ALBERT

Description:    The study assessed the composition and abundance of insect assemblages associated with two submerged macrophytes, Lagarosiphon ilicifolius and Vallisneria aethiopica , in fishless ponds. Six ponds were used, with each plant occurring singly in two ponds, whilst the remainder had both plants. The insects were sampled using a 500-μm mesh. The number of insect taxa, diversity and total abundance on Lagarosiphon were greater than on Vallisneria when the plants occurred in separate ponds. In ponds comprising both plants, the total insect abundance on Lagarosiphon was greater than on Vallisneria . In all ponds, anisopteran naiads were dominant. Hemicordulia , Diplacodes and Trithemis made up 36.2, 27.1 and 15.2%, respectively, of the total number of insects on Lagarosiphon in single plant ponds. Trithemis was the only odonate in ponds comprised exclusively of Vallisneria and made up 68.7% of insects. In ponds that were cultured with both plants, four anisopteran taxa, Hemicordulia , Diplacodes , Trithemis and Tramea, were collected. In single plant ponds, the body-size class distribution of naiads on Lagarosiphon was characterised by a broader range, with significantly greater numbers of smaller and larger size classes than on Vallisneria (Kolmogorov–Smirnov test, P  〈 0.05). The study shows that in fishless waters, epiphytic insect assemblages may differ between the two plant species, especially when they are widely separated in space, probably due to greater predator–prey interactions on Vallisneria than on Lagarosiphon . The two plants may also differentially affect water physicochemical conditions, which may possibly influence insect ovipositing behaviour, and so affect insect community assemblage. Content Type Journal Article Pages 1-12 DOI 10.1007/s10452-011-9363-y Authors Crispen Phiri, University Lake Kariba Research Station, P.O. Box 48, Kariba, Zimbabwe Albert Chakona, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140 South Africa Jenny A. Day, Freshwater Research Unit, Zoology Department, University of Cape Town, 7707 Rhodes Gift, Western Cape, South Africa Journal Aquatic Ecology Online ISSN 1573-5125 Print ISSN 1386-2588