DIEL RHYTHMS OF SEXUAL BEHAVIOR AND PHEROMONE TITERS IN Isoceras sibirica ALPHERAKY (LEPIDOPTERA, COSSIDAE)

Abstract

The adult behavior and sex pheromone titers of Isoceras sibirica Alpheraky (Lepidoptera, Cossidae) were investigated to determine the diel periodicity of pheromone production during one scotophase and the effect of age on pheromone production. The results showed that females began to call on the first night after eclosion and called mainly during the second half of scotophase. The percentage of females calling was highest in 1- to 3-day-old females and lowest in 4- to 5-day-old females. The onset of scotophase calling occurred earlier as females aged. The responses to the pheromone source of males aged 1-5 days were monitored in a wind tunnel. Peak activity was observed in 3-day-old males, 4 h after the onset of the scotophase. The mating of all 1- to 3-day-old moths began after 6 h in scotophase and some 4- to 5-day-old moths began during the fourth hour. The average duration of copulation was 34.2 ± 18.2 min (N = 45) and ranged from 17.0 to 56.3 min. Gas chromatography-mass spectrometry (GC-MS) analysis of hexane extracts of pheromone glands revealed that the titers of the three sex pheromone components, (Z)-9-tetradecenyl acetate (Z9-14:Ac), (Z)-7-tetradecenyl acetate, and (Z)-9-hexadecadecenyl acetate were very low on the first night after eclosion, increased and peaked on the second night, then decreased with age. During the first 4 h of the scotophase, titers remained invariant, whereas from 4 to 6 h, pheromone titers increased sharply and peaked, with the greatest peak observed in the primary component, Z9-14:Ac. After the peak, all recorded titers declined until they reached a minimum between the ninth and tenth hours of the dark cycle. In field tests, most of the males were captured in traps during 00:00-02:00 h (13 ± 0.48), and females aged 2 days attracted more males than females of other ages. We infer that the I. sibirica mating system is organized around circadian control of mate calling and mating.

A temporal comparison of sex-aggregation pheromone gland content and dynamics of release in three members of the Lutzomyia longipalpis (Diptera: Psychodidae) species complex

“…A drop in pheromone gland content with advancing age is common in many groups of insects, such as flies, e.g. Isoceras sibirica [ 40 ], and moths, e.g. Ctenopseustis spp ., Planotortrix octo and Epiphyas postvittana [ 41 ].…”

Periodical and Age-Related Variation in Sexual Communication of the Legume Pod Borer,Maruca vitrata(Lepidoptera: Crambidae)

“…More calling was observed in older females (3-to 5-day-old), mainly due to advanced onset time and extended period of calling. The findings that onset time of calling was advanced with increase in age have been reported in other moths (Kochansky et al 1977;Kou & Chow 1987;Delisle & Royer 1994;Xiang et al 2010;Liu et al 2013). Specifically, the advanced onset time of calling with increase in age in Lepidopteran species is an adaptation that permits older females to increase their chances of mating before younger females start calling (Delisle & Royer 1994).…”

“…Some other species showed a similar synchronous relationship between calling and the amount of pheromone with the change of age or time, such as Spodoptera exigua, Autographa gamma, Cornutiplusia circumflexa, Isoceras sibirica, and Agrotis ipsilon (Dong & Du 2001;Mazor & Dunkelblum 2005;Xiang et al 2010;Liu et al 2013). This coincidence between pheromone production and female calling indicates a common regulatory mechanism for both processes (Gemeno & Haynes 2000).…”

Daily rhythmicity in the sexual behaviour of Monema flavescens (Lepidoptera: Limacodidae)

“…The result that females began calling earlier during the scotophase and for a longer time as they aged is in agreement with that recorded for several other species of moths (Seol et al, 1986;Delisle, 1992;Spurgeon et al, 1995;Mazor & Dunkelblum, 2005). Older females advance their calling time to increase their mating success relative to younger females, otherwise they would be at a disadvantage compared to the younger females if they did not spend more time calling (Delise, 1995;Xiang et al, 2010;Liu, 2013).…”