Table 2

Mosquitocidal and hemolytic activities of Cyt1Ab1 inclusions, solubilized and proteolytically processed against third instar C. quinquefasciatus larvae and sheep red blood cells


Half Lethal Concentration

(LC50) g /ml

Half Hemolytic Dose

(HD50) g/ml

Cyt1Aa1crystal inclusions

Cyt1Ab1crystal inclusions

0.74 (0.5-0.9)*

1.3 (0.9 -1.7)


Not hemolytic

Cyt1Ab1 Solubilized

Not toxic

4.5 (3.4-6.1)

Cyt1Ab1 activated by C. quinquefasciatus gut extracts

Not toxic

1.4 (0.4-2.0)

Cyt1Ab1 activated by trypsin

Not toxic

2.2 (1.6-3.3)

Cyt1Ab1 activated by chymotrypsin

Not toxic

1.9 (1.5-2.6)

*Values represent the 95% confidence limits, determined by Probit analysis.



The alkali-solubilized toxin showed an HD50 of 4.5 g/ml in sheep red blood cells, this activity was potenciated when the toxin was in vitro processed by mosquito larvae gut extracts, trypsin and chymotrypsin. Mosquitocidal activity assay of the Cyt1Ab1 against third instar C. quinquefasciatus larvae showed a LC50 of 1.3 g/ml. In contrast, the soluble and processed toxin did not show any toxicity in the bioassays evaluated, even at the concentration of 25 g/ml.