EFFECT OF TEMPERATURE ON POPULATION BUILDUP OF KHAPRA BEETLE, TROGODERMA GRANARIUM (EVERTS) AND ITS DAMAGE INTENSITY CAUSED TO STORED WHEAT

The study was conducted in Grain Storage Research Institute of Southern-zone Agricultural Research Centre, PARC, Karachi during 2009-10, to evaluate the effect of temperature on population buildup of khapra beetle, Trogoderma granarium (Everts) and its damage intensity caused to stored wheat (Triticum aestivum). Fifteen kg wheat sample (irrespective of variety) was collected from Sindh Government godowns located in Landhi, Karachi and fumigated with Aluminium phosphide tablets to nullify the possibility of previous infestation. The insect initially reared on healthy wheat grains at 30±2°C and 70±5% relative humidity. Later on, 30 larvae of 5th instar were used in the experiment. The results reveal that, maximum population of 958 khapra was observed at room temperature (220C) followed by 747, 611 and 4 at 320C, 340C and 410C, respectively. The maximum weight loss of 19.25% caused by khapra was recorded at room temperature, followed by 16.00%, 14.23% and 0.11% at 320C, 340C and 410C, respectively. The maximum damaged grain % (22.36%) was recorded also at room temperature, followed by 18.47%, 12.035 and 0.24% at 320C, 340C and 410C, respectively. The data also reveals that, maximum healthy grain % (99.76%) was recorded at 410C, followed by 87.96, 81.52 and 77.63at 340C, 320C and at room temperature. The results show that, room temperature is ideal for khapra production and temperature 410C is not favourable for the production of khapra beetle. From the results it is also depicted that, insect population has positive correlation with weight loss% and damaged grain%. population significantly.