Influence of substrate on the body-waving behaviour of nematodes

Abstract

The soil-dwelling nematodes Steinernema carpocapsae, S. scapterisci, S. feltiae, S. glaseri, Heterorhabditis bacteriophora, H. megidis, Phasmarhabditis hermaphrodita and Caenorhabditis elegans were placed on agar plates each containing four substrates (peat, sand, sandy loam and leaf litter). The body-waving behaviour of infective juveniles was recorded over a 10-day period in the presence or absence of an insect, Galleria mellonella, a susceptible host of some species. Body-waving behaviour differed amongst species and varied significantly in relation to substrate, time and the presence of G. mellonella. Steinernema carpocapsae showed body-waving behaviour more than other species and this tendency increased significantly with time. More S. carpocapsae were seen body waving on peat and leaf litter than on either sandy loam or sand. Conversely, sand promoted body waving in S. scapterisci. Body waving by C. elegans was more common on peat than on any of the other substrates. Heterorhabditis megidis, not previously known to body wave, did so in low numbers on peat and sandy loam. The remaining four species did not body wave. Previous work has shown that the presence of S. glaseri increases body waving by S. carpocapsae. We investigated whether substrate influenced this interaction and also included S. scapterisci in the study. The presence of S. glaseri significantly altered rates of body waving in S. carpocapsae and S. scapterisci in a way that was substrate-dependent. Our data suggest that body-waving behaviour is determined by substrate quality and differing body-waving behaviours may be a mechanism by which nematodes avoid competition.

Host-finding behaviour in the nematodePristionchus pacificus

“…The slug-parasitic nematode P. hermaphrodita attaches to hosts by crawling and is devoid of nictation, whereas insect parasitic Steinernema spp. attach by nictating [13,16]. Nictation behaviour has been also described in the animal-parasitic nematodes Heligmosomoides polygyros [17] and Strongyloides ratti [18].…”

“…Infective juveniles of some ambusher nematode species show a specific search behaviour in which the animals stand on their tail and wave. This standing behaviour has been termed 'winken' [6], 'nictation' [7][8][9], 'standing' [10 -12] and most recently 'body waving' [13]. For a complete revision about the terminology of this behaviour, see Kruitbos & Wilson [14]; for the sake of simplicity, we refer to this behaviour as nictation.…”

“…In different species of nictating nematodes, juveniles can either stay in an erect pose or wave their bodies in three-dimensional spirals and loops [7,8,15]. In the laboratory, nictation behaviour is only observed when the nematodes are exposed to irregular substrates [13]. Foraging strategies of host finding in nematodes from the order Rhabditida have been extensively studied, e.g.…”

Prospects in the Application Technology and Formulation of Entomopathogenic Nematodes for Biological Control of Insect Pests

“…In the greenhouse, the dispersal of seven EPN species and their efficacy against the black vine weevil O. sulcatus depended on the potting media the nematodes were applied in (Ansari & Butt, 2011). The influence of the environment on the behavior of EPNs has also been suggested in Kruitbos et al (2009). These examples suggest that using the right EPN species in the appropriate milieu can improve its efficacy in controlling a given target pest.…”

“…The foraging behavior possibly influences the ability of a particular nematode to control a specific insect pest; ambushers are likely to infect highly active insects whereas cruisers will be more effective at killing rather sessile insects (Campbell, Lewis, Stock, Nadler, & Kaya, 2003;Gaugler, 1988). However, recent work suggests that EPN foraging behavior not only depends on their taxonomy but also on the substratum into which they are released (Kruitbos, Heritage, Hapca, & Wilson, 2009. Further, laboratory tests are often performed on agar or on homogenized soil matrices, and are therefore only suggestive of EPN efficacy in the field.…”