A Long Photoperiod Promoted the Development, Reproduction, and Predation of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) at an Average Greenhouse Temperature during the Winter.

Simple Summary: Harmonia axyridis (Pallas) is a widely distributed predatory natural enemy insect in North China but its application is limited in greenhouses owing to a low daily average temperature from December to February of next year in greenhouses and the facultative diapause of adult H. axyridis. Owing to the sensitivity of H. axyridis to photoperiod, it is of great importance to explore the feasibility of using the photoperiod to regulate the life parameters and predation ability of this ladybird in greenhouses during the winter, but the effects of photoperiods on life parameters and predation by H. axyridis are not well understood so far. In this study, development, reproduction, and population parameters were studied by constructing two-sex life tables, and effects of photoperiod on predation were tested by predation experiments in both laboratory and greenhouse settings. The results from this article may provide a basis for utilizing H. axyridis in greenhouses during the winter. To explore the feasibility of adjusting the photoperiod to regulate the life parameters and predation ability of Harmonia axyridis Pallas in greenhouses during the winter, life tables were constructed for H. axyridis under the three following photoperiods: 9L:15D (light/dark), 12L:12D, and 16L:8D at 15 °C, an average greenhouse temperature during the winter when aphids severely damage vegetables. The effects of photoperiods on predation by this ladybird were tested in both laboratory and greenhouse settings. The results showed that increased illumination promoted the development and reproduction of H. axyridis; under medium and long photoperiods, the pre-adult periods were 3.61 days and 4.34 days shorter than that under the short photoperiod, respectively, and the fecundity increased by 1.78 and 2.41 times. Population parameters r, λ, and R0 increased as illumination time increased, whereas T decreased. Increased illumination also increased the predation by third- and fourth-instar larvae and adults. The amounts of predation by fourth-instar larvae and adults increased by 22.16% and 75.09% under the medium photoperiod, and those under the long photoperiod increased by 71.96% and 89.64%, respectively. The numbers of Myzus persicae Sulzer predated by H. axyridis under the long photoperiod were higher than those under the short photoperiod in a greenhouse, and the predation parameters were influenced. [ABSTRACT FROM AUTHOR]