Bioatividade do extrato de mastruz (chenopodium ambrosioides L.) no controle de alphitobius (Panzer, 1797)(Coleoptera: Tenebrionidae).

Abstract

The brazilian poultry system has been consolidating as the main national agrobusiness activities in which has contributed at that agroindustrial economy segment of this country. However, it stands out as a potential problem to reducing the poultry productivity the pests, such as the beetle alphitobiusdiaperinus (little bell pepper). against the need of finding alternative methods to the pesticides, of lower impact and risk to the human health and to the environment. Botanical insecticides have benn researched in many Latin American countries. Considering the good prospect for the use of vegetable extracts such as an alternative to the family producers, this work has had its main goal to evaluating the bioinsecticide action of mastruz Chenopodiunambrosioides L., to controlling and repellency of the A. diaperinus, aiming at its use in poultry. For efficiency evaluation, it has used concentration of the 2,5; 5,0; 7,5 and 100% + a witness (0%). The evaluations were carried out among 7, 14, 21 and 28 days after the bioassay installation. For data analysis was used polynomial regression analyse, considering its level concentrations and the evaluation times. For each concentration, it is made six repetitions. The studied variable was the numbers of dead insects, it is also the cumulative average mortality evaluated. The efficiency of the extract on adults of A. diaperinus was calculated by the ABBOTT method (1925) for all evaluations. In the bioassay on repellency, it was simulated the condition of poultry, using in each experimental unity rice straw and poultry feed. In each repetition, it has introduced 30 adult insects of A. diaperinus, not sexed, with 24 hours of starvation. The number of dead and alive insects in the treated receptors and not treated as well, and they were evaluated 24 hours after the introduction of the insects. The repellency index (IR) was calculated by the formula IR= 2G ( G + P) where G= % of the insects in the treatment and P= % of the insects in the witnesses. The values of IR vary between 0-1, indicating: IR=1, neutral product; IR>1 attractive product and IR<1, repellency product (LIN et al., 1990 ) The values for the repellency index were submitted to polynominal regression of analysis. It was also used the chi-square test (x) (p<0, 05) for comparison between the average number of insects in each of the concentrations studied with the number of the insects in the witness. According to the results, it is concluded that (1) the mastruz extract has presented lower control efficiency over adults A. diaperinus; (2) propably the filter paper failed to retain the mastruz extract, therefore, presenting little insecticidal action on A. diaperinus and; (3) the mastruz extract presented repellentaction and attractive to the concentrations of the 2,5; 5,0 and 10% and 7,5% respectively.