The effects of some botanical insecticides and pymetrozine on life table parameters of silver leaf whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae)

Abstract

The objective of this research was to assess the effects of extracts of two medicinal plant species: Allium sativum (Linn) and Calotropis procera (Aiton), and a formulation containing azadirachtin on life table parameters of silver leaf whitefly (SLW), Bemisia tabaci biotype B (Gennadius) (Hemiptera: Aleyrodidae), grown on greenhouse tomato plants. The effects were compared to that of pymetrozine, a synthetic insecticide. Bioassays were carried out in a greenhouse under controlled conditions of 27 ? 2?C, R.H. of 55 ? 5% and 16:8 h (L:D) photo period. All treatments significantly affected the survivorship and fertility of SLW female adults, reducing the net reproduction rate, mean generation time and intrinsic rate of increase of this insect. The net reproductive rate [R0] values for the populations treated with garlic extract, milkweed extract, pymetrozine, azadirachtin, control for extracts (ethanol + distilled water) and control for pesticides (distilled water) were 23.58, 19.32, 10.78, 8.23, 49.66, 57.55; the intrinsic rate of increases [rm] were 0.134, 0.139, 0.110, 0.090, 0.177, 0.178; the mean generation times [T] were 23.49, 21.23, 21.66, 23.50, 22.06, 22.69; the doubling times [DT] were 5.14, 4.95, 6.27, 7.56, 3.91, 3.87, and the finite rates of increase [?] were 1.144, 1.149, 1.116, 1.094, 1.193, 1.195, respectively. Azadirachtin had the highest effect on the life table parameters of SLW. Our findings indicated that, although herbal extracts were not effective as much as the chemical insecticides, they can be effective in pest control. Therefore, they are suitable choices for replacing chemical insecticides and for alternative use with azadirachtin in SLW IPM program.Cilj ovog istrazivanja bio je da se proceni delovanje ekstrakta dve lekovite biljne vrste, Allium sativum (Linn) i Calotropis procera (Aiton), kao i formulacije azadirahtina na zivotne parametre leptiraste vasi duvana Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) gajene na biljkama paradajza u stakleniku. Delovanje je uporedjeno sa sintetickim insekticidom pimetrozinom. Biotest je uradjen u stakleniku pod kontrolisanim uslovima, na temperaturi od 27 ? 2?C, pri relativnoj vlaznosti 55?5% i sa fotoperiodom 16:8 h (D:N). Svi tretmani su imali znacajan uticaj na prezivljavanje i plodnost odraslih zenki leptiraste vasi duvana, smanjujuci neto stopu reprodukcije, srednje vreme generacije i prirodnu stopu rasta ovog insekta. Vrednosti neto stope reprodukcije [R0] za populaciju tretiranu ekstraktom belog luka, ekstraktom kalotropisa (sodomske ili mrtvomorske jabuke), pimetrozinom i azadirahtinom, kao i kontrolom za ekstrakte (etanol + destilovana voda) i kontrolom za pesticide (destilovana voda) bile su 23,58; 19,32; 10,78; 8,23; 49,66; 57.55; vrednosti prirodne stope rasta [rm] su bile 0,134; 0,139; 0,110; 0,090; 0,177; 0,178; srednje vreme generacije [T] bilo je 23,49; 21,23; 21,66; 23,50; 22,06; 22,69; vreme udvostrucenja [DT] 5,14; 4,95; 6,27; 7,56; 3,91; 3,87; i konacna stopa rasta [?] 1,144; 1,149; 1,116; 1,094; 1,193; 1,195; respektivno. Azadirahtin je imao najvece dejstvo na zivotne parametre leptiraste vasi duvana. Rezultati ispitivanja su pokazali da biljni ekstrakti, iako nisu imali izrazeno delovanje kao hemijski insekticidi, mogu biti efikasno upotrebljeni u suzbijanju stetnih insekata. Otuda su oni pogodni kao alternativa hemijskim insekticidima, a mogu se upotrebiti i sa azadirahtinom u integralnom upravljanju leptirastom vasi duvana.