İstanbul'da sivrisinek öücadelesinde larvasit olarak kullanılan Bacillus thuringiensis subsp. israelensis ve Bacillus sphaericus'a karşı direnç gelişiminin araştırılması

Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis are used as larvicides for mosquito control in Istanbul. We conducted this study between 03/07/2018 and 14/08/2020 and investigated whether the dominant C. pipiens species developed resistance to these bacteria in 39 districts of Istanbul. It was found that bacteria of Bacillus thuringiensis subsp. israelensis type killed 99.75% of C. pipiens larvae within 24 h and 100% within 48 h. It was determined that Bacillus sphaericus type bacteria killed 84.72 % of C. pipiens larvae within 24 h and 91.93 % within 48 h. According to our empirical observations and Abbott's formula results, resistance to Bacillus thuringiensis subsp. israelensis type bacteria was not detected in C. pipiens larvae, but resistance to Bacillus sphaericus type bacteria was detected in 5 regions and 13 counties. The region with the highest resistance was region 1 with an Abbott value of 0.84, and the region with the lowest resistance was region 6 with an Abbott value of 0.98. With an Abbott value of 0.70, the population of Esenyurt district had the highest resistance to B. sphaericus, while the population of Ümraniye district had the lowest resistance with an Abbott value of 0.89. One-Way Analysis of Variance (OWA) for independent groups was used to detect a possible difference that may exist between regions with resistant C. pipens larvae based on Abbott values tested for B. sphaericus, and Analysis of Covariance (ANCOVA) was applied to compare the effect value of B. sphaericus from the 24th and 48th hour. It was found that there was a significant relationship (p<0,05) in the differences between statistical analyzes. From the multiple comparison tests, Tukey HSD and Abbott 48-hour measurement, there was a significant difference between the effect values of B. sphaericus only in region 1 and region 6, with the Post Hoc test, and it was found that region 4 had a significant difference from other regions in the 24-48 hours change. As a result, we can see that the points of resistance are decreasing in the regions and spreading from the centre to the countryside. By studying the protease activity of the resistant C. pipiens larvae, we tried to show the relationship between the increase of protease enzymes and resistance compared with the control group. We measured the level of protease activity in C. pipiens larvae that became resistant in the regions; the highest region 3 had a protease activity of 10.75 U/mg protein, and the lowest region 1 had a protease activity of 5.83 U/mg protein. In our experimental study of resistance, we have shown that there is a correlation between the development of resistance to B. sphaericus and protease activity, but we believe that further information can be obtained with genetic diversity and mutational analysis to explain the mechanism.