Comparing the effectiveness of a biopesticide with three synthetic pesticides for aphid control in wheat.

摘要

An experiment was conducted on two wheat cultivars, Inqilab-91 and Saleem 2000, in Peshawar, Pakistan, during 2004-05 to compare the efficacy of a biopesticide (Bacillus thuringiensis+abamectin at 1 g l-1) with different synthetic pesticides (Lorsban (chlorpyriphos) at 5 ml, Trend (acetamiprid) at 4 ml and Megamos (methamidophos) at 1.25 ml l-1) against wheat aphids. Three aphid species, namely Rhopalosiphum padi, Schizaphis graminum and Sitobion fragariae, were collected from the host. The aphid density on Saleem-2000 was significantly lowest in Lorsban treatment with 0.67, 0.76, 2.16 and 8.55 aphids per leaf, while significantly highest in Trend treatment with 1.87, 2.17, 3.60 and 11.55 aphids per leaf after 1, 2, 3, and 7 days of chemical treatment, respectively. The mean aphid density per leaf over the entire two-week period was significantly lowest in Lorsban and highest in Trend treatments. The mean aphid density in the control during this period increased from 21.3 to 31.2 per leaf (9.2-38.2%). The aphid density on Inqilab-91 was significantly lowest in Lorsban treatment with 1.31, 2.66, 1.75 and 3.89 aphids per leaf-1, while highest in Trend with 3.33, 2.10, 3.90 and 6.36 aphids per leaf after 1, 2, 3, and 7 days. The mean aphid density per leaf over the entire two weeks was significantly lowest in Lorsban and highest in Trend treatment. The mean aphid density in the control during this period increased from 26.2 to 36.4 per leaf (33.8-52.3%). The mean yield (kg ac-1) of Saleem-2000 was significantly highest in Lorsban (734), Megamos (716) and BtA (713), while lowest in Trend (676) as well as the control (675). On the other hand, the mean yield (kg ac-1) of Inqilab-91 was significantly highest in Lorsban (644), Megamos (622) and BtA (616), while lowest in Trend (615) and the control (585 kg).