2 research outputs found
Toxicity of the active fraction of Pergularia tomentosa and the aggregation pheromone phenylacetonitrile on Schistocerca gregaria fourth-instar nymph: effects on behavior and acetylcholinesterase activity
Chemical insecticides remain the most used approach in locust control although they present a serious
menace to human health and the environment. The search for alternative control methods, efficient and
environmentally friendly, has become indispensable. The aim of this work is to study the effect of the
aggregation pheromone, phenylacetonitrile, alone or in combination with the active fraction of
Pergularia tomentosa on Schistocerca gregaria fourth-instar nymph. Toxicity bioassays showed that the
combination of phenylacetonitrile with the active fraction of P. tomentosa significantly increased nymph
mortality. Results also showed that the aggregation pheromone caused significant mortality especially
after 6 hours of exposure. The pheromone also caused neurotoxic effects on S. gregaria nymph due to
the disturbance of the acetylcholinesterase activity. We also noted the presence of cannibalism
phenomenon. Phenylacetonitrile seems to have an effect on phase ployphenism of S. gregaria imagos
that exhibit specific traits to the solitarious phase
Effects of Latex from Pergularia tomentosa and the Aggregation Pheromone, Phenylacetonitrile, on Locusta migratoria Larvae
Despite being a serious risk to human health and environment, chemical insecticides remain the most
used for locust control. Searching for alternative control methods, effective and compatible with the
environment, has become of increasing interest. Plant latex is an endogenous fluid secreted from highly
specialized laticifer cells and has been suggested to act as a plant defense system. The aim of the
present investigation was to study the insecticidal potentialities of Pergularia tomentosa latex at
different concentrations, alone or in combination with the penylacetonitrile (PAN), on the 4th instar
larvae of Locusta migratoria. The obtained results showed that the latex revealed an interesting
insecticidal activity against L. migratoria larvae, resulting in a mortality reaching 96.49 %, 6 days after
treatment. Toxicity bioassays revealed that PAN, associated with the latex, is able to accelerate and to
increase the mortality rate. Pheromone-based treatment affected the health of treated insects by
significantly reducing their respiratory rhythms. PAN was shown able to alter, quantitatively and
qualitatively, the larval blood cells as expressed by the significant decrease in the number of the
differential haemocyte counts (prohemocyte, plasmatocytes and granulocytes) and the important cell
lysis