Damage potential of indigenous Heteroptera species occurring on Macadamia nuts (Macadamia integrifoliaMaiden & Betche & Macadamia tetraphylla L. Johnson) in South Africa during the early and late season

Abstract

The assemblage structure of heteropterans affecting macadamia nuts changed considerably during the previous ±30 years, prompting a relook at the economic status of commonly occurring pest species. The five most abundant species were confined in sleeve cages on bearing branches of macadamia trees containing early or late season nuts and feeding damage was subsequently monitored. All species except Coenomorpha nervosa were able to damage nuts during the early season before hardening of the seed coat (shell/testa). During the late season after hardening of the seed coat, Chinavia pallidoconspersa with relative short mouthparts was able to inflict significant damage. This is the second most abundant species on macadamias in South Africa and normally occurs in high numbers during the autumn and winter when most nuts are mature. Mouthpart length appear to be only partially responsible for the ability of heteropterans to feed on the kernels of mature nuts and the possible effect of strong digestive enzymes is discussed. C. pallidoconspersa will require some form of control if sufficient numbers are present in the orchards, especially towards the end of the normal production season.