O'Callaghan, Kathryn M. and Zenner, Annemie N.R.L. and Hartley, Cathryn J. and Griffin, Christine (2014) Interference competition in entomopathogenic nematodes: male Steinernema kill members of their own and other species. International Journal for Parasitology, 44 (13). pp. 1009-1017. ISSN 0020-7519

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Abstract

There is evidence of competition within and between helminth species, but the mechanisms involved are not well described. In interference competition, organisms prevent each other from using the contested resource through direct negative interactions, either chemical or physical. Steinernema spp. are entomopathogenic nematodes; they enter a living insect host which they kill and consume with the aid of symbiotic bacteria. Several studies have demonstrated intra- and interspecific competition in Steinernema, mediated by a scramble for resources and by incompatibility of the bacterial symbiont. Here we describe a mechanism by which male Steinernema may compete directly for resources, both food (host) and females, by physically injuring or killing members of another species as well as males of their own species. A series of experiments was conducted in hanging drops of insect haemolymph. Males of each of four species (Steinernema longicaudum, Steinernema carpocapsae, Steinernema kraussei and Steinernema feltiae), representing three of the five phylogenetic clades of the genus, killed each other. Within 48 h, up to 86% of pairs included at least one dead male, compared with negligible mortality in single male controls. There was evidence of intraspecific difference: one strain of S. feltiae (4CFMO) killed while another (UK76) did not. Males also killed both females and males of other Steinernema spp. There was evidence of a hierarchy of killing, with highest mortality due to S. longicaudum followed by S. carpocapsae, S. kraussei and S. feltiae. Wax moth larvae were co-infected with members of two Steinernema spp. to confirm that killing also takes place in the natural environment of an insect cadaver. When insects were co-infected with one infective juvenile of each species, S. longicaudum males killed both S. feltiae UK76 and Steinernema hermaphroditum. Wax moths co-infected with larger, equal numbers of S. longicaudum and S. feltiae UK76 produced mainly S. longicaudum progeny, as expected based on hanging drop experiments.

Item Type:	Article
Additional Information:	The definitive published version of this article is available at doi:10.1016/j.ijpara.2014.07.004
Keywords:	Resource competition; Interspecific competition; Intraspecific competition; Contest behaviour; Lethal combat; Male–male fighting;
Academic Unit:	Faculty of Science and Engineering > Biology
Item ID:	6821
Identification Number:	https://doi.org/10.1016/j.ijpara.2014.07.004
Depositing User:	Dr. Christine Griffin
Date Deposited:	18 Jan 2016 15:15
Journal or Publication Title:	International Journal for Parasitology
Publisher:	Elsevier
Refereed:	Yes
Funders:	Science Foundation Ireland (SFI), Higher Education Authority (HEA), European Regional Development Fund (ERDF)
URI:	http://www.sciencedirect.com/
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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