Relative Seasonal Occurrence of Economically Significant Heteropterans (Pentatomidae and Coreidae) on Macadamias in South Africa: Implications for Management

The relative abundance of all heteropterans recovered during this survey was influenced by the phenological development of the host plant (macadamia). Bathycoelia distincta Distant (Hemiptera: Pentatomidae) was the dominant heteropteran and occurred during all four phenological stages of the host plant that were monitored. However, abundance levels of this pest decreased during winter when fewer nuts were available. This decrease was immediately accompanied by a concomitant increase in the relative abundance levels of lesser important heteropterans. B. distincta, Pseudatelus raptorius (Germar) (Hemiptera: Pentatomidae) and Pseudotheraptus wayi Brown (Hemiptera: Coreidae) were the only heteropterans able to reproduce in macadamias which further strengthened the hypothesis of seasonal resource-based competition by the dominant species. All heteropterans recovered from these surveys can be categorised into two major groups namely: a group with a fairly large body size and long mouthparts which is able to reproduce successfully in macadamias and which occur mainly when nuts are available, as well as a group with smaller body size, shorter mouthparts, which cannot reproduce in this crop and which is only abundant when there are no or few nuts available on the trees.