Assessment of two natural toxin microcystin and nodularin for the control of Anopheles multicolor (Diptera: Anophelidae)

Laboratory experiments were conducted to determine the efficacy of two cyanobacterial toxins (microcystin and nodularin) against the different larval instars, pupal and adult stages of Anopheles multicolor. Experiments were carried out in plastic cups, and the two toxins were tested at four concentrations, where the LC10, LC25, LC50 and LC90 for the first instar larvae under laboratory conditions were 2.95, 3.80, 4.95 and 7.45 μg /ml and 4.37, 6.40, 8.85 and 14.39 μg/ml for microsystin and nodularin respectively. While the LC50 for the first, second, third and fourth larval instars were 6.70, 8.92 and 9.70 μg/ml for microsystin and nodularin, respectively. The most sensitive instar was the 1st and the most resistance instar was the fourth larval instar. The delayed effects of sublethal concentrations (LC10, LC25 and LC50) of the two tested toxins on some biological activities were also studied and discussed when treating the fourth larval instar.