Studies on the effect of delayed initial feeding on survival of Macrobrachium dayanum (Henderson) larvae under laboratory conditions

Abstract

The present study was carried out to evaluate the effect of initial starvation and subsequent refeeding or delayed initial feeding on the survival of newly hatched larvae of Macrobrachium dayanum under laboratory conditions. In the delayed initial feeding experiments, the feeding rate of the starved newly hatched larvae of M. dayanum increased with the age up to 4 th dph (day post hatching) when first food was offered. After a period of 5 th dph the percentage of larvae feeding decreased sharply up to 9 th dph and on 10 th dph, no larva was found to feed and were very weak to accept the food. During the experiment, the point of no return (PNR50) (when 50% of the unfed larvae are unable to feed when offered food) was reached in M. dayanum at 6 th dph. Before PNR was reached, starved larvae of M. dayanum were able to capture their prey. Even when the larvae were provided food regularly after PNR50 was reached, they were too weak to capture food and showed 100% (PNR100) mortality ultimately on day 8 th in case of M. dayanum.