Non-chemical control of Aceria guerreronis on coconuts.
Aceria guerreronis, the coconut mite, has been a serious pest of coconuts in the Americas and West Africa for many years, and has recently been reported from the Indian sub-continent. It is thus a threat to the coconut industries of Asia and Oceania. Despite its spectacular effects, the coconut mite does not always cause the degree of yield loss attributed to it. Consequently, crop loss assessments in different areas and with different varieties are required. Crop breeding can produce great benefits, but is a long-term, and probably only partial, solution to the pest. There is some research, and some anecdotal, evidence to suggest that plant nutrition is an important feature. Fertilizer experiments, monitoring mineral composition of the coconut, would demonstrate if certain mineral ranges and ratios influence mite levels and effect. The palms may become more tolerant of mite populations, showing reduced losses despite visible evidence of attack, or mite populations may begin to fall, reducing the inoculum available to continue the spread of the pest. No natural enemy appears likely to be successful as a classical biological control agent. Intervention techniques will be required if either predators or pathogens are to be used. The latter are the more likely to produce effective control and a programme to develop an effective myco-acaricide should begin immediately. Isolates are already known, with Hirsutella species the most likely candidates, but more should be sought in areas with a long history of coconut mite problems. However, any programme to develop a myco-acaricide must focus not only on isolate characteristics, but also on aspects of formulation, application and ecology.