The Control Efficiency of Parasitoids on Brontispa longissima(Gestro)in Sanya City
The control effect of the parasitoid of coconut leaf beetle,Brontispa longissima(Gestro) in the releasing sites in Sanya was investigated two times to evaluate the controlling efficiency of Tetrastichus brontispae Ferriere and Asecodes hispinarum based on releasing sites,the injury degree of coconut palm,the density of coconut leaf beetle and the parasiting rate of the two parasitoids.The results showed that the injury degree of coconut palm was gradually reduced in Sanya,the coconut palms in 60% of the releasing sites were in light injury,and the beetle density was remarkably reduced.The result also showed Tetrastichus brontispae Ferriere was distributed more widely than it in 2007,its parasitoids could be found in all sites.And the distributed area of Asecodes hispinarum was reduced.The parasiting rate of Tetrastichus brontispae Ferriere for the first investigation was higher than it in 2007 while that for Asecodes hispinarum for the first investigation was lower than it in 2007.Its showed that the two parasitoids could survive in Sanya,the survival ability and control efficiency of Tetrastichus brontispae F.were better than that of Asecodes hispinarum.The study has an important value in using parasitoids for controlling the coconut leaf beetle.