Yazar "Karagoz, Mehmet" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim
    Öğe
    The effect of chemical insecticides on the scavenging performance of Steinernema carpocapsae: Direct effects and exposure to insects killed by chemical insecticides
    (Academic Press Inc Elsevier Science, 2021) Nalinci, Esra; Karagoz, Mehmet; Gulcu, Baris; Ulug, Derya; Gulsen, Sebnem Hazal; Cimen, Harun; Hazir, Selcuk
    Entomopathogenic nematodes are used widely in biological insect control. Entomopathogenic nematodes can infect live insects as well as dead insects (i.e., they can act as scavengers). It is important to determine compatibility of entomopathogenic nematodes with other pest management tactics such as chemical insecticides. We hypothesized that chemical insecticides have negative impact on scavenging nematodes. According to our hypothesis, we first investigated the effects of direct exposure of Steinernema carpocapsae infectivity juveniles (IJs) to three chemical insecticides, cypermethrin, spinosad or diflubenzuron in terms of nematode survival and virulence. Subsequently, using the same chemicals, we tested the effects of insecticide-killed insects on scavenger nematode penetration efficiency, time of emergence and the number of nematode progeny. Prior to our study, the impact of pesticides on scavenger nematode fitness had not been studied. Fall webworm, Hyphantria cunea, and greater wax moth, Galleria mellonella, larvae were used as host insects. The survival rate of IJs after direct exposure was 83% for cypermethrin and 93-97% for the other insecticides and control. There were no significant differences in the survival and virulence of the nematodes after 24 h exposure to insecticides. The number of nematodes that invaded the insecticide-killed host was significantly higher in cypermethrin and spinosad treated groups and live H. cunea than in the diflubenzoron treated group and freeze-killed control. However, no significant differences were observed in time of emergence. Significantly more progeny IJs emerged from Spinosadkilled insects than the freeze-killed control. In conclusion, we discovered that the fitness of scavenging IJs is not diminished by insecticides in insect cadavers. In fact, in some cases the exposure to chemical insecticides may enhance virulence.
  • Küçük Resim
    Öğe
    Environmental tolerance of entomopathogenic nematodes differs among nematodes arising from host cadavers versus aqueous suspension
    (Academic Press Inc Elsevier Science, 2020) Gulzar, Sehrish; Usman, Muhammad; Wakil, Waqas; Gulcu, Baris; Hazir, Canan; Karagoz, Mehmet; Shapiro-Ilan, David I.
    Environmental factors such as temperature and desiccation impact the survival and efficacy of entomopathogenic nematodes (EPNs). Most studies on environmental tolerance have focused on EPNs applied in aqueous suspension. Another approach for EPN application is via infected host cadavers. Emergence in host cadavers is also more representative of nematodes in natural populations. In prior studies, certain advantages in fitness have been observed with the cadaver application approach relative to aqueous application, yet the impact of environmental stress on these approaches requires investigation. In this study, we compared the effects of various temperatures (heat and cold) and desiccation intervals (48 and 72 hr) on the survival, virulence and reproductive capacity of Heterorhabditis bacteriophora and Steinernema glaseri when applied via cadaver versus aqueous suspension. In the heat tolerance bioassays, following exposure to 30 degrees C, 35 degrees C and 37. 5 degrees C, nematodes (from both species) in the cadaver treatments exhibited higher survival, and reproductive capacity compared with aqueous application. No survival was observed above 37.5 degrees C regardless of species or application approach. In cold tolerance, no differences were observed between the cadaver and aqueous treatments after a sequence of exposures from 10 degrees C to -2 degrees C. In desiccation assays, following exposure to 85% relative humidity for 2 or 3 days, nematodes (from both species) exhibited higher survival and reproduction in the cadaver treatment than in the aqueous treatment, whereas no differences were observed in virulence. This is the first study to find differential stress tolerance among nematodes emerged from infected host cadavers versus those applied in aqueous suspension. Our findings indicate additional advantages when using the cadaver approach for biocontrol applications, and suggest EPNs existing in natural populations may have broader environmental tolerance than those applied via aqueous suspension.