Partners in biological control of cocoa pests: Mutualism between Dolichoderus thoracicus (Hymenoptera: Formicidae) and Cataenococcus hispidus (Hemiptera: Pseudococcidae)

Abstract

The observed mutualistic relationship between the black cocoa ant Dolichoderus thoradcus (Smith) and the mealybug Cntaenococcns hispidus (Morrison) \vas examined. The importance of C. hispidus to D. thoradcus as a food source was investigated by giving D. thoradcus access to C. hispidus only, to C. hispidus and other food sources, and denying access to any obvious food sources. Dolichoderus thorncicus was seen to depend on C. liispidus alone as a source of food over an eight-week period of observation without showing ill effects. The role of D. thoradcus in spreading C. liispidus was studied in an experiment consisting of combinations of D. tliorncictts and C. hispidus exclusion. It was shown that D. thoradcus was responsible for carrying C. hispidus across a 'mealybug excluder'. Data on the frequency and duration of transport of C. hispidus by D. thoradcus were obtained by direct observation for a total of 90 h over 17 days. Both adults and nymphs of C. hispidus were carried by D. thoradcus with its mandibles in a brief and erratic manner, in the general direction of the trail. Such transportation is nevertheless considered to be important in view of the large number of individuals of D. tJioracicus moving along a trail. The close mutualistic relationship between D. thoradcus and C. hispidus reiterates the necessity to manipulate both organisms for control of cocoa pests.