CONICET | Buscador de Institutos y Recursos Humanos

Cannibalism (CANN) and intraguild predation (IGP) may provide critical energy and nutrients to individuals, and eliminate potential competitors. However, these negative competitive interactions that also may affect the coexistence of predatory species. The spatial and temporal co-occurrence of aphidophagous ladybird species in crops creates opportunities for CANN and IGP, especially when aphids become scarce. The Lotka-Volterra model predicts the coexistence of two species if intraspecific competition is stronger than interspecific interference interactions. Cycloneda sanguinea L. and Eriopis connexa (Germar) (Coleoptera: Coccinellidae) coexist in sweet pepper crops in La Plata (Argentina) consuming mainly Myzus persicae (Hemiptera: Aphidae). The present study used laboratory experiments to estimate levels of CANN and IGP by adults and larvae on eggs, and by adults on larvae, in both the presence and absence of prey in an effort to explain the effect of prey on coexistence of these two predators. Levels of CANN by C. sanguinea and E. connexa were high in absence of aphids, and decreased when prey was present. IGP was bidirectional and asymmetric. Adults and larvae of E. connexa were more voracious intraguild predators of C. sanguinea than vice versa, the former being the stronger intraguild predator and interference competitor. E. connexa always won when larvae of the same instar were paired whereas the larger larvae always won when larvae were of different instars, regardless of species. In the presence of prey, CANN by both species decreased, but IGP by E. connexa on C. sanguinea remained high, suggesting that E. connexa could displace C. sanguinea via interspecific interference competition. Other factors potentially affecting the coexistence of C. sanguinea and E. connexa in sweet pepper crops are discussed.