التحرَّي عن المقاومة الناتجة من استخدام المستخلصات النباتية لنباتي الآس Myrtus communis L. واليوكالبتوس Eucalyptus camaldulensis Dehnh. و مبيد Mazkill في مكافحة يرقات بعوض Culex molestus Forskal و إدارتها

Investigation of resistance by using of plants extracts of Myrtus communis L. and Eucalyptus camaldulensis Dehnh. in control of the larvae of Culex molestus Forskal mosquitoes and its management

SUMMARY
The present study was conducted with the aim of evaluating the sensitivity of the domestic mosquito Culex molestus Forskal (1775) in the Holy City of Kerbala for the year 2021 , the effect of selective pressure for extracts of Myrtus communis, Eucalyptus camaldulensis and Mozkill in fourth-instar larvae of mosquitoes on the appearance of resistance and the possibility of inhibiting resistance in mosquitoes. A case study of resistance inversion, as well as a study of phenotypic distortions that could be caused by the plant extracts used in the study, and a study of the ages of immature and adult roles resulting from the treatment of the fourth larval instar of mosquitoes.
The results of the study showed the presence of susceptibility in the Cx. molestus mosquito strain for plant extracts and Mozkill after three generations, where the LC50 values were 0.72, 0.77, 0.2 mg/ml, respectively, for cold and boiled Myrtus extract and hexane, while it reached 1.05, 0.91, 1.15 mg/ml, respectively for cold and boiled Eucalyptus extract and hexane. As for Mozkill, the LC50 value was 1.01 mg/ml, and the strains were more sensitive to Myrtus extracts compared to Eucalyptus extracts and Mozkill.
The results of the selective pressure with plant extracts and larvicide Mozkill showed the appearance of resistance when the insect was exposed to these substances for six generations, where the LC50 values increased to 5.19, 4.29, 2.8 mg / ml, respectively for cold and boiled water extract and hexane of Myrtus and 5.915, 5.82, 5.88 mg/ml, respectively, for the extract of cold and boiled water and hexane of Eucalyptus plant, and the LC50 value of Mozkill was 5.67 mg/ml in the sixth generation, compared with 1.21, 1.26, 0.69 mg/ml, respectively, in the parental generation of the Myrtus plant and 1.19, 1.05, 1.29, respectively for the parental generation of Eucalyptus and 1.05 mg/ml for the parental generation of the larvicide Mozkill, and it was found that there was an increase In the rates of resistance to the mosquito strain with the progression of generations, it was 1.68, 1.63, 3.45 times in the parents’ generation and rose to 7.20, 5.57, 14.0 times in the sixth generation for the cold and boiled extract and hexane, The percentages of resistance to cold and boiled Eucalyptus extract and hexane in the parents’ generation reached 1.13, 1.15, 1.12 times , respectively, and 5.63, 6.39, 5.11 times, respectively in the sixth generation. As for the percentage of resistance in Mozkill insecticide, it reached 1.03 times for the parent generation, , and in the sixth generation it reached 5.61 times, and the development of resistance was evident in the mosquito strains treated with plant extracts and Mozkill pesticide.
The results of the case of reversal of resistance of mosquito strains in which resistance appeared towards the plant extracts used in the study and Mozkill pesticide when left for two generations without exposure to selection pressure with plant extracts and the pesticide, a reversal occurred in the resistance ratios 7.20 , 5.57 , 14.0 times respectively and decreased to in the sixth generation the resistance ratios became 3,59, 2.19, 1.0 times respectively, and in cold and boiled Eucalyptus extract and hexane, the resistance ratios reached in The first generation 5.63, 6.39, 5.11 times, respectively, and the resistance ratios decreased to 3.15, 3.53, 2.82 times in the sixth generation respectively. As for Mozkill, it reached The resistance ratio is 5.61 times in the first generation and decreased to 4.50, 3.39 times, respectively, for the sixth generations.
With regard to the management of resistance, the results showed when using the exchange mechanism between the extracts of myrtle and eucalyptus and Mozkill for five generations was effective in decreasing the resistance rates for mosquito strains, as there was a decrease in LC50 values and resistance rates when using cold Myrtus extract, so the LC50 value reached 5.19 mg / ml, and the resistance ratio was 7.20 times, respectively, in the sixth generation, and when exchanging using cold Eucalyptus extract, the value of LC50 and resistance ratio decreased to 1.20 mg / ml and 1.66 times, respectively, in the tenth generation, and when using Eucalyptus extract The values of LC50 and the resistance ratio in the sixth generation reached 5.915 mg/ml and 5.63 times, respectively, and when exchanged with cold Myrtus extract, the value of LC50 and the resistance ratio decreased to 2.25 mg/ml and 2.14 times, respectively, in the tenth generation. When exchanging between Mozkill and cold Myrtus extract, the value of LC50 and resistance ratio reached 5.67 mg / ml and 5.61 times, respectively, in the sixth generation, and these ratios decreased to 2.61 mg / ml and 2.58 fold, respectively, in the tenth generation. and at the exchange between Mozkill and cold Eucalyptus extract decreased the value of LC50 and the resistance ratio to 2.02 mg / ml and 2.0 times, respectively, in the sixth generation.
Several of phenotypic abnormalities of the larvae treated with plant extracts and the subsequent roles of the insect were observed when treating the fourth instar larvae of the mosquito under study (the pupae and adults resulting from the treated larvae) it was noticed that the percentage of abnormalities decreased with the progression of the generations treated with the concentrations , and this percentage of abnormalities decreased with the decrease in the concentration .
That studying the effect of these plant extracts and Mozkill pesticide in the average lifespan of fourth-instar larvae, pupae and adults resulting from the treatment, it was noted that the age rate decreased compared to the control treatment.