Susceptibility of Culex pipiens L. in Sharkia Governorate, Egypt to Chitin Synthesis Inhibitors and their Biochemical Characterizations

F.A. El-Sitiny, Mona; E. Gad, Mohammed; F. Khater, Hanem; G. Mahmoud, Mohammed

doi:10.21608/bjas.2023.320686

Susceptibility of Culex pipiens L. in Sharkia Governorate, Egypt to Chitin Synthesis Inhibitors and their Biochemical Characterizations

Document Type : Original Research Papers

Authors

¹ Plant Protection Department, Agricultural Faculty, Zagazig University, Egypt

² Zoology Department, Faculty of Science (Boys) Al-Azhar University, Naser City, Cairo11884, Egypt

³ Parasitology Department, Faculty of Veterinary Medicine, Banha University, Egypt

10.21608/bjas.2023.320686

Abstract

Culex pipiens is an important vector in Egypt. The tolerance levels of insect growth regulators (IGRs) on 4th
instar larvae of Cx. pipiens collected from the Faqous region, Sharkia Governorate, Egypt, and their biochemical
characterization were determined. The data indicated that LC50 values post-treatment (PT) of the field strain with
diflubenzuron, novaluron, and lufenuron were 0.08, 0.60, and 0.16 μg/ml, respectively. Whereas the corresponding values
for the laboratory strain were 0.07, 0.16, and 0.02 μg/ml, respectively. The relative tolerances of the field strain reached 1.14
(low), 3.75 (medium), and 8.00 (high) folds, respectively, when compared to the laboratory strain. The total protein
levels in larvae treated with diflubenzuron, novaluron, and lufenuron and those of laboratory strain were 17.00, 20.00,
27.33, and 13.33 mg/g b.wt, respectively, whereas such values for the target enzyme of acetylcholine esterase,
AChE, were 210.00, 283.33, 310.00, and 225.00 AChBr/min./g.b. wt, respectively. Their effect on the detoxifying
enzymes reached 242.00, 386.67, 483.33, and 235.00 µ Meb min-1 mg-1 protein, respectively, for carboxylesterases;
28.00, 35.67, 62.33, and 22.00 µmol min-1 mg-1 protein in case of glutathione- S- transferase; 560.00, 723.33,
921.67, and 503.33 ηmol min-1 mg-1 protein, respectively, for α – esterase; and 128.33, 151.67, 175.00, and
131.67, ηmol min-1 mg-1 protein, respectively, for β – esterase. The tolerance levels for the applied IGRs revealed
that the field strain from the Faqous region was highly tolerant to lufenuron, followed by novaluron, and
diflubenzeron; therefore, diflubenzeron is the IGR of choice to be applied in such area.

Keywords