Effects of ethanolic extracts of Rubia tinctorum, Ferula gummosa and Nesidiocoris tenuis (Hem.: Miridae) on sweet potato whitefly, Bemisia tabaci (Hem.: Aleyrodidae), and comparison with Spirotetrmat

The efficiency of plant extracts of Rubia tinctorum L. (Rubiaceae) and Ferula gummosa Boiss(Apiaceae) and release of the mirid bug Nesidiocoris tenuis Reuter (Miridae) were compared with Espirotermat to control sweet potato whitefly, Bemisia tabaci Genn. (Hem: Aleyrodidae) in semi-field conditions. LC50 of plant extracts and pesticide for sweet potato whitefly was calculated. In the main experiment, plant extracts and pesticides were sprayed on tomato plants in cages covered with mesh fabric. LC50 values of pesticides and plant extracts were sprayed on plants. Nymph of mirids was hanged to plant tomatoes. Subsequent days after treatment, number of sweet potato whitefly was counted. The experiments were carried out at 25 ±5 °C, 50±5 RH and photoperiod of 16:8 h (L:D). LC50 of R. tinctorum and F. gummosa extracts as well as Espirotermat was 22.359, 45.641 and 0.404 mg/ml, respectively. Post density decreased R. tinctorum and F. gummosa extracts, Spirotermat and the mird bug 86.54, 83.73, 89.16 and 87.67 percent pf egg stage, 80.20, 76.28, 82.56 and 79.38 percent of nymphal stage, 80.66, 75.26, 85.89 and 81.86 percent of total immature stages as well as 81.89, 79.49, 84.85 and 81.98 of total nymphal stages. Findings from experiments could be promising for further studies on plant extract of Rubia tinctorum and the mirid bug as on alternative to chemical pesticides in natural conditions.