Gene silencing by RNAi via oral delivery of dsRNA by bacteria in the South American tomato pinworm, Tuta absoluta.

BACKGROUND: RNA interference (RNAi) has been evaluated in several insect pests as a novel strategy to be included in integrated pest management. Lepidopterans are recognized to be recalcitrant to gene silencing by RNAi. As such, double-stranded RNA (dsRNA) delivery needs to be adjusted to assure its stability until it reaches the target gene transcript for silencing. Gene silencing by RNAi offers the potential to be used in the control of Tuta absoluta (Meyrick), one of the main insect pests of tomato (Solanum lycopersicum) worldwide. Here, we tested the delivery of dsRNA expressed in Escherichia coli HT115(DE3) and supplied to larvae in an artificial diet by screening target genes for silencing. We tested six target genes: juvenile hormone inducible protein (JHP); juvenile hormone epoxide hydrolase protein (JHEH); ecdysteroid 25-hydroxylase (PHM); chitin synthase A (CHI); carboxylesterase (COE); and arginine kinase (AK). RESULTS: Based on larval mortality, the duration of the larval stage in days, pupal weight, and the accumulation of the target gene transcript, we demonstrated the efficacy of bacterial dsRNA delivery for the functional effects on larval development. Providing dsRNA targeted to JHP, CHI, COE and AK by bacteria led to a significant decrease in transcript accumulation and an increase in larval mortality. CONCLUSION: Bacteria expressing dsRNA targeting essential T. absoluta genes supplied in artificial diet are efficient to screen RNAi target-genes. The oral delivery of dsRNA by bacteria is a novel potential alternative for the control of T. absoluta based on RNAi. © 2019 Society of Chemical Industry.

Putative sex pheromone of the Asian citrus psyllid, Diaphorina citri, breaks down into an attractant.

Under laboratory conditions, mating activity in Asian citrus psyllid (ACP) started 4 days after emergence, peaked at day 7, and showed a clear window of activity starting 8 h into the photophase and extending through the first hour of the scotophase. We confirmed that ACP males are attracted to emanations from conspecific females. Traps loaded with a candidate compound enriched with female extract, lignoceryl acetate (24Ac), at various doses were active only after being deployed for several weeks in the field, suggesting that a degradation product, not the test compound, was the active ingredient(s). Lignocerol, a possible product of 24Ac degradation, was not active, whereas acetic acid, another possible degradation product, was found in the airborne volatile collections from lures matured under field conditions and detected in higher amounts in volatiles collected from females at the peak of mating activity than in male samples. Acetic acid elicited dose-dependent electroantennographic responses and attracted ACP males, but not females, in Y-type and 4-way olfactometers. Field tests showed that acetic acid-baited traps captured significantly more males than control traps. Surprisingly, captures of females in acetic acid-baited traps were also higher than in control traps, possibly because of physical stimuli emitted by captured males.

Artificial diet for laboratory rearing of Condylorrhiza vestigialis (Guenée, 1854) (Lep Crambidae)

ABSTRACT The Brazilian Poplar Moth, Condylorrhiza vestigialis (Guenée), compromises the wood productivity of poplar trees (Populus sp.), mainly affecting the matchstick industry in southern Brazil. Considering the lack of information on rearing techniques for this insect, the objective of this study was to develop an artificial diet to rear C. vestigialis with biological characteristics similar to the wild insects. A properly diet will enable bio-ecological studies and biological control programs using the baculovirus Condylorrhiza vestigialis multiple nucleopolyhedrovirus (CvMNPV). To attain this objective, first, three artificial diets were tested. Only the diet based on corn, wheat germ and yeast as a protein source (Diet 3) was able to supply the nutritional requirements of the moth and support completion of its life cycle. In the second experiment, Diet 3 was compared to the natural diet of C. vestigialis. The artificial diet supported a viability of 81% of the eggs, while only 40% developed on the natural diet. Life-table data showed the same pattern: the net reproductive rate (Ro) of C. vestigialis reared on the artificial diet was 401.70, and on the natural diet was 151.22. The artificial diet is adequate for mass rearing of C. vestigialis, to support biological control programs using the baculovirus.

Artificial diet for laboratory rearing of Condylorrhiza vestigialis (Guenée, 1854) (Lep.: Crambidae).

The Brazilian Poplar Moth, Condylorrhiza vestigialis (Guenée), compromises the wood productivity of poplar trees (Populus sp.), mainly affecting the matchstick industry in southern Brazil. Considering the lack of information on rearing techniques for this insect, the objective of this study was to develop an artificial diet to rear C. vestigialis with biological characteristics similar to the wild insects. A properly diet will enable bio-ecological studies and biological control programs using the baculovirus Condylorrhiza vestigialis multiple nucleopolyhedrovirus (CvMNPV). To attain this objective, first, three artificial diets were tested. Only the diet based on corn, wheat germ and yeast as a protein source (Diet 3) was able to supply the nutritional requirements of the moth and support completion of its life cycle. In the second experiment, Diet 3 was compared to the natural diet of C. vestigialis. The artificial diet supported a viability of 81% of the eggs, while only 40% developed on the natural diet. Life-table data showed the same pattern: the net reproductive rate (Ro) of C. vestigialis reared on the artificial diet was 401.70, and on the natural diet was 151.22. The artificial diet is adequate for mass rearing of C. vestigialis, to support biological control programs using the baculovirus.

How much is a pheromone worth?

Pheromone-baited traps have been widely used in integrated pest management programs, but their economic value for growers has never been reported.  We analyzed the economic benefits of long-term use of traps baited with the citrus fruit borer Gymnandrosoma aurantianum sex pheromone in Central-Southern Brazil. Our analysis show that from 2001 to 2013 citrus growers avoided accumulated pest losses of 132.7 million to 1.32 billion USD in gross revenues, considering potential crop losses in the range of 5 to 50%. The area analyzed, 56,600 to 79,100 hectares of citrus (20.4 to 29.4 million trees), corresponds to 9.7 to 13.5% of the total area planted with citrus in the state of São Paulo. The data show a benefit-to-cost ratio of US$ 2,655 to US$ 26,548 per dollar spent on research with estimated yield loss prevented in the range of 5-50%, respectively. This study demonstrates that, in addition to the priceless benefits for the environment, sex pheromones are invaluable tools for growers as their use for monitoring populations allows rational and reduced use of insecticides, a win-win situation.

Structural insights regarding an insecticidal Talisia esculenta protein and its biotechnological potential for Diatraea saccharalis larval control.

Talisin is a seed-storage protein from Talisia esculenta that presents lectin-like activities, as well as proteinase-inhibitor properties. The present study aims to provide new in vitro and in silico biochemical information about this protein, shedding some light on its mechanistic inhibitory strategies. A theoretical three-dimensional structure of Talisin bound to trypsin was constructed in order to determine the relative interaction mode. Since the structure of non-competitive inhibition has not been elucidated, Talisin-trypsin docking was carried out using Hex v5.1, since the structure of non-competitive inhibition has not been elucidated. The predicted non-coincidence of the trypsin binding site is completely different from that previously proposed for Kunitz-type inhibitors, which demonstrate a substitution of an Arg(64) for the Glu(64) residue. Data, therefore, provide more information regarding the mechanisms of non-competitive plant proteinase inhibitors. Bioassays with Talisin also presented a strong insecticide effect on the larval development of Diatraea saccharalis, demonstrating LD50 and ED50 of ca. 2.0% and 1.5%, respectively.

Will the Convention on Biological Diversity put an end to biological control?

Will the Convention on Biological Diversity put an end to biological control? Under the Convention on Biological Diversity countries have sovereign rights over their genetic resources. Agreements governing the access to these resources and the sharing of the benefits arising from their use need to be established between involved parties. This also applies to species collected for potential use in biological control. Recent applications of access and benefit sharing principles have already made it difficult or impossible to collect and export natural enemies for biological control research in several countries. If such an approach is widely applied it would impede this very successful and environmentally safe pest management method based on the use of biological diversity. The International Organization for Biological Control of Noxious Animals and Plants has, therefore, created the "Commission on Biological Control and Access and Benefit Sharing". This commission is carrying out national and international activities to make clear how a benefit sharing regime might seriously frustrate the future of biological control. In addition, the IOBC Commission members published information on current regulations and perceptions concerning exploration for natural enemies and drafted some 30 case studies selected to illustrate a variety of points relevant to access and benefit sharing. In this article, we summarize our concern about the effects of access and benefit sharing systems on the future of biological control.

Poderá a Convenção em Diversidade Biológica por um fim no Controle Biológico? Baseando-se na Convenção sobre Diversidade Biológica, os países têm soberania sobre seus recursos genéticos. Acordos que governam o acesso a tais recursos e o compartilhamento dos benefícios provenientes do seu uso precisam ser estabelecidos de comum acordo com as partes envolvidas. Isto também é aplicável a espécies coletadas com uso potencial em controle biológico. Recentes aplicações dos princípios de introdução e compartilhamento dos benefícios têm tornado difícil, ou mesmo impossível, coletar e exportar inimigos naturais em muitos paises para pesquisas em controle biológico em muitos países. Como esta é uma medida amplamente utilizada, tais procedimentos poderão impedir este bem sucedido e ambientalmente seguro método de manejo de pragas, baseado no uso da diversidade biológica. A Organização Internacional para Controle Biológico de Plantas e Animais Nocivos (IOBC) criou a "Comissão em Controle Biológico e Introdução e Benefícios Mútuos" para estudar o assunto. Tal comissão está desenvolvendo atividades nacionais e internacionais para esclarecer como o regime de compartilhamento de benefícios pode prejudicar seriamente o futuro do controle biológico. Além disto, membros da Comissão da IOBC publicaram informações sobre regulamentos atuais e suas opiniões relacionadas à exploração de inimigos naturais, listando cerca de 30 casos para ilustrar os pontos relevantes para a introdução e compartilhamento de benefícios. No presente artigo, é sumarizado o ponto de vista dessa comissão na IOBC sobre os efeitos dos sistemas de introdução e compartilhamento para o futuro do Controle Biológico.

Bioinsecticidal activity of Talisia esculenta reserve protein on growth and serine digestive enzymes during larval development of Anticarsia gemmatalis.

Plants synthesize a variety of molecules to defend themselves against an attack by insects. Talisin is a reserve protein from Talisia esculenta seeds, the first to be characterized from the family Sapindaceae. In this study, the insecticidal activity of Talisin was tested by incorporating the reserve protein into an artificial diet fed to the velvetbean caterpillar Anticarsia gemmatalis, the major pest of soybean crops in Brazil. At 1.5% (w/w) of the dietary protein, Talisin affected larval growth, pupal weight, development and mortality, adult fertility and longevity, and produced malformations in pupae and adult insects. Talisin inhibited the trypsin-like activity of larval midgut homogenates. The trypsin activity in Talisin-fed larvae was sensitive to Talisin, indicating that no novel protease-resistant to Talisin was induced in Talisin-fed larvae. Affinity chromatography showed that Talisin bound to midgut proteinases of the insect A. gemmatalis, but was resistant to enzymatic digestion by these larval proteinases. The transformation of genes coding for this reserve protein could be useful for developing insect resistant crops.

Development of a control alternative for the citrus fruit borer, Ecdytolopha aurantiana (Lepidoptera, Tortricidae): from basic research to the grower

São descritas todas as etapas da pesquisa, desenvolvidas de 1995 a 2000, para a síntese do feromônio sexual de Ecdytolopha aurantiana (Lima, 1927), visando ao monitoramento desta praga que causa perdas da ordem de 50 milhões de dólares ao ano à citricultura paulista. As pesquisas básicas são apresentadas, incluindo o desenvolvimento de uma dieta artificial para o inseto, estudo de suas exigências térmicas e hídricas, estudos comportamentais, síntese da substância atraente para o macho desde a formulação até a distribuição do feromônio ao agricultor, e a sua comercialização. Trata-se de um caso de sucesso, a um custo de 50 mil dólares, com pesquisas inter- e multidisciplinares e que pode ser adotado para outros insetos-praga do país.

Biologia e parasitismo de Trichogramma atopovirilia Oatman & Platner e Trichogramma pretiosum Riley (Hymenoptera, Trichogrammatidae) em ovos de Spodoptera frugiperda (J.E. Smith) (Lepidoptera, Noctuidae) / Biology and parasitism of Trichogramma atopovirilia Oatman & Platner and Trichogramma pretiosum Riley (Hymenoptera, Trichogrammatidae) on eggs of Spodoptera frugiperda (J.E. Smith) (Lepidoptera, Noctuidae)

Comparou-se a capacidade de paratisimo e o desenvolvimento de Trichogramma atopovirilia Oatman & Platner e T. pretiosum Riley visando à seleção da espécie mais adequada para o controle de Spodoptera frugiperda (J. E. Smith). Os experimentos foram conduzidos em laboratório à temperatura de 25±2ºC, U.R. de 70±0 por cento e fotoperíodo de 14L:10E. Tanto T. atopovirilia como T. pretiosum desenvolveram-se bem e mostraram-se adaptados a ovos de S. frugiperda, mesmo após serem criados por várias gerações em ovos de Anagasta kuehniella Zeller. Entretanto, fêmeas de T. atopovirilia foram mais agressivas e de maior especificidade à praga, já que apresentaram maior capacidade de parasitismo em posturas com diferentes barreiras físicas e maior aceitação pelo hospedeiro natural, em relação à A. kuehniella. Por este maior parasitismo e especificidade de T. atopovirilia aos ovos da praga, deve-se dar preferência à utilização desta espécie para controle de S. frugiperda.

The parasitism capacity and development of Trichogramma atopovirilia Oatman & Platner and Trichogramma pretiosum Riley were studied in order to select the most suitable species to control Spodoptera frugiperda (J. E. Smith). The experiments were conducted under laboratory conditions at 25±2ºC, 70±10% RH and 14L:10D photoperiod. Both T. atopovirilia and T. pretiosum showed good development and adaptation to S. frugiperda eggs even after being reared for several generations in eggs of Anagasta kuehniella Zeller. However, T. atopovirilia females were more aggressive and showed higher specificity to the pest, with a higher parasitism capacity in eggs laid with different physical barriers and were more accepted by the natural host in comparison with A. kuehniella. Because of the higher parasitism rate and specificity of T. atopovirilia to the pest's egg this species should be given preference to control S. frugiperda.