BIOLOGY AND HOST PREFERENCE OF SAWTOOTHED GRAIN BEETLE, Oryzaephilus surinamensis L. (COLEOPTERA: SILVANIDAE) ON DATE CULTIVARS AND THEIR MANAGEMENT USING EDIBLE PLANT PRODUCTS

Abstract

The sawtoothed grain beetle, Oryzaephilus surinamensis L. (Coleoptera: Silvanidae) constitutes one of the major pests of date palm in storage conditions throughout the world. The experiments were conducted to find out the biology of O. surinamensis while fed on five different date cultivars (Mariyam, Medjul, Dabas, Zahidi and Saad) as well as to evaluate the efficacy of edible plant products against the pest. Both the experiments were conducted at laboratory conditions prevailed 30 ± 5 °C, 80 ± 10 % RH. The study revealed that the highest incubation period of the insect was recorded 3.92 days on Saad but minimum 3.42 days on Mariyam. The larval period ranged from 12.13 (Mariyam) to 14.08 days (Saad) while pupal period 4.56 (Mariyam) to 5.14 days (Saad). The larval to pupal period was 16.69 to 19.22 days. The duration of egg to adult stages of female from 20.1 to 23.14 days. The highest and the lowest pre-oviposition periods were 7.35 (Dabas) and 6.15 days (Mariyam), respectively. The Mariyam date cultivar experienced the highest damage of 22.5 % in October but the lowest 4.5 % in Saad during the month of December. The maximum (91.92 %) egg hatching was found in Mariyam date cultivar while minimum (81.72 %) was noticed in Dabas date cultivar. Survival and mortality percentage of larvae and pupae were recorded and pupal survival rate was found higher than larval survival rate. The highest larval and pupal survival rate was 91.58 and 93.57 %, respectively, in Mariyam date cultivar. Some edible plant products with different concentration (4 %, 2 %, and 0.05 %) were tested against O. surinamensis on different dates to determine the mortality percentage. Clove powder showed 100 % mortality at 4 % and 2 % concentrations after 5 and 7 days which were the highest among the edible plant powders.