The efficiency of two methods of egg's lacewing releasing with 1:5 ratio in greenhouse

Lacewings are the predatory insects that widely used in biological control programs. Among them, Chrysoperla carnea (Stephens) (Neu.: Chrysopidae) is a promising biological control agent in releasing against pests in greenhouses and fields. In this study, two release methods of lacewing’s eggs were compared: distribution of eggs mixed with sawdust as an egg carrier and dispensation of the eggs using chrysobag (the special net bags). Experiments were conducted on the cucumber Cucumis sativum L., against cotton aphid, Aphis gossypii Glover in netted cages. Ratio 1:5 was compared in two methods in a condition that each cage contained 4 plants and density of aphids was higher than that of the last experiments. This experiment was conducted in a randomized complete block design. First egg release showed no significant difference between two methods. Approximately 80-84% reduction in population density of aphids was observed compared with control treatment. However 2nd egg release, 7 days after 1st release, showed 94-95% reduction in aphid population. Better control of aphids was observed with repeated egg release. If experiments conducted in cage without presence of generalist predators (such as ants) of eggs, two methods had the same effect to control aphids. Although two methods had the same efficacy without presence of ant, if eggs released in greenhouses and fields, chrysobag protects eggs from ants and other predators. Therefore, chrysobag with a high efficiency and without bad affect on host plant. Chrysobag method suggested to be used in commercial greenhouses and field.