Factors influencing the occurrence of entomopathogenic nematodes in the Central Rift Valley Region of Kenya

Abstract

A survey for entomopathogenic nematodes in the central Rift valley region of Kenya was conducted at altitudes between 1800 and 3000 m above sea level and from croplands and noncropland habitats. The sampling depth was 0–30 cm. GPS (global positioning system) was used to measure site positions. One hundred and twelve soil samples were collected and entomopathogenic nematodes trapped through Galleria mellonella. Entomopathogenic nematode presence was demonstrated by G. mellonella mortality and viable ones bulked through the same host. Nematode recoveries from two consecutive extractions were 30% per extraction and 52% for cumulative extractions. Recoveries from agro ecological zones ranged between 18% and 71%. Recovery frequency was higher from disturbed cropland habitats than the stable noncrop habitats. Steinernema species were more frequent than Heterorhabditis (9 : 1). Nematode occurrence clustered at 2–3% carbon and pH 5.3–6.3 with no specific pattern demonstrated from soil types. Nematode species of the two genera from high altitudes lost their culturing ability within 1 month of isolation. There was a tendency for recovering both nematode genera at the shores of water bodies. This is the first report of Steinernema yirgalemense and S. weiseri in Kenya and of S. karii in the central Rift valley region. The Heterorhabditis species has not been confirmed yet. This has widened the genetic base of entomopathogenic nematodes from Kenya. The entomopathogenic nematodes are available for developement as biological control agents of athropod pests.

Isolation and identification of entomopathogenic nematodes from citrus orchards in South Africa and their biocontrol potential against false codling moth

“…S. yirgalemense was described by Nguyen et al (2004) from Yiglemen in Ethiopia, where it was found to be the dominant species. It was also reported from the Central Rift Valley of Kenya (Mekete et al, 2005;Mwaniki et al, 2008). The nematode belongs to the bicornutum-group of six described species, of which the exsheathed IJ has two hornlike structures in the cephalic region (Nguyen, 2007).…”

“…In Kenya, new strains of Heterorhabditis bacteriophora and Heterorhabditis indica have been isolated. Isolates of S. yirgalemense, S. karii and Steinernema weiseri have also been reported from the Central Rift Valley Region of Kenya (Mwaniki et al, 2008). In Ethiopia, the dominant species detected was S. yirgalemense (6.3%), with only two isolates of H. bacteriophora (0.7%) (Mekete et al, 2005).…”

Distribution of entomopathogenic nematodes in Southern Cameroon

“…Recovery rates in tropical and sub-tropical regions were 3% in central Andean region of Colombia (Lopez-Nunez et al, 2007), 6% in Guadeloupe , 6.9% in Ethiopia (Mekete et al, 2005), 7% in Chile (Edgington et al, 2010), 12% in Costa Rica (Uribe-Lorío et al, 2005), 12.08% in Brazil (Dolinski et al, 2008), 13.2% in the Pampas region of Argentina (Stock, 1995), 20.04% in the South Andamans (Prasad et al, 2001a) and 52% in Kenya (Mwaniki et al, 2008). However, comparisons must be made with caution because different sampling approaches and different baiting insects were used in the reported surveys.…”

“…However, comparisons must be made with caution because different sampling approaches and different baiting insects were used in the reported surveys. In most of the cases where EPN recovery rates were the highest, either sampling sites were selected based on insect habitats or outbreaks (Uribe-Lorío et al, 2005;Stock, 1995), another baiting insect than G. mellonella was used (Prasad et al, 2001b), or a combination of two nematode extraction methods was used (Mwaniki et al, 2008). The current survey did not consider insect habitats or outbreaks and used only G. mellonella as bait insect.…”

“…The effects of factors such as geographical location, climatic conditions, habitat type and soil properties on the occurrence and distribution of EPN have been studied for several areas (e.g. Campos-Herrera et al, 2007;Mrácek et al, 2005;Mwaniki et al, 2008;Prasad et al, 2001b). However, no similar study has been conducted in Southern Cameroon.…”