Development, survival and reproduction of Orius niger (Hemiptera: Anthocoridae) under different photoperiod and temperature regimes

The successful use of the predatory bug Orius spp. (Hemiptera:Anthocoridae) for the biological control of pests, namely western flower thrips Frankliniella occidentalis (Pergande), in greenhouses during winter depends on overcoming the obstacles of short photoperiods and low temperatures which limit the efficacy of the predators through diapause induction, slowed development, reduced survival and reproduction. Thus, research has focused on determining the insect species least vulnerable to these problems. This study investigated the effect of varying day-lengths (9, 11, 13 and 16 h) at 26 degrees C as well as constant (18, 22, 26 and 30 degrees C) and fluctuating (10/22 degrees C) temperatures on biological characteristics of Orius niger (Wolff). Photoperiod did not induce reproductive diapause and did not significantly affect development, survival of eggs and nymphs, longevity, fecundity or sex ratio; with the exception of the 16 h day-length which led to a shorter duration of nymphal development. Fluctuating temperatures and a constant temperature of 18 degrees C increased the incubation period, duration of nymphal development, total developmental time, generation time and longevity, compared to the constant temperatures of 22, 26 and 30 degrees C, but decreased fecundity compared to 22 and 26 degrees C. On the other hand, sex ratio was not influenced by 10/22 and 18 degrees C. Egg hatch rate and nymph survival differed significantly between temperature regimes, being lower at 18 and 10/22 degrees C. These results suggest that O. niger would be able to survive and reproduce under winter conditions in unheated Mediterranean greenhouses and is a candidate for use in the biological control of pests.