Olfaction is an essential sensory modality of insects which is known to vary with age. In short-lived insects odour response generally declines rapidly with increasing age, but how increasing age affects the olfactory response of long-lived insects is less known and there may be different life-time patterns of olfactory response. Here, we examine the effect of age on olfactory response and exploratory activity of a long-lived tephritid fruit fly, Bactrocera tryoni from sexual maturity (3 weeks) to advanced age (15 weeks). Males were tested against a male-specific attractant, cue-lure, which is associated with courtship and sexual selection in this species; while females were tested against guava-juice, a highly attractive oviposition host fruit odour. Trials were done in the laboratory using a Y-tube olfactometer at three weekly intervals. The probability of olfactory response of both males and females to tested odours declined with age. Males retained a constant attraction to cue-lure until 12 weeks of age, but then showed a significant drop in olfactory response at 15 weeks. However, females showed the highest attraction to guava-juice odour until six weeks of age and declined gradually thereafter. The change on odour response over time can be associated with an age-related change in initial locomotor activity for females as there was no change, over the life of the experiment, in selective female orientation to the odour source once flies started exploring within the olfactometer. However, for 15 week-old males, there was a simultaneous drop in both locomotor activity and selective olfactory orientation. The consistent attraction of male to cue-lure might be related to life-long reproductive activities of males, as males are thought to mate continuously during life. On the other hand, females' highest attraction to guava-juice odour in early life followed by a gradual decline might be linked with their oviposition rate which peaks in early life.

中文翻译：

---

高龄对昆士兰果蝇Bactrocera tryoni（Froggatt）（Diptera：Tephritidae）雌雄的嗅觉响应的影响。

嗅觉是昆虫必不可少的感觉方式，已知其随着年龄而变化。在短寿命昆虫中，气味响应通常随着年龄的增长而迅速下降，但是，随着年龄的增长，长寿命昆虫的嗅觉响应如何受到影响尚不清楚，并且嗅觉响应的生命周期可能会有所不同。在这里，我们研究了年龄从性成熟（3周）到高龄（15周）对长寿的拟南芥果蝇Bactrocera tryoni的嗅觉反应和探索活动的影响。对雄性进行了针对雄性特异性引诱剂诱饵的测试，该诱饵与该物种的求爱和性选择有关；而女性则接受了番石榴汁测试，番石榴汁是一种极具吸引力的产卵宿主气味。在实验室使用Y型管嗅觉仪每三个星期进行一次试验。随着年龄的增长，男性和女性对测试气味的嗅觉响应的可能性均下降。直到12周龄，雄性对诱饵都保持着持续的吸引力，但随后在15周时，嗅觉反应显着下降。然而，女性对番石榴汁气味的吸引力最大，直到六周龄，此后逐渐下降。随着时间的推移，气味反应的变化可能与雌性的初始运动能力的年龄相关，因为在实验过程中，一旦果蝇在嗅觉计内开始探索，在整个实验过程中，雌性朝向气味源的选择性方向就没有变化。但是，对于15周大的男性，运动能力和选择性嗅觉取向同时下降。雄性对诱饵的持续吸引可能与雄性的终生生殖活动有关，因为人们认为雄性在生活中会不断交配。另一方面，女性在早期生活中对番石榴汁气味的最大吸引力随后逐渐下降可能与她们在早期生活中达到最高的排卵率有关。