Eur. J. Entomol. 104 (3): 377-383, 2007 | 10.14411/eje.2007.056
Dispersal and reproductive responses of the water strider, Aquarius paludum (Hemiptera: Gerridae), to changing NaCl concentrations
- 1 Laboratory of Insect Ecology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan; e-mail: firstname.lastname@example.org
- 2 Laboratory of Environmental Physiology, Faculty of Education, Kochi University, Kochi 780-8520, Japan; e-mail: email@example.com
The responses of females of the water strider, Aquarius paludum, to changes in NaCl concentration were examined in the laboratory. The insects were sampled seasonally in 2002 and 2003 at two reservoirs in Kochi, Japan, connected by a waterway, one at the mouth of the river with high NaCl concentrations (the range in NaCl concentration during a year: 0.1-1.08%) and one 700 m upstream, where the salinity was lower (0.03-0.23%). Sudden increase in NaCl concentration, from 0.45 to 0.9%, after adult strider emergence suppressed reproduction and promoted flight activity, whereas a decrease in salinity did not affect either trait. In the field, A. paludum was univoltine in brackish and multivoltine in freshwater ponds. Thus, the number of breeding periods per year was limited by fluctuations in the NaCl concentration in brackish habitats. Our results suggest that A. paludum can breed in brackish waters when the NaCl concentration is below the limitation for reproduction and growth. Abrupt increases in NaCl concentration caused by seawater surges, such as those following typhoons, can trigger the migration of individuals, which move to areas of lower NaCl concentration and so mix the genes of individuals inhabiting brackish and freshwater bodies.
Keywords: Gerridae, brackish water, NaCl concentration, reproductive traits, flight activity, Aquarius paludum
Received: June 26, 2006; Accepted: February 27, 2007; Published: July 25, 2007
- ANDERSEN N.M. 2000: The evolution of dispersal dimorphism and other life history traits in water striders (Hemiptera: Gerridae). Entomol. Sci. 3: 187-199
- CHENG L. 1985: Biology of Halobates (Heteroptera: Gerridae). Annu. Rev. Entomol. 30: 111-135 Go to original source...
- DROVER S., LEUNG B., FORBES M.R., MALLORY M.L. & MCNICOL D.K. 1999: Lake pH and aluminum concentration: consequences for developmental stability of the water strider Rheumatobates rileyi (Hemiptera: Gerridae). Can. J. Zool. 77: 157-161 Go to original source...
- HARADA T. 1992: The oviposition process in two direct breeding generations in a water strider, Aquarius paludum (Fabricius). J. Insect Physiol. 38: 231-244 Go to original source...
- HARADA T. 1993: Reproduction by overwintering adults of water strider, Aquarius paludum (Fabricius). Zool. Sci. 10: 313-319
- HARADA T. 1998: To fly or not to fly: response of water striders to drying out of habiat. Ecol. Entomol. 23: 370-376 Go to original source...
- HARADA T. 2003: Hardiness to low temperature and drought in a water strider, Aquarius paludum in comparison with other insect groups. Trends Entomol. 3: 29-41.
- HARADA T., TABUCHI R. & KOURA J. 1997: Migratory syndrome in the water strider, Aquarius paludum (Hemiptera: Gerridae) reared in high versus low nymphal densities. Eur. J. Entomol. 94: 445-452
- HARADA T., INOUE T., ONO I., KAWAMURA N., KISHI M., DOI K., INOUE S. & HODKOVA M. 2000: Endocrine, ecophysiological and ecological aspects of seasonal adaptations in a water strider, Aquarius paludum (A mini review). Entomol. Sci. 3: 157-165
- JAPAN WEATHER ASSOCIATION. 2003: Annual Weather Reports, Japan. Meteorological Business Support Center, Tokyo, pp. 66-67
- JAPAN WEATHER ASSOCIATION. 2004: Annual Weather Reports, Japan. Meteorological Business Support Center, Tokyo, pp. 68-69
- JOHNSON B. 1969: Migration and Dispersal of Insects by Flights. Methuen, London, 763 pp
- KISHI M., HARADA T. & SPENCE J.R. 2002: Adult flight in a water strider exposed to habitat drydown in the larval stages. Naturwissenschaften 89: 552-554
- KISHI M., FUJISAKI K. & HARADA T. 2006: How do water striders, Aquarius paludum, react to brackish water simulated by NaCl solutions? Naturwissenschaften 93: 33-37 Go to original source...
- SPENCE J.R. & ANDERSEN M.N. 1994: Biology of water striders - interactions between systematics and ecology. Annu. Rev. Entomol. 39: 101-128 Go to original source...
- VEPSALAINEN K. 1978: Wing dimorphism and diapause in Gerris: determination and adaptive significance. In Dingle H. (ed.): Evolution of Insect Migration and Diapause. Springer, New York, pp. 218-253