title: Gregarious pupation act as a defensive mechanism against cannibalism and intraguild predation.
abstract: Coccinellid pupae use an array of defensive strategies against their natural enemies. This study aims to assess the efficiency of gregarious pupation as a defensive mechanism against intraguild predators and cannibals in coccinellid. The study was designed specifically (i) to determine the natural occurrence of gregarious pupation in the field for different coccinellid species, and (ii) to evaluate the adaptive value of gregarious pupation as a defensive mechanism against 2 types of predators (i.e., cannibals and intraguild predators). In the field, gregarious pupation consisted of a group of 2-5 pupae. The proportion of gregarious pupation observed varied according to species, the highest rate being observed with Harmonia axyridis Pallas (Coccinellidae; 14.17%). Gregarious pupation had no impact on the probability that intraguild predators and cannibals locate pupae. Intraguild predation occurred more often in site with gregarious pupation, while cannibalism occurred as often in site with gregarious pupation as in site with isolated pupa. However, for a specific pupa, the mortality rate was higher for isolated pupae than for pupae located in a gregarious pupation site both in the presence of intraguild predators and in the presence of cannibals. The spatial location of pupae within the group had no impact on mortality rate. Since it reduces the risk of predation, it is proposed that gregarious pupation act as a defensive mechanism for H. axyridis pupae.
authors: Université du Québec à Montréal, Département des Sciences Biologiques CP 8888, Succ. Centre Ville, Montréal, Canada.
authors: Claudia
authors: C
authors: Roberge
authors: Université du Québec à Montréal, Département des Sciences Biologiques CP 8888, Succ. Centre Ville, Montréal, Canada.
authors: Bruno
authors: B
authors: Fréchette
authors: Centre de recherche sur les grains Inc (CÉROM), 740 chemin Trudeau, St-Mathieu-de-Beloeil, Québec, J3G 0E2, Canada.
authors: Geneviève
authors: G
authors: Labrie
authors: Université du Québec à Montréal, Département des Sciences Biologiques CP 8888, Succ. Centre Ville, Montréal, Canada.
authors: François
authors: F
authors: Dumont
authors: Université du Québec à Montréal, Département des Sciences Biologiques CP 8888, Succ. Centre Ville, Montréal, Canada.
authors: Eric
authors: E
authors: Lucas
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002190:Cannibalism; D001517:Coleoptera / Q000254:growth & development / Q000502:physiology*; D011235:Predatory Behavior; D011679:Pupa; D011792:Quebec; D013045:Species Specificity; D014863:Wasps
keywords: Coccinellidae; Pentatomidae; Selfish herd; attack abatement; dilution effect; encounter effect; grouping behavior