Insect succession on three coffee typs in Ghana

Abstract

The experiment was conducted for a 7-year period (198188) at Tafo, Ghana on three newly-established coffee plots of a local variety (Coffea canephora) and two introduced vari~ties (c. canephora and C. arabica). Insect counts were made weekly on 50 randomly selected plants of each coffee variety. Among the insects recorded during the 1st year of establishment were three economically important pests viz. the defoliators (Epicampoptera strandi glauca Hamps., E. ivoirensis Watson), the grasshopper (Zonocerus variegatus Linnaeus) and the leaf skeletonizer (Leucoplema dohertyi Warren). Three other economically-important pests, the stem borer (Bixadus sie';ricolaWhite), the twig borer (Xylosandrus compactus Eichh.) and the berry borers (Hypothenemus hampei Ferrari) were not found throughout the 7-year experimental period. The biting ants (Oe{:ophylla longinoda Latr., Crematogaster africana Mayr and C. clariventris Mayr) which constitute a great nuisance during harvesting, weeding and other farm operations, were not found until the 6th year after establishment. The ants (G. olivieri. P. megacephala and C. vividus), the mealybug (Planococcoides njalensis (Laign» and Stictococcidae were the most numerous insects recorded on all three coffee types, especially during the 4th and 5th years of establishment. Aphids, psyllids, crickets, spiders, grasshoppers, among other insects, reduced in numbers or were absent during a severe and prolonged drought period in 1983-84. It was concluded that findings from the study could serve as a useful guidance to coffee farmers in Ghana, and perhaps other producer countries in the West African ,sub-region, regarding which insect pests to expd:t during the early years of establishment.