Abstract
Resistance management is very important for devising control strategies of polyphagous insect-pests like Helicoverpa armigera Hübner (Lepidoptera: Noctuidae). Considering the importance of resistance management, demographic features of selected and unselected populations of H. armigera were studied in 6 different treatments viz. emamectin benzoate, Helicoverpa armigera Nucleopolyhedrosis Virus (HaNPV), emamectin benzoate+HaNPV, spinetoram, spinetoram+HaNPV and control. Higher values for fecundity, intrinsic rate, the finite rate of increase (λ) were recorded in the control of selected as compared to the rest of treatment. Similarly, higher values for these population parameters viz. oviposition days, fecundity, intrinsic rate, the finite rate of increase were calculated in the unselected control. Similarly, net reproductive rate (R0) for selected and unselected control was higher as compared to the rest of the treatments. It may happen because these kinds of selection pressures can result in decreased fitness of the test insect thus decreased fitness of H. armigera in different treatments was observed as compared to the control. Additionally, quicker development of susceptible insects was observed because susceptible insects were growing without any stressor (xenobiotics) as compared to the rest which contributed to their faster development.
Highlights
American bollworm (ABW), Helicoverpa armigera Hubner (Lepidoptera: Noctuidae), is one of the important pest attacks to a range of agricultural crops, such as fiber crops, horticultural plants, and vegetables [1,2,3]
In emamectin benzoate-selected population, pre-adult duration was significantly more i.e. 27.97 days in Helicoverpa armigera Nucleopolyhedrosis Virus (HaNPV)+Emamectin benzoate treatment while it was lower in control i.e. 25.51 days
Higher Adult pre-oviposition period (APOP) and Total pre-oviposition period (TPOP) were 3.00 and 29.00 days in HaNPV+spinetoram treatment which decreased to minimum in spinetoram treatment i.e. 1.44 and 28.00 days, respectively
Summary
American bollworm (ABW), Helicoverpa armigera Hubner (Lepidoptera: Noctuidae), is one of the important pest attacks to a range of agricultural crops, such as fiber crops, horticultural plants, and vegetables [1,2,3]. In Pakistan, it has been considered the most dangerous and yield decliner of field crops from 1990s to early 21st century [4]. Polyphagous nature, several generations, high fertility rate, migratory behavior, and development of resistance are among the important reasons that have made this pest very destructive [5, 6]. Annual losses of around 3 billion USD have been reported due to its attack [7].
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