Trypsin inhibitor fromEnterolobium contortisiliquumseeds impairsAedes aegyptidevelopment and enhances the activity ofBacillus thuringiensistoxins

BACKGROUND Disease vector insects are barriers for human development. The use of synthetic chemicals to control these vectors has caused damage to the environment and contributed to the arising of resistant insect populations. This has led to an increased search for plant-derived molecules with insecticidal activity or that show synergistic effects with known insecticidal substances, such as protease inhibitors. Thus, we aimed to evaluate the effect ofEnterolobium contortisiliquumtrypsin inhibitor (EcTI) onAedes aegyptidevelopment as well as its effect on insecticidal activity ofBacillus thuringiensistoxins. RESULTS EcTI showed an apparent molecular mass about of 20 kDa in SDS-PAGE and was able to inhibitin vitrothe activity of trypsin and proteases from midgut ofAe. aegyptilarvae. EcTI was not able to cause acute toxicity on mosquito larvae even at 1000 mu g mL(-1), however it promoted a delay in larval development after prolonged exposure. The zymogram results for EcTI-treated larvae (from 50 to 200 mu g mL(-1)) showed an increase of midgut proteases activity as a larvae defense mechanism, however no changes in the enzyme profile was observed. These same concentrations were able to enhance up to three fold the insecticidal activity ofB. thuringiensistoxins without causing toxicity toArtemiasp. nauplii, a non-target organism. CONCLUSIONS The results offer a novel approach by combining EcTI andB. thuringiensistoxins for combatingAe. aegyptilarvae.