Abstract

The experiment assessed the nest activity index, stock depletion rate and haulage capacity of the three ant worker-size categories as susceptibility indices of millet, sorghum, rice and wheat grains. Results of the study indicated significant (P<0.01) difference in all the assessed parameters among the test cereals, worker-ant sizes and their interaction. Millet grains were significantly more susceptible compared to other test cereal grains, sorghum, wheat and rice. Result further indicate that Minor ants were significantly more numerous at foraging site, grain depletion rate was faster for Major ants, while the capacity and activity of Media ants was significantly higher. The significant interaction expressed variation in all the parameters. Foraging activity of Minor ants was significantly higher on millet, Major on sorghum and Media ants on rice and wheat. Stock depletion and haulage capacity were significantly higher for Major ants on millet and sorghum, as the case was for Media ants on rice and wheat. In conclusion, millet was the most vulnerable to attack by M. galla than the other test cereal grains and losses due to Media were significantly higher.

Key words: Messor galla, worker-size, nest activity index, stock depletion rate, haulage capacity.