Cannibalism: Do risks of fighting and reprisal reduce predatory rates?

Abstract

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.

Opportunistic random searcher versus intentional search image user

“…Although Nabis exhibits more complex behaviour than our theoretical model, we found that the cannibalistic Nabis uses a search image but not with absolute intention because it can also encounter non-desired prey types; however, the its encounter sequence is not determined by the preys’ densities, i.e., Nabis encounters its preferred prey with a higher probability than its potential conspecific prey. This finding corroborates results on the subject that have been published elsewhere 29 .…”

“…pseudoferus exhibit a type II functional response. In general, other Nabis species also present type II responses in their nymph and adult stages 29 . On the other hand, cannibalism in N .…”

“…On the other hand, cannibalism in N . pseudoferus has also been documented and is an aspect of great importance in the biology of this species 29 because N . pseudoferus is also used as a biological pest control agent of lepidopterans in greenhouses crops 30 , 31 .…”

Do Development and Diet Determine the Degree of Cannibalism in Insects? To Eat or Not to Eat Conspecifics

“…Such behavior in predatory Nabis species was observed when they were attacking larger, phytophagous species (e.g., Spodoptera exigua (Hübner), Lep. : Noctuidae) [103].…”

Technical review on derivation methods for behavior dependent functional responses

“…Moreover, Aljetlawi et al (2004) derived a functional response function that accounted for both predator and prey size. Furthermore, Cabello et al (2007) introduced new expressions for Holling type III in terms of a new parameter called entomophagous potential (of a parasitoid or predator), which is important from the view point of biological pest control (e.g., Fernandez-Maldonado et al 2017).…”