School of Biology and Environmental Science, Queensland University of Technology (QUT), Brisbane, QLD, 4001, Australia.
School of Mathematical Sciences, Queensland University of Technology (QUT), Brisbane, QLD, 4001, Australia.
Sci Rep. 2021 Jun 1;11(1):11410. doi: 10.1038/s41598-021-90960-7.
Bactrocera tryoni is a polyphagous fruit fly that is predicated to have continuous breeding in tropical and subtropical Australia as temperature and hosts are not limiting. Nevertheless, in both rainforest and tropical agricultural systems, the fly shows a distinct seasonal phenology pattern with an autumn decline and a spring emergence. Temperature based population models have limited predictive capacity for this species and so the driver(s) for the observed phenology patterns are unknown. Using a demographic approach, we studied the age-structure of B. tryoni populations in subtropical Australia in an agricultural system, with a focus on times of the year when marked changes in population abundance occur. We found that the age-structure of the population varied with season: summer and autumn populations were composed of mixed-age flies, while late-winter and early-spring populations were composed of old to very old individuals. When held at a constant temperature, the longevity of adult reference cohorts (obtained from field infested fruits) also showed strong seasonality; the adults of spring and early autumn populations were short-lived, while late autumn and late winter adults were long-lived. While still expressing in modified landscapes, the data strongly suggests that B. tryoni has an endogenous mechanism which would have allowed it to cope with changes in the breeding resources available in its endemic monsoonal rainforest habitat, when fruits would have been abundant in the late spring and summer (wet season), and rare or absent during late autumn and winter (dry season).
地中海实蝇是一种多食性果实蝇，预计在澳大利亚的热带和亚热带地区连续繁殖，因为温度和寄主都不受限制。然而，在热带雨林和热带农业系统中，这种蝇表现出明显的季节性物候模式，秋季下降，春季出现。基于温度的种群模型对该物种的预测能力有限，因此，观察到的物候模式的驱动因素尚不清楚。我们采用人口统计学方法，在亚热带澳大利亚的农业系统中研究了地中海实蝇种群的年龄结构，重点研究了种群数量发生明显变化的年份。我们发现，种群的年龄结构随季节而变化：夏季和秋季的种群由混合年龄的苍蝇组成，而冬季末和春季初的种群由老到非常老的个体组成。当在恒定温度下饲养时，成年参考组（从田间受感染的果实中获得）的寿命也表现出很强的季节性；春季和初秋种群的成虫寿命短，而晚秋和晚冬成虫寿命长。尽管仍在改良的景观中表达，但数据强烈表明，地中海实蝇有一种内在机制，使其能够应对其特有季风雨林栖息地中繁殖资源的变化，当果实在晚春和夏季（湿季）丰富时，以及在晚秋和冬季（干季）稀少或不存在时。
