Sunning as a technique for disinfesting stored beans

Abstract

The effectiveness of sunning (solar heating) as a small farm technique for controlling the bean bruchids Zabrotes subfasciatus (Boheman) and Acanthoscelides obtectus (Say) was investigated. Bean seeds infested with mixed-stage larvae were placed on clear or black polyethylene sheets or inside polyethylene pouches with clear upper and black lower surfaces and exposed to the sun for five hours each day for 0, 3 and 5 successive days. No live insects emerged from seeds heated in the pouches while the few that emerged from seeds on the black sheets resulted in damage to less than 1% of the seeds. Of the three polyethylene systems used, the clear sheet was the least useful, while the pouches even for only 3 days, were the most effective in eliminating infestations. These studies demonstrated that effective bruchid control can be achieved with daily 5-h exposure periods of seeds for a successive 5-day duration. However, the success of the method of control may be influenced by the time of the year and prevailing environmental conditions.