Effects of different application methods of azadirachtin against sweetpotato whitefly Bemisia tabaci Gennadius (Hom., Aleyrodidae) on tomato plants

Abstract

Studies on three different neem treatment methods (seed, soil and foliar) and two different commercial neem products (NeemAzal T/S 1% azadirachtin and NeemAzalU 17% azadirachtin) against sweetpotato whitefly (WF) Bemisia tabaci Gennadius (Hom., Aleyrodidae) on tomato plants were conducted in cages in air-conditioned cultivation rooms. All three methods of neem treatments resulted in reduced colonization and oviposition. Overall oviposition intensity was significantly reduced (44%) by the treatment of tomato seeds but an even higher reduction (74%) was achieved through soil drenching both with 3.0 g/l NeemAzalU and foliar spraying (82%) with 10 ml/l of NeemAzal TS compared with control treatments. In contrast, soil and foliar treatment increased fecundity per female up to 33% and 32%, respectively, at the highest tested concentrations. Reduced egg hatch could be observed only at high neem concentrations; 62% and 51% of deposited eggs hatched at the highest dose rates of NeemAzalU in case of seed and foliar treatments, respectively; whereas only 43% of deposited eggs hatched in case of foliar treatments at highest dose rates of NeemAzal T/S. Seed (35%), foliar (93%) and soil treatments (91%) caused high mortality rates of immatures and reduced number of hatching adults compared with control plants treated with a blank formulation or water. The mortality among immatures increased in relation to azadirachtin concentrations. Concerning susceptibility of different developmental stages, young larvae were the most sensitive. Foliar treatment was the most efficient, with 100% mortality for all three larval stages at high concentrations (10 ml/l of NeemAzal T/S) compared with 78-87% mortality with soil treatment (at 3.0 g/l NeemAzalU). The findings are discussed in the context of integrated control of WF in protected cultivation environments in the humid tropics.

Bio-rational management of whitefly (Bemisia tabaci) for suppressing tomato yellow leaf curl virus

“…The findings of the present study are in agreement with Kumar et al (2005); Hilje et al (2001); Palumbo et al (2001); Csizinsky et al (1997) and Sastry, (1989) who also found that uprooting, application of oils and insecticides had some positive impact on disease reduction and yield increase. Among the tested oils, neem was found as the best to reduce the TYLCV disease incidence of tomato and there by produced higher yield.…”

Toxicity of neem oil to Bemisia tabaci biotype B nymphs reared on dry bean

“…The insecticidal effect of neem in specifi c nymphal stages of B. tabaci was recently reported. However, mean comparisons between these stages were not performed (Kumar et al, 2005;Kumar & Poehling, 2006. These authors also observed high susceptibility of the fi rst three nymphal stages to neem foliar application, inferring that the fi rst instar was more susceptible than the fourth one.…”

Bazı bitki ekstraktlarının Avrupa Sünesi [Eurygaster maura L. (Heteroptera: Scutellaridae)]'nin farklı dönem nimflerine toksik etkileri

“…Gelişme dönemi ilerledikçe böceklerde kimyasallara karşı etkilenmenin azaldığı sonucu birçok araştırıcı tarafından da rapor edilmiştir (Kumar et al, 2005;Gökçe et al,2006;Ateyyat et al, 2009;Silva et al, 2012).…”