Abstract
The effect of the presence of gregarious fifth-instar nymphs on the sexual maturation of newly molted gregarious immature adult males and females of the desert locust S. gregaria was investigated by monitoring color changes (yellowing of body), sexual activity, aggregation–maturation pheromone titers (as measured by phenylacetonitrile levels in males), oocyte length, and oviposition time. Maturation was significantly delayed in adults that were reared together with fifth-instar nymphs (visual, tactile, and chemical signals present) with respect to all parameters measured. Male and female nymphs were equally effective in inducing this delay. Nymphs kept in an upper compartment of two-chamber cages (no visual or tactile contact possible) were similarly effective, but their feces were ineffective, suggesting the mediation of a volatile signal from the nymphs themselves. This was confirmed by examining the effect of volatiles trapped from nymphs and testing synthetic blends of previously identified nymphal aggregation pheromone components (C6, C8–C10 aliphatic aldehydes and acids, guaiacol, and phenol) on the sexual maturation of adults. These and previous studies suggest a dual role for nymphal volatiles as nymphal aggregants and adult maturation retardants, similar to the adult volatiles that are known as adult aggregants and maturation accelerants. The results are discussed in terms of the role of the two pheromone systems in synchronizing maturation of the gregarious adults.
Similar content being viewed by others
REFERENCES
AMERASINGHE, F. P. 1978. Pheromonal effect on sexual maturation, yellowing, and the vibration reaction in immature male desert locust Schistocerca gregaria. J. Insect Physiol. 24:309–314.
HIGHNAM, K. C., and LUSIS, O. 1962. The influence of mature males of the neurosecretory control of ovarian development in the desert locust. Qt. J. Microsc. Sci. 103:73–83.
LOHER, W. J. 1960. The chemical acceleration of the maturation process and its hormonal control in the male of the desert locust. Proc. R. Soc. B 153:381–397.
MAHAMAT H., HASSANALI, A., ODONGO, H., TORTO, B., and EL BASHIR, S. 1993. Studies on the maturation-accelerating pheromone of the desert locust Schistocerca gregaria (Orthoptera: Acrididae). Chemoecology 4:159–164.
NORRIS, M. J. 1954. Sexual maturation in the desert locust Schistocerca gregaria (Forskål) with special reference to the effect of grouping. Anti-Locust Bull. 18:1–14.
NORRIS, M. J. 1962. Group effects on the activity and behavior of adult males on the desert locust, Schistocerca gregaria (Forskål) in relation to sexual maturation. Anim. Behav. 10:275–291.
NORRIS, M. J. 1963. Laboratory experiments on gregarious behavior in ovipositing females of the desert locust, Schistocerca gregaria (Forskål) in relation to sexual maturation. Entomol. Exp. Appl. 6:269–363.
NORRIS, M. J. 1964. Accelerating and inhibiting effects of crowding on sexual maturation in two species of locusts. Nature 203:784–785.
NORRIS, M. J., and PENER, M. P. 1965. An inhibitory effect of allatectomized males and females on the sexual maturation of young male adults of Schistocerca gregaria (Forskål) (Orthoptera: Acrididae). Nature 208:1122.
OBENG-OFORI, D., TORTO, B., and HASSANALI, A. 1993. Evidence for mediation of two releaser pheromones in the aggregation behavior of the gregarious desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae). J. Chem. Ecol. 19:1665–1670.
OBENG-OFORI, D., TORTO, B., NJAGI, P. G. N., HASSANALI, A., and AMIANI, H. 1994a. Fecal volatiles as part of the aggregation pheromone complex of the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae). J. Chem. Ecol. 20:2077–2087.
OBENG-OFORI, D., NJAGI, P. G. N., TORTO, B., HASSANALI, A., and AMIANI, H. 1994b. Sex differentiation studies relating to releaser aggregation pheromone of the desert locust, Schistocerca gregaria. Entomol. Exp. Appl. 73:85–91.
POPOV, G. B. 1958. Ecological studies on oviposition by swarms of the desert locust Schistocerca gregaria (Forskål). Entomol. Exp. Appl. 6:279–303.
RICHARDS, M. J., and EL MANGOURY, M. A. 1968. Further experiments on the effects of social factor on the rate of sexual maturation in the desert locust. Nature 219:865–866.
TORTO, B., OBENG-OFORI, D., NJAGI, P. G. N., HASSANALI, A., and AMIANI, H. 1994. Aggregation pheromone system of the adult gregarious desert locust Schistocerca gregaria (Forskål). J. Chem. Ecol. 20:1749–1762.
TORTO, B., NJAGI, P. G. N., HASSANALI, A., and AMIANI, H. 1996. Aggregation pheromone system of nymphal gregarious desert locust Schistocerca gregaria (Forskål). J. Chem. Ecol. 22:2273–2281.
UVAROV, B. P. 1966. Grasshopper and Locusts, Vol. I. Cambridge University Press, Cambridge, 496 pp.
UVAROV, B. P. 1977. Grasshopper and Locusts, Vol. II. Center for Overseas Pest Research, London, 613 pp.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Assad, Y.O.H., Hassanali, A., Torto, B. et al. Effects of Fifth-Instar Volatiles on Sexual Maturation of Adult Desert Locust Schistocerca gregaria . J Chem Ecol 23, 1373–1388 (1997). https://doi.org/10.1023/B:JOEC.0000006470.30501.73
Issue Date:
DOI: https://doi.org/10.1023/B:JOEC.0000006470.30501.73