Abstract
BackgroundTo manage the cabbage butterfly, Pierisbrassicae (L.) (Lepidoptera: Pieridae), it is not wise to use insecticides on leafy vegetables which are eaten mostly fresh. During the past decades, the efforts to manage the pest, through chemical insecticides have raised serious health. Investigations were carried out to isolate naturally occurring GVs (PbGV) as a potent biopesticide against P.brassicae and to explore their efficacy with the application of phagostimulants.ResultsAmong the four naturally occurring isolates obtained from Northwestern Himalayas, Sudhmahadev isolate was found to be the most promising based on virulence and speed of kill against all the instars tested in the laboratory, showing the natural incidence of PbGV infection in field conditions. In concentration and time–response bioassay, all the isolates of P.brassicae Granulosis virus were found high virulent against second instar larvae of cabbage butterfly. Therefore, for enhanced efficacy of PBGV, its combined application with phagostimulants (Lepidiumsativum + Teepol + jaggery) or sticker (Teepol + jaggery), applied in field trials, resulted into greater mortality of larval instars than the single one. Overall, the results indicated that the introduction of a more isolates PBGV strain into populations of P.brassicae could be of vital importance for eco-friendly suppression of this pest globally with the combination of phagostimulants. The application virus alone with the pre-standardized concentration of 1 × 1012 OBs/ha did not reduce the larval population density to the desirable extent in the greenhouse chamber and therefore was not included in field experiments. Overall, the most promising treatments in reducing the larval population of the pest were PbGV + Teepol + B.thuringiensis (93.49 and 91.39%) and PbGV + Teepol + L.sativum (88.79 and 86.97%) over control in both greenhouse and field trials, respectively.ConclusionsIn this study, the native isolates of PbGV from different target locations to test their efficacy against different instars of P.brassicae were explored. Using native PBGV isolates with phagostimulant combinations played an important role for regulating the pest effectively. These phagostimulants not only protected the OBs from degradation in the presence of sunlight but also increased the speed of killing. The biocontrol potential of PbGV in both laboratory and field conditions indicated that baculoviruses are sustainable alternative to chemical insecticides.
Highlights
To manage the cabbage butterfly, Pieris brassicae (L.) (Lepidoptera: Pieridae), it is not wise to use insecticides on leafy vegetables which are eaten mostly fresh
The Himachal Pradesh, Poonch, Chatha, and Sudhmahadev isolates were named as PbGV-IND HP, PbGV-IND PH, PbGV-IND CH, and PbGV-IND SD, respectively, by adopting the most commonly used methods (Erlandson 2009)
Nonsignificant differences were observed in median lethal concentration (LC50) of all the isolates (F = 263.30; df = 3, 8; p = 0.16), Sudhmahadev isolate exhibited a 57.79–70.49%, 38.74–48.28% and 77.29– 80.36% reduction in the L C50 in second, third and fourth larval instars of P. brassicae, respectively, as compared to other isolates (Table 1)
Summary
To manage the cabbage butterfly, Pieris brassicae (L.) (Lepidoptera: Pieridae), it is not wise to use insecticides on leafy vegetables which are eaten mostly fresh. Baculoviruses are naturally involved in the regulation of insect populations and individual isolates often have a very narrow host range and, no side effects or harmful effects on mammals, birds, other animals, aquatic systems and beneficial insects These microbes may establish themselves in the pest population and exert long-term protection. Their use is being encouraged by international concerns for a reduction in pesticides within the environment, as by the event of resistance to chemical insecticides by target pests Their usage is hampered due to the inactivation of OBs in the presence of sunlight and the slow speed of action to kill the insect. When a highly purified preparation of P. brassicae virus was exposed to direct sunlight, total inactivation of the virus occurred between 12 and 19 h (David et al 1968)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
