The Diversity of Chironomidae (Diptera) Associated with Hydrilla verticillata (Alismatales: Hydrocharitaceae) and Other Aquatic Macrophytes in Lake Tanganyika, Burundi

Abstract

Abstract To search for potential biological control agents of the aquatic weed, Hydrilla verticillata (L.f.) Royle, emerging chironomid adults were collected from aquatic macrophytes sampled between 2007 and 2009 from near shore sites in Lake Tanganyika, Burundi. Initial surveys identified H. verticillata populations at all sampled locations between Bujumbura and Nyanza Lac. Twenty-six (26) species of Chironomidae emerged from collections of four plant species; Hydrilla, Ceratophyllum demersum variety apiculatum (Cham.) Asch., Potamogeton schweinfurthii A.Benn., and Vallisneria spiralis f. aethiopica (Fenzl) T.Durand and Schinz. Twenty-four of the chironomid species were new country records, but none of them represented undescribed species. Dicrotendipes fusconotatus (Kieffer) dominated the chironomid community, comprising 82% of 32,090 reared adults. The six most common species contributed over 96% of the total midge fauna. Most species were uncommon or rare; nine species were represented by 10 or fewer specimens. A species accumulation curve for the 25 chironomid species reared from Hydrilla suggested that our sampling completely describes the community associated with this plant in northern Lake Tanganyika. Quantitative β-diversity values indicated that chironomid communities of the two Hydrocharitaceae species, Hydrilla and Vallisneria, were most similar to each other, even though they have very different growth forms. Chironomids also emerged in greater numbers from the two Hydrocharitaceae than from the other plants. No chironomid species, including Polypedilum wittei Freeman and Polypedilum dewulfi Goetghebuer, two species formerly considered for possible biological control of Hydrilla, were specific to that plant. Polypedilum species emerged from all sampled aquatic macrophytes. No chironomid-caused damage was seen on Hydrilla. African Chironomidae do not appear to be suitable candidates for biological control of Hydrilla.