Interactions between aphid species and beneficial organisms in sweet pepper protected crop.
The interactions between different aphid species and beneficial organisms have been studied in the west region of Portugal, on sweet pepper protected crops. Assays were carried out during the years of 1998, 2002, 2003 and 2004. Aphid species and natural enemies were weekly collected, quantified and identified in laboratory. The aphid species that reached economic thresholds were Aphis craccivora Koch, Aphis gossypii Glover and Myzus persicae (Sulzer). Aulacorthum solani (Kaltenbach) and Macrosiphum euphorbiae (Thomas) were also observed. Indigenous predator activity by anthocorids, cecidomyiids, coccinelids, chrysopids, spiders, syrphids and some parasitoids, contributed to the control of aphid populations. However, in sweet pepper protected crops, aphid populations can reach high levels and the activity of natural enemies may be insufficient to control them. Introduction of beneficial enemies are mostly necessary. A biological control programme was implemented and adapted to the conditions observed during the assays. Therefore, to control A. craccivora and A. gossypii populations, whose reproductive rate is very high in protected pepper crops, the introductions of predators, namely coccinelids, should be considered due to its efficacy in controlling these aphid species. M. persicae populations can be controlled with parasitoid releases when the first colonies are observed. In this study the predator Coccinella septempunctata L. and the parasitoid Aphidius colemani Viereck were used.