STUDIES OF LATHROMEROIDEA SP.NOV. (HYMENOPTERA: TRICHOGRAMMATIDAE), A PARASITOID OF GERRID EGGS

1993 ◽  
Vol 125 (4) ◽  
pp. 693-702 ◽  
Author(s):  
Nidia Priscila Henriquez ◽  
John R. Spence
Keyword(s):  
Body Length ◽  
Sex Ratios ◽  
Reproductive Behaviour ◽  
Egg Parasitoid ◽  
Host Size

AbstractUse of gerrids (Hemiptera: Gerridae) as primary hosts by the solitary egg parasitoid Lathromeroidea sp.nov. is established and parasitoid reproductive behaviour is described. Four species of Limnoporus (L. dissortis Drake and Harris, L. notabilis Drake and Hottes, L. rufoscutellatus Latreille, and L. esakii Miyamoto) and two of Gerris (G. buenoi Kirkaldy and G. pingreensis Drake and Hottes) were successfully parasitized in the laboratory. A greater proportion of wasps eclosed successfully from eggs of Gerris than from Limnoporus. Host size was directly proportional to both weight and body length of adult parasitoids. Sex ratios were female-biased, with males emerging before females.

Host size-dependent sex allocation behaviour in a parasitoid: implications forCatolaccus grandis(Hymenoptera: Pteromalidae) mass rearing programmes

1998 ◽  
Vol 88 (1) ◽  
pp. 37-45 ◽  
Author(s):  
K.M. Heinz
Keyword(s):  
Biological Control ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Boll Weevil ◽  
Mass Rearing ◽  
Host Size ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Control Programmes

AbstractAn often encountered problem associated with augmentative and inundative biological control programmes is the high cost of producing sufficient numbers of natural enemies necessary to suppress pest populations within the time constraints imposed by ephemeral agroecosystems. In many arrhenotokous parasitoids, overproduction of males in mass-rearing cultures inflates costs (per female) and thus limits the economic feasibility of these biological control programmes. Within the context of existing production technologies, experiments were conducted to determine if the sex ratio ofCatolaccus grandis(Burks), an ectoparasitoid of the boll weevilAnthonomous grandisBoheman, varied as a function of boll weevil larval size. Results from natural and manipulative experiments demonstrate the following behavioural characteristics associated with C.grandissex allocation behaviour: (i) femaleC. grandisoffspring are produced on large size hosts and male offspring are produced on small hosts; (ii) whether a host is considered large or small depends upon the overall distribution of host sizes encountered by a female parasitoid; and (iii) female parasitoids exhibit a greater rate of increase in body size with host size than do male parasitoids. The observed patterns cannot be explained by sex-specific mortality of immature parasitoids developing on the different host size categories. In subsequent experiments, laboratory cultures ofC. grandisexposed daily to successively larger sizes ofA. grandislarvae produced successively greater female biased offspring sex ratios, cultures exposed daily to successively smaller sizes of host larvae produced successively greater male biased offspring sex ratios, and cultures exposed daily to equivalent host size distributions over time maintained a uniform offspring sex ratio. By increasing the average size ofA. grandislarval hosts exposed toC. grandisby 2.5 mg per day in mass rearing cultures, the percentage of male progeny can be reduced from 33% to 23% over a period of four consecutive exposure days.

The effect of host size on quality attributes of the egg parasitoid, Trichogramma pretiosum

1992 ◽  
Vol 64 (1) ◽  
pp. 37-48 ◽  
Author(s):  
Baorong Bai ◽  
Robert F. Luck ◽  
Lisa Forster ◽  
Beth Stephens ◽  
J. A. M. Janssen
Keyword(s):  
Quality Attributes ◽  
Egg Parasitoid ◽  
Host Size ◽  
Trichogramma Pretiosum

Life history of the maritime platygastrid Echthrodesis lamorali Masner 1968 (Hymenoptera: Platygastridae: Scelioninae)

2016 ◽  
Author(s):  
◽  
Candice Ann Owen
Keyword(s):  
South Africa ◽  
Life History ◽  
Southern Africa ◽  
Sex Ratios ◽  
Egg Parasitoid ◽  
Western Cape ◽  
Distributional Range ◽  
Morphological Adaptations ◽  
History Of ◽  
The Individual

Echthrodesis lamorali Masner 1968 (Hymenoptera: Platygastridae, Scelioninae) is an intertidal parasitoid wasp that uses the eggs of the maritime spider, Desis formidabilis O.P. Cambridge 1890 (Araneae: Desidae), as a host. This species is one of only three known maritime parasitoids globally, and is the only known spider egg parasitoid that attacks its host within the intertidal region in southern Africa. Originally described from ‘The Island’, Kommetjie (Western Cape, South Africa), this shore was the only known locality of the species at the commencement of this thesis. Furthermore, the extent of the parasitism pressure the wasp exerts on D. formidabilis was largely unknown, along with its basic biology (drivers of its broad-scale and fine-scale distribution patterns; parasitism incidence; and sex ratios) and morphological and physiological adaptations for living within the frequently saltwater-inundated environment. This thesis unravelled these aspects, as well as experimentally provided data for many components of the life history of E. lamorali that had only been hypothesized by other authors, at a variety of scales, from the country-wide ecosystem, to single shores, and finally to the scale of the individual. While the distribution of E. lamorali was found to be much wider than previously thought, it remained restricted to the shores of the Cape Peninsula (Western Cape, South Africa). The host spiders were located throughout a much wider distributional range than the wasp, from East London in the east to the Peninsula, but some behavioural and morphological differences were found between those within and outside of the range of the parasitoid, suggesting range-limitation imposed by the host on E. lamorali. This limitation may be strengthened by the general lack of suitable shore types within the close vicinity of the Peninsula. Modelling using macro-climatic conditions suggested that maximum temperatures and humidities were also largely limiting to E. lamorali, although these patterns were not observable in the micro-climates in which the species survives. The wasp populations and spiders within the range of E. lamorali as identified in Chapter 2 were assessed to determine any preferences for local conditions, including location along the Peninsula, nesting sites and intertidal zones within single shores, using AICc modelling, which detected parasitism patterns in D. formidabilis and E. lamorali populations, as well as the sex ratios in the latter species. The models showed that the spider population size and distribution was more influenced by bottom-up factors such as abiotic components of the shore than by parasitism, which only showed density dependence with the host at certain scales. Both host and parasitoid populations illustrated a preference for the middle zone on single shores. Observed spider nest characteristics suggested opportunistic nesting behaviour in the species, although preference was shown for construction along an east-west orientation and in locations with low sun exposure. Along with larger population sizes on the west coast over the east coast (not reflected by E. lamorali), these observations suggest that D. formidabilis prefers cooler environments. Spider brood success was 50% in unparasitized egg-sacs, but this figure halved when E. lamorali gained access to the eggs (of which 100% within a single compartment were parasitized each time). Encapsulation of the embryo was found to be positively correlated with parasitism, indicating some form of host resistance. Resultant parasitoid broods illustrated a strong female bias in the species, as is common for this group of insects. The life history of E. lamorali was then assessed at a smaller scale, that of the individual. Scanning electron microscopy of whole E. lamorali specimens and light microscopy of sectioned specimens demonstrated no morphological adaptations in the trachea and spiracles to cope with saltwater inundation. On the other hand, respirometry experiments categorically demonstrated that the species copes with inundation through the formation of a physical gill over the full habitus, and the induction of a state of torpor to reduce metabolic needs, when submerged. This precludes the need for any further morphological adaptations. Determination of the wasp’s critical thermal tolerance illustrated a wide temperature range with a particularly cold lower limit of -1.1ºC ± 0.16, suggesting the presence of related genera or ancestors in much colder environments. With a much broader distribution than previously thought, and the inclusion of the distributional range of E. lamorali within the Table Mountain National Park, this species is being effectively conserved and managed through the umbrella-conservation of the park. Links to the host proved to vary at differing scales, proving the need for scale considerations to be included in other similar biological and ecological studies. Finally, the species showed a physiological adaptation to its intertidal existence. Echthrodesis lamorali, the only discovered maritime spider egg parasitoid in Southern Africa, displayed unusual characteristics at every scale of its life history and as such, warrants further investigation.

Interactions between the scelionid egg parasitoid Tiphodytes gerriphagus (Hymenoptera) and its gerrid hosts (Heteroptera)

1986 ◽  
Vol 64 (12) ◽  
pp. 2728-2738 ◽  
Author(s):  
John R. Spence
Keyword(s):  
Egg Production ◽  
Adult Life ◽  
Late Summer ◽  
Egg Parasitoid ◽  
The Body ◽  
Host Size ◽  
Lower Growth ◽  
Adult Life Span ◽  
Jelly Coat ◽  
Parasitoid Population

Tiphodytes gerriphagus parasitized eggs of five Gerris and two Limnoporus species in the laboratory and the parasitoids were reared from field-collected eggs of G. buenoi, G. comatus, G. pingreensis, L. dissortis, and L. notabilis. Eggs of G. buenoi and L. dissortis were parasitized over about 80% of development. Wasps preferred eggs of G. buenoi over those of L. dissortis, which were larger but covered by a jelly coat. However, under field conditions, eggs of L. dissortis laid at the water surface were parasitized more than submersed eggs of Gerris species. Host size (= species) had no apparent effect on adult life-span but affected the body length of adult parasitoids. Size of females was affected more than that of males and lifetime fecudity also varied with host size. Parasitoids laid most of their eggs during the first 4 days after emergence, averaging 8–11 parasitized hosts per day. Tiphodytes gerriphagus was reared from eggs of Limnoporus collected throughout western Canada. Rates of parasitism peaked just after egg production by L. dissortis, suggesting selection for early oviposition by gerrids. Most Limnoporus populations were heavily parasitized by late summer, but in some temporary or newly created habitats, rates of parasitism were lower. Growth of the parasitoid population at a new habitat was slower than at nearby ponds with large resident wasp and gerrid populations, and the lower parasitoid abundance was associated with greater production of L. dissortis. Adults of T. gerriphagus appear to overwinter in gerrid eggs at the bottom of ponds. At temporary sites, wasps may fail to survive the winter and recolonize more slowly than Limnoporus. Interaction with parasitoids may explain the patchy nature of L. dissortis distribution and its restriction to temporary habitats. Presence of T. gerriphagus may also affect the outcome of competitive interactions among gerrid species.

scholarly journals The influence of sex ratio on the reproduction of pirarucu, Arapaima gigas, in captivity

2018 ◽  
Vol 48 (1) ◽  
pp. 38-41 ◽  
Author(s):  
Adriana Ferreira LIMA
Keyword(s):  
Reproductive Success ◽  
Sex Ratio ◽  
Sex Ratios ◽  
Reproductive Behaviour ◽  
Arapaima Gigas ◽  
Earthen Ponds ◽  
In Captivity

ABSTRACT Because sex ratio in the broodstock can influence the reproductive behaviour of a species, the influence of sex ratio on the reproductive success of pirarucu, Arapaima gigas, in captivity was assessed. Pirarucu breeders were stocked in 0.10-0.13 ha earthen ponds at three sex ratios in quadruplicate: one male to one female (1M1F); one male to two females (1M2F); and two males to one female (2M1F). Eight spawning events occurred, seven of them with the 1M1F sex ratio, which was the most successful of the three tested sex ratios.

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