Bacillus thuringiensis and Nuclear Polyhedrosis Virus for the Enhanced Bio-control of Helicoverpa armigera

Abstract

A number of entomopathogenic microbial agents infect a wide array of insects and cause epizootics from time to time. Bacillus thuringiensis (Bt) and Nuclearpolyhedrosis virus (NPV) are two important potential pathogens of Helicoverpa armigera. Investigations were carried out on integration of B. thuringiensis and Nuclearpolyhedrosis virus to determine its impact on survival of second and fourth instar larvae under laboratory conditions. Both Bt and NPV were applied using diet incorporation method. Larvae continued to feed for 48 h when a batch of fifteen insects was exposed to diet mixed with any of the treatment. Mortality was recorded every 48 h until larvae died or pupated. The susceptibility of H. armigera larvae decreased with older stage as greater mortality was recorded in second instar larvae (95.45%) in comparison to fourth instar larvae (82.48%) in combined application of Bt and NPV. Application rate of Bt was the key for type of interaction as only one synergistic interaction (CTF≥20) was recorded when lower dose of Bt was combined with NPV, rest of the combinations were additive and independent (CTF≤20). Reduction in the pupation, adult emergence and egg eclosion was found directly related to pathogenicity of the applied agents. This study would be helpful to extend the integrated use of pathogens under field condition to many important insect pests.

Interaction of HaNPVs with two novel insecticides against Helicoverpa armigera Hubner (Noctuidae: Lepidoptera)

“…The interaction between microbial agent and insecticides depends upon the type of insecticide and insect pest under study. For example, there was synergistic interaction between NPV and Azadiractum ( Wakil et al (2012) and NPV and Bacillus thuringiensis ( Qayyum et al, 2015 ) against H. armigera , NPV and Imidacloprid ( Trang et al, 2002 ) against S. litura . The antagonistic interaction between NPV and insecticide might be due to the decrease in feeding potential or change in pH of insect gut ( El-Helaly and El-Bendary, 2013 ).…”

“…It has been reported to damage about 200 plant species including some important agriculture crops like cotton, maize, beans and tomato ( Pogue, 2004 , Moral-Garcia, 2006 , Baker et al, 2008 , Baker et al, 2010 ) and is mainly controlled by insecticides ( Brevault and Achaleke, 2005 ). However, due to the over-reliance on insecticides, this pest has shown resistance against many insecticides that is major cause of sporadic outbreaks of this pest ( Ahmad et al, 2001 , Torres-Vila et al, 2002 , Ahmad et al, 2003 , Rajagopal et al, 2009 , Alvi et al, 2012 , Qayyum et al, 2015 , Ahmad et al, 2019 ).…”

Evaluation of Nuclear Polyhedrosis Virus (NPV) and Emamectin Benzoate against Spodoptera litura (F.) (Lepidoptera: Noctuidae)

“…Both pathogens were applied, using a diet incorporation method. A diet piece of 0.5 g was offered to the larvae placed in glass vials (7 cm height, 3 cm in diameter) (Qayyum et al 2015). The artificial diet, mixed with the three concentrations of NPV (2 × 10 9 , 3×10 9 , and 4 × 10 9 POB ml −1 ) and emamectin benzoate (0.1 ppm) or a combined suspension of these was used.…”

“…Mortality rate was recorded every 24 h and the last count was recorded till pupation of both larval instars. The larvae were poked with a blunt needle and those unable to move in a coordinated manner were considered as dead (Ma et al 2008;Qayyum et al 2015). Pupation and adult emergence data were also recorded hereafter.…”

TRANSGENIC EXPRESSION OF TRANSLATIONAL FUSION OF SYNTHETIC Cry1Ac AND Hvt GENES IN TOBACCO CONFERS RESISTANCE TO Helicoverpa armigera AND Spodotera littoralis LARVAE

“…With the introduction of genetic transformation techniques, it is now possible to incorporate genes into the plant genome that confer resistance to targeted pest insects (Shelton et al, 2002). Insect resistant cotton containing Bt toxins is a rapidly adopted technology in the world (James, 2012;Qayyum et al, 2015). The natural ability of insects to develop resistance threatens the benefits achieved by growing the Bt crops (Tabashnik, 1994).…”