Tracing the distribution of natural enemies of non-native invasive eucalypt insect pests in sub-Saharan Africa

Abstract

Eucalypt forestry in sub-Saharan Africa is challenged by non-native eucalypt-feeding insects. In recent studies, six invasive eucalypt insect pests, namely Blastopsylla occidentalis, Glycaspis brimblecombei, Gonipterus sp.n.2, Leptocybe invasa, Thaumastocoris peregrinus and Ophelimus maskelli were confirmed present in sub-Saharan Africa. We investigated the diversity and distribution of natural enemies of these pests in six countries in the region. Plant parts (leaves, petioles and stem) infested with the insect pests were sampled from multiple sites in each country. The emerged natural enemies were identified using morphological characteristics and DNA sequence data. Nine species of natural enemies were confirmed present in the surveyed countries, namely Anaphes nitens, Closterocerus chamaeleon, Megastigmus sp., M. pretorianensis, Psyllaephagus blastopsyllae, P. bliteus, Quadrastichus mendeli, Selitrichodes kryceri and S. neseri. No natural enemies were found in Ghana and Sierra Leone despite the presence of L. invasa in both of those countries. Interestingly, most of these natural enemies were unintentionally introduced into the surveyed countries. Results of this study showed that both insect pests and natural enemies introduced into one country are likely to affect many other countries in the region. These findings call for a more coordinated approach to the management of plantation pests in the region.