TOLERANCE OF HETERACRIS LITTORALIS (ORTHOPTERA: ACRIDIDAE) TO THE TOXIC PLANT, NERIUM OLEANDER (APOCYNACEA)

Document Type : Original Article

Authors

Department of Entomology1, Faculty of Science, Cairo University, Giza P.O. Box 12613, Egypt.

Abstract

Nerium oleander (Apocynacea) is a highly toxic plant that has never been reported to be selected as a food or even as a resting place by any acridid species. The study tested the competence of Heteracrislittoralis (Orthoptera: Acrididae) to tolerate and survive on this plantfor considerable periods, and to resume normal capacity of development and reproduction when favourable food plant became available. Nymphal survival and development were followed by monitoring three cohorts of freshly hatched hoppers. The first cohort fed oleander leaves; the second one (control) fed clover; while the third cohort fed oleander leaves for 35 days, and then switched to clover. Age specific survivorship and reproductive parameters of the adults were followed by monitoring three cohorts of newly fledged adults fed on the same
patterns. Moulting was suspended in nymphs fed oleander; when food plant was switched to clover, the insects resumed normal development and reached the adult stage. Adult cohort reared on N. oleander exhibited a normal age specific survivorship curve, but ovarian development was suspended. Suspension of ovarian development by N. oleander was accompanied by very low indices of food consumption and conversion of digested food into body substance.
But, after switching to normal food, clover, the insects resumed normal ovarian development with significant prolonged longevity, and the fecundity was approximately equal to the same parameter in the control cohort. This reflects a strong evolutionary biotic potential against the selective power of plant defense.

Keywords

Journal of the Egyptian Society of Parasitology
Volume 49, Issue 3
December 2019
Pages 579-587

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