Institution of the Agricultural Research and Higher Education
Abstract
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