Vermicomposts intensify the effects of herbal extracts and synthetic insecticides on population growth parameters of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The cotton whitefly, Bemisia tabaci (Hem: Aleyrodidae) is an important pest of a wide variety of agricultural crops across the world. The control of B. tabaci largely relies on wide application of chemical insecticides. However, development of alternative methods for integrated management of this pest is favored with respect to the rapid development of resistance to insecticides, as well as harmful effects of these compounds on human health, environment and non-target organisms. In this research, the effects of abamectin and three herbal extracts, taken from Sophora alopecuriodes (Fabaceae), Ricinus communis (Euphorbiaceae), and Aloe vera (Liliaceae), in combination with vermicomposts taken from two waste sources (cattle manure (CMV) and pistachio waste (PWV)) were studied on population growth parameters of B. tabaci. Tomato seeds (variety CH-Felat) were planted in plastic pots containing one of the three following media: (i) 100% sterile plant growth media (BAGA); (ii) 70% BAGA and 30% PWV; (iii) 70% BAGA and 30% CMV. The resultant leaflets were dipped in 25% lethal concentration (LC25) of each herbal extract and abamectin for 5 s, and 20 adult B. tabaci were released in cages containing each pot. After 24 h, adults were removed and the eggs were incubated for life table studies. This experiment was performed in a growth chamber with controlled condition and data were analyzed using the age-stage two-sex life table. Exposure to abamectin and herbal extracts significantly affected (P<0.05) the net reproductive rate (R0), intrinsic rate of increase (r) and finite rate of increase (λ) of B. tabaci. Vermicompost treatment intensified the effects of the insecticides on all studied parameters, with the highest and the lowest values of r, λ, R0 were recorded for whiteflies in BAGA and PWV groups, respectively. The highest values of r, λ and R0 (0.153±0.039 day-1, 1.165±0.0045 day-1 and 43.30±4.05 offspring/individual respectively) were recorded for whiteflies in BAGA group with no insecticide application (control). Whereas, whiteflies in PWV group that had been treated with Aloe vera extract exhibited the least values of r, λ and R0 (0.0252±0.0099 day-1, 1.025±0.010 day-1 and 1.900±0.466 offspring/individual, respectively). According to our results, combined application of herbal extracts and environmentally friendly vermicomposts, together with other types of IPM strategies, may improve the control efficiency of B. tabaci under greenhouse condition. In this context, the use of A. vera extract in combination with PWV proved to more efficiently affect population growth parameters of B. tabaci.
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