Characterization of dimethoate resistance inOxycarenus hyalinipennis(Costa): resistance selection, cross-resistance to three insecticides and mode of inheritance

Dusky cotton bugOxycarenus hyalinipennis(Costa) (Hemiptera: Lygaeidae) has been found to infesting cotton and other plants in Pakistan and some other countries. However, in Pakistan the increasing infestation ofO. hyalinipenniswas controlled with different insecticides, but some degree of resistance has been reported. Inheritance and cross-resistance of dimethoate resistance selection have not been documented inO. hyalinipennispreviously. Therefore, this study for the first time characterized dimethoate resistance inO. hyalinipennisby inducing it in the laboratory for six generations. The selected population was 9.70- and 157-fold resistant compared with the field and laboratory population, respectively. The dimethoate resistance selection did not bring about any cross-resistance with lambda-cyhalothrin (1.47-fold) but had a very low cross-resistance with chlorfenapyr (3.03-fold) and acephate (2.21-fold) compared with the field population. The overlapping in 95% confidence limits of LC(50)ratios of F-1(R female x S male) and F-1` (R male x S female) indicated the lack of maternal effects, whereas their degree of dominance of 0.54 and 0.51 suggested an incompletely dominant resistance inheritance. Multiple factors were involved in dimethoate resistance as implied from Chi-square analyses of backcrosses. In conclusion,O. hyalinipennisdevelops easily resistance to dimethoate due to selection. Lack of/or very low cross-resistance with lambda-cyhalothrin, chlorfenapyr and acephate implies that these insecticides can be used in rotation. Moreover, dimethoate resistance inheritance was incompletely dominant, autosomal and polygenic which implies that resistance to dimethoate can be delayed by using it in rotations, alterations, mosaics and combinations.