Host size, superparasitism and sex ratio in mass-reared Diachasmimorpha longicaudata, a fruit fly parasitoid

Abstract

We analyzed the relationship among host size, superparasitism and sex-ratio in mass reared Diachasmimorpha longicaudata (Hymenoptera: Braconidae). Individual host pupae of Anastrepha ludens (Diptera: Tephritidae) were measured (length and width), and the number of oviposition scars per pupa was used as a reliable indicator of superparasitism. The probability of an emerging parasitoid being a female was positively associated with the number of oviposition scars on the host cuticle, but not with the host size. The number of scars per host pupae from which females emerged was slightly but significantly higher than in those pupae giving raise to males. In D. longicaudata, the influence of host size on sex allocation decisions of individual females seems to be overridden by the level of superparasitism, which itself was positively correlated with pupa length. This suggests that larger pupae could experience a higher number of ovipositions than their smaller counterparts, and that a high level of superparasitism may conduct to a female biased sex ratio. We discuss the relevance of these findings which could provide new elements (e.g., the manipulation of superparasitism) for optimizing the mass rearing of this parasitoid.

Females of the parasitoid wasp, Dendrocerus carpenteri (Hymenoptera: Megaspilidae), adjust offspring sex allocation when competing for hosts

“…Mated females allocate offspring sex according to host size, depositing fertilized eggs on the larger fi fth-instar nymphs and unfertilized eggs on the smaller third-and fourth-instar nymphs; however, after encountering a conspecifi c, females increasingly laid fertilized eggs resulting in both self-and conspecifi c superparasitism (Ito & Yamada, 2016). Montoya et al (2011) and DiazFleischer et al (2015) observed an increasingly femalebiased sex ratio with higher levels of superparasitism in mass-reared Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) attacking fruit fl y larvae, a result confi rmed by fi eld collections of infested mango fruits (Montoya et al, 2013). In contrast, in many gregarious parasitoids, superparasitizing females produce a relatively more male-biased sex ratio as predicted by models of local mate competition (Wylie, 1965;Suzuki & Iwasa, 1980;Suzuki et al, 1984;Godfray, 1994;West, 2009).…”

Density of Diachasmimorpha longicaudata (Ashmead) and host Ceratitis capitata (Wied) larvae for the increase of parasitoid female production

“…Superparasitism is a specialty of parasitoid females in which an egg is deposited in a host that is already parasitized by another co-specific or by themselves (i.e., self superparasitism) (VAN ALPHEN; VISSER, 1990). Superparasitism might explain the greater emergence of females and the high parasitism rates obtained in ratios of 1:1 (larvae/ females) in the present study, since superparasitism is correlated to the highest ratio of females in the progeny of D. longicaudata (ALVARENGA et al, 2016;GONZÁLEZ et al, 2010;MONTOYA et al, 2011MONTOYA et al, , 2012. In the past, superparasitism was considered to be a female error, attributed to the failure to discriminate an already parasitized host.…”

“…Thus, the main objective of the mass production of this parasitoid is higher female production, since the higher the number of females produced, the more efficient and cheap will be their production, and the more accessible will be their use in biological control programs (OLIVEIRA et al, 2014). Thus, knowledge of the factors that maximize female progeny production is essential for the success of the parasitoids rearing aimed at augmentative releases (MONTOYA et al, 2011).…”

“…Variations in the number of females and males in D. longicaudata offspring occur due to the size of the host (also referred to as the quality of the host) (OLIVEIRA et al, 2014), the occurrence of superparasitism (MONTOYA et al, 2011(MONTOYA et al, , 2012, the competition among females (ALVARENGA et al, 2016), and the host density and availability (DIAZ-FLEISCHER et al, 2015). D. longicaudata females tend to increase their parasitism activity when the space is divided with co-specific females, which can lead to superparasitism (ALVARENGA et al, 2016).…”

Padrão de dispersão espacial e temporal de Diachasmimorpha longicaudata (Hymenoptera: Braconidae) criado em larvas de Ceratitis capitata e Anastrepha fraterculus (Diptera: Tephritidae)

“…Alvarenga et al (2015) (MONTOYA et al,2011(MONTOYA et al, , 2012. No trabalho realizado por Sá (2015) (CAMARGOS, 2010).…”