Population Assessment of Common Stored Pest Species in Date Fruit Zahedi Cv. Based on Spectroscopic Method

This study aimed to define sampling programs for pests, Oryzaephilus surinamensis (Linnaeus), Ephestia kueheniella (Zeller) and Plodia interpunctella (Hübner) using spectrophotometer in date Zahedi cultivar. The experiments were conducted in a completely randomized design with factorial arrangement. The first factor consisted of eggs, larvae, pupae and adult and the second including 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 densities of the above stages. Results showed that the maximum absorption wavelength for egg, larva, pupa and adult of O. surinamensis, was 1220, 1240, 1280, 1300 nm, for E. kuheniella 1210, 1270, 1320, 1360 nm and for P. interpunctella 1310, 1320, 1380, 1400 nm, respectively. The lowest number of sampling (each sample 110 g date fruits) for an accurate estimation of the egg, larva, pupa and adult of O. surinamensis were 1, 2, 1, 2, for E. kuheniella 1, 1, 3, 3 and for P. interpunctella 1, 1, 2 3, 2 samples, respectively, Relative Variation )RV( and Relative net precision )RNP( indices were used to validate the sampling accuracy. The RV for development stages of O. surinamensis were 2.23, 3.26, 3.15, 2.52, for E. kuheniella 2.52, 1.42, 1.64, 1.78, 3.71 and for P. interpunctella 2.23, 3.27, 3.15, 3.52 respectively. The accuracy level of samplings was lower than 10 in all cases, The RNP values for O. surinamensis were 39.79, 18.06, 32.29, 22.37, for E. kuheniella 22.54, 27.58, 13.15, 10.33 and for P.interpunctella 36.51, 23.71, 15.58 10.99 respectively. Based on the results, the spectrophotometer could detect the hidden pest stages (egg and pupa) with maximum accuracy and minimum cost.