Study on aphid control by applying Harmonia (Leis) axyridis

摘要

The larvae of the varied color ladybug Harmonia (Leis) axyridis eat aphids. The first larval instar can eat 32 aphids a day. The second larval instar can eat 85 aphids per day. The third and the fourth larval instars can consume 169 and 203 aphids every day, respectively. Each larval instar can eat 120 aphids on average. The adult can eat 160 aphids every day.[1] The amount of aphids consumed by the adult of the varied color ladybug Harmonia (Leis) axyridis is higher than that of other ladybugs. The ladybugs have a broad appetite (wide eating patterns). They can eat almost all kinds of aphids. They aggregate during hibernation. The population of this ladybug is very large. Therefore, it is a natural enemy worthy of development and utilization. Since the aggregation habit of the ladybug in hibernation was reported in the 1960's, [2] many valuable studies about the ladybug have been done. The investigation on site hibernation[3] , occurrence and habits[4-5] and the study of controlling cucumber aphid and cotton aphid etc. were included in this research. However, because the adult has a habit of disperal toward higher elevations, it is difficult to establish a source of ladybug colonies in flatlands. Moreover the larvae are suicidal. It is not easy to raise the ladybug on a large scale. Therefore, for a long time the ladybug has not played an important role in controlling aphids in the field. Changbai Mountain is a region with the largest quantity of hibernating ladybugs [3]. It is also the place where the aggregation habit of adults in hibernation was first discovered [1]. We have done some experiments and research in Changbai Mountain since 1987 on biological characteristics of the varied color ladybug Harmonia (Leis) axyridis, such as oviposition of hibernating adults and hatching behavior from eggs to larvae. While we summarize previous research evidence, we base our work on the principle of “taking from nature, applying to field, developing in laboratory and releasing to nature”. We have done some release experiments to control soybean aphid and have simulated experiments for farmers rearing ladybugs by themselves. Now the data is presented as follows.