Conservation biological control: Improving the science base

Abstract

Based on the notion that monocultures and highly simplified farmscapes are associated with pest outbreaks (1), there has been an increased focus on “conservation biological control” [also called “ecological engineering” (2)] within the last decades to minimize economic losses to pests (3, 4), and at the same time avoid the use of pesticides. This is expected to be achieved by enhancing natural enemy abundance and functional efficiency through the designing of areas surrounding crops to provide alternative food sources (e.g., pollen, nectar, or prey) or escapes from agricultural disturbances (refugia) (2, 5). Now, in a metaanalysis on the role of surrounding vegetation on crop pests and their natural enemies, Karp et al. (6) come to the conclusion that there is no such general rule when the data are examined globally, across crops, landscapes, and biogeographical areas. Thus, on the surface, the conclusion questions what is assumed to be one of the core beliefs of many people working in the area of agroecology, especially those who regard agroecology rather as a philosophy than as a research field (7). Karp et al. (6) have compiled a pest-control database of over 130 studies, encompassing more than 6,700 sites worldwide to “model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition.” While this database, made publicly available, is already a huge achievement in itself, it remains to be seen whether further inputs can significantly contribute to the intended purpose, “to answer critical questions about the ecology of pest control,” or whether its value will be mostly found in other ways, such as providing the beginnings of a global “taxonomy” of farmscapes through the lens of pest-control literature. Many of us who have done research on the effects of landscapes on pest management do not … [↵][1]1To whom correspondence should be addressed. Email: josef.settele{at}ufz.de. [1]: #xref-corresp-1-1