No abstract

A series of foraging bouts of Episyrphus balteatus (DeGeer) females were observed and recorded throughout the day in phacelia (Phacelia tanacetifolia Bentham) patches. The dominant transitions of interplant movement, approaching and probing bouts were statistically more frequent in the morning than in the afternoon. In the morning, interplant movement of foragers was significantly longer and they were moving at higher places of phacelia patches. They approached and probed flowers considerably longer in morning compared to afternoon. A significant positive relationship between the number of open flowers in a patch and the patch residence time was observed in the morning. The proportion of females having swollen abdomen filled with phacelia pollen (68.2%) in the afternoon was significantly higher than that (31.82%)in the morning. In our study, E. balteatus females spent more time foraging in phacelia patches in morning compared to afternoon. Based on the results and by considering the dual resources requirements of a female hoverfly (flower foraging and searching for aphids to lay eggs), we will discuss the effective diurnal foraging of E. balteatus females in phacelia patches.

The study was carried out to detect and quantify the left over residue of fenvalerate and acephate in tomato and yard long bean using Gas Chromatography coupled with Flame Thermionic Detector. Four supervised field trials were undertaken sprayed with the prescribed dose of fenvalerate at the rate of 1mL/L of water and acephate at the rate of 2g/L of water. The samples of tomato and yard long bean were collected at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15 days after spray (DAS). The residue of acephate was detected up to 11 DAS in tomato and 14 DAS in yard long bean and all of the detected quantities were above Maximum Residue Limit (MRL) set by European Union. No residue was detected at 12 DAS in tomato and 15 DAS in yard long bean. The residue of fenvalerate was detected up to 12 DAS in tomato and 13 DAS in yard long bean, of which the quantities of residue of fenvalerate was above EU-MRL at 9 DAS in tomato and 11 DAS in yard long bean. Fenvalerate contained 0.076-0.008 mg/kg residue in tomato and 0.049-0.021 mg/kg residue in yard long bean which were below EU-MRL at 10 to 12 DAS in tomato and 12 to 13 in yard long bean which were below EU-MRL. No residue was detected at 13 DAS in tomato and 14 DAS in yard long bean. So, in case of acephate the pre-harvest interval (PHI) was determined at 12 DAS in tomato and 15 DAS in yard long bean and for fenvalerate it was 10 DAS in tomato and 12 DAS in yard long bean. Asian Australas. J. Food Saf. Secur. 2022, 6 (2), 73-80