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Abstract

At all developmental stages, Diplonychus indicus Venk. & Rao (Heteroptera: Belostomatidae) bugs make predatory attempts and catch prey both from ambush and while foraging actively. The distribution of predatory movements between these two foraging modes does not vary significantly during development, although a bug generally performs more predatory attempts from ambush than during active search. Both modes were subdivided and six different predatory movement types were recorded. These different predatory types are not all performed at the same frequency at all developmental stages. The proportion of predatory attempts including a preliminary lunge decreases with age whereas the proportion of simple predatory attempts (strike) increases with age. There is a significant effect of developmental stage and of predatory mode on capture success. General capture success rate increases with age and success rates vary with predatory type. Capture success of predatory attempts made while swimming is always lower than capture success of simple predatory attempts (strike). These rates do not vary during development. On the contrary, success rates for the predatory types dive and lunge increase with developmental stage. For some predatory categories, capture success varies with predator-prey distance. The data then suggest that the bugs are undershooting.