9‐hexadecenal. Increasing the level of (Z)‐9‐hexadecenal in the mixture to 26.2% reduced catches. Adding 2.3% (Z)‐7‐hexadecenal to the mixture did not enhance or reduce attraction, while adding 8.7% (Z)‐11‐hexadecenol significantly reduced male catches. The combination of (Z)‐11‐hexadecenal and (Z)‐9‐hexadecenal was effective only when released from rubber dispensers but not from polyethylene vials. A load of 2 mg of the mixture on rubber dispensers effectively attracted males for at least 31 days. The H. zea lure which contained all the pheromonal components of that species was also effective in attracting H. armigera males. The H. virescens lure attracted significantly fewer H. armigera males than the H. zea lure. RÉSUMÉ ESTIMATION DANS LA NATURE DES CONSTITUANTS DE LA PHÉROMONE SEXUELLE D'HÉLIOTHIS ARMIGERA Les (Z)‐11‐hexadecenal et (Z)‐9‐hexadecenal sont des attractifs sexuels in efficaces pour les mâles de H. armigera. L'attraction dépend de la perception d'un mélange de 90 à 99% de (Z)‐11‐hexadecenal avec 1 à 10% (Z)‐9‐hexadecenal, L'augmentation jusqu'à 26,2% de la teneur en (Z)‐9‐hexadecenal réduit les captures. L'addition de 2,3% de (Z)‐7‐hexadecenal au mélange ne modifie pas l'attractivité, tandis que celle de 8,7% de (Z)‐11‐hexadecenol, réduit significativement les captures de mâles. Le mêlange de (Z)‐11‐hexadecenal et de (Z)‐9‐hexadecenal n'a été efficace qu'avec des diffuseurs en caoutchouc, par contre il a été sans effet à partir de récipients de polyéthylène. Une charge de 2 mg de mélange dans des diffuseurs en caoutchouc attire effectivement les mâles pendant ou moins 31 jours. L'attractif sexuel de H. zea qui contient tous les constituants de la phéromone de cette espèce attire aussi efficacement les mâles de H. armigera. Celui de H. virescens attire significativement moins de mâles de H. armigera que l'attractif sexuel de H. zea.