The Effect Of Harmonia Axyridis (Pallas) On Control Of Sucking Pests In Tea Plantations

Toxoptera aurantii Boyer, Dendrothrips minowai Priesner and Empoasca vitis(Gothe), three types of sucking pests are most common in tea plantations of Guizhou Province. These pests adversely impact the formal tea growth and decrease the tea quality and quantity by sucking the tender shoots and leaves of tea. As a very common predatory enemy in tea plantations, Harmonia axyridis(Pallas) has a good control capacity to many target tea pests. Up to now, the ladybirds have been successfully applied into various ecosystems, such as soybean field, cotton field, strawberry field,etc. However, its use in tea plantations is still lack. Thus, how the enemies are applied to suppress these tea pests and the extreme regulating role of which to control pests would need to be one trend.In this paper, two major aspects were included as follows:On the one hand, the dominant species of H. axyridis collected this time was investigated, that is ab. conspicua Fald. Then maintenance of this lady beetle was done. The data results showed that the fresh Spodoptera exigua(Hiibner) eggs were only suitable to them; and for different stages of H. axyridis to Brevicoryne brassicae(Linnaeus), the optimum predator-prey ratios were greatly different; and the non-sibling cannibalism to eggs was stronger for adults. Meanwhile, the potential control of sucking pests was done in the laboratory. The results suggested that for the third larvae of H. axyridis, the comprehensive control value was the largest to thrips adults, followed by tea aphid nymphs and leafhopper nymphs; and for adults of H.axyridis, it was the largest to tea aphid nymphs, followed by thrips adults and leafhopper nymphs. The effect of tea aphid and thrips on biological traits on the ladybirds was researched. The results showed that the thrips was unsuitable to them,but tea aphid was suitable to them.On the other hand, the semi-field experiments were conducted in tea plantationsin Fenghuang hills, Meitan County, Guizhou Province. And the insects used in the field were eggs, third larvae, adults of H. axyridis. The results showed that significant difference was observed among the three treatments at 1 day after released, 5.51% for eggs treatment, 11.31% for third larvae treatment,-61.24% for adults treatment. Then the effectiveness was increasing, and there was no significant difference. The maximum values were gained at 11 days after released, 100.00% for three treatments.Hence, from the point of durability, the three stages were all available to control tea aphid; and from the point of quick-acting, the third larvae were a better choice.