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Density-dependent reductions in grasshopper fecundity in response to nematode parasitism

Published online by Cambridge University Press:  02 April 2012

Angela Nardoni Laws
Angela Nardoni Laws
Affiliation:
Department of Biology, University of Notre Dame, Notre Dame, IN 46556, United States of America (e-mail: [email protected])
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Abstract

Grasshoppers (Orthoptera: Acrididae) are hosts to many internal parasites, including nematodes. However, the effects of nematode parasitism on grasshopper fecundity and how these effects vary with population density are unclear. I report on the fecundity of Melanoplus dawsoni (Scudder) infected and uninfected with mermithid nematodes in northern Wisconsin from 2002 to 2005. Each year grasshoppers were stocked over a range of five densities into field enclosures. Fecundity, body size, and nematode prevalence were measured for female grasshoppers. Nematode prevalence was moderately high, ranging from 15% in 2003 to 37% in 2004. Fecundity was measured by examining grasshopper reproductive tracts. On average, past reproductive activity (number of eggs laid) and current reproductive activity (number of eggs forming) of parasitized grasshoppers were reduced by 40% and 48%, respectively. Interestingly, the reduction in fecundity was less for parasitized females in the low-density treatments (25%-50% of field density) than for those in the moderate- and high-density treatments, suggesting that grasshoppers can compensate somewhat for negative effects of parasites on fecundity when per-capita resources are high. No difference in hind-femur length between parasitized and unparasitized females was observed, indicating that nematode infection did not affect grasshopper body size.

Résumé

Les criquets (Orthoptera: Acrididae) servent d'hôtes à de nombreux parasites internes et, en particulier à des nématodes. Il n'est cependant pas clair comment le parasitisme par les nématodes affecte la fécondité des criquets, ni comment ces effets varient en fonction de la densité de population. On trouvera ici des informations sur la fécondité de Melanoplus dawsoni (Scudder) infectés et non infectés par les nématodes dans le nord du Wisconsin de 2002 à 2005. À chaque année pendant cinq ans, des criquets ont été gardés dans des enclos de terrain présentant cinq densités différentes. La fécondité, la taille corporelle et la fréquence des nématodes ont été déterminées chez les femelles adultes. La fréquence des nématodes était modérée, variant de 15 % en 2003 à 37 % en 2004. La fécondité a été déterminée à l'examen du système reproducteur. En moyenne, l'activité reproductive passée (œufs pondus) et l'activité présente (œufs en formation) sont réduites de respectivement 40 % et 48 % chez les criquets parasités. Fait intéressant, la réduction de la fécondité des femelles parasitées est moins importante chez les criquets dans les conditions expérimentales de faible densité (25 % – 50 % de la densité en nature) que chez les criquets dans les conditions expérimentales de moyenne ou de forte densité; cela laisse croire que les criquets peuvent compenser dans une certaine mesure les effets négatifs des parasites sur la fécondité lorsque les ressources par individu sont abondantes. Il n'existe pas de différence de longueur du fémur entre les femelles parasitées et non parasitées, ce qui indique que l'infection à nématodes n'affecte pas la taille corporelle des criquets.

[Traduit par la Rédaction]

Type
Articles
Information
The Canadian Entomologist , Volume 141 , Issue 4 , August 2009 , pp. 415 - 421
Copyright
Copyright © Entomological Society of Canada 2009

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References

Anderson, R.M., and May, R.M. 1978. Regulation and stability of host–parasite population interactions I. Regulatory processes. Journal of Animal Ecology, 47: 219–247.CrossRefGoogle Scholar
Baker, G.L., and Capinera, J.L. 1997. Nematodes and nematomorphs as control agents of grasshoppers and locusts. Memoirs of the Entomological Society of Canada, 171: 157–211.CrossRefGoogle Scholar
Belovsky, G.E., and Slade, J.B. 1995. Dynamics of two Montana grasshopper populations: relationships among weather, food abundance and intraspecific competition. Oecologia, 101: 383–396.CrossRefGoogle ScholarPubMed
Branson, D.H. 2003 a. Effects of a parasitic mite on life-history variation in two grasshopper species. Evolutionary Ecology Research, 5: 397–409.Google Scholar
Branson, D.H. 2003 b. Reproduction and survival in Melanoplus sanguinipes (Orthoptera: Acrididae) in response to resource availability and population density: the role of exploitative competition. The Canadian Entomologist, 135(3): 415–426.CrossRefGoogle Scholar
Branson, D.H. 2006. Life-history responses of Ageneotettix deorum (Scudder) (Orthoptera: Acrididae) to host plant availability and population density. Journal of the Kansas Entomological Society, 79(2): 146–155.CrossRefGoogle Scholar
Capinera, J.L. 1987. Observations on natural and experimental parasitism of insects by Mermis nigrescens Dujardin (Nematoda, Mermithidae). Journal of the Kansas Entomological Society, 60(1): 159–162.Google Scholar
Danner, B.J., and Joern, A. 2004. Development, growth, and egg production of Ageneotettix deorum (Orthoptera: Acrididae) in response to spider predation risk and elevated resource quality. Ecological Entomology, 29(1): 1–11.CrossRefGoogle Scholar
Forbes, M.R.L. 1993. Parasitism and host reproductive effort. Oikos, 67 (3): 444–450.Google Scholar
Hatcher, M.J., Dick, J.T.A., and Dunn, A.M. 2006. How parasites affect interactions between competitors and predators. Ecology Letters, 9(11): 1253–1271.CrossRefGoogle ScholarPubMed
Hurd, H. 2001. Host fecundity reduction: a strategy for damage limitation? Trends in Parasitology, 17(8): 363–368.CrossRefGoogle ScholarPubMed
Joern, A., and Klucas, G. 1993. Intra- and interspecific competition between two abundant grasshopper species (Orthoptera: Acrididae) from a sandhills grassland. Environmental Entomology, 22: 352–361.CrossRefGoogle Scholar
Marcogliese, D.J., and Cone, D.K. 1997. Food webs: a plea for parasites. Trends in Ecology and Evolution, 12(8): 320–325.CrossRefGoogle ScholarPubMed
Mouritsen, K.N., and Poulin, R. 2002. Parasitism, community structure and biodiversity in intertidal ecosystems. Parasitology, 124: S101–S117.CrossRefGoogle ScholarPubMed
Onsager, J.A. 1977. Comparison of 5 methods for estimating density of rangeland grasshoppers Orthoptera-Acrididae. Journal of Economic Entomology, 70(2): 187–190.CrossRefGoogle Scholar
Pfadt, R.E. 1994. Field guide to common western grasshoppers. Wyoming Agriculture Experimental Station, Laramie, Wyoming.Google Scholar
Phipps, J. 1949. The structure and maturation of the ovaries in British Acrididae (Orthoptera). Transactions of the Royal Entomological Society of London, 100: 233–247.CrossRefGoogle Scholar
Singh, T. 1958. Ovulation and corpus luteum formation in Locusta migratoria migratorioides Reiche and Fairmaire and Schistocerca gregaria (Forskål). Transactions of the Royal Entomological Society of London, 110: 1–20.CrossRefGoogle Scholar
Sundberg, S.V., Luong-Skovmand, M.H., and Whitman, D.W. 2001. Morphology and development of oocyte and follicle resorption bodies in the lubber grasshopper, Romalea microptera (Beauvois). Journal of Orthoptera Research, 10(1): 39–51.CrossRefGoogle Scholar
Systat Software, Inc. 2000. Systat. Version 10. Systat Software, Inc. Chicago, Illinois.Google Scholar
Wall, R., and Begon, M. 1987. Population density, phenotype and reproductive output in the grasshopper Chorthippus brunneus. Ecological Entomology, 12: 331–339.CrossRefGoogle Scholar
Webster, J.M., and Thong, C.H.S. 1984. Nematode parasites of orthopterans. In Plant and insect nematodes. Edited by Nickle, W.R.. Marcel Dekker, Inc, New York. pp. 697–726.Google Scholar
Zar, J.H. 1999. Biostatistical analysis. Prentice Hall, Upper Saddle River, New Jersey.Google Scholar