Comparative assessment of the fumigant action of volatile oils from three garlic cultivars on faba bean beetle Bruchidius incarnatus (Boh.)

Abstract

The study aims to assess the insecticidal activity, oviposition inhibitory and ovicidal effects of volatile oils from different garlic cultivars on faba bean beetle, Bruchidius incarnatus (Boh.) (Chrysomelidae: Bruchinae). The oils were tested at various concentrations and time intervals.  Results showed that all volatile oils caused significant mortality to the test insects. The effects were time and dose-related. The 72 h median lethal doses (LD50%) of male and female B. incarnatus were 0.03 and 0.006% (Chinese oil); 3.77 and 0.06% (Egyptian oil) and 0.03 and 3.77% (Sudanese). The respective median lethal times (LT50, at 0.01%) for male and female were 55.88 and 57.57 h (Chinese oil); 48.62 and 57.76 h (Egyptian oil) and 79.93 and 84.99 h (Sudanese oil). The results of egg hatchability of B. incarnatus exposed to the lowest concentration (0.01%) were: 31, 32 and 34% for Chinese, Egyptian and Sudanese oils, respectively. The respective median lethal doses (LD50 %) for Chinese, Egyptian and Sudanese oils were 0.025, 0.034 and 0.21%. The results indicated that there were significant differences among the three garlic oils; however, the efficacy of the three types of garlic oils against the test insects can be in this order: Chinese> Egyptian> Sudanese oil. Key words: Bruchinae, fumigation, faba bean, garlic.