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Family planning in a stemborer parasitoid: sex ratio, brood size and size-fitness relationships in Parallorhogas pyralophagus (Hymenoptera: Braconidae), and implications for biological control

Published online by Cambridge University Press:  09 March 2007

J.S. Bernal*
Affiliation:
Biological Control Laboratory, Texas A&M University, College Station, TX 77843-2475, USA
P.O. Gillogly
Affiliation:
Biological Control Laboratory, Texas A&M University, College Station, TX 77843-2475, USA
J. Griset
Affiliation:
Biological Control Laboratory, Texas A&M University, College Station, TX 77843-2475, USA
*
*Fax: (409) 845 7977 E-mail: julio-s-bernal@tamu.edu

Abstract

Various aspects were studied of the brood size and sex allocation strategies, and of size-fitness relationships in Parallorhogas pyralophagus (Marsh), a gregarious ectoparasitoid of Eoreuma loftini Dyar. Brood size was significantly correlated with host size; larger hosts were allocated larger broods. Brood sex ratios were fixed precisely at 1 male per 4 females, and eggs were likely to be deposited in that order; differential mortality did not contribute to this precise sex ratio. The sex allocation strategy of P. pyralophagus is likely to conform to strict, i.e. single foundress, local mate competition. Adoption of this strategy is probably influenced by a limited insemination capacity of males; a smaller proportion of females (0.09 vs. 0.21) remained virgin in broods with precise or higher sex ratios (≥0.20 males) relative to broods with lower than precise sex ratios (< 0.20 males). Moreover, all females were inseminated in most broods (60%) with precise or higher sex ratios, whereas this did not occur in broods with lower than precise sex ratios. The hypothesized occurrence of strict local mate competition in P. pyralophagus was supported also by observations that: (i) offspring brood sex ratios were independent of maternal brood sex ratios and number of parental females concurrently allocating offspring to a group of hosts, and; (ii) the rate of superparasitism under no-choice conditions was low (~20%), suggesting that rates of outbreeding in the field are low. Other results suggested that fitness in P. pyralophaguswas correlated with adult size; longevity and reproductive capacity both increased with adult size in males and females. However, adult size may be more important for females than for males because the differences in reproductive capacity between the largest and smallest individuals was up to 7.3 times greater in females versus <2 times in males.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2001

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References

Antolin, M.F. (1999) A genetic perspective on mating systems and sex ratios of parasitoid wasps. Researches in Population Ecology 41, 2937.CrossRefGoogle Scholar
Bennett, D.M. & Hoffmann, A.A. (1998) Effects of size and fluctuating asymmetry on field fitness of the parasitoid Trichogramma carverae (Hymenoptera: Trichogrammatidae). Journal of Animal Ecology 67, 580591.CrossRefGoogle Scholar
Bernal, J.S., Luck, R.F., Morse, J.G. (1999) Host influences on sex ratio, longevity, and egg load of two Metaphycus species parasitic on soft scales: implications for insectary rearing. Entomologia Experimentalis et Applicata 92, 191204.CrossRefGoogle Scholar
Butcher, R.D.J., Whitfield, W.G.F. & Hubbard, S.F. (2000) Single-locus complementary sex determination in Diadegma chrysoctictos (Gmelin) (Hymenoptera: Ichneumonidae). Journal of Heredity 91, 104111..CrossRefGoogle ScholarPubMed
Butcher, R.D.J., Whitfield, W.G.F. & Hubbard, S.F. (2000) Complementary sex determination in the genus Diadegma (Hymenoptera: Ichneumonidae). Journal of Evolutionary Biology 13, 593606.CrossRefGoogle Scholar
Dasrat, B., Rajkumar, A., Richards-Haynes, C., Quashie-Williams, C. & Eastwood, D. (1997) Evaluation of Allorhogas pyralophagus Marsh (Hymenoptera: Braconidae) for the biological control of Diatraea spp. (Lepidoptera: Pyralidae) in sugar-cane in Guyana. Crop Protection 16, 723726.CrossRefGoogle Scholar
Ellers, J., van Alphen, J.J.M. & Sevenster, J.G. (1998) A field study of size-fitness relationships in the parasitoid Asobara tabida. Journal of Animal Ecology 67, 318324.CrossRefGoogle Scholar
Godfray, H.C.J. (1994) Parasitoids: behavioral and evolutionary ecology. 473 pp. Princeton, Princeton University Press.CrossRefGoogle Scholar
Godfray, H.C.J. & Hardy, I.C.W. (1993) Sex ratio and virginity in haplodiploid insects. pp. 402417 in Wrensch, D.L. & Ebbert, M.A. (Eds) Evolution and diversity of sex ratio in insects and mites. New York, Chapman & Hall.CrossRefGoogle Scholar
Green, R.F., Gordh, G. & Hawkins, B.A. (1982) Precise sex ratios in highly inbred parasitic wasps. American Naturalist 120, 653665.CrossRefGoogle Scholar
Hamilton, W.D. (1967) Extraordinary sex ratios. Science 156, 477488..CrossRefGoogle ScholarPubMed
Hardy, I.C.W., Dijkstra, L.J., Gillis, J.E.M. & Luft, P.A. (1998) Patterns of sex ratio, virginity and developmental mortality in gregarious parasitoids. Biological Journal of the Linnaean Society 64, 239270.CrossRefGoogle Scholar
Hartl, D.L. (1971) Some aspects of natural selection in arrhenotokous populations. American Zoologist 11, 309325.CrossRefGoogle Scholar
Heimpel, G.E. (1994) Virginity and the cost of insurance in highly inbred Hymenoptera. Ecological Entomology 19, 299302.CrossRefGoogle Scholar
Heinz, K.M. (1998) Host size-dependent sex allocation behaviour in a parasitoid: implications for Catolaccus grandis (Hymenoptera: Pteromalidae) mass rearing programmes. Bulletin of Entomological Research 88, 3745.CrossRefGoogle Scholar
Hopper, K.R. & Roush, R.T. (1993) Mate finding, dispersal, number released, and the success of biological control introductions. Ecological Entomology 18, 321331.CrossRefGoogle Scholar
Jones, W.T. (1982) Sex ratio and host size in a parasitic wasp. Behavioral Ecology and Sociobiology 10, 207210.CrossRefGoogle Scholar
Kazmer, D.J. & Luck, R.F. (1995) Field tests of the size-fitness hypothesis in the egg parasitoid Trichogramma pretiosum. Ecology 76, 412425.CrossRefGoogle Scholar
Martinez, A.J., Bard, J. & Holler, T.A. (1988) Mass rearing sugarcane borer and Mexican rice borer for production of parasites Allorhogas pyralophagus and Rhacontus rosilensis. USDA-APHIS-PPQ, APHIS 83–1.Google Scholar
Meagher, R.L., Wilson, L.T. & Pfannenstiel, R.S. (1996) Sampling Eoreuma loftini (Lepidoptera: Pyralidae) on Texas sugarcane. Environmental Entomology 25, 716.CrossRefGoogle Scholar
Meagher, R.L., Smith, J.W., Browning, H.W. and Saldaña, R.R. (1998) Sugarcane stemborers and their parasites in southern Texas. Environmental Entomology 27, 759766.CrossRefGoogle Scholar
Melton, C.W. & Browning, H.W. (1986) Life history and reproductive biology of Allorhogas pyralophagus (Hymenoptera: Braconidae), a parasite imported for release against Eoreuma loftini (Lepidoptera: Pyralidae). Annals of the Entomological Society of America 79, 402406.CrossRefGoogle Scholar
Rodríguez, del, Bosque, L.A., Smith, J.W. & Browning, H.W. (1988) Damage by stalkborers (Lepidoptera: Pyralidae) to corn in northeastern Mexico. Journal of Economic Entomology 81, 17751780.CrossRefGoogle Scholar
Smith, J.W., Browning, H.W. & Bennet, F.D. (1987) Allorhogas pyralophagus [Hym., Braconidae], a gregarious external parasite imported into Texas, USA, for biological control of the stalkborer Eoreuma loftini [Lep., Pyralidae] on sugarcane. Entomophaga 32, 477482.CrossRefGoogle Scholar
Smith, J.W., Wiedenmann, R.N. & Overholt, W.A. (1993) Parasites of lepidopteran stemborers of tropical gramineous plants. 89 pp. Nairobi, ICIPE Science Press.Google Scholar
van den, Assem J., van Iersel, J.J.A. & Los-den, Hartogh R.L. (1989) Is being large more important for female than for male parasitic wasps? Behaviour 108, 160195.CrossRefGoogle Scholar
Visser, M.E. (1994) The importance of being large: the relationship between size and fitness in females of the parasitoid Aphaereta minuta (Hymenoptera: Braconidae). Journal of Animal Ecology 63, 963978.CrossRefGoogle Scholar
Werren, J.H. (1993) The evolution of inbreeding in haplodiploid organisms. pp.42–94 in Thornhill, N.W. (Ed.) The natural history of inbreeding and outbreeding. Chicago, University of Chicago Press.Google Scholar
West, S.A., Flanagan, K.E. & Godfray, H.C.J. (1996) The relationship between parasitoid size and fitness in the field: a study of Achrysocharoides zwoelferi (Hymenoptera: Eulophidae). Journal of Animal Ecology 65, 631639.CrossRefGoogle Scholar
Youm, O., Browning, H.W. & Gilstrap, F.E. (1988) Population dynamics of stalk borers attacking corn and sorghum in the Texas Rio Grande Valley. Southwestern Entomologist 13, 199204.Google Scholar
Zar, J.H. (1996) Biostatistical analysis. 662 pp. + Apps. Upper Saddle River, Prentice Hall.Google Scholar