Author: I.K.A. IBRAHIM AND Z.A. HANDOO
Publishing Date: 2007
Volume 25 Issue 2
Information concerning the occurrence and distribution of cyst nematodes (Heterodera sp.) in Egypt is important to assess their potential to cause economic damage to many crop plants. A nematode survey was conducted in Alexandria and El-Behera Governorates in northern Egypt during 2001 to 2006 to identify the species of cyst nematodes Heterodera sp.) associated with some crop plants and grasses. A total of 162 soil and root samples were collected from the rhizosphere region of the surveyed plants and at a depth of 15-40 cm. Roots were washed free of soil and examined for female and cyst nematode infection. Nematodes from a composite sample of 250 cm3 soil were extracted by means of Cobb’s wetsieving and centrifugal sugar floatation techniques (Ayoub, 1980). Nematodes were fixed in 2 % formaldehyde solution, identified to genus, and counted under binocular tereomicroscope. Females were removed from the roots and cysts were sieved from soil, after which juveniles were hatched from cysts kept in water in a Syracuse watch glass in the laboratory. The procedures used for preparing and measuring specimens were essentially same as used by Golden & Birchfield (1972). Nematode identifications were based on the morphology of secondstage juveniles, adult females, and cysts and their identities were confirmed with taxonomic keys (Mulvey & Golden, 1983; Golden, 1986). Morphological characters used for identification included cyst shape, characteristics of cyst terminal cone including nature of fenestration, vulval-slit length, shape and presence or absence of bullae, underbridge length, and cyst wall pattern . The second-stage juvenile morphologies critical for identifications were the following: body and stylet length, shape of stylet knobs, shape, and length of tail and hyaline tail terminus. Nematode population density (nematodes per 250 g soil) was determined for each species and recorded. Frequency of occurrence (FO) and population densities of cyst nematode species (Heterodera sp.) and associated host plants in Alexandria and El-Behera governorates are given.