Behavioural plasticity induced by intraspecific competition in host orientation in a parasitoid

Abstract

1. Accurate measurement of external conditions is fundamental for survival. For parasitoids, in particular, sensing the environmental conditions is key because they are short-lived animals that must acquire information shortly after emergence.2. This study investigated whether conspecifics during larval growth can influence and modify the decision to orient to different quality hosts in a parasitoid with an active host-seeking larva. How the density of conspecifics during growth modifies these decisions was also studied.3. When larvae were submitted to increases in the intensity of pre-parasitism competition and then offered different host odours, they increased the orientation to poor-quality hosts likewise. It was also found that this behaviour is general to orientation to hosts in different physiological states.4. These results show that pre-parasitism competition can influence and modulate orientation to poor-quality hosts when high-quality hosts are not available.

Compensatory mechanisms during development contribute to overcome intraspecific competition in a dipteran solitary ectoparasitoid with larval active host seeking behaviour

“…This characteristic of the system implies that early born parasitoid larvae are already in the soil waiting for their hosts to become available. The first hosts available are second instar hosts that, although not optimal, are likewise parasitised when conspecific larvae are abundant in the soil also searching for hosts (Crespo et al, 2015;Martínez et al, 2017). However, in February, the field scenario is somewhat different.…”

“…Previous studies have shown that M. ruficauda larvae have the ability to discriminate different characteristics of the host like species, instar, between parasitised, and unparasitised hosts and it has been determined that larvae are repelled from stressed hosts (Crespo & Castelo, 2009;Crespo et al, 2015). Although the third instar is the preferred instar, the presence of conspecific larvae (competitors) in the ground modulates this selectivity inducing orientation to second instar and parasitised hosts in a dense-dependent way (Castelo & Capurro, 2000;Castelo & Corley, 2010;Crespo et al, 2015;Martínez et al, 2017).…”

Habitats and parasitoid abundance influence spatial density dependence patterns, rendering an asilid fly as a potential biological controller of white grubs

“…In order to find its host, M. ruficauda larva orientates to its host through the detection of cues produced in the host's posterior intestine (Castelo and Lazzari, 2004;Crespo and Castelo, 2008;Groba and Castelo, 2012). Larvae of M. ruficauda can discriminate among hosts from different instars, parasitism status, and species (Crespo and Castelo, 2008;Crespo et al, 2015;Martıńez et al, 2017). Given the split strategy in this system involved in the host location, the second instar larva can be claimed to be the ecological equivalent of females in hymenopteran parasitoids.…”

Behavioural Response in an Asilid Fly: Influence of Ecological and Environmental Factors on Spatial Density Dependence

“…In order to nd its host, M. ru cauda larva orientates to its host through detection of cues produced in the host's posterior intestine (Castelo and Lazzari 2004, Crespo and Castelo 2008, Groba and Castelo 2012. Larvae of M. ru cauda can discriminate hosts from different instars, parasitism status and species (Crespo and Castelo 2008, Crespo et al 2015, Martínez et al 2017. Given the split strategy in this system involved in host location, second instar larva can be claimed to be the ecological equivalents of female in hymenopteran parasitoids.…”