Semi-field evaluation of the effects of sub-lethal doses of pesticides, with and without adult Schistocerca gregaria pheromone, on hoppers
Loading...
Date
2016
Authors
Magzoub, B.
Hassanali, A.
Korena, H.
Widaatalla, A.
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract
Previously, we reported a chain of effects induced by phenylacetonitrile, the gregarious-phase adult
cohesion pheromone of the desert locust, Schistocerca gregaria (Forsk al) (Orthoptera: Acrididae), on
conspecific hoppers. Specifically, the nymphs became hyperactive and displayed high levels of
intraspecific predation, as surviving individuals gradually shifted to the solitary phase. The findings
suggested that the pheromone could induce a significant level ofmortality of the nymphs and predispose
them to greater sensitivity to lower doses of insecticides. In this study, we compared the effects
of the pheromone and various doses of three pesticides (fipronil, malathion, and carbosulfan) to
pheromone-exposed and unexposed crowd-reared hoppers in semi-field enclosures. The pheromone
on its own displayed a high level of cumulative mortality of the nymphs (89%). Although combinations
with fractional pesticide doses gave control efficiencies that were, in most cases, higher than
with individual pesticides, pheromonal and pesticidal effects were only partially complementary,
probably because of the feeding-deterrent effects of the pesticides and the resulting reduction in
cannibalism. However, our results demonstrate the possibility of significantly reducing the levels of
pesticides used in hopper control and, thus, their negative environmental effects
Description
Research Article