Effective Control of a Field Population of Helicoverpa armigera by Using the Small RNA Virus Helicoverpa armigera Stunt Virus (Tetraviridae: Omegatetravirus)

Abstract

The first comprehensive field trial using an insect small RNA virus as a control agent on a cropping system was conducted with the Helicoverpa armigera stunt virus (family Tetraviridae, genus Omegatetravirus, HaSV). The virus was semipurified, quantified, and applied at two rates, 4 x 10(15) and 4 x 10(14) virus particles/ha, with minimal formulation on sorghum against the bollworm Helicoverpa armigera (Hübner). For comparison, a commercial preparation of Helicoverpa zea single-nucleopolyhedrovirus (HzSNPV, Gemstar) was applied at the same time at 9.27 x 10(11) polyhedral inclusion bodies/ha. The HaSV application rates were determined by a novel procedure using laboratory LC50 bioassay data for HaSV and HzSNPV and calibration to the known field application rate of the HzSNPV. The baculovirus and the higher rate of HaSV produced statistically equivalent reductions in the larval populations of around 50% at both 3 and 6 d postapplication (dpa) compared with untreated plots. The 10-fold lower rate of HaSV reduced the larval population by 50% at 3 dpa and approximately 30% at 6 dpa. Persistence of HaSV over a 72-h period was found to be similar to that of HzSNPV, although the amount of HaSV available on the sorghum heads increased at 130 h postapplication, due most likely to dispersal of newly produced virus from cadavers and frass. The results from this trial indicate that HaSV could be used as an effective biopesticide for the control of H. armigera in sorghum and the ramifications for its broader use are discussed.

Characterization of a novel member of genus Iflavirus in Helicoverpa armigera

“…However, several studies have reported that Bt-resistance has evolved in the field (Gunning et al, 2005;Zhang et al, 2012). Thus, other forms of biological pest control, including the use of host-specific viral pesticides, derived from baculovirus (Allaway and Payne, 1984;Chen et al, 2001;Fuxa, 2004;Sun et al, 2002;Sun et al, 2004), small RNA viruses (Christian et al, 2005) and densoviruses (El-Far et al, 2012), has attracted more attention from researchers. Moreover, high-through-put analytical methods such as metagenomics and RNA sequencing provide sensitive and effective methods for the discovery of novel viruses and asymptomatic disease agents that may be useful as biological control products (Diatchenko et al, 1996;Ge et al, 2012;Marguerat and Bähler, 2009;Mokili et al, 2012;Radford et al, 2012;Roossinck et al, 2015), or conversely, may negatively or positively impact upon the biopesticide products being used.…”

Densovirus Is a Mutualistic Symbiont of a Global Crop Pest (Helicoverpa armigera) and Protects against a Baculovirus and Bt Biopesticide

“…In China, the introduction of Bt-cotton in the 1990s has seen a dramatic decline in the H. armigera moth population. However, there are signs of Bt-resistance emerging [23], [24], fueling renewed interest in other forms of biological pest control, including the use of host-specific viral pesticides, derived from densoviruses [25], small RNA viruses [26] and baculoviruses [27], [28], [29], [30], [31]. Previously, we reported a novel densovirus (HaDNV-1, from the family Parvoviridae) in H. armigera moths that possesses a monosense genome that is 4926 nucleotides in length and clustered with the members of the genus Iteravirus in phylogenetic analysis [32].…”

A Baculovirus-Expressed Dicistrovirus That Is Infectious to Aphids

“…Here we describe the construction of a full-length clone of the RNA genome of Rhopalosiphum padi virus (RhPV) and baculovirusmediated expression of the clone to produce virions that are infectious to aphids. This study suggests that baculovirus vectors may be useful for the production of SRV biopesticides (11,12,30,42).…”

“…There are several examples of the use of SRVs for insect pest control (11,42), including the use of Cricket paralysis virus for control of the olive fruit fly (30) and Helicoverpa armigera stunt virus (Tetraviridae) for control of H. armigera (12). Baculovirus expression of infectious clones of SRV provides an alternative approach to the production of viruses such as H. armigera stunt virus, for which susceptible cell lines have not been identified.…”