Okky Setyawati Dharmaputra

Pest management of psocids in milled rice stores in the humid tropics

Abstract Psocids (Liposcelis spp.) are often abundant in tropical storage systems where very large populations can develop relatively soon after fumigation treatments. In order to improve pest management strategies against these pest some factors governing the potential of psocid populations to increase under tropical conditions were investigated in a large‐scale milled rice store and in the laboratory. The factors studied included the success of pest control, rice milling degree, fungal growth and variations in ambient temperature and humidity. Fumigation failure and low milling degree of the rice stock were confirmed as important factors encouraging rapid and substantial psocid population growth while fungal infection rates, routine spraying of store and bag stack and variations in ambient climatic conditions made no obvious contribution to observed fluctuations in psocid numbers. Suggestions are made for improved pest management strategies that need to be tested under operational conditions.

Validation of analytical parameters of a competitive direct ELISA for aflatoxin B1 in peanuts

Abstract Analytical validation of a competitive direct SUNQuik ELISA with a reference High Performance Liquid Chromatography (HPLC) method and other methods including a minicolumn method and the VICAM Aflatest® system for aflatoxin in peanuts was conducted. Both the ELISA and the VICAM Aflatest® system, using the same peanut extracts were analytically comparable with the HPLC method (R=0.998, p<0.000). The minicolumn method was also found to be acceptable as a low cost rapid semi-quantitative test. Despite the large variation in sampling, the correlation between the SUNQuik ELISA and HPLC using the different peanut sub-samples was considered acceptable over the range of 0–1200 µg kg−1 (R=0.938). No false negatives were found using the SUNQuik ELISA and false positives were either nil or negligible in all the studies conducted. The repeatability of the SUNQuik ELISA run on the same day was good with only±10% deviation. The reproducibility of the SUNQuik ELISA between days was also acceptable, but with a higher deviation. Applying the SUNQuik ELISA for aflatoxin surveys of peanuts in Indonesia proved that the method can deliver high quality, cost- and time-effective analysis with very little establishment capital and maintenance.