CONICET | Buscador de Institutos y Recursos Humanos

The relationship between predator diversity and biological control (BC) may vary as a result of interactions within the community. Cycloneda sanguinea and Eriopis connexa (Coccinellidae) are Neotropical predators common in horticultural landscapes in Argentina. In a previous laboratory study we found that intraguild predation was bidirectional and asymmetric, with E. connexa being the stronger IG predator both in the presence and absence of aphids. Moreover, we found that larvae of both species in the same sweet pepper plant initially preferred the plant upper stratum but then dispersed, suggesting that they would avoid intraguild predation. With this background, to know the effect of this trophic interaction on the BC of aphids in semi-field conditions, we analyzed: 1- the temporal and spatial co-occurrence of both predators, 2- the effect of both predators, together or separately, on the decrease of aphid density, and 3- the density of each predator at the end of the experiment. The results showed that the species co-occurred at temporal scale but not on the same plants. C. sanguinea alone generated a more rapid decline in aphid density and the lowest number of predators at the end of the experiment was recorded in treatments with both species. So, the intraguild predation would not affect the BC of aphids in the short term but in the long term E. connexa could exclude C. sanguinea from the system. Nevertheless, C. sanguinea would be a better competitor for exploitation of the share resource than E. connexa, giving to the IG prey an advantage over the IG predator. This, added to the capacity of dispersion previously observed, would enable the temporary coexistence of both predators. Finally, from the applied point of view, it would be preferred to release C. sanguinea over E. connexa (augmentative BC) and/or to improve the resources of the habitat that enhance the population growth or the maintenance of this species in the crop (conservation BC).