EFEITO RESIDUAL DE FORMULAÇÃO MICROENCAPSULADA DE GRAVIOLA SOBRE Plutella xylostella L. (LEPIDOPTERA: PLUTELLIDAE) EM CAMPO

Abstract

The present work aimed to evaluate the residual power of a formulation of the ethanolic extract of Annona muricata (graviola) seeds on Plutella xylostella under field conditions. Tests were performed in two seasons (winter and summer), evaluating the residual effect  of the formulation on 1st instar larvae. For such 160 potted cabbage plants were distributed in the field in rows of 10 plants. After reaching 8 to 10 definitive leaves, they were sprayed with the microencapsulated LC₅₀ and LC₉₅ (estimated in previous work), Azamax® (200 mL / 100L) and distilled water + Tween® (Control), being 40 plants for each treatment; using a costal spray, depositing a spray volume of approximately 100 mL / plant. After two hours leaves were taken from the central plants of the beds of each treatment. These were taken to the laboratory and made seven discs of each treatment. These discs were placed in petri dishes and ten larvae were deposited in each one, totaling seven plates for each treatment. After three days the number of dead larvae was evaluated. This process was performed every two days until the mortality caused by the products was close to the control. The experiments in both seasons were conducted following the same methodology. Data were subjected to statistical analysis in factorial scheme (2 x 4 x 7) (Times x Treatments x Days) and means compared by Tukey test using the SAS statistical program. There was interaction between the three factors tested (F = 1,689; P = 0,0396). As well as interaction between the factors (days x treatments) for the two separate seasons: summer (F = 1.83; P = 0.0252) and winter (F = 3.86; P <0.0001). The results showed that the microencapsulated (CL95) was effective until the eighth day after application independent of the time causing mortality greater than 50% resembling the commercial product AZAMAX®.