R.L. Kalra

Residues of DDT and HCH in butter and Ghee in India 1978–1981

Abstract Organochlorine pesticide residues were analysed in 105 samples of butter and 5 samples of ghee collected from different parts of India during 1978–1981. Residues of both DDT and HCH were detected in all the samples. DDT residues existed in the form of p,p′-TDE, p,p′-DDT. HCH residues were mainly alpha- and beta-isomers. Mean levels of 3·31 μg g−1 ΣDDT and 1·89 μg g−1 ΣHCH found in butter samples were higher than those reported from most other countries. The level of DDT residues exceeded the extraneous residue limit of 1·25 μg g−1 prescribed by the Food and Agricultural Organization/World Health Organisation in 83 butter samples and all 5 ghee samples. The residues of HCH in the majority of samples were also high, though no residue limit for this insecticide has been prescribed.

Contamination of bovine (buffalo, Bubalus bubalis (L.)) milk from indoor use of DDT and HCH in malaria control programmes

Samples of bovine (Buffalo, Bubalus bubalis (L.)) milk collected from randomly selected houses of Ludhiana and Sangrur districts of Punjab, India, where DDT and HCH, respectively, had been sprayed for the control of malaria, were analysed for insecticide residues between September 1985 and June 1986. The average concentration of DDT residues in samples from the DDT sprayed area were approximately 4-12 times higher than those in the corresponding samples from HCH sprayed areas. Mean levels of HCH residues in samples from the HCH sprayed area were greater than those in samples from DDT sprayed areas by factors of 2-11. Milk samples collected from four rural houses in each district before and after applications of DDT or HCH for mosquito control also showed that indoor use of these insecticides results in a substantial increase in residue levels. About 74% of the samples analysed contained DDT residues above the extraneous residue limit of 0.05 mgkg-1 (whole milk basis). Estimated maximum daily intakes of DDT and beta-HCH through consumption of contaminated milk by 1-3-year-old children exceeded their acceptable daily intakes by nearly three and five times, respectively.

Contamination of stored food and feed commodities from indoor use of HCH and DDT in malaria control programmes

Samples of wheat grain, straw, flour and green fodder taken from houses sprayed with either HCH or DDT for mosquito control showed the presence of HCH residues at concentrations of up to 91.2, 208.8, 33.1 and 459.0 mg kg-1 and DDT residues up to 11.3, 86.1, 2.2 and 5.4 mg kg-1, respectively. The mean level of HCH residues in samples of wheat grain collected from randomly selected houses in areas sprayed with HCH for the control of malaria was approximately 8 times higher than that for corresponding samples from DDT sprayed areas. In contrast, DDT residues in wheat grain samples from the DDT sprayed area were 3 times higher than the samples from the HCH sprayed area. The results suggest that significant amounts of residues of HCH and DDT become transferred to commodities stored in houses sprayed with these insecticides for mosquito control.

Evaluation of insecticide resistance management based integrated pest management programme

Insecticide resistance management (IRM) programme was launched in 26 cotton-growing districts of India in 2002 to rationalize the use of pesticides. The IRM strategy is presented within a full Integrated Pest Management (IPM) context with the premise that unless full-fledged efforts to understand all aspects of resistance phenomenon are made, any attempt to implement IPM at field level would not bear results. Unlike earlier IPM programmes, this programme is directly implemented by the scientists of state agricultural universities; thus the information flow is directly from research subsystem to farmers. The extension methodology is different from IPM-farmer field school model, but much the same information is provided in didactic form, through active participation of the farmers throughout the cotton-growing season, by deploying scouts in villages. The knowledge gain of the farmers covered under IRM programme was measured by employing before/after quasi-experimental research design. The overall knowledge gain was significant in terms of identification of insect pests and natural enemies of cotton crop, proper use of insecticides and timely sowing of the crop, but farmers did not reach the desired level of knowledge with respect to other cultural practices, which result in suppression of pest buildup. In the absence of any effective bio-agents, the level of IPM integration is limited to cultural practices, thresholds, agro ecosystem analysis and use of insecticides according to good agricultural practices.

Diffusion of Innovation Theory and Integrated Pest Management

The Diffusion of Innovation Theory dominated the theory and practice of agricultural extension system all over the world for almost half a century. It came under criticism too during the period. The theory was not considered adequate to manage the process of dissemination of IPM technology. The inadequacies may be due to the attributes of IPM innovation as well as due to the sophisticated demands of IPM technology that was not amenable to the limited version of the theory. The diffusion and adoption of agricultural innovation has been a focal measure of agriculture development. IPM is a combination of different technologies that has not diffused as other simple one of technologies. Diffusion of IPM requires educating the farmers for its adoption and it must deal with farmers’ needs, perceptions, constraints, objectives and its complexity demands. IPM is location specific and it requires several years of experiments, trials, repetitions and validations in a given area. It requires a clear understanding about the IPM tactics. The IPM tactics may vary from crop to crop and area to area. It needs a planned strategy of imparting knowledge and skill and active learning and active adoption by the farmers. The diffusion of innovation research has to give up the “ex-post-facto” design, which has been a prisoner of socio-economic factors influencing the adoption of innovation and in correlating the effects to these factors. The diffusion researchers should employ “action research” design to study the IPM implementation and feed the result to develop farmer-acceptable IPM system. The coordination of all the stakeholders of agricultural innovation system need to emphasise the outcomes of technology and knowledge generation and adoption of IPM practices rather than merely strengthening of research and extension systems.

Contamination of bovine milk with DDT and HCH residues in relation to their usage in malaria control programme.

The contribution of spraying DDT and HCH for malaria control towards the contamination of bovine milk was investigated by analysing milk samples collected from preselected localities sprayed with either DDT or HCH in the Punjab. A direct correlation was found between the amounts of residues of these insecticides in milk and their typical usage pattern for the mosquito control programme. It is considered that these results may have significant bearing on the regulatory control of DDT and HCH residues in milk.

Absorption of DDT and HCH residues by wheat during storage in rural houses treated with these insecticides for malaria control

Abstract Wheat kept in gunny bags of 20 kg capacity in rural houses sprayed with DDT or HCH for mosquito control was found to acquire the residues of these insecticides up to 4.40 or 22.14 mg kg −1 , respectively, during an 8 month storage period. Wheat stored in sealed polyethylene bags of 20 kg capacity also absorbed residues of these insecticides up to 3.17 and 14.12 mg kg −1 , respectively. Samples kept in gunny or polyethylene packets of 100 g capacity absorbed DDT and HCH residues at levels higher than those kept in bags of 20 kg size. This may be due to their relatively large surface area available for exposure to the ambient environment. Absorption of residues of DDT and HCH by wheat stored in sealed polyethylene bags suggests that considerable transference of these insecticide residues can occur through vapour phase. Thus, the potential exists for the contamination of food commodities with substantial amounts of residues during their storage in rural premises treated with insecticides for malaria control and this may have significant implications in the regulation of insecticide residues in foods.

Dissipation of quinalphos residues on cauliflower (Brassica oleracea L. var.capitata)

The dissipation of quinalphos on the main and spring crops of cauliflower sprayed at a rate of 250 g a.i./ha was studied. The residues of the insecticide were estimated in the samples taken at various intervals by using gas-liquid chromatography and the TLC-enzyme inhibition technique. Quinalphos residues took about 7 and 4 days to reach a level lower than 0.25 ppm on the curds of the main and spring crops, respectively. The oxygen analog of quinalphos was also detectable, in negligible amounts. About 95% of the insecticide degraded on the cauliflower within 8 days. Repeated applications of the insecticide did not result in any build-up of the residues.

Use of low-purity solvents and reagents for analysis of residues of synthetic pyrethroid pesticides by gas chromatography with electron-capture detection

Abstract As most of the impurities commonly encountered in solvents and reagents elute from a gas chromatographic column at retention times much smaller then those of synthetic pyrethroids, inexpensive laboratory-grade solvents and reagents can be acceptable for the determination of residues of these pesticides. However, before analysis of the samples, it is desirable to check the suitability of such solvents and reagents by running reagent blanks.