Cannibalism: Do risks of fighting and reprisal reduce predatory rates?
2017
Fernández Maldonado, Francisco Javier | Gallego Granados, Juan Ramón | Valencia, Alicia | Gámez Cámara, Manuel Angel | Varga, Zoltan | Garay, József | Cabello García, Tomás
Cannibalism is a common phenomenon among insects. It has raised considerable interest both from a theoretical perspective and because of its importance in population dynamics in natural ecosystems. It could also play an important role from an applied perspective, especially when using predatory species in biological control programmes. The present paper aims to study the cannibalistic behaviour of Nabis pseudoferus Remane and the functional response of adult females. In a non-choice experiment, adult females showed clear acceptance of immature conspecifics as prey, with relatively high mortality values (51.89 ± 2.69%). These values were lower than those occurring for heterospecific prey, Spodoptera exigua Hübner, under the same conditions (80.00 ± 2.82%). However, the main result was that the rate of predation on heterospecific prey was reduced to 59.09 ± 7.08% in the presence of conspecific prey. The prey-capture behaviour of adult females differed when they hunted conspecific versus heterospecific prey. This was shown in the average handling time, which was 23.3 ± 3.3 min in the first case (conspecific) versus 16.6 ± 2.5 min in the second (heterospecific). Furthermore, the values increased in the former case and declined in the latter according to the order in which the prey were captured. The difference in handling time was not significant when adjusting the adult female functional response to conspecific nymphs. We argue that these results likely indicate risk aversion and a fear of reprisal among conspecifics.
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