Title: Prey capture by the four larval instars of Chaoborus crystallinus
Abstract:Prey capture ability of fourth‐instar Chaoborus larvae has been studied widely but relatively little comparable information is available for the first three larval instars. In this laboratory study I ...Prey capture ability of fourth‐instar Chaoborus larvae has been studied widely but relatively little comparable information is available for the first three larval instars. In this laboratory study I measured strike and contact efficiencies of all four instars of Chaoborus crystallinus. The effectiveness of prey escape behavior was also recorded. As larval size increased the size of successfully captured and ingested prey also increased. There was no loss of ability to ingest the smallest prey by the largest larvae. Prey width was a better index of successful capture and ingestion than was prey length. Fast swimming and infrequent swimming were effective precontact prey escape behaviors. The effectiveness of akinesis and spininess, two postcontact escape mechanisms, depended on larval size; they were effective when prey width approached larval gape diameter but relatively ineffective when prey width was much less than larval gape diameter. Gelatinous prey were readily attacked once but were almost always immediately rejected and seldom attacked again. Early instar Chaoborus larvae are abundant and effective predators whose role in structuring zooplankton communities is only beginning to be appreciated.Read More