First Report of Aphelenchoides Bicaudatus (Imamura, 1931) Filipjev and Schuurmans Stekhoven, 1941 Associated with Grass in South Africa.

Aphelenchoides bicaudatus associated with grass in South Africa was identified morphologically and molecularly. This population is characterized by a body length of 409 - 529 µm, a stylet length of 9.5 - 13 µm, a post-vulval uterine sac of 45 - 50 µm, and the characteristic tail bifurcated at the end with one prong longer than the other. Molecular analyses based on the 18S and ITS rDNA data confirmed the primary morphological identification of the A. bicaudatus species. The obtained phylogenetic trees revealed a close positioning of the South African population to other representatives of A. bicaudatus with the maximum (1.00) posterior probability value. Principal component analysis (PCA) also indicated a variation within the populations of A. bicaudatus. This is the first report of A. bicaudatus from South Africa.

An Investigation into the Physico-chemical Factors Affecting the Abundance and Diversity of Aquatic Insects in Organically Manured Aquadams and Their Utilization by Oreochromis mossambicus (Perciformes: Cichlidae).

The interaction between the fish Oreochromis mossambicus (Percifomes: Cichlidae) and aquatic insects after application of chicken, cow, and pig manure was studied in 7,000-liter plastic aquadams. Principal component analysis showed that most of the variation in water quality after application of manure was accounted for by potassium, nitrogen, dissolved oxygen, phosphate, and alkalinity. Canonical correspondence analysis showed that Gyrinidae, Elminidae, Hydrophilidae, Hydraenidae, and Athericidae were associated with high nutrient levels (nitrogen, phosphorus, and potassium) characteristic of the chicken manure. However, the most abundant aquatic insects Gerridae, Notonectidae, and Culicidae were close to the centre of the ordination and not defined by any nutrient gradient. The Shannon-Wiener diversity was highest in the aquadams treated with chicken manure. The most frequently occurring aquatic insects in the diet of O. mossambicus were culicid mosquitoes in all the treatments. However, in the laboratory, Chironomidae were the most preferred because they lacked refuge. Notonectidae and Gerridae were not recorded in the diet of O. mossambicus despite their abundance. This may be because of their anti-predation strategies. Laboratory experiments showed that Notonectidae, Gyrinidae, and Gerridae fed on Chironomidae and Culicidae. This implies that aquatic predatory insects competed for food with O. mossambicus.