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VOL. 11, ISSUE 1 (2026)
Toxicological and control efficiency of chitosan and congest against Eutetranychus orientalis and Tydeus californicus under laboratory and semi-field conditions
Authors
Rania H Mahmoud, Asmaa R Abdel-Khalik, Rania A El-Nahas
Abstract
Eutetranychus orientalis
and Tydeus californicus infestations are a major threat to eggplant
production, requiring effective and environmentally friendly control
strategies. Thus, the study aimed to investigate the bioassays, reproductive
effects, and semi-field efficacy of congest and chitosan against immature and
adult stages of both mite species. Significant acaricidal activity was
demonstrated by congest and chitosan against E. orientalis and T.
californicus; compound type, concentration, and exposure duration all had a
significant impact on efficacy. Congest continuously demonstrated significantly
greater toxicity than chitosan against the two mite species' immature and adult
stages in lab bioassays. Congest had the lowest LC5₀ values (0.022-0.029 for E.
orientalis and 0.025 for T. californicus) after seven days of
exposure, while chitosan continued to be significantly less toxic despite
time-dependent improvement. Both compounds significantly decreased oviposition
and larviposition in a concentration-dependent manner, according to
reproductive assays; congest caused the most suppression (ODI up to 44.75% in E.
orientalis and 35.73% in T. californicus). Congest significantly
reduced mite populations in semi-field conditions; at higher concentrations, it
reduced both the immature and adult stages of the two mite species by more than
90% in just seven days. Chitosan, on the other hand, produced a moderate but
steady degree of suppression that became more noticeable as exposure time and
concentration increased. These results show that while chitosan offers a slower
but dependable complementary control effect, congest is very effective for
rapid mite suppression.
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Pages:51-60
How to cite this article:
Rania H Mahmoud, Asmaa R Abdel-Khalik, Rania A El-Nahas "Toxicological and control efficiency of chitosan and congest against <i>Eutetranychus orientalis</i> and <i>Tydeus californicus</i> under laboratory and semi-field conditions". International Journal of Zoology Studies, Vol 11, Issue 1, 2026, Pages 51-60
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