Pests in urban entomology can be described as insects that affect human health. Insects in urban entomology include cockroaches, ants, termites, houseflies, ticks, insects and mites, bedbugs, lice, and mosquitoes (Robinson 2005).
Mosquitoes are one of the most important urban pests that belong to the Culicidae family of the Nematocera suborder. These pests are found in temperate and tropical regions of the world, except the polar regions (Lancaster and Briers 2008). These pests not only disturb people but they are also an important health hazard as diseases’ vectors that spread malaria, dengue, yellow fever, and an important virus of the recent years Zika (Epstein et al. 1998). There are 112 genera and 3539 species belonging to the Anophelinae and Culicinae subfamilies of the Culicidae family (Harbach 2014). About 50 species of mosquitoes have been identified in Turkey until today (Muslu et al. 2011). Six mosquito species, including Culex pipiens Linnaeus, 1758; C. martini Medschid, 1930; C. deserticola Kirkpatrick, 1924; Aedes caspius Pallas, 1771; Anopheles superpictus Grassi, 1899; and Culiseta longiareolata Macquart, 1838, were found in Antalya; the dominant type was identified as C. pipiens (Çetin and Yanıkoğlu 2004).
Control methods against mosquitos’ larvae include mechanical, biological, chemical, and an integrated approach where all of the above are used (Alten and Çağlar 1998). The chemical control targeted both larvae and adults, but larvae being the important ones. These pests live in water at all stages, except the adult stage. Today, insecticides used as larvicides are of biological origin, but they are very limited in number. Because of the environmental problems caused by insecticides and the effects of non-target organisms, alternative methods of combating these pests are sought. For a sustainable environment, the importance of biological control is increasing among these applications. But unfortunately, the high price of these biological agents at the moment makes it difficult for their broader implementation in the systems of production (Laznik and Trdan 2011).
One of the most successful groups of biological agents for controlling soil insect pests is the entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae. Nematodes in both families are obligate insect-parasitic organisms that are mutualistically associated with bacteria from the genera Photorhabdus (heterorhabditids) and Xenorhabdus (steinernematids), which are carried within the nematode digestive tracts (Kaya and Gaugler 1993). Nematodes in the infective juvenile (IJ) stages search for an adequate host in the soil and enter the insect host through natural openings (mouth, anus, and spiracles) or through the cuticle. The symbiotic bacteria are then released into the insect hemocoel (Dowds and Peters 2002) at which point the bacteria multiply and produce toxins. The nematodes also contribute to this process, and insect host is killed within 48 h by septicemia and toxemia (Kaya and Stock 1997; Duchaud et al. 2003). Once nutrients within the insect cadaver are exhausted, progeny nematodes develop into the IJ stages and emerge from the cadaver into the soil to search for another host (Griffin et al. 2005). A total of 86 species of EPN have been identified worldwide (64 belonging to Steinernema, 1 to Neosteinernema, and 21 to Heterorhabditis) (Kepenekci 2014).
The first EPN belonging to the genus Steinernema, detected in Turkey, in soil samples collected from Rize (Turkey), was identified by Özer et al. (1995) as S. feltiae. Kepenekci et al. (1999) identified the first nematode in Turkey from the genus Heterorhabditis as H. bacteriophora, which was found in an Aelia population (Aelia rostrata Boh.) collected from Ekecik (Aksaray, Turkey) winter quarters. To utilize EPNs in the biological control of pathogens in Turkey, the principal species and hosts, present, should be determined. Although several surveys have been conducted on this subject, there is not yet sufficient information (Kepenekci and Atay 2014).
Narksuwan et al. (2004) tested the EPNs S. carpocapsae (Weiser), S. siamkayai, S. feltiae, H. indica, and H. bacteriophora against Aedes aegypti (L.), Culex quinquefasciatus, C. gelidus, Anopheles dirus, and A. minimus mosquito species, and all of them were successfully suppressed A. aegypti (L.), C. quinquefasciatus, C. gelidus species (Edmunds et al. 2017). Kepenekci et al. (2014) evaluated the efficacy of S. feltiae, S. carpocapsae, S. kraussei, and H. bacteriophora against Chironomidae family members in their study. They determined that these EPN species could survive for up to 96 h in water and even after that they could parasitize the larvae of Chironomus plumosus. They caused more than 20% mortality after 24 h.
In this study, efficacy of five EPN species, isolated from Kyrgyzstan and Turkey, was evaluated against C. pipiens larvae collected from the stagnant waters in paddy fields at Samsun (Turkey)’s Bafra province under laboratory conditions.