EFFECT OF EMAMECTIN BENZOATE ON SEVERAL LARVAL STAGES OF COTTON LEAFWORM ALABAMA ARGILLACEA HÜB. (LEPIDOPTERA:NOCTUIDAE)

AÇÃO DO BENZOATO DE EMAMECTIN SOBRE DIVERSOS ESTÁGIOS LARVAIS DO CURUQUERÊ-DO-ALGODOEIRO ALABAMA ARGILLACEA HÜB. (LEPIDOPTERA:NOCTUIDAE)

The objective of this work was to determine the performance of emamectin benzoate on several larval stages of cotton leafworm. The statistical design was full random distribution, with seven treatments and four replicates, and the trial was conducted in laboratory conditions. Two types of application were made: directly on the insect and on leaves that were later given to the insects to feed. The four larval stages used were determined as described: under 0.5 cm lenght, between 0.51 and 1.0 cm, between 1.01 cm and 2.0 cm and above 2.01 cm. The direct application was also made on pupae and pre-pupae stages. The treatments were: emamectin at 3.84, 5.76, 7.68 and 9.6 g a.i./ ha; abamectin at 9.0 g a.i./ha; lufenuron at 15.0 g a.i./ha and one untreated check. Larvae mortality was assessed at 12, 24, 48 and 72 hours after the treatment for both direct application and leaf application. The conclusion about the application on leaves was that all larval stages died 12 h after starting eating the leaves treated with emamectin at 9.6 g a.i./ha and 24 h after starting eating the leaves treated with emamectin at 7.68 g a.i./ha. Emamectin at 3.84 and 5.76 g a.i./ha promoted high mortality of larvae under 1.0 cm, 48 hs after start feeding. High larvae mortality was observed on leaves treated with lufenuron 48 hs after feeding started although later stages were able to transform into pupal stage. All treatments applied directly on the insects provided high mortality on larvae smaller than 1.0 cm. The mortality was also high for all treatments on larvae bigger than 2.01 cm but less than the mortality on younger larvae.

KEY WORDS:
Cotton leafworm; emamectin; abamectin; lufenuron.