Williams, Trevor

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https://academica-e.unavarra.es/handle/2454/50181

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Williams

First Name

Trevor

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Producción Agraria

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1173239

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2621

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Open Access
Effect of optical brighteners on the insecticidal activity of a nucleopolyhedrovirus in three instars of Spodoptera frugiperda
(Blackwell Science, 2003-10-17) Martínez Castillo, Ana Mabel; Simón de Goñi, Oihane; Williams, Trevor; Caballero Murillo, Primitivo; Producción Agraria; Nekazaritza Ekoizpena
Certain optical brighteners are effective UV protectants, and can improve the insecticidal activity of baculoviruses. We evaluated the effect of 10 optical brighteners, from four chemically different groups, on the insecticidal activity of a nucleopolyhedrovirus (SfMNPV) in third instar Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). The most effective optical brighteners were Blankophor BBH and Calcofluor M2R, both of which are stilbenes. The distyryl-biphenyl derivative, Tinopal CBS, had no effect, whereas the stilbenes, Blankophor CLE and Leucophor SAC and the styryl-benzenic derivative, Blankophor ER, resulted in a decrease in virus induced mortality compared to larvae infected with SfMNPV alone. Mixtures of SfMNPV + 0.1% Calcofluor M2R had relative potencies of 2.7, 6.5, and 61.6 in the second, third, and fourth instars, respectively. The mean time to death differed with instar, but was not affected by the addition of 0.1% Calcofluor M2R. Analysis of published studies indicated that the concentration of Calcofluor M2R-related stilbenes was positively correlated with the relative potency observed in mixtures with homologous NPVs. The average magnitude of optical brightener activity did not differ significantly between early instars of 10 species of Lepidoptera. We conclude that virus formulations containing optical brighteners may be valuable for control of late instar lepidopteran pests.
Open Access
Selection of a nucleopolyhedrovirus isolate from Helicoverpa armigera as the basis for a biological insecticide
(Wiley, 2014-05-01) Arrizubieta Celaya, Maite; Williams, Trevor; Caballero Murillo, Primitivo; Simón de Goñi, Oihane; Producción Agraria; Nekazaritza Ekoizpena; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua
Background: the cotton bollworm, Helicoverpa armigera, is an insect that causes damage in a wide range of crops in Spain.Seven isolates of H. armigera single nucleopolyhedrovirus (HearSNPV) from the Iberian Peninsula were subjected to molecularand biological characterization and compared with a Chinese genotype (HearSNPV-G4). Results: the estimated sizes of the Iberian genomes varied between 116.2 and 132.4 kb, compared to 131.4 kb of theHearSNPV-G4 reference genome. Phylogenetic analysis based on the lef-8, lef-9 and polh genes revealed that the Iberianstrains were more closely related to one another than to other HearSNPV isolates. Occlusion body (OB) concentration-mortalityresponses (LC 50 values) did not differ signiﬁcantly among Iberian isolates when tested against a Helicoverpa armigera colonyfrom Oxford (UK). Despite being the fastest killing isolate, HearSNPV-SP1 was as productive as isolates with lower virulence,with an average yield of 3.1 × 109 OBs larva−1 . OBs of HearSNPV-SP1 and HearSNPV-G4 were similarly pathogenic against arecently established colony from southern Spain, although HearSNPV-SP1 was faster killing than HearSNPV-G4 against a rangeof instars. Conclusion: the insecticidal properties of HearSNPV-SP1 mean that this strain is likely to prove useful as the basis for abiological insecticide for control of Helicoverpa armigera in Spain.
Open Access
Spodoptera frugiperda multiple nucleopolyhedrovirus as a potential biological insecticide: genetic and phenotypic comparison of field isolates from Colombia
(Elsevier, 2011-04-24) Barrera Cubillos, Gloria Patricia; Simón de Goñi, Oihane; Villamizar, Laura; Williams, Trevor; Caballero Murillo, Primitivo; Producción Agraria; Nekazaritza Ekoizpena; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Thirty-eight isolates of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV), collected from infected larvae on pastures, maize, and sorghum plants in three different geographical regions of Colombia, were subjected to molecular characterization and were compared with a previously characterized Nicaraguan isolate (SfNIC). Restriction endonuclease analysis (REN) using six different enzymes showed two different patterns among Colombian isolates, one profile was particularly frequent (92%) and was named SfCOL. The physical map of SfCOL was constructed and the genome was estimated to be 133.9 kb, with few differences in terms of number and position of restriction sites between the genomes of SfNIC and SfCOL. The PstI-K and PstI-M fragments were characteristic of SfCOL. These fragments were sequenced to reveal the presence of seven complete and two partial ORFs. This region was collinear with SfMNPV sf20–sf27. However, two ORFs (4 and 5) had no homologies with SfMNPV ORFs, but were homologous with Spodoptera exigua MNPV (se21 and se22/se23) and Spodoptera litura NPV (splt20 and splt21). Biological characterization was performed against two different colonies of S. frugiperda, one originating from Colombia and one from Mexico. Occlusion bodies (OBs) of the SfCOL isolate were as potent (in terms of concentration–mortality metrics) as SfNIC OBs towards the Mexican insect colony. However, SfCOL OBs were 12 times more potent for the Colombian colony than SfNIC OBs and three times more potent for the Colombian colony than for the Mexican colony. SfCOL and SfNIC showed a slower speed of kill (by ∼50 h) in insects from the Colombian colony compared to the Mexican colony, which was correlated with a higher production of OBs/larvae. SfCOL is a new strain of SfMNPV that presents pathogenic characteristics that favor its development as the basis for a biopesticide product in Colombia.
Open Access
Nucleopolyhedrovirus coocclusion technology: a new concept in the development of biological insecticides
(Frontiers Media, 2022) Williams, Trevor; López Ferber, Miguel; Caballero Murillo, Primitivo; Institute for Multidisciplinary Research in Applied Biology - IMAB
Nucleopolyhedroviruses (NPV, Baculoviridae) that infect lepidopteran pests have an established record as safe and effective biological insecticides. Here, we describe a new approach for the development of NPV-based insecticides. This technology takes advantage of the unique way in which these viruses are transmitted as collective infectious units, and the genotypic diversity present in natural virus populations. A ten-step procedure is described involving genotypic variant selection, mixing, coinfection and intraspecific coocclusion of variants within viral occlusion bodies. Using two examples, we demonstrate how this approach can be used to produce highly pathogenic virus preparations for pest control. As restricted host range limits the uptake of NPV-based insecticides, this technology has recently been adapted to produce custom-designed interspecific mixtures of viruses that can be applied to control complexes of lepidopteran pests on particular crops, as long as a shared host species is available for virus production. This approach to the development of NPV-based insecticides has the potential to be applied across a broad range of NPV-pest pathosystems.
Open Access
Population genetic structure determine the virulence and transmissibility of Spodoptera frugiperda multiple necleopolyhedrovirus
(Elsevier, 2007-12-28) Simón de Goñi, Oihane; Williams, Trevor; López Ferber, Miguel; Taulemesse, Jean-Marie; Caballero Murillo, Primitivo; Producción Agraria; Nekazaritza Ekoizpena; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
A Nicaraguan isolate of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfNIC) survives as a complex mixture of genotypes (named A to I). The speed of kill, time-mortality distribution, and occlusion body (OB) production of single genotypes (A, B and F) and co-occluded mixtures of genotypes, in a 75% + 25% ratio, were compared to determine the contribution of each genotype to the transmissibility of the viral population. Pure genotypes differed markedly in their speed of kill in second instar S. frugiperda. The speed of kill of SfNIC was attenuated compared to that of the dominant genotype B, indicating that interactions involving two or more genotypes likely determine host killing traits in the virus population. Genotypes A, F and defective genotype C, had no significant effects on the distribution of insect deaths over time when present as minority components in mixtures comprising 75% of genotype B. Similarly, the mortality pattern over time of insects infected by genotype F, the fastest-killing genotype tested, was not affected by the presence of genotypes A or C. Semi-quantitative PCR studies indicated that the genetic composition did not differ significantly between SfNIC-infected insects that died soon (67 h) or late (139 h) after inoculation, suggesting that stability in genotypic composition is important for virus survival. Median OB production per insect was correlated with mean time to death so that attenuated speed of kill of SfNIC resulted in high OB yields. We conclude that (i) minority genotypes play a functional role in determining the timing of mortality of infected hosts and (ii) the genotypic structure of the virus population is stably maintained to maximize the likelihood of survival.
Open Access
Iflavirus increases its infectivity and physical stability in association with baculovirus
(PeerJ, 2016) Jakubowska, Agata; Murillo Pérez, Rosa; Carballo Palos, Arkaitz; Williams, Trevor; Lent, Jan W. M. van; Caballero Murillo, Primitivo; Herrero, Salvador; Nekazaritza Ekoizpena; Producción Agraria; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Virus transmission and the prevalence of infection depend on multiple factors, including the interaction with other viral pathogens infecting the same host. In this study, active replication of an iflavirus, Spodoptera exigua iflavirus 1 (order Picornavirales) was observed in the offspring of insects that survived following inoculation with a pathogenic baculovirus, Spodoptera exigua multiple nucleopolyhedrovirus. Tracking the origin of the iflavirus suggested the association of this virus with the occlusion bodies of the baculovirus. Here we investigated the effect of this association on the stability and infectivity of both viruses. A reduction in baculovirus pathogenicity, without affecting its infectivity and productivity, was observed when associated with the iflavirus. In contrast, viral association increased the infectivity of the iflavirus and its resistance to ultraviolet radiation and high temperature, two of the main factors affecting virus stability in the field. In addition, electron microscopy analysis revealed the presence of particles resembling iflavirus virions inside the occlusion bodies of the baculovirus, suggesting the possible co-occlusion of both viruses. Results reported here are indicative of facultative phoresis of a virus and suggest that virus virus interactions may be more common than currently recognized, and may be influential in the ecology of baculovirus and host populations and in consequence in the use of baculoviruses as biological insecticides.
Open Access
Anticarsia gemmatalis nucleopolyhedrovirus from soybean crops in Tamaulipas, Mexico: diversity and insecticidal characteristics of individual variants and their co-occluded mixtures
(Florida Entomological Society, 2018) Ángel, Christian del; Lasa, Rodrigo; Rodríguez del Bosque, Luis A.; Mercado, Gabriel; Beperet Arive, Inés; Caballero Murillo, Primitivo; Williams, Trevor; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
In 1999, Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) was introduced into a major soybean-growing region in Tamaulipas, Mexico, for control of its lepidopteran host, Anticarsia gemmatalis Hilbner (Lepidoptera: Noctuidae). The virus introduction proved to be highly successful in controlling this agronomically important pest. In order to determine the genotypic diversity and insecticidal traits of Mexican AgMNPVs, we obtained 30 field-collected isolates from Tamaulipas State. Five distinct variants (genotypes 1-5) were identified from plaques replicated in A. gemmatalis larvae by examination of restriction profiles using HindIII. Initial screening indicated that none of the variants, or co-occluded mixtures of variants in different proportions, was more pathogenic than the 30 field isolates mixture or a reference variant from Brazil (AgMNPV-2D). Mean occlusion body production also was similar among genotype variants, the mixture of 30 field isolates and AgMNPV-2D treatments, but was significantly reduced in 1 co-occluded mixture. Speed of kill also was similar among variants (except genotype 1) and their mixtures. Lethal concentration metrics indicated that these results were unlikely due to selection of variants with reduced pathogenicity during the plaque purification process. We conclude that the mixture of 30 field isolates most likely would prove suitable for use as a biological insecticide in the soybean-growing region of Mexico.