Effect Of Some Plant Extracts and Nicotinamide on Certain Histopathological Aspects In The Red Palm Weevil Larvae, Rhynchophorus Ferrugineus (Oliver) (Coleoptera: Curculionidae)

摘要

BACKGROUND The red palm weevil Rhynchophorus ferrugineus (Oliver) is a devastating insect pest of date palm, hatched grubs burrow into the trunk and feed on tissue of the stem, larvae and adult emergence within the same stem allow successive generations. However, little studies had applied on the insecticidal effect against the insect. OBJECTIVE In the present study, Larvae of the red palm weevil, Rhynchophorus ferrugineus of the second-generation fed on pieces of date palm core rinsed in sub-lethal concentrations (LC50s) of nicotinamide IGR, in addition to two crude plant extracts of Carapichea ipecacuanha and Eucalyptus camaldulensis, to show their toxicological and histopathological effects on the treated larvae.RESULTS The phytochemical studies showed two major fractions; piperine and rhodopin extracted from Carapichea ipecacuanha; gallic acid and lucenin-2extracted from Eucalyptus camaldulensis. The toxicological studies showed nearable effects and results in nicotinamide and crude extract of Carapichea ipecacuanha, while that of Eucalyptus camaldulensis was the least. The histopathological studies showed hazard malformation in the epithelial layer of the dissected treated larval midgut. CONCLUSION The present study demonstrates that both natural acetonic plant extract of Carapichea ipecacuanha and Eucalyptus camaldulensisis addition to synthetic nicotinamide IGR are capable of production of high mortality rates of Rhynchophorus ferrugineus larvae. The study further reveals that plant extracts and IGR exert effects on larval midgut histology, in this way, disrupt midgut epithelial layer of treated larvae. These disruptions may be the cause of strong larvicidal activity. Very nearable results of both nicotinamide IGR and Carapichea ipecacuanha extract may be due to presence of alkaloid fractions in both.