Natural habitat connectivity and organic management modulate pest dispersal, gene flow, and natural enemy communities.

The simplification and fragmentation of agricultural landscapes generate effects on insects at multiple spatial scales. As each functional group perceives and uses the habitat differently, the response of pest insects and their associated natural enemies to environmental changes varies. Therefore, landscape structure may have consequences on gene flow among pest populations in space.

Agroinoculation of Geminiviral Infectious Clones into Plants.

Most geminiviruses are not transmitted by mechanical inoculation. Therefore, pathogenicity and plant-pathogen interaction studies rely on agroinoculation using infectious clones, which involves cloning the geminiviral genome in a binary vector (see previous chapter for details). A suspension containing the infectious clone inserted into Agrobacterium tumefaciens cells is then inoculated into plants, i.

Construction of Geminivirus Infectious Clones for Agroinoculation into Plants.

The production of geminiviral infectious clones provides a standardized inoculum for use in several host-virus studies. Geminiviruses present either one (monopartite) or two (bipartite) circular single-stranded DNA components, which commonly range from 2.6 to 2.

How To Be a Successful Monopartite Begomovirus in a Bipartite-Dominated World: Emergence and Spread of Tomato Mottle Leaf Curl Virus in Brazil.

Begomoviruses are members of the family , a large and diverse group of plant viruses characterized by a small circular single-stranded DNA genome encapsidated in twinned quasi-icosahedral virions. Cultivated tomato ( L.) is particularly susceptible and is infected by >100 bipartite and monopartite begomoviruses worldwide.

Sweetpotato Genotypes 'CIP BRS Nuti' and 'Canadense' Are Resistant to , . , and . .

Sweetpotato is a staple crop in Brazil presenting a smaller number of pathogens and diseases in comparison with other root and tuberous crops. Root-knot nematodes are among the most serious sweetpotato root pathogens. The impact of these pathogens also extends to succeeding crops.

Nanopore sequencing of tomato mottle leaf distortion virus, a new bipartite begomovirus infecting tomato in Brazil.

During a survey in a tomato field in Luziânia (Goiás State, Brazil), a single plant with mottling, chlorotic spots, and leaf distortion was found. A new bipartite begomovirus sequence was identified using nanopore sequence technology and confirmed by Sanger sequencing. The highest nucleotide sequence identity match of the DNA-A component (2596 bases) was 81.

Evidence of Spread of Bemisia tabaci (Hemiptera: Aleyrodidae) Mediated by Internal Transportation of Ornamental Plants in Brazil.

Two Bemisia tabaci (Gennadius) species, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED), are major pests that are dispersed throughout the world. While MEAM1 was introduced in Brazil in the 1990s, MED was reported recently with limited spread. Here, a survey was performed to examine whether MED whiteflies are widely present in the Federal District region, in central Brazil.

siRNA biogenesis and advances in topically applied dsRNA for controlling virus infections in tomato plants.

A non-transgenic approach based on RNA interference was employed to induce protection against tomato mosaic virus (ToMV) infection in tomato plants. dsRNA molecules targeting the cp gene of ToMV were topically applied on plants prior to virus inoculation. Protection was dose-dependent and sequence-specific.

A Temporal Diversity Analysis of Brazilian Begomoviruses in Tomato Reveals a Decrease in Species Richness between 2003 and 2016.

Understanding the molecular evolution and diversity changes of begomoviruses is crucial for predicting future outbreaks of the begomovirus disease in tomato crops. Thus, a molecular diversity study using high-throughput sequencing (HTS) was carried out on samples of infected tomato leaves collected between 2003 and 2016 from Central Brazil. DNA samples were subjected to rolling circle amplification and pooled in three batches, G1 (2003-2005, N = 107), G2 (2009-2011, N = 118), and G3 (2014-2016, N = 129) prior to HTS.

New features on the genomic organization of a novel dicistrovirus identified from the sweet potato whitefly Bemisia tabaci.

The whitefly Bemisia tabaci is an agricultural pest causing large economic losses worldwide. We analysed the genomic sequence of a new viral member of the family Dicistroviridae identified by high-throughput sequencing of total RNA extracted from whiteflies. The virus, tentatively named Bemisia-associated dicistrovirus 2 (BaDV-2), has a genome of 8012 nucleotides with a polyadenylated 3' end.

Complete genome sequence of a new bipartite begomovirus infecting tomato in Brazil.

A novel bipartite begomovirus infecting begomovirus-resistant tomato plants was detected via Illumina sequencing analysis, and its genome sequence was confirmed by Sanger sequencing. The DNA-A (2627 nt) and DNA-B (2587 nt) have a genome organization that is typical of New World bipartite begomoviruses, sharing 82.5% identity with tomato golden leaf distortion virus and 75.

Complete genome sequence and phylogenetic analysis of a novel dicistrovirus associated with the whitefly Bemisia tabaci.

A novel single-stranded RNA virus was detected in a whitefly (Bemisia tabaci) sample subjected to high-throughput sequencing. The 8293 nt-long genome presents a polyadenylated 3' end, and contains two ORFs encoding putative 1596 and 849 aa-long proteins. These putative proteins display significant similarity to replicase and capsid polyproteins, respectively, of discitroviruses.

Erratum to: Discovery of two small circular ssDNA viruses associated with the whitefly Bemisia tabaci.

The complete genome sequences of two novel small circular DNA viruses isolated from sweet-potato whiteflies collected in Central-West (AdDF) and Southeast (AdO) regions of Brazil were determined by Next Generation Sequencing (NGS), and confirmed by cloning and Sanger sequencing. The genomes are 2,199 and 2,211 nt-long, respectively, encoding a putative coat protein (CP) and a replication-associated protein (Rep) and showing a genomic organization typical of viruses from the family Genomoviridae. Phylogenetic analysis with deduced amino acid sequences of Rep indicates that the virus from AdO is closely related to other members of the genus Gemycircularvirus, while the virus from AdDF is related to those of the genus Gemyduguivirus.

Discovery of two small circular ssDNA viruses associated with the whitefly Bemisia tabaci.

The complete genome sequences of two novel small circular DNA viruses isolated from sweet-potato whiteflies collected in central-West (AdDF) and Southeast (AdO) regions of Brazil were determined by Next Generation Sequencing (NGS), and confirmed by cloning and Sanger sequencing. The genomes are 2,199 and 2,211 nt-long, respectively, encoding a putative coat protein (CP) and a replication-associated protein (Rep) and showing a genomic organization typical of viruses from the family Genomoviridae. Phylogenetic analysis with deduced amino acid sequences of Rep indicates that the virus from AdO is closely related to other members of the genus Gemycircularvirus, while the virus from AdDF is distantly related to other genomovirus.

RNAi-mediated knockdown of the voltage gated sodium ion channel TcNav causes mortality in Tribolium castaneum.

The voltage-gated sodium ion channel (VGSC) belongs to the largest superfamily of ion channels. Since VGSCs play key roles in physiological processes they are major targets for effective insecticides. RNA interference (RNAi) is widely used to analyse gene function, but recently, it has shown potential to contribute to novel strategies for selectively controlling agricultural insect pests.

Transgenic plants expressing ω-ACTX-Hv1a and snowdrop lectin (GNA) fusion protein show enhanced resistance to aphids.

Recombinant fusion proteins containing arthropod toxins have been developed as a new class of biopesticides. The recombinant fusion protein Hv1a/GNA, containing the spider venom toxin ω-ACTX-Hv1a linked to snowdrop lectin (GNA) was shown to reduce survival of the peach-potato aphid Myzus persicae when delivered in artificial diet, with survival <10% after 8 days exposure to fusion protein at 1 mg/ml. Although the fusion protein was rapidly degraded by proteases in the insect, Hv1a/GNA oral toxicity to M.

Novel biopesticide based on a spider venom peptide shows no adverse effects on honeybees.

Evidence is accumulating that commonly used pesticides are linked to decline of pollinator populations; adverse effects of three neonicotinoids on bees have led to bans on their use across the European Union. Developing insecticides that pose negligible risks to beneficial organisms such as honeybees is desirable and timely. One strategy is to use recombinant fusion proteins containing neuroactive peptides/proteins linked to a 'carrier' protein that confers oral toxicity.

Improving Cry8Ka toxin activity towards the cotton boll weevil (Anthonomus grandis).

Background: The cotton boll weevil (Anthonomus grandis) is a serious insect-pest in the Americas, particularly in Brazil. The use of chemical or biological insect control is not effective against the cotton boll weevil because of its endophytic life style. Therefore, the use of biotechnological tools to produce insect-resistant transgenic plants represents an important strategy to reduce the damage to cotton plants caused by the boll weevil.

Ectopic expression of a Meloidogyne incognita dorsal gland protein in tobacco accelerates the formation of the nematode feeding site.

Meloidogyne spp., plant-parasitic nematodes present worldwide, are intensively studied because of the damage caused to a large variety of agronomically important crops. Several reports indicate that proteins from the Meloidogyne spp.

Analysis of Cry8Ka5-binding proteins from Anthonomus grandis (Coleoptera: Curculionidae) midgut.

Biotech crops expressing Bacillus thuringiensis Cry toxins present a valuable approach for insect control. Cry8Ka5, which is highly toxic to the cotton boll weevil (Anthonomus grandis), was used as a model to study toxin-ligand interactions. Three Cry-binding proteins were detected after toxin overlay assays.

Susceptibility of Anthonomus grandis (cotton boll weevil) and Spodoptera frugiperda (fall armyworm) to a cry1ia-type toxin from a Brazilian Bacillus thuringiensis strain.

Different isolates of the soil bacterium Bacillus thuringiensis produce multiple crystal (Cry) proteins toxic to a variety of insects, nematodes and protozoans. These insecticidal Cry toxins are known to be active against specific insect orders, being harmless to mammals, birds, amphibians, and reptiles. Due to these characteristics, genes encoding several Cry toxins have been engineered in order to be expressed by a variety of crop plants to control insectpests.