Predatory versatility in the water bug Diplonychus indicus

First instar Diplonychus indicus Venk. et Rao (Heteroptera:Belostomatidae) larvae possess a behavioural plasticity similar to that of adults. This highly versatile predator alternates frequently from foraging actively to ambushing and vice versa. No significant variations in the use of these two predatory modes during post-embryonic development could be evidenced. The present study stresses similarities between the use of different predatory modes by young and old larvae and by adults. Changes per unit time from one predatory mode to the other increased with age, as frequency of attempts increased with age. Adults changed predatory modes approximately seven times per hour. Most changes were made after one, two, or, more rarely, three predatory attempts of the same mode. The maximum number of consecutive attempts of one predatory mode increased with age. There was no evidence that any specialization occurred during development. No proximal causes for these changes of predatory mode were found. Changes were not correlated with the outcome of previous predatory attempts, nor did changing predatory mode increase the probability that the next attempt would be successful.