Recep Ay

Resistance to Bifenthrin and Resistance Mechanisms of Different Strains of the Two-Spotted Spider Mite (Tetranychus urticae) from Turkey

Nine different strains of the two-spotted spider miteTetranychus urticae Koch (Acari: Tetranychidae) were collected on cotton from Adana, Antalya, Izmir, Manisa and Urfa in Turkey. Their responses to bifenthrin were investigated using conventional bioassay and biochemical assays. LC50 and LC90 values of bifenthrin were determined for all strains by using a residual bioassay with a petri dish-spray tower. Resistance ratios were determined by comparing the samples with a standard susceptible strain, GSS. The resistance ratios of the strains ranged from <1 to 669-fold (at LC50). Of the investigated field strains, only three (two from Adana and one from Urfa) were resistant to bifenthrin. There was a correlation between esterase enzyme activity and bifenthrin resistance according to polyacrylamide gel electrophoresis and microtiter plate assays in the three resistant strains.

Toxicity, inheritance and biochemistry of clofentezine resistance in Tetranychus urticae

Abstract  This study evaluates the toxicological and biochemical response of two‐spotted spider mites to clofentezine selection pressure. The mortality rate of Tetranychus urticae in adult females depends on increased clofentezine concentration and clofentezine was found to be effective against females. The resistance rate of the CUM strain selected 12 times once per generation with clofentezine was increased from 1.28‐ to 105.27‐fold. The interaction of some synergists with clofentezine was analyzed in the clofentezine‐resistant CLOF 12 strain. Synergists had no effect on clofentezine toxicity. The clofentezine‐resistant CLOF 12 strain showed resistance against chlorpyrifos, abamectin, propargite, fenpyroximate and amitraz. The modes of inheritance of resistance to clofentezine were found to be incompletely dominant and not sex‐linked. Esterase enzyme activity was detected both by gel electrophoresis and microplate reader methods, while glutathione S‐transferase (GST) and monooxygenase (P450) activity were detected only by the microplate reader method. During the selection period the esterase, the GST and the P450 enzymes activities were raised from 7.69, 7.09 and 0.003 3 to 18.40, 13.11 and 0.003 7 milli‐optical density/min/mg proteins, respectively. An increase was observed in the band intensity of esterases and esterase enzymes may play a role in clofentezine resistance in T. urticae.

Toxicity of insecticides and acaricides to the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae)

This study determined the side effects of a selection of pesticides on the eggs, nymphs and adults of the predatory mite Neoseiulus californicus. It assessed the acaricides spirodiclofen, cyhexatin, hexythiazox and clofentezine; the insecticides indoxacarb, chlorantraniliprole, diflubenzuron and pyriproxyfen; and the insecticide/acaricides abamectin and spiromesifen. A spray tower-leaf disk method was used to determine the side effects of pesticides on N. californicus. Three doses of each pesticide were applied: a field application dose (T), half of the field application dose (T/2) and double the field application dose (2T). Dead–live counts were made at days 1, 3, 5 and 7 after application. Daily observations were made during egg applications to observe whether the eggs were hatching. None of the pesticides, except for hexythiazox, showed any effect on the eggs of predatory mites. At the 2T dose, chlorantraniliprole and hexythiazox were harmless, and cyhexatin and pyriproxyfen were found to be slightly harmful to N. californicus nymphs and adults. At T and T/2 doses, all of the pesticides except abamectin were found to be harmless to nymphs. Abamectin was harmful at all doses to nymphs. At the T and T/2 doses in adults, chlorantraniliprole, indoxacarb and diflubenzuron were harmless; clofentezine, cyhexatin, spiromesifen, spirodiclofen and pyriproxyfen were slightly harmful; and abamectin was harmful and moderately harmful, respectively. The effect of pesticides varies with predatory mite stages.

Determination of the inheritance, cross‐resistance and detoxifying enzyme levels of a laboratory‐selected, spiromesifen‐resistant population of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae)

BACKGROUND Neoseiulus californicus of the family Phytoseiidae is an effective predatory mite species that is used to control pest mites. RESULTS The LC50 and LC60 values of spiromesifen were determined on N. californicus using a leaf-disc method and spraying tower. A laboratory selection population designated SPR13 was found to have a 52.08-fold resistance to spiromesifen following 13 selection cycles. This population developed low resistance to hexythiazox and moderate cross-resistance to propargite, clofentezine, spirodiclofen, etoxazole and milbemectin. PBO, IBP and DEM synergised resistance 3.75-, 2.54- and 1.93-fold respectively. Crossing experiments revealed that spiromesifen resistance in the SPR13 population was intermediately dominant and monogenic. In addition, detoxifying enzyme activities were increased 2.74-fold for esterase, 3.09-fold for glutathione S-transferase and 2.17-fold for cytochrome P450 monooxygenase in the SPR13 population. CONCLUSIONS Selection for spiromesifen under laboratory conditions resulted in the development of spiromesifen resistance in the predatory mite N. californicus. Predatory mites that are resistant to pesticides are considered valuable for use in resistance management programmes within integrated pest control strategies.

Enzyme variation among some southwest Turkey populations of the two-spotted spider mite, Tetranychus urticae Koch

Ten different two-spotted spider mite (Tetranychus urticae Koch) populations were collected from greenhouses in two geographically different regions of Turkey, Antalya and Isparta. Individual spider mites were homogenized in microplates using multi-homogenizer, and the genetic variations in the esterase of these populations were studied by nondenaturing polyacrylamide gel electrophoresis. The results showed that esterase enzymes were polymorphic in all populations in both regions. However more intrapopulation and interpopulation variations were observed in the population from Antalya region.

Etoxazole resistance in predatory mite Phytoseiulus persimilis A.-H. (Acari: Phytoseiidae): Cross-resistance, inheritance and biochemical resistance mechanisms.

Phytoseiulus persimilis of the family Phytoseiidae is an effective predatory mite species that is used to control pest mites. The LC50 and LC60 values of etoxazole were determined on P. persimilis using a leaf-disc method and spraying tower. A laboratory selection population designated ETO6 was found to have a 111.63-fold resistance to etoxazole following 6 selection cycles. This population developed low cross-resistance to spinosad, spiromesifen, acetamiprid, indoxacarb, chlorantraniliprole, milbemectin and moderate cross-resistance to deltamethrin. PBO, IBP and DEM synergised resistance 3.17-, 2.85- and 3.60-fold respectively. Crossing experiments revealed that etoxazole resistance in the ETO6 population was an intermediately dominant and polygenic. In addition, detoxifying enzyme activities were increased 2.71-fold for esterase, 3.09-fold for glutathione S-transferase (GST) and 2.76-fold for cytochrome P450 monooxygenase (P450) in the ETO6 population. Selection for etoxazole under laboratory conditions resulted in the development of etoxazole resistance in the predatory mite P. persimilis that are resistant to pesticides are considered valuable for use in resistance management programmes within integrated pest control strategies.

Biochemical and molecular characterizations of cypermethrin resistance in laboratory-selected cypermethrin-resistant strains of Tetranychus urticae Koch. (Acari: Tetranychidae)

ABSTRACT Pyrethroids are commonly used pesticides for controlling agricultural pests. A pyrethroid resistant strain of T. urticae was obtained after laboratory selection with cypermethrin for determining mechanisms of cypermethrin resistance. TaqMan diagnostic assay as well as sequencing of voltage gated sodium channel (VGSC) gene were performed in order to detect previously known mutations in German susceptible strain (GSS) confirming that it does not carry any of the known VGSC mutations. Therefore, GSS strain was selected with cypermethrin and the resistant C6 strain was generated that is free of VGSC mutations. Toxicity assay data revealed relatively high resistance levels of the C6 strain (54.24-folds) in comparison to GSS. All inhibitors (piperonyl butoxide (PBO), esterases, P450; S-benzyl-O, O-diisopropylphosphorothioate (IBP), esterases; and diethyl maleate (DEM), glutathione S-transferase (GST)) were used in combined toxicity assays against the major detoxification enzymes, synergized resistance by 1.41-, 1.61-, and 2.27-fold, respectively. In the C6 strain, activities of P450, GST, and esterase showed elevated activity in comparison to GSS. By application of TaqMan diagnostic assay, we confirmed that both GSS and C6 T. urticae strains are free of VGSC mutations, indicating that detoxification-based cypermethrin resistance mechanisms are involved in resistance and have significant effect on the phenotype.

Isparta İli Elma Bahçelerinden Toplanan Panonychus ulmi Koch’nin Bazı Akarisitlere Karşı Duyarlılık ve Detoksifikasyon Enzim Düzeyleri

Isparta ili elma bahcelerinden toplanan Panonychus ulmi Koch populasyonlarinin etoxazole, spirodiclofen, hexythiazox’a karsi duyarlilik ve detoksifikasyon (esteraz, glutation-S-transferaz (GST), sitokrom P450 monooxygenaz (P450) ve asetilkolinesteraz (AChE)) enzim duzeyleri belirlenmistir. Bu amacla Isparta ili ve ilcelerinden 2012 ve 2013 yili uretim sezonunda toplam 13 adet P. ulmi populasyonu toplanmistir. Akarisiter akarlara ilaclama kulesi-yaprak biyoassay yontemi ile uygulanmistir. Elde edilen veriler POLO PC programi ile analiz edilmis ve LC50 degerleri elde edilmistir. Tarla populasyonlarinin LC50 degerleri hassas populasyonun LC50 degerlerine oranlanarak direnc oranlari hesaplanmistir. P. ulmi populasyonlarinin spirodiclofen’e karsi direnc duzeyleri <1-1.95 kat, hexythiazox’a <1-2.36 kat ve etoxazole <1-7.30 kat arasinda degismistir. Butun populasyonlarda detoksifikasyon enzim duzeyleri farkli substratlarla biyokimyasal olarak incelemistir. Detoksifikasyon enzimlerinin duzeyleri populasyonlara gore degismistir.