‘Divergent male ontogenies’ in Aphelinidae (Hymenoptera: Chalcidoidea): a simplified classification and a suggested evolutionary sequence

Walter, G. H.

doi:10.1111/j.1095-8312.1983.tb00777.x

Cited by 93 publications

(76 citation statements)

References 70 publications

(111 reference statements)

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“…Male larvae develop in early-to lateinstar conspeci®c female larvae. Oviposition is relatively rapid, and requires about 10 s. Parasitism of brown soft scale by C. semicircularis is impaired by honeydew-collecting ants, but to a lesser degree than in M. stanleyi (CendanÄ a 1937;Bartlett 1961;Annecke 1964;Jarraya 1975;Walter 1983a; personal observations).…”

Section: Natural Historiesmentioning

confidence: 99%

“…We also obtained sex ratio data for Coccophagus semicircularis (FoÈ rster) (Hymenoptera: Aphelinidae), an obligate autoparasitoid (Walter 1983a) frequently recovered from brown soft scale in our ®eld study. In obligate autoparasitoids, females develop as primary parasitoids, whereas males develop as secondary parasitoids of conspeci®c females (Walter 1983a).…”

Section: Introductionmentioning

confidence: 99%

“…In obligate autoparasitoids, females develop as primary parasitoids, whereas males develop as secondary parasitoids of conspeci®c females (Walter 1983a). Theories of sex allocation in autoparasitoids have provided several predictions concerning sex ratio variability and bias (Colgan and Taylor 1981;Godfray and Waage 1990;Godfray and Hunter 1992;Hunter and Godfray 1995).…”

Section: Introductionmentioning

confidence: 99%

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Sex ratios in field populations of two parasitoids (Hymenoptera: Chalcidoidea) of Coccus hesperidum L. (Homoptera: Coccidae)

Luck

Morse

1998

Oecologia

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We tested several assumptions and predictions of host-quality-dependent sex allocation theory (Charnov et al. 1981) with data obtained for the parasitoid Metaphycus stanleyi Compere on its host, brown soft scale (Coccus hesperidum L.), in a California citrus grove and in the laboratory. Scales ceased growing after parasitization by M. stanleyi. Thus, M. stanleyi may gauge host quality (=size) at oviposition. Host size positively influenced adult parasitoid size, and parasitoid size in turn influenced adult longevity of M. stanleyi. However, parasitoid fitness gains with host size and adult size were similar in males versus females. Sex allocation to individual hosts by M. stanleyi depended on host size; females consistently emerged from larger hosts than males. Host size was important in a relative sense; the mean host sizes of females versus males, and of solitary versus gregarious parasitoids varied with the available host size distribution. The offspring sex ratio of M. stanleyi reflected the available host size distribution; the sex ratio of emerging parasitoids varied with the available host size distribution. We did not detect a "critical host size" below which males emerged, and above which females emerged; rather, only females emerged from hosts in the upper size range, and a variable ratio of males and females emerged from hosts in the lower size range. We conclude that the sex ratio of field populations of M. stanleyi is driven largely by the available size distribution of C. hesperidum. In addition, we tested predictions resulting from theoretical analyses of sex allocation in autoparasitoids with data obtained on Coccophagus semicircularis (Förster) parasitizing brown soft scale in the field. The sex ratio of C. semicircularis was consistently and strongly female biased (ca. 90% females). Based on available theoretical analyses, we suggest that this sex ratio pattern may have resulted from a very low encounter rate of secondary hosts coupled with a strong time limitation in C. semicircularis females. This explanation was the most plausible given constraints stemming from the detection of secondary hosts, their variable location within primary hosts, and their handling times. Finally, the size of hosts which yielded single versus multiple parasitoids, and the sizes of these parasitoids, were compared. These comparisons suggested that: (1) M. stanleyi females gauge host sizes precisely, and in terms of female offspring; thus a fitness penalty is not incurred by females which share a host, while males benefit from sharing a host, and; (2) instances where multiple C. semicircularis emerged from a single host were probably the result of parasitism by different females, or during different encounters by a single female.

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Section: Natural Historiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sex ratios in field populations of two parasitoids (Hymenoptera: Chalcidoidea) of Coccus hesperidum L. (Homoptera: Coccidae)

Luck

Morse

1998

Oecologia

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“…Encarsia pergandiella Howard is in a group of parasitic wasps in the Aphelinidae that have been called "heteronomous" (Walter, 1983); males and females exhibit different host relationships. E. pergandiella, in particular, is an "autoparasitoid" (Walter, 1983).…”

Section: Introductionmentioning

confidence: 99%

Origin of males by genome loss in an autoparasitoid wasp

1993

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Autoparasitoid wasps lay fertilized (female) eggs in homopteran nymphs and unfertilized (male) eggs in immature parasitoids, often in females of their own species. Autoparasitoid host relationships are generally obligate; a male egg will not develop in the homopteran host even if laid there. While sex is controlled by the female by selective fertilization of eggs, the sex ratio is constrained by the availability of the appropriate hosts. However, in a population of the autoparasitoid Encarsia pergandiella in Ithaca, NY, some of the males develop, like females, as primary parasitoids of whiteflies. A cytogenetic examination of eggs laid in whiteflies revealed that these 'primary' males are haploid, but develop from fertilized eggs. Following fertilization, one set of chromosomes becomes overcondensed and is lost, thus converting the fertilized (female) egg into a haploid (male) egg. Genetic analysis suggests that the production of primary males is heritable; males that develop from parasitoid hosts do not produce primary sons, whereas primary males do. However, the transmission and/or expression of the primary male trait is low and variable. Only about 50 per cent of primary male matings result in any primary sons, and only about 28 per cent of all offspring produced on whiteflies are male. X-irradiation of primary males had no effect on the number of primary sons produced but greatly reduced the number of daughters, suggesting that it is the paternal genome that is lost in the production of primary males. Paternal inheritance of genome loss has been described in one other parasitic wasp, Nasonia vitripennis (Walker). There, chromosome loss is caused by a supernumerary chromosome (PSR). A supernumerary chromosome was not observed in the primary male E. pergandiella. It is unknown how widespread primary male production is among populations of E. pergandiella and other autoparasitoids.

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“…Inter and intraspecific variation found in parasitoid sex ratios indicates that an understanding of sex allocation is important to study the reproductive strategies of parasitoids, In majority of parasitic Hymenoptera, sex ratios commonly range from a slight male bias to entirely female broods and it was also well known that many parasitoids regulate their sex ratios by selecting different stages of hosts or even different species of host itself (Clausen 1940;WaIter 1983). Further, behavioural diversity of adult parasitoids in the process of host location determines the efficiency of a given species as an effective control agent.…”

Section: Introductionmentioning

confidence: 99%

Reproductive strategies of an egg parasitoid,Trissolcus sp. (Hymenoptera: Scelionidae) on two different hosts

Senrayan¹,

Velayudhan²,

Rajadurai³

1988

Proc. Indian Acad. Sci. (Anim. Sci.)

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‘Divergent male ontogenies’ in Aphelinidae (Hymenoptera: Chalcidoidea): a simplified classification and a suggested evolutionary sequence

Cited by 93 publications

References 70 publications

Sex ratios in field populations of two parasitoids (Hymenoptera: Chalcidoidea) of Coccus hesperidum L. (Homoptera: Coccidae)

Sex ratios in field populations of two parasitoids (Hymenoptera: Chalcidoidea) of Coccus hesperidum L. (Homoptera: Coccidae)

Origin of males by genome loss in an autoparasitoid wasp

Reproductive strategies of an egg parasitoid,Trissolcus sp. (Hymenoptera: Scelionidae) on two different hosts

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