Studies on the biology, ecology and management of sap sucking bugs of cashew with particular reference to helopeltis schoutedenireuter (hemiptera: miridae) in Ghana

Knowledge of the insect complex associated with any crop is essential for developing control strategies for the crop. Literature on cashew insects in Ghana is scanty and few known pest species include Anoplocnemis curvipes (F) and Helopeltis schoutedeni Reut. Although fruit yield increases may be obtained with the use of » chemical insecticides, complete reliance on them for crop production does not appear to the answer to increased and sustainable production. It was therefore necessary to relop more efficient, sustainable and environmentally acceptable management tegies against important insect pests of the crop in anticipation for extensive ivation country-wide. Field surveys were conducted from July 2003 to October 2005 in 13 major cashew growing areas within 10 districts of the Northern, Upper West, Brong-Ahafo and Eastern Regions of Ghana to collect and identify the insect fauna on hew. Helopeltis schoutedeni Reuter (Hemiptera: Miridae) was selected for detailed "dies on the basis of its prevalence and devastating effect on cashew. Its biology was died in the laboratory at 24.9 0 C to 33 ° C and 72.4% to 88.5% Relative humidity H.). Petri dish laboratory bioassay and field experiments were also conducted to ^ermine the efficacy and persistence of lambda-cyhalothrin, imidacloprid and a cock- of cypermethrin and dimethoate on H. schoutedeni The relationships between O. ginoda and flushing shoots damage by sap sucking bugs, as well as the effectiveness O. longinoda as a bio-control agent in the protection of cashew were investigated. The ijor sap sucking insect species were Helopeltis schoutedeni (Reut.), Anoplocnemis rvipes (F.) and Pseudotheraptus devastans (Dist.). Investigations were also conducted methods by which O. longinoda can be successfully established on cashew trees already inhabited by some competing ant species. A total of 170 insect taxa were collected and 57 were identified to at least the generic level. The life cycle of the most lent pest, H. schoutedeni, from egg to adult emergence lasted 24.0 days. Both the )h and adult fed on the plant by sucking sap from flushing shoots, panicles and fruits they caused serious tree damage in all the localities throughout the year even though population sizes in the localities differed significantly OP=0.05). The H. schoutedeni ations showed a mono-modal distribution that peaked from December to February gradually declined from April to August. The pattern of dispersion of the bug in the tations was clumped (S2IM> 1) throughout the study period. In the laboratory ssay, lambda-cyhalothrin and a cock-tail of cypermethrin and dimethoate were found effective. The persistence tests indicated that, one day after application, both insecticides gave100% kill but only the cock-tail killed more than 95% after seven days. There was a negative correlation between numbers of O. longinoda nest and percentage pest damage flushing shoots. Plots treated with both insecticides recorded the smallest H. /lOHtedera-infested trees followed by O. longinoda-tieated plots. O. longinoda monstrated potency as a natural control agent for most of the insect pests. Of the 210 s that were examined in a 1.5 hectare plantation, 89 (42.4%) were colonized by ant cies. Methods used to overcome antagonism from resident ants are reported. Both bda-cyhalothrin and a cock-tail of cypermethrin and dimethoate may be used to ntrol H. schoutedeni should there be its massive invasion of a cashew farm, but the ~k-tail is a better choice for prophylactic use as it showed longer persistence. .longinoda is as effective as the insecticides in suppressing populations of H. houtedeni, A. curvipes and P. devastans on cashew trees.

Source: KNUST