Higher establishment success in specialized parasitoids: support for the existence of trade-offs in the evolution of specialization

Most animals do not feed on all the resources available to them, but the mechanisms behind the evolution of dietary specialization are still debated. A central but unanswered question is whether specialists generally gain fitness advantages on their resource compared to generalists, experiencing a trade-off between the ability to use a broad range of resources and the fitness reached on each single one.Empirical tests so far suffered from difficulties in measuring fitness; they were restricted to few species, and results were equivocal. This lack of support for the importance of trade-offs gave rise to theories explaining the evolution of specialization without such trade-offs.Using a large dataset of intentional biological control introductions of 254 species of parasitoids from 15 families to locations outside their native range, we show that establishment success, a measure of total fitness, is higher in specialized species. This result holds when controlling for possible confounding factors such as the number of introduced individuals (propagule pressure).The outcome of this study provides robust evidence that dietary specialization implies fitness advantages in an entire species-rich taxon, indicating that trade-offs might be widely involved in the evolution of specialization

Biological control of Opisina arenosella Walker (Lepidoptera oecophoridae)

"First published in Biocontrol news and information, v. 8, no. 4, 1987

The uptake of biological control in Latin America and the Caribbean.

Biological control started to be used in the 1880s in Latin America and the Caribbean and has since developed into a widely applied pest management method. Currently almost 32 million hectares are under classical, more than 31 million hectares under augmentative and hundreds of thousands of hectares under conservation biocontrol. Achievements in this region have been impressive and are documented in this chapter. Several factors frustrate the implementation of biocontrol on an even larger area. The most important are the dominance of the pesticide industry, the negative effect of pesticides on biological and natural pest control, governmental 'subsidies' to keep chemical control cheap, the lack of funding for research and implementation of biocontrol, and an expensive, time-consuming regulatory framework. However, inherent positive characteristics of biocontrol contribute to sustainable pest management, a healthier and biodiverse environment, pesticide-free food and improved yields. These characteristics, together with the large-scale natural enemy prospecting programmes, the documentation of the many cases of natural control and the successful regional collaboration on area-wide control of new invasive pests, point at a bright future for biocontrol in Latin America and the Caribbe