Confirmation of the existence of alloparasitoids in nature – host relationships of an Australian Coccophagus species that parasitizes mealy bugs

Abstract

Heteronomous hyperparasitoids are parasitic wasps with sex-related host relationships that are unique to a group of genera in the chalcidoid family Aphelinidae. Females are primary parasitoids of various sedentary bugs (mainly, scale insects, mealy bugs, and whiteflies). Males, in contrast, are hyperparasitic, and they frequently develop at the expense of female conspecifics. Alloparasitoids constitute a special category of heteronomous hyperparasitoids, for their males never develop through female conspecifics. The existence of alloparasitic host relationships and the utility of the category 'alloparasitoid' have both been questioned. Here, we present results that confirm the existence of the alloparasitic way of life among heteronomous aphelinids. We investigated an undescribed species of Coccophagus (Hymenoptera: Aphelinidae), an Australian parasitoid that attacks the introduced lantana mealy bug, Phenacoccus parvus Morrison (Homoptera: Pseudococcidae), in Queensland. A year-long field survey regularly returned large numbers of female Coccophagus spec. near gurneyi individuals from P. parvus (total n = 4212), but only few males (n = 11). Males emerged from samples only when the encyrtid parasitoid Anagyrus diversicornis (Howard) (Hymenoptera: Encyrtidae) was present in samples in relatively high numbers. Laboratory oviposition tests confirmed that A. diversicornis is a male host and showed that males do not develop at the expense of conspecific females. Other studies show that males are attracted in numbers to virgin females held in cages above mealy bug-infested Lantana montevidensis (Spreng.) Briq. (Verbenaceae) in the field, demonstrating that they are common in the population as a whole. This confirms that the males need hosts other than conspecific females and that their usual hosts are present outside of the lantana/ P. parvus system. The implications of these results for developing a realistic classification of heteronomous host relationships are discussed.

Ecological disjunction across the sexes in an alloparasitoid: Host requirements, sex ratios and mate localization (Hymenoptera: Aphelinidae)

“…nr gurneyi females, but not males. Males did not develop through P. parvus because they cannot develop autoparasitically, and parasitoids that can sustain male development were present only sporadically in P. parvus during the study (Walter & Abeeluck ). Coccophagus sp.…”

“…A few species have males that, although hyperparasitic, never develop at the expense of their conspecific females. Such species are called alloparasitoids (Walter ; Walter & Abeeluck ).…”

“…When only Coccophagus males are reared from a host species (some not even the Coccidae with which the females are inevitably associated) (e.g. Walter & Abeeluck ; Schroer et al . ; Zhou et al .…”

“…Briq.) (Walter & Abeeluck ). Males of the undescribed Coccophagus were seldom found in such samples, and overall adult sex ratios at emergence, at 0.3% males ( n = 4,212), are more biased (perhaps along with some of the species reported by Zhou et al .…”

The effect of obligate hyperparasitoids on biological control: Differential vulnerability of primary parasitoids to hyperparasitism can mitigate trophic cascades

“…Four types of hyperparasitoids are described (Sullivan and Völkl, 1999;Walter and Abeeluck, 2006); but only two types (i.e., facultative and obligate) are found where Lepidoptera are plant pests (Sullivan and Völkl, 1999), which is a focus of this study. Facultative hyperparasitism is a form of omnivory, where a parasitoid feeds on two trophic levels by acting both as a primary parasitoid and a hyperparasitoid (Brodeur, 2000).…”