Abstract
Despite of extensive application of insecticides, severe infestation of date palms is reported with Ommatissus lybicus every year. The development of insecticide resistance in the field strains receiving heavy pesticide regimes can be a reason for unsuccessful control. Seventeen field strains of O. lybicus from Oman were appraised for resistance against deltamethrin and fenitrothion in years 2017 and 2018. Eleven field strains depicted susceptibility (RR < 3-fold) while six strains expressed minor (RR = 3–5-fold) to low level (RR = 5–10-fold) of resistance against deltamethrin when compared with lab-susceptible strain. In case of fenitrothion, fourteen field strains exhibited minor to low level of resistance and only two showed susceptibility. Intermediate resistance (RR = 10–40-fold) was also reported in one field strain against fenitrothion. A significant but low resistance (RR = 7.86-fold) was observed in a lab strain selected with deltamethrin for resistance development mechanism studies. The deltamethrin-selected strain exhibited minor resistance development (RR = 3.13-fold) against fenitrothion. Significant reduction in resistance was observed with higher toxicity values when the two pesticides were tested along with piperonyl butoxide (PBO) against all the field collected dubas bug strains. Higher susceptibility of field strains to deltamethrin suggest it a suitable alternate candidate to deter resistance development in O. lybicus.
Highlights
In order to manage such a notorious pest, the Ministry of Agriculture in Oman has tested several pesticides from pyrethroid and organophosphate groups by aerial and ground applications
Inability to fly over long distances and intensive pesticide exposures of dubas bug populations can result in formation of diverged populations which may result in development of resistant strains[30]
Aerial spraying of insecticides in spring and ground application in winter is carried out every year to control this notorious pest
Summary
In order to manage such a notorious pest, the Ministry of Agriculture in Oman has tested several pesticides from pyrethroid and organophosphate groups by aerial and ground applications. The excessive application of pesticides to date palm orchards to control this pest has contributed to the development of resistance in dubas bug populations to several conventional chemical insecticides[28,29]. Keeping in view the economic importance of dubas bug and lack of knowledge for the resistance in dubas bug against insecticides, the study was designed to determine the resistance level of dubas bug to the most commonly applied insecticides (deltamethrin and fenitrothion). This is the first report of the resistance in dubas bug against the conventional insecticides most commonly used for its control in the Sultanate of Oman. The findings can be utilized as baseline data for future resistance monitoring and to devise a useful strategy for dubas bug management
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