The influence of temperature, photoperiod, and diet on development and reproduction in the four-spot lady beetle Harmonia quadripunctata (Pontoppidan) (Coleoptera, Coccinellidae)

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This is the first report on the effects of temperature (from 17 to 30°C), photoperiod (from 10 to 16 h of light), and diet (the wheat aphid Schizaphis graminum and the green peach aphid Myzus persicae) on preimaginal developmental rates, adult body mass, preoviposition period, and female fecundity of the predatory lady beetle Harmonia quadripunctata (Pontoppidan) under the laboratory conditions. A constant temperature of 30°C was lethal to the embryos. Judging from the data obtained at 17, 20, and 25°C, the lower temperature threshold for total egg-to-adult development equaled 12.0°C and the respective sum of effective temperatures was 274 degree-days. Preimaginal development was somewhat faster under short-day conditions, the threshold for this quantitative photoperiodic response being approximately 14 h at the rearing temperatures of 20 and 25°C. At a temperature of 25°C, the mean body mass of newly emerged adults was greater for those individuals that during the larval stage had been fed on the green peach aphid (16.4 mg in males and 18.4 mg in females) than in those fed with the wheat aphid (13.8 mg in males and 15.3 mg in females). The preoviposition period (measured from adult emergence to the first egg laid) also depended on temperature and had a lower threshold of 13.4°C and a sum of effective temperatures of 152 degree-days. Maximum fecundity was observed at 25°C and 16-h day length; under these conditions, the oviposition period lasted over 100 d, and the average lifetime fecundity was about 800 eggs per female. Under short-day conditions, females of H. quadripunctata entered reproductive diapause. The photoperiodic threshold for this qualitative response at the temperatures of 20 and 25°C was about 14 h when fed on the peach aphid and 15 h when fed on the wheat aphid. Relatively small body size, low fecundity, and a strong photoperiodic response that hinders rapid adaptation to novel climates probably explain the fact that H. quadripunctata, in contrast to H. axyridis, has not become an aggressive invader.