New research on the coconut mite, Eriophyes guerreronis K., in the Ivory Coast.
In 1975 Eriophyes guerreronis (Keifer) appeared at several points in the coconut-palm plantations of the south-eastern Ivory Coast, and its attacks have become more extensive from year to year, as previously happened in other African and Latin American countries [see RAE/A 66, 2035, etc.]. The authors review the mechanics and symptoms of mite attack, and note that in young nut clusters the percentage of nuts attacked was higher during wet periods. The methods of studying the incidence of E. guerreronis in relation to the yield of coconuts and on their copra content are described and the results given. The main damage consisted of reduction in the amount of copra/nut, which varied from about 7% to about 15% reduction. Studies on varietal susceptibility showed that the varieties West Africa Tall and Malayan Yellow Dwarf were both very susceptible to E. guerreronis, whereas the hybrid between them known as Port-Bouet 121 was among several varieties that were more tolerant of mite attack. In control tests, quinomethionate, monocrotophos and cyhexatin at 40-80 g toxicant/hl, applied every 4-9 weeks, gave promising results, but microbiological control appeared likely to present the greatest economic advantage in the future.