Superparasitism in gregarious hymenopteran parasitoids: ecological, behavioural and physiological perspectives

Abstract

. Superparasitism in gregarious wasps occurs with the deposition of a clutch of eggs by a female into a host already parasitized by itself or a conspecific female. This review synthesizes and interprets the available results in the literature reported from field studies, and from behavioural and physiological investigations. To study superparasitism at the ecosystem level, methodological issues have to be solved to determine threshold values beyond which multiple offspring can be indisputably classified as originating from superparasitism. This life strategy is then discussed from the parasitoid's perspective, considering time and egg limitation, host discrimination, clutch size, offspring body size and sex ratio, as well as development time and survival rate of offspring, with special emphasis on physiological facilitation and constraints. Then, superparasitism in gregarious species is evaluated from the host's angle, addressing host survivorship and development, host food consumption and growth. Although superparasitism may be beneficial for either the first or the superparasitizing female, depending on the system, it is detrimental for both of them under conditions of extreme superparasitism. Recent methodological and experimental advances encourage further studies on the adaptive host choice under field and laboratory conditions, as well as on mechanisms underlying success of the first or the superparasitizing female and their progeny.

Indirect interaction between butterfly species mediated by a shared pupal parasitoid

“…Adult P. apum are small (1-2 mm). Like other gregarious Pteromalus, a mother will lay multiple eggs in a single host pupa, and multiple females will successfully parasitize a single host (Askew and Shaw 1997;Dorn and Beckage 2007). Consequently, a brood of 1-110 P. apum eclosing from a single host pupa may include both siblings and non-siblings (T.S.…”

Benefits of gregarious feeding by aposematic caterpillars depend on group age structure

“…In these cases, older larvae may harm or outcompete smaller, younger larvae by directly consuming certain host plant parts or by inducing host defences to which the younger larvae have not mounted a response. Asymmetric competition among larvae of different ages is known from parasitoids (Dorn and Beckage 2007) and suggests that repeated oviposition on the same hosts (superparasitism) may represent a 'better-than-nothing' strategy in the face of limited host abundance. Alternatively, older larvae could weaken a host more effectively than young larvae, which may then benefit from feeding in mixed-age groups.…”

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

“…Superparasitism may result in offspring mortality and in the loss of search time and resources invested by the female in egg production and oviposition Godfray, 1994;Dorn & Beckage, 2007). The modalities of larval interactions determining winners and losers in such contests depend on the lifestyle of the species involved, the number and specifi c identity of the superparasitizing female(s) and the sex and age of competing larvae, among other factors (Mackauer, 1990;Brodeur & Boivin, 2004;Harvey et al, 2013).…”