Inheritance mode and properties of fipronil resistance in Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae)

Wazir Shabana,Ali Shad Sarfraz 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.4

The dusky cotton bug (DCB), Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae) is one of the most important pests of cotton. Fipronil belongs to phenylpyrazole and is being used against various insect pests. To reduce the resistance to this insecticide, the present study was planned to examine the inheritance mode and preliminary mechanism of resistance to fipronil in DCB. A fipronil selected strain had a 9855-fold level of resistance after 11 generations of selection with fipronil. The median lethal concentration of reciprocal crosses F 1 (FiproSel.♂×Lab-Pop♀) and F 1 - (Fipro-Sel.♀× Lab-Pop♂) showed no significant difference and degree of dominance values were 0.60 and 0.58 for F1 and F1 - ), respectively, suggesting autosomal and incompletely dominance of resistance to fipronil in fipronil selected strain of DCB. Monogenic model of inheritance revealed polygenic resistance to fipronil. Realized heritability (h 2 ) value was 0.24 for fipronil resistance. The study of synergism indicated that PBO (Piperonyl butoxide) and DEF (S, S-butyl phosphorotrithioateases) did not enhance the toxicity of fipronil on both populations. The study on inheritance mode of fipronil resistance in DCB may help delay the resistance with insecticides.

Spinosad resistance in an invasive cotton mealybug, Phenacoccus solenopsis: Cross-resistance, stability and relative fitness

Muhammad Babar Shahzad Afzal,Sarfraz Ali Shad 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2

Spinosad is new chemical insecticide, which acts on nicotinic acetylcholine receptor. Selection of Phenacoccus solenopsis with spinosad was carried out in the laboratory to characterize spinosad resistance. Cross resistance, stability and fitness cost of spinosad resistance were evaluated. Phenacoccus solenopsis showed a 282.45-fold resistance to spinosad after seven rounds of selection. Spinosad selected population (Spinosad-SEL pop) showed different levels of cross-resistance to profenofos, spinetoram and deltamethrin in comparison with unselected population. Spinosad resistance decreased significantly from282.45 to 25.4-fold when resistant population was not exposed to the insecticide for up to six generations, indicating unstable resistance. Relative fitness of Spinosad-SEL pop was 0.51with decrease in survival rate, fecundity, intrinsic rate of male and female, biotic potential and mean relative growth rate of male,whereas prolonged developmental time fromegg to adultmale and female, and generation time of both sexes compared with the unselected population. Resistance to spinosad indicates the need to rotate insecticides with others of differing modes of action and implementing alternative methods for P. solenopsis management.

Characterization of indoxacarb resistance in Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae): Cross-resistance, stability and fitness cost

Muhammad Babar Shahzad Afzal,Sarfraz Ali Shad,Esteban Basoalto,Masood Ejaz,Jose Eduardo Serrao 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.4

The cottonmealybug, Phenacoccus solenopsis Tinsley is an important agricultural insect pest of cotton in Pakistan. Some populations of P. solenopsis are reported to have significant levels of insecticide resistance, resulting in its control failure. In our study, we selected a population of P. solenopsis with indoxacarb, which resulted in a 2223-fold resistance level after five generations compared with the unselected strain. This selected-population also developed a moderate level of cross-resistance to spinosad (36-fold), but only very low cross-resistance to chlorpyrifos (2.3-fold) and bifenthrin (4.5-fold) compared with the unselected population. Indoxacarb resistance in this population was associated with several negative fitness attributes which would slow the selection for resistance in field popualtions. A significant decline in indoxacarb resistance was observed when the selected-population was left unexposed for eight generations. These results suggest that field populations of P. solenopsis should be surveyed for indoxcarb resistance and associated cross-resistances, and that alternative chemistries should be adopted and rotated to improve the control and resistance management tactics.

Assessing the resistance risk to emamectin benzoate in Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae): selection, cross-resistance dynamics and estimates of realized heritability

Afzal Muhammad Babar Shahzad,Riaz Muhammad,Shad Sarfraz Ali,Ijaz Mamuna 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.4

Emamectin benzoate, a non-systemic, translaminar, and broad spectrum insecticide, is excessively used in cotton. It kills the pest by suppressing the muscle contraction. Phenacoccus solenopsis Tinsley (Hemiptera: Pseudo coccidae) is one of the major sap sucking pests of cotton in many countries and has been shown resistance to various insecticides. In this study, we have continuously selected P. solenopsis with emamectin benzoate in the laboratory from G 3 to G 18 to determine the resistance development and resistance risk to emamectin benzoate and also to evaluate the dynamics of cross-resistance (CR) development with three other insecticides. After continuing selection of P. solenopsis for 16 generations with emamectin benzoate, the emamectin selected strain (Ema-SEL) developed a 280.15-fold resistance when tested at G 19 . Ema-SEL strain showed no CR to abamectin (0.28–1.65-fold), and profenofos (0.12–0.29-fold), but a very low to low CR to cypermethrin (6.02–11.29-fold). Abamectin was negatively cross-resistant with emamectin benzoate in Ema-SEL strain at G 13 , G 15 and G 19 while profenofos also exhibited similar results at G 13 , G 15 , G 17 and G 19 . Realized heritability (h 2 ) of resistance to emamectin benzoate was 0.24 from G 3 to G 19 . The results of projected rate of resistance development showed that if h 2 = 0.24, 0.34, and 0.44 at slope = 1.08, then 2.03, 1.43, and 1.11 generations, respectively are required for tenfold increase in LC 50 at 95 % selection intensity. Results of the present study suggested that P. solenopsis has the ability to develop resistance to emamectin benzoate but it can be managed by the alternate use of other insecticides including abamectin, profenofos and cypermethrin due to lack of/or very low to low CR with these insecticides.

Evaluation of resistance stability and fitness costs in dimethoate-selected strain of Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae)

Usama Khan Hafiz Muhammad,Banazeer Ansa,Afzal Muhammad Babar Shahzad,Ali Shad Sarfraz 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3

Dimethoate belongs to organophosphate (OP) group of insecticides, used worldwide against several economic insect pests. This study was done to evaluate the fitness costs and stability of dimethoate resistance in a previ ously selected strain of dusky cotton bug, Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae), a serious sucking pest of cotton. Previously, dimethoate selected (Dimeth-SEL) strain was developed after selecting O. hyalinipennis for six generations in the laboratory. The selected strain expressed resistance ratios (RRs) of 157.76-, and 14.13-fold to dimethoate when compared with Lab Pop, and Unsel Pop, respectively. Data on fitness traits of selected strain reveal that the relative fitness (Rf) of Dimeth-SEL was 0.77 along with significant decrease in nymphal survival, hatchability, net reproductive rate (R0), intrinsic rate of natural increase (r m ), and biotic potential (Bp). The Rf evaluated for Cross 1 and Cross 2 was 1.02 and 0.91, respectively. For resistance stability, Dimeth-SEL (G 6 ) was left unexposed to dimethoate for five generations (G 7 -G 11 ) and the bioassay results at G 11 showed that removal of selected strain from selection pressure resulted in a significant decline in dimethoate resistance. It can be inferred from these results that resistance to dimethoate was developed in O. hyallinipennis at the expense of very high energetic costs and that these costs might also contributed in lowering the resistance levels towards susceptibility after stopping the selection for several generations. These results have practical implications in managing the dimethoate resistance against O. hyallinipennis by implementing the insecticide rotation strategy and also by delaying the dimethoate spray in the field for some generations.