The potential of middle eastern flora as a source of new safe bio-acaricides to control Tetranychus cinnabarinus, the carmine spider mite

Twenty-nine plant extracts of local species were evaluated for their potential as a source of bioactive ingredients with significant acaricidal activity that could lead to the development of new and safe bio-acaricides. The crude extracts (70% ethanol) of these plants were tested for their acaricidal activity against the carmine spider mite Tetranychus cinnabarinus in a bioassay under controlled conditions. Mortality, repellency, and the number of eggs laid were measured. Extracts from Eucalyptus camaldulensis and Inula viscosa caused more than 25% mortality. Sixteen plant extracts showed significant repellency compared with the control. The six best extracts, resulting in more than 75% repellency, were from Allium sativum, Capparis spinosa, Cupressus sempervirens, Lupinus pilosus, Rhus coriaria and Tamarix aphylla. Extracts from 16 plants were found to cause a significant reduction in the number of eggs laid compared with the control. The greatest reduction was achieved by extracts from C spinosa, Cyperus rotundus, E. camaldulensis, L pilosus, Punica granatum, R. coriaria and T aphylla. A relatively negative fit was found between the mean number of repelled mites and the number of eggs laid (r=-0.65), which might indicate that most repelled mites were unable to lay eggs before leaving the leaf discs of the bioassay. Our results show that several plant extracts have good potential for acaricidal activity and are worth further investigation.