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

Francisco J Fernandez,Tomas Cabello,Manuel Gamez,Jozsef Garay

doi:10.3390/insects11040242

Francisco J Fernandez, Tomas Cabello + Show 2 more

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https://doi.org/10.3390/insects11040242

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Journal: Insects	Publication Date: Apr 14, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: Eötvös Loránd University

Abstract

Cannibalism in insects plays an important role in ecological relationships. Nonetheless, it has not been studied as extensively as in other arthropods groups (e.g., Arachnida). From a theoretical point of view, cannibalism has an impact on the development of more realistic stage-structure mathematical models. Additionally, it has a practical application for biological pest control, both in mass-rearing and out in the field through inoculative releases. In this paper, the cannibalistic behavior of two species of predatory bugs was studied under laboratory conditions—one of them a generalist predator (strictly carnivorous), Nabis pseudoferus, and the other a true omnivore (zoophytophagous), Nesidiocoris tenuis—and compared with the intraguild predation (IGP) behavior. The results showed that cannibalism in N. pseudoferus was prevalent in all the developmental stages studied, whereas in N. tenuis, cannibalism was rarely observed, and it was restricted mainly to the first three nymphal stages. Cannibalism and intraguild predation had no linear relationship with the different cannibal–prey size ratios, as evaluated by the mortality rates and survival times, although there were variations in cannibalism between stages, especially for N. pseudoferus. The mathematical model’s implications are presented and discussed.

Highlights

IntroductionOmnivores can be classified according to their diet or their role in ecological food webs [1]
Omnivores can be classified according to their diet or their role in ecological food webs [1].Omnivory may be opportunistic, obligatory or facultative, based on the relative importance of plant and prey materials in the insect’s diet
The size of N. pseudoferus, especially the length, increased from 1.84 ± 0.04 mm for the first instars to 7.11 ± 0.06 mm in adult females, while in N. tenuis, it increased from 0.96 ± 0.03 mm to 3.12 ± 0.02 mm (Figure 1)

Summary

Introduction

Omnivores can be classified according to their diet or their role in ecological food webs [1]. Obligatory or facultative, based on the relative importance of plant and prey materials in the insect’s diet. According to their ecological role in food webs, an omnivore that feeds on more than one trophic level is commonly termed a “trophic omnivore” [1]. Intraguild predation is an example of trophic omnivory in which a predator consumes other predators with whom it shares a common herbivore prey [1,2]. “True omnivory”, is a particular case of trophic omnivory in which the consumer feeds on both plants and prey [1]. According to Hurd [3], generalist arthropod predators are typically bitrophic: they simultaneously occupy the third and fourth trophic levels by virtue of feeding both on herbivores and each other, i.e., they engage in intraguild predation (IGP)

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