Abstract:
As part of the valorization of Saharan plants and the search for natural
alternatives to chemical insecticides, this study aimed to evaluate the insecticidal
activity of aqueous and methanolic extracts of Zilla macroptera against adults of
Tribolium castaneum (Coleoptera: Tenebrionidae), a major pest of stored food
products. The extracts were obtained by maceration and applied using two methods:
direct contact and ingestion. The insecticidal effect was assessed under in vitro
conditions.
Bioassays were carried out using different concentrations (20, 40, 60 mg/ml)
over exposure periods of up to 10 days. The main evaluated parameters were lethal
doses (DL25, DL50, DL90) and lethal times (TL25, TL50, TL90). The results showed that
insecticidal efficacy was influenced by the applied concentration, solvent type, and
mode of application. The methanolic extract demonstrated greater toxicity at lower
doses, while the aqueous extract acted more rapidly at high concentrations.
In contrast, ingestion resulted in very low efficacy, with TL50 values exceeding
several hundred hours, indicating limited digestive bioavailability. However, contact
application produced significant mortality rates starting from the fifth day of exposure.
These findings highlight the insecticidal potential of Zilla macroptera and
support its use in developing natural plant-based insecticides within an environmentally
friendly biological control strategy. Further studies are recommended to identify the
active compounds responsible for the observed toxicity
