SignificanceDecades of research have fostered the now-prevalent assumption that noncrop habitat facilitates better pest suppression by providing shelter and food resources to the predators and parasitoids of crop pests. Based on our analysis of the largest pest-control database of its kind, noncrop habitat surrounding farm fields does affect multiple dimensions of pest control, but the actual responses of pests and enemies are highly variable across geographies and cropping systems. Because noncrop habitat often does not enhance biological control, more information about local farming contexts is needed before habitat conservation can be recommended as a viable pest-suppression strategy. Consequently, when pest control does not benefit from noncrop vegetation, farms will need to be carefully comanaged for competing conservation and production objectives.

No abstract

No abstract

No abstract

The movement between alfalfa and maize of three of the most common aphidophagous coccinellids in southern Europe was determined using carbon and nitrogen stable isotope analysis at four periods during the growing season. The isotope analysis revealed movement between alfalfa and maize but patterns were different between the three species. While Coccinella septempunctata L. (Coleoptera: Coccinellidae) only moved from alfalfa to maize, Propylea quatuordecimpunctata L. (Coleoptera: Coccinellidae) continuously dispersed between the two adjacent crops. Hippodamia variegata Goeze (Coleoptera: Coccinellidae) showed an intermediate pattern. Results suggest that, while alfalfa acts as a source of the three species to maize, maize also plays a role as a source of P. quatuordecimpunctata and H. variegata to alfalfa. The specific movement traits that emerged for the three coccinellid species suggest that crop management affects them differently and point out that the association between crops is very valuable for improving coccinellid biological control services.

No abstract

The combined effect of the temperature and relative humidity on the survival and development time of the eggs of Spanish populations of the weevil Hypera postica, a key pest of alfalfa around the world, was evaluated under laboratory conditions. The experimental temperatures ranged from 8 to 36 °C, in 4 °C increments. Three relative humidity ranges were defined: high, medium, and low. Eggs of the alfalfa weevil successfully developed until larval emergence at all of the 24 conditions tested. However, the temperature and relative humidity affected the survival of the eggs. The egg developmental time decreased as the temperature increased from 8 to 32 °C, and the longest time was recorded at a low relative humidity (RH). The relationship between the development rate and temperature fit well to the lineal model for relative humidity. The minimum development threshold (T0) and the thermal requirement for egg development (K) ranged between 3 and 4 °C and 209 and 246 degree-days, respectively. According to these values and the occurrence of eggs and larvae (in winter) and adults (in autumn) in field samplings, the period of oviposition was determined. The results of the study contribute to better understanding the annual cycle and phenology of H. postica in the Iberian Peninsula and southern Europe.

No abstract