An overview of techniques that can help minimize defoliation of cacao, Theobromo cacao L., and other crops, by Chinese rose beetle, Adoretus sinicus

The Chinese rose beetle, Adoretus sinicus (Coleoptera: Scarabaeidae: Rutelinae: Adoretini), native to Japan and Taiwan, invaded the Hawaiian Islands where it was first reported on Oahu in 1891.  Defoliation by adult beetles can cause significant damage to over 250 plant species.  One crop for which economically significant damage occurs is cacao, Theobromo cacao L., where feeding preferentially targets young plants and can lead to tree death and failure of orchard establishment.  Methods.  Cacao growers were surveyed in 2014 to assess the importance of Chinese rose beetle damage, and tests were conducted to assess the effectiveness of nighttime illumination, weed mat application, use of shade cloth/plastic film protective cylinders and insecticide application as means of minimizing cacao plant defoliation.  Results/Conclusion. Cacao growers listed concern for Chinese rose beetle as one of the top production concerns, second only to concern for diseases of cacao.  Nighttime illumination of cacao plants, initiated before the time of adult emergence, was shown to significantly reduce leaf damage by adult Chinese rose beetles, but use of this control technique is limited in part by problems of agricultural theft.  A weed mat ground cover was shown to decrease cacao leaf damage.  Shade cloth/film cylinders were found to very effectively minimize first year defoliation.  In tests of field sprays of kaolin clay, pyrethrin, Beauvaria bassiana, imidicloprid, and azadirachtin, lowest leaf damage was found in azadirachtin, imidicloprid and Beauvaria bassiana treatments, while pyrethrin was the most effective insecticide in decreasing adult beetle longevity in laboratory studies.