Differential responses in spider oviposition on crop-edge gradients in agroecosystems with different management

POMPOZZI, GABRIEL; MARRERO, HUGO J.; PANCHUK, JUSTINA; GRAFFIGNA, SOFÍA; HAEDO, JOANA P.; MARTÍNEZ, LUCÍA C.; TORRETTA, JUAN P.

AGRICULTURE, ECOSYSTEMS AND ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021 vol. 322

0167-8809

Semi-naturalhabitats in agricultural landscapes offer reproduction and feeding sites fornatural predators of pests. Spiders are among the most abundant and diversegeneralist predators and can efficiently suppress pest populations inagroecosystems. However, despite the importance of these habitats, there is asignificant gap of knowledge on oviposition sites of spiders in agroecosystems.Our main goal was to investigate if semi-natural habitats play an importantrole in spider oviposition in two crops with different agriculturalmanagements. Our specific objectives were to estimate where spider ovipositionis highest (in semi-natural habitats or in crops); if there are differentresponses between crops (alfalfa and soybeans); and to measure trap-nestsefficiency as shelter and breeding places for vegetation-dwelling spiders. Weused trap-nest technique, a novel method to collect spiders and their eggsacs.We carried out the study in 15 sites in soybean and 10 sites in alfalfa cropsin order to sample spiders? eggsacs and shelters. Each sampled site consistedof a semi-natural habitat (enclosures or edges) and its adjacent crop. We foundthat the number of eggsacs decreased from semi-natural habitats towards theinterior of the soybean crop and the opposite pattern in alfalfa, where thenumber of eggsacs significantlyincreased within the crop. Our results provideevidence that spider reproduction takes place outside the crops, albeit only insoybean crops. Our findings were different in alfalfa with minimum use ofagrochemicals and with a lesser seasonal disturbance, with a higher spideroviposition compared to semi-natural habitats. In addition, our results haveseveral important implications for the management of agroecosystems. Weconsider that the use of these trap-nests is a suitable and a reliable tool tostudy vegetation-dwelling spiders in different ecosystems.