Gall-forming nematode, Anguina woodi (Nematoda: Anguinidae) and Chalcid wasp (Hymenoptera: Eurytomidae), on dune grass from the Western Cape, South Africa

Abstract

In 2021/2022, galls formed by a nematode, Anguina woodi, were found on the stems, leaves and leaf sheaths of dune grass, Ehrharta villosa var. villosa on Milnerton Beach, Blouberg Beach and Langebaan, Western Cape Province, South Africa. These galls were spongy in texture, deep purple to blackish in colour and non-pedunculate. They were found in clusters, but also as single entities. Larger, harder galls varying from beige to dark brown in colour, apparently caused by insects, were also found on the stems of dune grass at Blouberg Beach and Langebaan Nature Reserve. Some nematode galls were found immediately next to or on top of the insect galls. Those found on top of insect galls seemed to be harder and drier than those found on stems not infected by insect galls. The co-infection of insects and anguinid nematodes has not been reported from the current study areas and was thus included in the present study. Both molecular and morphological studies were conducted on the nematodes and wasps leading to the identification of a host specific, gall-forming nematode from all three localities. The wasps were identified morphologically and molecularly to the family Eurytomidae (Hymenoptera). No insect galls were found on dune grass from Milnerton Beach. The paper includes speculations on a probable association between nematodes and insects.