Does Wolbachia infection affect Trichogramma atopovirilia behaviour?

Abstract

Unisexual Trichogramma forms have attracted much attention due to their potential advantages as biocontrol agents. Fitness studies have been performed and understanding the cost that Wolbachia may inflict on their hosts will help in deciding if Wolbachia infected (unisexual) forms are indeed better than sexual forms when used in biological control programmes. The influence of Wolbachia on the foraging behaviour (including walking activity and speed) of T. atopovirilia is reported in this paper. Temperature strongly affected T. atopovirilia female walking activity, but Wolbachia infected and uninfected females differed in none of the behavioural components that were measured such as walking activity and walking speed. Walking activity was highest at 25 °C and differed significantly from that at 20 and 15 °C. Trichogramma wasps were highly affected at 15 °C. Behaviour analysis with females showed that female wasps spend most of the time on drilling + ovipositing on host eggs followed by host drumming and walking while drumming. The parasitism rate and number of offspring did not differ significantly between infected and cured Trichogramma females. Biological control implications of these findings are discussed.Keywords: Hymenoptera, Parasitoid, thelytoky, alpha-Proteobacteria, foraging behaviour. A infecção por Wolbachia afeta o comportamento de Trichogramma atopovirilia? ResumoFormas unissexuais de Trichogramma têm despertado a atenção de pesquisadores devido as potenciais vantagens deste parasitóide como agente de controle biológico. O estudo do "Fitness" tem sido avaliado e entender o custo de ser infectado por Wolbachia ajudará em determinar se formas infectadas por Wolbachia (unisexuais) são realmente melhores que as sexuadas quando utilizadas em programas de controle biológico. A influência de Wolbachia no comportamento de procura (incluindo a atividade e a velocidade de caminhamento) de T. atopovirilia é relatada neste artigo. A temperatura afetou grandemente a atividade de caminhamento de fêmeas de T. atopovirilia, entretanto os componentes de comportamento tais como a atividade e a velocidade de caminhamento não diferiram em relação às fêmeas infectadas e não infectadas. A atividade de caminhamento foi maior a 25 °C e diferiu significativamente de 20 e 15 °C. Fêmeas de Trichogramma foram altamente afetados a 15 °C. Em função da análise do comportamento com fêmeas, pode-se verificar que houve maior tempo gasto no processo de oviposição, seguido pelo toque com as antenas sobre os ovos dos hospedeiros e do caminhamento ao mesmo tempo que toca os ovos com as antenas. A taxa de parasitismo e o número de descendentes não diferiram significativamente entre fêmeas de Trichogramma infectadas e curadas da infecção por Wolbachia. As implicações dos resultados obtidos sobre o controle biológico são discutidas.Palavras-chave: Hymenoptera, Parasitóide, telitoquia, alpha-Proteobacteria, comportamento de procura.

Does Wolbachia infection affect decision‐making in a parasitic wasp?

“…Farrokhi et al (2010) reported that Wolbachia-infected Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) females had a longer host-handling time than females of the uninfected strain. In contrast, according to Almeida et al (2010), Wolbachia-infected and uninfected females of Trichogramma atopovirilia Oatman & Platner did not differ with regard to walking activity or walking speed. In conclusion, Wolbachia infection can have variable effects on host fitness.…”

“…In contrast, according to Almeida et al. (), Wolbachia ‐infected and uninfected females of Trichogramma atopovirilia Oatman & Platner did not differ with regard to walking activity or walking speed. In conclusion, Wolbachia infection can have variable effects on host fitness.…”

“…For example, Almeida et al. () reported that the parasitism rate and the number of offspring did not differ significantly between infected and cured T. atopovirilia females. Other studies have found that uninfected strains performed better for some life‐history traits but not for all; generally, there was no evaluation of the resulting fitness.…”

Phylogeny of the Trichogramma endosymbiont Wolbachia, an alpha-proteobacteria (Rickettsiae)

“…Cytoplasmic incompatibility results in aborted karyogamy (O'Neill and Karr, 1990) and occurs when infected males are crossed with females that are either uninfected (unidirectional incompatibility) (Hoffmann et al, 1986) or infected with another bacterial variant (bidirectional incompatibility); (2) feminization in isopods where genetic males are converted into functional females (Martin et al, 1994;Rousset et al, 1992); (3) the induction of complete parthenogenesis in some haplodiploid species (Almeida and Stouthamer, 2015;Almeida et al, 2010;Stouthamer et al, 1990Stouthamer et al, , 1993. Parthenogenesis-inducing Wolbachia bacteria allow infected female to produce offspring from unfertilized eggs due to a first mitotic division modification (Stouthamer and Kazmer, 1994) and the genetic basis for the loss of female sexual function could be explained by a dominant nuclear effect (Russell and Stouthamer, 2011); (4) fecundity increase of the host for the egg parasitoid Trichogramma bourarachae (Pintureau and Babault, 1980;Vavre et al, 1999b) and (5) male-killing in a wide range of insects.…”

ITS-2 sequences-based identification of Trichogramma species in South America

“…In addition females can also be identified which is not possible in the morphologically based system. Species found in South America are thelytokous, either because of infection with parthenogenesis inducing Wolbachia (T. pretiosum and T. atopovirilia) (Grenier et al, 1998;Almeida et al, 2001Almeida et al, , 2010Ciociola Junior et al, 2001a) or because of some nuclear genetic factor (T. cacoeciae Marchal) (Stouthamer et al, 1990;Almeida and Stouthamer, 2003). Variation of ITS2 sequence within Trichogramma species is relatively small in comparison to the difference found between species and all morphologically distinct cryptic species are also distinguished by sequence differences .…”