Azadirachtin biopesticide: A review of studies conducted on its analytical chemistry, environmental behaviour and biological effects
Titel:
Azadirachtin biopesticide: A review of studies conducted on its analytical chemistry, environmental behaviour and biological effects
Auteur:
Sundaram, Kanth M. S.
Verschenen in:
Journal of environmental science and health. Part B, Pesticides, food contaminants, and agricultural wastes
Paginering:
Jaargang 31 (1996) nr. 4 pagina's 913-948
Jaar:
1996-07
Inhoud:
This paper provides a brief review of studies conducted in our laboratory on the analytical chemistry, environmental behaviour and biological effects of azadirachtin-A, a neem-based pesticide. Azadirachtin-A (AZ-A) was isolated from samples of neem seed kernels, leaves, bark, root and stem, obtained from Kanthayapalayam, South India. The extracts were subjected to column cleanup and AZ-A concentration was quantified by using a high-performance liquid chromatographic (HPLC) method. A flow diagram is given describing the procedures involved. AZ-A was also isolated from four commercial formulations and from several forestry substrates, and its concentration in each sample was quantified by HPLC. To investigate the environmental behaviour of AZ-A, five studies were conducted: (i) persistence of AZ-A on balsam fir and red oak foliage, (ii) dissipation of AZ-A in forest nursery soils, (iii) leaching in sandy loam forest soil, (iv) adsorption and desorption of AZ-A in sandy loam soil, and (v) rate of hydrolysis in buffer solutions and natural waters. A summary of the data is given in the paper. The biological effects of azadirachtin on two-spotted spider mites infecting young trembling aspen plants was studied after applying AZ-A and its four formulations onto aspen leaf discs. The repellency, oviposition deterrence, mortality and fecundity were investigated. The data indicated that the toxic effects were significantly influenced by AZ-A concentration and formulation ingredients. The photostability of AZ-A was examined following application onto red maple foliage and the effect of three UV stabilizers on the rate of degradation was investigated over a 10-d period. The data indicated that the half-life of degradation could be increased on maple foliage by the addition of 2,4-dihydroxybenzophenone to AZ-A at a concentration of 1:1 w/w. In addition, the mechanisms of energy transfer between AZ-A and the UV protectant molecules are also described.
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