DoesWolbachiainfection affect decision‐making in a parasitic wasp?

Abstract

Various physiological effects of Wolbachia infection have been reported in invertebrates, but the impact of this infection on behavior and the consequences of these behavioral modifications on fitness have rarely been studied. Here, we investigate the effect of Wolbachia infection on the estimation of host nutritive resource quality in a parasitoid wasp. We compare decision-making in uninfected and Wolbachia-infected strains of Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) on patches containing either fresh or old host eggs. For both strains, fresh eggs were better hosts than older eggs, but the difference was smaller for the infected strain than for the uninfected strain. Oviposition behavior of uninfected wasps followed the predictions of optimal foraging theory. They behaved differently toward high-vs. low-quality hosts, with more hosts visited and more ovipositions, fewer high-quality hosts used for feeding or superparasitism, and a sex ratio that was more biased toward females in patches containing high-quality hosts than in patches containing low-quality ones. Uninfected wasps also displayed shorter acceptance and rejection times in high-quality hosts than in hosts of lower quality. In contrast, infected wasps were less efficient in evaluating the nutritive quality of the host (fresh vs. old eggs) and had a reduced ability to discriminate between unparasitized and parasitized hosts. Furthermore, they needed more energy and therefore engaged in host feeding more often. This study highlights possible decision-making manipulation by Wolbachia, and we discuss its consequences for Wolbachia fitness.

Decrease of memory retention in a parasitic wasp: an effect of host manipulation by Wolbachia?

“…However, the memory duration of the infected wasps who were able to learn (i.e., who displayed an orientation towards the conditioned odor), was significantly shortened, regardless of the number of training sessions undergone. As our 2 strains had the same genetic background (Kishani Farahani et al ., ), their difference in memory retention should be attributed first to the Wolbachia infection of the infected strain. This reduced memory duration could result from the manipulation of host behavior by Wolbachia , intended to increase Wolbachia transmission.…”

“…Indeed, Wolbachia can be transmitted via the superparasitism behavior of their hosts by horizontal transmission (i.e., when a female oviposits into a host that has already been parasitized, the contaminated larvae can transmit the Wolbachia to the other larvae present in the host; Huigens et al, 2000Huigens et al, , 2004. A previous study (Kishani Farahani et al, 2015) has shown that infected females display higher superparasitism rates. As infected wasps produce only female offspring, it would lead to lower genetic diversity among this population in comparison to uninfected populations (Stelzer, 2011;Simon et al, 2003).…”

“…The current study was conducted on two naturally infected and uninfected wasp populations. It has been shown that these strains have the same genetic background and thus all observed difference will be due to Wolbachia prevalence (Kishani Farahani et al, 2015). In many comparative studies investigating the effects of Wolbachia between stains, uninfected strains are produced via antibiotic treatment to an infected strain.…”

“…Genetic similarity was performed based on the size of the nuclear ribosomal DNA (nrDNA) internal transcribed spacer 2 (ITS-2) region amplified through PCR. The sequences were aligned and then subjected to a maximum parsimony analysis (with MEGA5 software), with heuristic search and TBR branch-swapping algorithm, in order to phylogenetically assess the identification and common origin of our strains (Kishani Farahani et al, 2015).…”

“…Wolbachia affects several life history traits in some species, either in a way that increases its transmission (Silva et al ., ; Hohmann et al ., ; Zchori‐Fein et al ., ; Panteleev et al ., ) or negatively due to side‐effects of Wolbachia infection (Fialho & Stevens, ; Weeks et al ., ). In the strains studied in this paper, we have shown that Wolbachia infection can impair the decision‐making process during patch exploitation, potentially increasing transmission, but at the expense of a decrease of fitness of the infected individuals (Kishani Farahani et al ., ). Here, we investigated the influence of Wolbachia infection on 3 experience‐dependent behaviors: (i) the ability to learn; (ii) the ability to retain memory; and (iii) the effect of additional experience on memory retention.…”