Year: 2025
Type: conference-paper
Abstract: Neem compounds, derived from the Azadirachta indica plant, especially the fruits and seeds, have a wide range of actions, as they can affect insects, mites, nematodes, fungi and bacteria. Thus, the neem compound, limonoid (azadirachtin) is one, which has been shown to be effective against insects by modifying vital functions in such a way that the insect is unable to feed, mate or undergo metamorphosis. It is also known to inhibit the biosynthesis of the hormone ecdysone that regulates the formation of chitin during moulting in insects. Another extract is neem oil, which has a historical background, is easily accessible and completely safe for fauna and the environment. Neem oil can easily disrupt the life cycle of an insect at any ontogenetic stage egg, larva, adult, without harming beneficial species. The purpose of our research was to evaluate the action of neem oil on the viability of the ontogenetic stages of the wax moth, as a result of contact with the surface treated with an alcoholic solution of the oil of different concentrations and the possibility of subsequent application of the procedure for sterilization of natural populations of Lepidoptera pests by means of pheromone traps. The biological material served as the wax moth, as a test object, from the laboratory culture of the larval stage, V instar and one-day imago. 2-hole lantern bottles were used for the application of the alcoholic solution of neem oil in the variants of 5; 10; 25 and 50%, as a chemical standard the 10% pyriproxyfen solution and the untreated control. The internal surface of the lantern bottles was processed with the given solutions. Larvae and adults separately were subjected to active contact with the processed surface for 5 min. in three repetitions of 10 individuals each. The expression of the effect of the action of the active substances on spermatogenesis and oogenesis of the individuals subjected to contact was analyzed according to the morphological aspect of the pupae, adults, the shape and numerical content of the eggs, as well as the viability at the embryonic and larval stages, expressing the degree of induced sterility and the decrease in the degree of reproduction. It is obvious that the impact of the contact of the individuals with the processed substrate on variants with different concentrations manifested an action directly proportional to the maximum concentration - minimum egg, expressed by the obvious decrease in the number of eggs in the egg. Thus, in the variant with the maximum concentration, practically the females develop a minimum egg and with 90-100% sterility of the eggs. The formation of chitin during the molting of V-instar larvae into pupae was manifested by the deformation of the pupae as a result of the incomplete formation of chitinous tissue. This indicates some changes at the cellular-molecular, functional level, which determine the viability and reproductive potential of adults. A deeper disclosure of the mechanism of the decrease in the reproductive potential of adults, as a result of the contact of larvae and adults with surfaces treated with an alcoholic solution of neem oil and pyriproxyfen, could be expressed by the effect at different ontogenetic stages in F1; F2; F5; which would indicate changes manifested at different molecular, cellular or organ levels. Given the fact that in Lepidoptera species the process of oogenesis and spermatogenesis occurs at the prepupa and pupa stages, it would confirm or deny the action at the cellular or molecular level of azadirachtin and pyriproxyfen.
Institution: Moldova State University
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W7204694334