Effects of the cochineal Dactylopius coccus on growth of the host cactus(Opuntia ficus-indica)

Effects of different cochineal beetle Dactylopius coccus Costa densities on growth of the host cactus(Opuntia ficus-indica Mill) were measured with regard to three dependent variables;cactus plant height,the number of new cladodes and the area of new cladodes.The results show that:1) D.coccus can inhibit cactus growth;plant height and the number and area of new cladodes were reduced at higher beetle densities.2) The rate of cactus growth decreased and the peak period of growth was also delayed at high beetle density.3) Beetle density should be controlled to be no more than 1 000 beetles per plant;higher densities will lead to cactus death.