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Phytosanitary Management Of Trogoderma Granarium Everts With Methyl Bromide Alternatives To Ensure Food Security And Safety

Ahmdani, Muhammad Shoab (2009) Phytosanitary Management Of Trogoderma Granarium Everts With Methyl Bromide Alternatives To Ensure Food Security And Safety. PhD thesis, PMAS-Arid Agriculture University, Rawalpindi.



Wheat crop occupies a central position in agriculture sector and our national economy. Pakistan’s contribution toward global wheat production is about 3.2 percent. The Punjab province is leading producer of wheat with a share of more than 70 percent of the total wheat production of the country. Despite being an agricultural country, food security of Pakistan has remained at stake since long because of poor yield and high post harvest losses caused by the storage pests. On the other hand country has a great exporting potential not only to achieve Millennium Development Goals (MDGs) relating to food security and safety but can earn foreign exchange and pay off country’s entire debts within 10 years just equaling our yield to that of Indian Punjab. Present investigations were, therefore, carried out to explore these potentials in terms of reducing post-harvest losses, food security and safety risks caused by the storage pests particularly the Khapra beetle which is a notified quarantine pest internationally. The studies revealed an average loss of 15.5 percent when 10 pairs of Khapra larvae were released for a period of 6 months under the natural conditions. Similarly there were found 33 and 8 percent increase in number of weeviled and broken grains, respectively. Besides, the beetle depleted approximately 4 percent carbohydrates that resulted in 0.35 and 1 percent increase in ash and crude fiber contents, respectively. Although total protein and fat percentages were slightly increased, yet these increases were predominantly due to the percentage loss of carbohydrates as well as production of protein aceous by-products of live insects, insect fragments, and excreta etc., which could not be sieved from the samples before chemical analysis. Further analysis of about 400 samples drawn from the entire province revealed that quality of Punjab wheat not only meets the international standards rather it is superior in many characteristics including protein content, moisture, bulk density, foreign matter, falling number. However, presence of quarantine pests such as T. granarium, Tilletia spores and Striga weeds render it unmarketable in the quality conscious world. A compatible grading system at the time of procurement and phytosanitary management of quarantine pests may guarantee vast acceptance of our wheat in the international market. Present research involved phytosanitary management of T. granarium with controlled and modified atmospheres (CA and MA) which have worldwide recognition as residuefree methods of insect control in warehouses, flourmills and granaries. Carbon dioxide and nitrogen base CAs proved effective in controlling T. granarium as well as the secondary insect pests, such as T. castaneum and S. granarius. The results revealed 100 percent control of T. granarium when exposed to 99 percent carbon dioxide based controlled atmosphere for 384 hours at 30 �C. The exposure time for complete mortality of T. castaneum and S. granarius was reduced to 96 hours under the similar conditions. The Khapra larvae were found to be the most resistant pests followed by S. granarius and T. castaneum. Carbon dioxide concentrations, exposure times and temperature significantly influenced mortality of the target pests. Higher values of these factors resulted in enhanced mortality and vice versa. We found a liberty to select these factors according to our ease and available resources to get a specific level of mortality. Likewise nitrogen based controlled atmosphere also proved effective, though time required to kill was higher as compared to Carbon dioxide based CAs. When atmosphere was modified by increasing the temperature, we achieved 100 percent mortality of the T. granarium larvae within 5 minutes and 12 hours at 60 and 54 �C, respectively. The other storage pests being admittedly the lesser thermo-tolerant may also be controlled under these conditions. Use of elevated temperatures is economically feasible, as most of the fumigations in Pakistan are carried out during June-Aug immediately after harvesting the crop when day time temperature usually touches 45 � 4 �C. With a little effort and energy cost we may raise the ware-house temperature to a level of 60 �C to disinfest our stores economically. The technology is fit for cereals stored for food purpose. In case of seed stores germination test and adjustment of the seed rate is recommended before sowing because results have revealed significant loss of wheat seed viability. Finally, phosphine (PH3) alone as well as in combination with 60 percent carbon dioxide was also tested as Methyl bromide (MB) alternative at different temperatures as a short term insect control strategy. A phosphine concentration of 2 mg-L-1 gave 100 percent mortality of five out of seven strains of T. granarium, when exposed for a period of 120 hours. Complete control of the other two target pests was, however, achieved after 24 hours under the similar conditions. Increased temperatures, phosphine concentrations and prolonged exposure exerted positive effect on the mortality. It was concluded that aforesaid independent variables may be manipulated to get complete control of even the resistant pests with low residues permissible under Sanitary and Phytosanitary (SPS) and Codex limits. Synergistic effect of carbon dioxide also helped in reducing PH3 concentrations to ensure phytosanitary management of T. granarium for Quarantine and Preshipment (QPS) and other purposes. In nutshell the present investigations have revealed that MB alternatives such as CAs, MAs as well as PH3 are very effective in reducing storage losses and controlling T. granarium and others storage pests. Efficacy of controlled atmospheres can be further improved by prestorage treatment of are house with 2 % deltamethrin, Lambda cyhalothrin or DDVP. The present findings will surely help in bridging the gap between food security demand/supply and will enable us to improve quality and safety of the treated cereals resulting in enhanced acceptance of our food crops in the international market.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Phytosanitary, Management, Trogoderma Granarium, Methyl Bromide, Food Security, Wheat crop, seed viability, atmosphere
Subjects:Agriculture & Veterinary Sciences(a) > Agriculture(a1) > Veterinary Sciences(a1.5)
ID Code:5960
Deposited By:Mr. Javed Memon
Deposited On:17 Jan 2011 10:03
Last Modified:21 Mar 2015 17:52

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