Biology and host specificity of Plectonycha correntina Lacordaire (Chrysomelidae), a candidate for the biological control of Anredera cordifolia (Tenore) Steenis (Basellaceae)

Field surveys conducted in Argentina proved Plectonycha correntina Lacordaire (Coleoptera: Chrysomelidae) to be a promising biocontrol agent against the Neotropical perennial climber, Anredera cordifolia (Tenore) Steenis (Basellaceae), a serious environmental weed in Africa and Australasia. Larvae and adults feed on the leaves. The host range was evaluated by no-choice larval survival tests and adult feeding and oviposition choice tests. Sixteen plant test species were selected from the Basellaceae (4 species), Portulacaceae (4), Crassulaceae (3), Cactaceae (3) and Aizoaceae (2) families. Larval development could only be completed on species of Basellaceae (A. cordifolia, Anredera krapovickasii (Villa) Sperling, Basella alba Linné, Ullucus tuberosus Caldas). The other test plant species sustained larval development for less than 96 hours. In multiple-choice tests involving plant species outside the Basellaceae, both in the presence and in the absence of A. cordifolia, P. correntina showed an almost complete preference for its natural host. Larvae that emerged from the few eggs laid on Talinum paniculatum (Jacquin) Gaertner (Portulacaceae) and Pereskia grandifolia Haworth (Cactaceae) died within 48 hours, without feeding. In the test among the Basellaceae, feeding and oviposition preference of P. correntina for A. cordifolia and B. alba were significantly higher than for A. krapovickasii and U. tuberosus. In multiple-choice and paired-choice feeding and oviposition tests, and in fecundity tests, P. correntina displayed a significantly greater preference for Madeira vine than for B. alba. The results indicate that the host range of P. correntina is restricted to the Basellaceae, with A. cordifolia as its primary host. Consequently, we consider P. correntina a safe and promising biocontrol agent for Madeira vine in countries such as Australia and New Zealand where no other Basellaceae occur.