title: Responses of holocyclic and anholocyclicRhopalosiphum padipopulations to low-temperature and short-photoperiod induction.
abstract: The different life cycles of aphid species make these organisms good models for studying the short-term consequences of sex. The bird cherry-oat aphidRhopalosiphum padihas a wide geographic distribution and correspondingly different life cycles. In this study, the life cycles ofR. padicollected from six different regions in China were characterized experimentally by comparing the responses of holocyclic and anholocyclic populations to low-temperature and short-photoperiod induction. Clones collected from Chuzhou, Taian, and Taigu consistently reproduced via obligate parthenogenesis, whereas clones from Hami and Baicheng were holocyclic in their response, and those from Lanzhou were both holocyclic and anholocyclic. Prolonged exposure to low temperature and a short photoperiod (LS) had negative effects on the offspring of anholocyclic aphids with regard to adult lifespan, total longevity, and fecundity compared with aphids maintained at a normal temperature and a long photoperiod (NL). Holocyclic LSR. padihad longer developmental times at all nymph stages, a shorter adult lifespan, shorter total longevity, and a lower fecundity than NL counterparts. The adult prereproduction period of gynoparae was significantly longer than that of virginoparae, and the total longevity of gynoparae was significantly shorter than that of virginoparae. Moreover, the net reproductive and gross reproduction rates, as well as the total fecundity, were roughly fivefold higher in virginoparae than in gynoparae, indicating that there is the short-term cost of sex. When maintained on their secondary host (Triticum aestivum), gynoparae, males, and oviparae produced by holocyclic populations could survive, and gynoparae produced oviparae. However, under NL conditions, oviparae could not produce overwintering eggs on the secondary host, whereas a few overwintering eggs were generated by oviparae under LS conditions. Taken together, these results illuminate the complexity of insect responses and contribute to a complete understanding of the aphid life cycle and its evolution.
authors.affiliation: Northwest A&F University Yangling Shaanxi Province China.
authors.forename: Xiong
authors.initials: X
authors.lastname: Peng
authors.affiliation: Northwest A&F University Yangling Shaanxi Province China.
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Qiao
authors.affiliation: Northwest A&F University Yangling Shaanxi Province China; State Key Laboratory of Crop Stress Biology for Arid Areas Key Laboratory of Crop Pest Integrated Pest Management on the Loess Plateau of Ministry of Agriculture Yangling Shaanxi Province China.
authors.forename: Maohua
authors.initials: M
authors.lastname: Chen
keywords: cost of sex; gynoparae; life cycle; life table; male; oviparae