Two year field study to evaluate the efficacy of Mamestra brassicae nucleopolyhedrovirus combined with proteins derived from Xestia c-nigrum granulovirus

Effects of Mixed Baculovirus Infections in Biological Control: A Comprehensive Historical and Technical Analysis

Baculoviruses are insect-specific DNA viruses that have been exploited as bioinsecticides for the control of agricultural and forest pests around the world. Mixed infections with two different baculoviruses have been found in nature, infecting the same host. They have been studied to understand the biology of virus interactions, their effects on susceptible insects, and their insecticidal implications. In this work, we summarize and analyze the in vivo baculovirus co-infections reported in the literature, mainly focusing on pest biocontrol applications. We discuss the most common terms used to describe the effects of mixed infections, such as synergism, neutralism, and antagonism, and how to determine them based on host mortality. Frequently, baculovirus co-infections found in nature are caused by a combination of a nucleopolyhedrovirus and a granulovirus. Studies performed with mixed infections indicated that viral dose, larval stage, or the presence of synergistic factors in baculovirus occlusion bodies are important for the type of virus interaction. We also enumerate and discuss technical aspects to take into account in studies on mixed infections, such as statistical procedures, quantification of viral inocula, the selection of instars, and molecular methodologies for an appropriate analysis of baculovirus interaction. Several experimental infections using two different baculoviruses demonstrated increased viral mortality or a synergistic effect on the target larvae compared to single infections. This can be exploited to improve the baculovirus-killing properties of commercial formulations. In this work, we offer a current overview of baculovirus interactions in vivo and discuss their potential applications in pest control strategies.

The genome sequence of the setaceous Hebrew character, Xestia c-nigrum, (Linnaeus, 1758)

We present a genome assembly from an individual male Xestia c-nigrum (the setaceous Hebrew character; Arthropoda; Insecta; Lepidoptera; Noctuidae). The genome sequence is 760 megabases in span. Most of the assembly is scaffolded into 31 chromosomal pseudomolecules, including the assembled Z sex chromosome. The mitochondrial genome has also been assembled and is 15.3 kilobases in length.

Cd exposure-triggered metabolic disruption increases the susceptibility of Lymantria dispar (Lepidoptera: Erebidae) larvae to Mamestra brassicae nuclear polyhedrosis virus: A multi-omics study

Biological control is an environmentally friendly and effective pest control strategy, but it is often affected by a variety of abiotic factors in the pest control area. Here, the susceptibility of gypsy moth larvae to Mamestra brassicae nuclear polyhedrosis virus (MbNPV) under Cd treatment at the low and high dosages was investigated, and the mechanism of Cd stress affecting virus susceptibility of gypsy moth larvae was analyzed from a metabolic perspective by combining transcriptome and metabolome of the larval fat body. Our results showed that the mortality of MBNPV infection on gypsy moth larvae pre-exposed to Cd was significantly higher than that of larvae without Cd pre-exposure, and the joint effects of Cd exposure and virus infection on larval mortality were demonstrated to be synergistic. Transcriptome analysis revealed that amino acid and carbohydrate transport and metabolism accounted for most of the differently expressed genes in the low Cd and high Cd treatment groups. Consistent with the transcriptome results, metabolome analysis also showed that most metabolites affected by Cd exposure were involved in amino acid and carbohydrate metabolism. Function analysis showed that the contents of several amino acids (e.g. tryptophan and tyrosine) with antioxidant properties were significantly increased in Cd-treated gypsy moth larvae. Taken together, Cd exposure as an environmental factor, promotes the susceptibility of gypsy moth larvae to MbNPV, and metabolic disruption, especially amino acids and carbohydrates-related metabolism, is responsible for the increased susceptibility of gypsy moth larvae to virus under Cd stress.

Special Issue "Insect Viruses and Pest Management"

Most revues consider the work on Lymantria monarcha in central Europe [...].

Biopesticide based sustainable pest management for safer production of vegetable legumes and brassicas in Asia and Africa

Vegetables are one of the important crops which could alleviate poverty and malnutrition among the smallholder farmers in tropical Asia and Africa. However, a plethora of pests limit the productivity of these crops, leading to economic losses. Vegetable producers overwhelmingly rely on chemical pesticides in order to reduce pest-caused economic losses. However, over-reliance on chemical pesticides poses serious threats to human and environmental health. Hence, biopesticides offer a viable alternative to chemical pesticides in sustainable pest management programs. Baculoviruses such as nucleopolyhedrovirus (NPV) and granulovirus (GV) have been exploited as successful biological pesticides in agriculture, horticulture and forestry. Maruca vitrata multiple nucleocapsid NPV (MaviMNPV) was found to be a unique baculovirus specifically infecting pod borer on food legumes, and it has been successfully developed as a biopesticide in Asia and Africa. Entomopathogenic fungi also offer sustainable pest management options. Several strains of Metarhizium anisopliae and Beauveria bassiana have been tested and developed as biopesticides in Asia and Africa. This review specifically focuses on the discovery and development of entomopathogenic virus and fungi-based biopesticides against major pests of vegetable legumes and brassicas in Asia and Africa. © 2019 Society of Chemical Industry.

The peritrophic membrane as a target of proteins that play important roles in plant defense and microbial attack

The peritrophic membrane (or peritrophic matrix: PM) is a thin membranous structure that lies along the midgut epithelium in the midgut lumen and consists of chitin and proteins. PM exists between ingested food material and midgut epithelium cells and it is on the frontline of insect-plant and insect-microbe interactions. Therefore, proteins that play major roles in plant defense against herbivorous insects and in microbial attack on insects should penetrate, destroy or modify the PM to accomplish their roles. Recently, it has become clear that some proteins crucial to plant defense or microbial attack have the PM as their primary target. In addition, several plant defense proteins have been reported to affect the PM, although it is still unclear whether the PM is their primary target. This review introduces several of these proteins: fusolin and enhancin, two proteins produced by insect viruses that greatly enhance infection of the viruses by disrupting the PM; the MLX56 family proteins found in mulberry latex as defense proteins against insect herbivores, which modify the PM to a thick structure that inhibits digestive processes; Mir1-CP, a defense cysteine protease from maize that inhibits the growth of insects at very low concentrations and degrades the PM structures; and chitinases and lectins. The importance, necessary characteristics, and modes of action of PM-targeting proteins are then discussed from a strategic point of view, by spotlighting the importance of selective permeability of the PM. Finally, the review discusses the possibility of applying PM-targeting proteins for the control of pest insects.

Bio-Insecticidal Potential of Nucleopolyhedrovirus and Granulovirus Mixtures to Control the Fall Armyworm Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae)

The ability of the isolate VG008 of S. frugiperda granulovirus (SpfrGV) to enhance the infectivity of the isolate SfCOL of S. frugiperda multiple nucleopolyhedrovirus (SpfrMNPV) was evaluated on S. frugiperda larvae. Bioassays were performed with mixtures by using different proportions 90%:10% (M1), 95%:5% (M2) and 97.5%:2.5% (M3) of SfCOL:VG008, respectively. All mixtures showed higher insecticidal activity that SfCOL. The mixture M3 showed the highest enhancement of SfCOL reducing 11.40 times the Mean Lethal Concentration and 96 h in the Mean Time to Death. The enhancer activity of proteins derived from VG008 (GVPs) were also evaluated in mixture with SfCOL. The GVPs increased 27% larval mortality caused by SfCOL and damaged the peritrophic membrane of S. litura larvae, suggesting that the key point in this enhancing activity is the initial step of the larva colonization, the midgut infection. M3 was formulated and evaluated under greenhouse conditions in maize plants using different doses. The highest efficacy was obtained with the highest dose of M3 (8 × 10¹¹ OBs/ha), which was similar to that found when formulated SfCOL was applied using an approximately twofold higher dose. The viral mixture M3 was selected as the active ingredient for developing a new biopesticide for a more efficient management of the pest in the field.