Cotton aphid, Aphis gossypii Glover, 1877 (Hemiptera: Aphididae), is a major pest in cotton fields. Neonicotinoids are important and highly prevalent insecticides currently used against A. gossypii and other herbivorous insect pests in the Mediterranean Region of Turkey. However, some insecticide applications against A. gossypii in the Çukurova Region have failed despite using high rates. Therefore, bioassays and enzyme analyses were conducted to determine resistance to imidacloprid and thiamethoxam in A. gossypii populations collected in 2015-2016 from cotton fields in this region. Resistance factors (RF) were 54.6 to 206.5 fold for imidacloprid and 5.7 to 65.7 fold for thiamethoxam. Populations from Kürkçüler (RF 206.5) had the highest LD50 for imidacloprid and from Körkuyu (RF 65.7) for thiamethoxam. Enzyme analysis revealed statistically higher metabolic resistance. Maximum enzyme activities were 17.8, 142.3 and 3.8 nM/min/mg protein for carboxylesterase for in Körkuyu, for glutathione S-transferase in Bahçe and for cytochrome P450 monooxygenase in Körkuyu, respectively. This study revealed the development of resistance in A.gossypii to neonicotinoid insecticides in Turkey and the need for new management strategies to break this resistance.

Toxic and in vitro anti-acetylcholinesterase and anti-carboxylesterase effects of various plant extracts on Aphis gossypii Glover, 1877 (Hemiptera: Aphididae) 1Bazı bitki ekstraktlarının Aphis gossypii Glover, 1877 (Hemiptera: Aphididae) üzerine toksik in vitro anti-asetilkolinesteraz ve anti-karboksil esteraz enzim etkisi

Turkey has great potential in vegetable production especially in greenhouses. However, plant pests such as Tetranychus urticae Koch can cause significant yield losses with the contribution of suitable climate conditions of greenhouses that allow to fast development of spider mites. Although synthetic acaricides are the most preferred control tools to manage T. urticae populations in Turkey, control failure has often been reported because of its ability to quickly develop resistance. In this study, bifenthrin and hexythiazox toxicity over five field-collected strains were evaluated and mechanisms of resistance have also been investigated via biochemical and molecular methods. Resistance mutations in voltage gated sodium channel and chitin synthase I which are the target sites of bifenthrin and hexythiazox, respectively, were found in various strains. The specific activity of P450 and GST enzymes was significantly increased in all field-collected strains comparing with susceptible strain. In addition, synergists of P450 and esterase enzymes enhanced the bifenthrin and hexythiazox toxicity, respectively. The results of this study will contribute to design proper resistance management strategies in Turkish greenhouses.

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Aphis gossypii Glover, 1877 (Hemiptera: Aphididae), which is a polyphagous species, is among the main pests of the cotton plants in the whole world. The Çukurova region is an area where polyculture agriculture activities are carried out. While insecticides in the neonicotinoid group are prevalently used in the cotton fields in this region for controlling A. gossypii, the problem of resistance is frequently encountered. This study determined the relative expression levels of the CYP6CY22 and CYP6CY13 genes, cytochrome P450, acetylcholine esterase (AChE) and glutathione S-transferase (GST) enzyme activities in six different populations of A. gossypii collected in 2018 from cotton fields in the province of Adana in Southern Turkey. In comparison to the reference culture, there was an increase in gene regulation by 81.9 fold in the CYP6CY22 gene in the Hamitbey population and by 6 fold in the CYP6CY13 gene in the Gazipaşa population. Additionally, the Hamitbey population showed 4.3 times higher (0.74 U/ml) cytochrome P450 enzyme activity. The Çiftlikler population showed 5.9 fold higher AChE (0.82 U/ml) and 4.3 fold higher GST (2.68 U/ml) activities. The analyses revealed that the A. gossypii populations were exposed to high amounts of insecticides. Consequently, overexpressed genes, high levels of enzyme activities and metabolic resistance in based on cytochrome P450 activity were observed in the study. Cotton aphid, Aphis gossypii Glover, 1877 (Hemiptera: Aphididae), is one of the significant pests among aphids that reaches the economic loss threshold. A. gossypii is a polyphagous species that has a very broad spectrum of hosts. As in the entire world, they create harm on especially cotton and Cucurbitaceae species in Turkey (Ozgur and Sekeroglu