Let the most motivated win: resource value components affect contest outcome in a parasitoid wasp

Juvenile hormone manipulation affects female reproductive status and aggressiveness in a non-social parasitoid wasp

“…1.). Mathiron et al (2018) showed that females with previous oviposition experience on pupae were more motivated to gain access to a 4 th instar larva. Contests occurred between females of the same age (3 days old), marked with different colors and visually matched for size; post-experiment data analysis confirmed that contestants of the same dyad did not differ significantly in body mass (Wilcoxon signed-ranks test: T=147.5, N=25, P=0.7).…”

“…Upon detection of a conspecific (females raised their antennae in the direction of their opponent), females frequently interrupted their behavioral oviposition sequence (Mohamad et al, 2010). They either simply kick their opponent with their legs without taking their ovipositor out of the capsule (defensive behavior) or can escalate to a full attack, in which case one female generally chases her opponent away from the capsule, hits her with her head or mounts her (Mathiron et al, 2018).…”

“…As gaining access to resources brings fitness benefits to individuals, both vertebrate and invertebrate animals commonly exhibit aggressive behaviors during conflicts over such resources (Collias, 1944;Breed and Bell, 1983;Briffa and Hardy, 2013). For example, in parasitoid insects, hosts represent an indivisible resource over which females compete to lay their eggs, and physical interactions between females for host access have been observed in various parasitoid species (Hughes et al, 1994;Petersen and Hardy, 1996;Field and Calbert, 1999;Goubault et al, 2007;Mohamad et al, 2010, Mathiron et al, 2018. In many animal taxa, aggressive conflicts have also been observed between individuals for sexual partners (West-Eberhard, 1979;Schwagmeyer and Woontner, 1985;Simmons, 1986), food (Barton, 1993;Vogel, 2005), territories (Rowland, 1989;Festa-Bianchet et al, 1990), and dominance status (Chase, 1974).…”

“…Females parasitize and feed upon larvae and pupae of Callosobruchus maculatus (Fab) (Coleoptera: Bruchidae), which infest cowpea seeds, Vigna unguiculata (L.) Walp (Fabaceae; Terrasse and Rojas-Rousse, 1986). When several females are simultaneously present on a host patch, they tend to protect the host that they exploit by displaying aggressive behaviors towards conspecific competitors (Mohamad et al, 2010;Mathiron et al, 2018).…”

“…Previous studies have investigated the role of different factors (e.g., egg load, host density and host quality) on aggressiveness and contest outcomes in E. vuilleti (Mohamad et al, 2010(Mohamad et al, , 2012(Mohamad et al, , 2013 5/24 Mathiron et al, 2018), but nothing is known about how hormones modulate aggressiveness during competition for host access.…”