Potential of Seena septemrionalis and Plucha dioscoridis extracts as alternative acaricidal against Tetranychus urticae Koch (Acari: Tetranychidae)

Senna septemtrionalis (Arsenic bush) Fabaceae and pulchea dioscoridis (pluchea) Asteraceae were collected from farm of faculty of Agriculture, Al-Azhar University, Assiut, Egypt during flowering stages. The extracts obtained from S. septemtrionalis and P. dioscoridis were tested against two-spotted spider mite Tetranychus urticae Koch as acaricidal. Bioassay experiments were carried out under laboratory and field conditions using two different solvents (Acetone and Methanol) by direct leaf spaying. The amount of plant extracts applied at laboratory condition were 1, 2, 3, 4 and 5% concentrations at 27±2°C temperatures and 65±5% relative humidity (RH.) on adult females and eggs of T. urticae. The concentration applied at the field was 4% concentration and dimethyl salphoccied (damson) was used by rate 0.1% as a solvent. The results revealed that, the concentration 4 and 5% gave high mortality than the low concentrations for all solvents. The extracts obtained from P. dioscoridis plant were the highest effective on eggs (67.72% at concentration 5%), adult females (86.51% for acetone and 82.02% for methanol after three days and at concentration 5% under laboratory conditions) and population of T. urticae (71.81 % for acetone and 76.82% for methanol after one week at concentration 4% under field conditions). When, S. septemtrionalis extracted by acetone as solvent gave high results at concentrations 2, 3, 4 and 5% after three days from spraying, while when extracted by methanol was effective only at 4 and 5% concentrations, both plants recorded highly reduction percentages after one week when applied on Cucumis sativus (Cucurbitaceae) cucumber under field condition at concentration 4%. Whereas, the P. dioscoridis extracts were the best. The acetone was the best solvent for both plants.