The cotton leafworm, Spodoptera littoralis (Boisduval), was collected from commercial cotton production fields in Adana, Turkey, and tested for susceptibility to the insecticide spinosad. The susceptibility of the field strain was also compared to the susceptible strain (S) of S. littoralis. | Turk J Biol 30 (2006) 5-9 © TÜB‹TAK The Efficacy of Spinosad on Different Strains of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) Hilal AYDIN, M. Oktay GÜRKAN Department of Plant Protection, Faculty of Agriculture, Ankara University, 06110 D›flkap›, Ankara – TURKEY Received: Abstract: The cotton leafworm, Spodoptera littoralis (Boisduval), was collected from commercial cotton production fields in Adana, Turkey, and tested for susceptibility to the insecticide spinosad. The susceptibility of the field strain was also compared to the susceptible strain (S) of S. littoralis. Lethal dose bioassays were performed with third instar larvae using the leaf dip method. The LC50 values for field and susceptible strains were and ppm, respectively. When LC50 values and 95% confidence intervals were compared with a susceptible laboratory reference strain, the field strain was approximately less sensitive than the susceptible strain. The present study suggests that spinosad is potentially important in the control of S. littoralis. Key Words: Spinosad, Spodoptera littoralis, Toxicity, Biological Activity Spinosad’›n Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)’in Farkl› Populasyonlar› Üzerindeki Etkinli¤i Özet: Pamuk Yaprakkurdu Spodoptera littoralis (Boisduval)’in bir popülasyonu Türkiye, Adana ili ticari pamuk tarlalar›ndan toplanm›fl ve insektisit, spinosad’a karfl› hassasiyeti test edilmifltir. Tarla popülasyonunun hassasiyeti Spodoptera littoralis’in hassas popülasyonu (S) ile karfl›laflt›r›lm›flt›r. Letal doz denemeleri yaprak disk yedirme metodunun 3. dönem larvalara karfl› kullan›lmas› ile gerçeklefltirilmifltir. Tarla ve hassas popülasyonlar›n LC50 de¤erleri s›ras›yla 43,691 ve 10,037 ppm olarak bulunmufltur. Tarla ›rk›n›n LC50 de¤eri ve % 95 güven aral›klar› hassas laboratuvar ›rk› ile karfl›laflt›r›ld›¤›nda bu ›rk›n hassas ›rka göre spinosad’a yaklafl›k olarak 4,4 kat daha az duyarl› oldu¤u bulunmufltur.
