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In this study the occurrence of entomopathogenic nematodes (EPNs) was determined in three senatorial districts of Osun State in relation to soil texture, vegetation, moisture and pH. A total of 110 soil samples were randomly collected from various cultivated fields in different locations. The soil samples were baited twice using last instar larvae of the Galleria mellonella (greater wax moth) for presence of entomopathogenic nematodes. Four EPN isolates were recovered viz., Heterorhabditis indica, Heterorhabditis bacteriophora, Steinernema karii and Steinernema wesieri. Of a total of 110 soil samples examined, EPNs were found in 90.90% soil samples, they belonged to the genera Steinernema and Heterorhabditis. Steinernema spp. was found prevalent in both cultivated and undisturbed soils. Frequency of occurrence of EPNs in the sampled soils from the different senatorial zones was determined: soil samples from the Central zone recorded the lowest prevalence 87.50% while the soil samples from Western senatorial zone revealed 91.43% presence of the EPNs. The highest frequency of occurrence of EPNs- 94.29% was recorded in the soil samples from Eastern senatorial zone. Nematode distribution and frequency was found to be related to soil pH (pH<4.5 to pH>7.2) and soil moisture. This is the first report of these nematodes from Osun State, Nigeria. [ABSTRACT FROM AUTHOR]

Chironomidae, or non-biting midges, are found worldwide in a wide variety of aquatic habitats. During periods of mass adult eclosion they can become a nuisance and health hazard. Current control methods target the aquatic larval stage and include the use of insect growth regulators or insecticides, which may be prohibited in certain environments or affect non-target organisms. The aim of this study was to investigate whether entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae, currently employed for control of terrestrial crop pests, could be used as a viable biocontrol for the aquatic larval stages of the Chrionomidae, offering an alternative to current chemical methods. We demonstrate that Steinernema feltiae (Filipjev, 1934), Steinernema carpocapsae (Weiser, 1955), Steinernema kraussei (Steiner, 1923) and Heterorhabditis bacteriophora (Poinar, 1975) are able to survive in water up to 96 h and are able to parasitize and kill Chironomus plumosus (Linnaeus, 1758) larvae, with mortality observed after just 24 h exposure and with < 20% survival after 4 days. We also show that following application to the water column, EPNs sink to the bottom of the lentic water body and can remain alive for more than 96 h. Taken together, we believe that several EPN species could be developed as a valid form of biocontrol for Chironomidae.

Chironomidae, or non-biting midges, are found worldwide in a wide variety of aquatic habitats. During periods of mass adult eclosion they can become a nuisance and health hazard. Current control methods target the aquatic larval stage and include the use of insect growth regulators or insecticides, which may be prohibited in certain environments or affect non-target organisms. The aim of this study was to investigate whether entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae, currently employed for control of terrestrial crop pests, could be used as a viable biocontrol for the aquatic larval stages of the Chrionomidae, offering an alternative to current chemical methods. We demonstrate that Steinernema feltiae (Filipjev, 1934), Steinernema carpocapsae (Weiser, 1955), Steinernema kraussei (Steiner, 1923) and Heterorhabditis bacteriophora (Poinar, 1975) are able to survive in water up to 96 h and are able to parasitize and kill Chironomus plumosus (Linnaeus, 1758) larvae, with mortality observed after just 24 h exposure and with < 20% survival after 4 days. We also show that following application to the water column, EPNs sink to the bottom of the lentic water body and can remain alive for more than 96 h. Taken together, we believe that several EPN species could be developed as a valid form of biocontrol for Chironomidae. [ABSTRACT FROM AUTHOR]

The influence of different temperature ranges on the reproductive potential of native and exotic species of entomopathogenic nematodes (EPNs) was checked on Galleria mellonella larvae. The native species included Steinernema asiaticum and Heterorhabditis indica whereas exotic species were S. feltiae and H. bacteriophora. G. mellonella larvae were exposed to 300 IJs of each species. After inoculation at different temperatures, the reproductive potential of EPNs increased with increasing temperature and was found to be the best at 25°C. No EPNs species could reproduce at 5°C. S. feltiae started reproduction at 10°C, while all remaining species reproduced at 15°C or higher temperatures. Maximum numbers of IJs were recovered from H. bacteriophora. Time taken for first emergence of IJs from the host was shortest at 25°C i.e. 7-8 days in case of S. asiaticum and S. feltiae, while 11-13 days for H. bacteriophora and H. indica. Maximum emergence time was taken by S. feltiae at 10°C. [ABSTRACT FROM AUTHOR]