Mixture compatibility of Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) with pesticides used in soybean

Compatibilidade da mistura de nucleopoliedrovírus de Anticarsia gemmatalis baculovírus (AgMNPV) com agrotóxicos utilizados na soja

Rodrigo Mendes Antunes Maciel Junio Tavares Amaro Fernanda Caroline Colombo Pedro Manuel Oliveira Janeiro Neves Adeney de Freitas Bueno About the authors

ABSTRACT:

Anticarsia gemmatalis (Hübner: 1818) (Lepidoptera: Erebidae) is one of the main pests that affect soybean crops, causing defoliation. In the vegetative stages, defoliation occurs together with weeds, and in the reproductive stages with pathogens. In this sense, to maintain plant health, it is necessary to carry out the combined use of pesticides. Thus, this research determined the compatibility of the entomopathogenic virus AgMNPV with the main herbicides and fungicides used in soy at different times of the mixture. The artificial diet was immersed in the solutions of the pesticides and their mixtures and supplied to A. gemmatalis caterpillars, immediately and after one and two hours of mixing. The evaluation was performed by quantifying the number of dead caterpillars by mixing the AgMNPV virus with herbicides and fungicides, even after two hours of mixing if compatible. The observed scenarios showed a compatibility of the virus with the herbicides and fungicides, with mortality rates between 70 to 99% for A. gemmatalis.

Key words:
velvetbean caterpillar; baculovirus; tank mix; integrated pest management; biological control

RESUMO:

Anticarsia gemmatalis (Hübner: 1818) (Lepidoptera: Erebidae) é uma das principais pragas que acometem a cultura da soja, causando desfolha. Nos estágios vegetativos a desfolha ocorre juntamente com ervas daninhas, e no reprodutivo com patógenos. Nesse sentido, para manter a fitossanidade, é necessário realizar a utilização combinada de pesticidas. Assim, o objetivo do presente trabalho foi determinar a compatibilidade do vírus entomopatogênico AgMNPV com os principais herbicidas e fungicidas utilizados na soja em diferentes tempos de mistura. A dieta artificial foi imersa nas soluções dos pesticidas e suas misturas e fornecida às lagartas de A. gemmatalis, imediatamente e após uma e duas horas de mistura. A avaliação foi realizada quantificando o número de lagartas mortas. A mistura do vírus AgMNPV com herbicidas e fungicidas, mesmo após duas horas de mistura se mostrou compatível. Os cenários observados mostram a compatibilidade do vírus com os herbicidas e fungicidas, com percentuais de mortalidade entre 70 a 99% para A. gemmatalis.

Palavras-chave:
lagarta-da-soja; baculovírus; mistura de tanque; manejo integrado de pragas; controle biológico

INTRODUCTION:

Soybean (Glycine max L. Merril) can be considered one of today’s most important crops. It is responsible for most of the global demand for oil and vegetable protein (OERKE & DEHNE, 2004OERKE, E. C.; DEHNE, H. W. Safeguarding production - Losses in major crops and the role of crop protection. Crop Protection , v.23, n.4, p.275-285, 2004. Available from: <Available from: https://www.sciencedirect.com/science/article/abs/pii/S0261219403002540 >. Accessed: Sep. 09, 2020. doi: 10.1016/j.cropro.2003.10.001.
https://www.sciencedirect.com/science/ar...
). From Argentina to the Southeast United States the velvetbean caterpillar Anticarsia gemmatalis (Hübner, 1818) (Lepidoptera: Eribidae) has been one of its most important pest (BORTOLOTTO et al., 2015BORTOLOTTO, O. C. et al. The use of soybean integrated pest management in Brazil: a review. Agronomy Science and Biotechnology, v.1, n.1, p.25, 2015. Available from: <Available from: https://www.embrapa.br/busca-de-publicacoes/-/publicacao/1013829/the-use-of-soybean-integrated-pest-management-in-brazil-a-review >. Accessed: Jan. 09, 2020. doi: 10.33158/asb.2015v1i1p25.
https://www.embrapa.br/busca-de-publicac...
; PANIZZI & CORREA-FERREIRA, 1997PANIZZI, A. R.; CORREA-FERREIRA, B. S. Dynamics in the insect fauna adaptation to soybean in the tropics. Trends in Entomology, v.1, n.1, p.71-88, 1997. Available from: <Available from: https://www.scienceopen.com/document?vid=06fbcd4c-5ad1-406b-a273-ec3334bfa113 >. Accessed: Sep. 09, 2020.
https://www.scienceopen.com/document?vid...
). Despite the high efficacy of Bt soybean cultivars in controlling this pest, A. gemmatalis still is the most abundant species at early crop season (vegetative stage) in different important soybean areas in Brazil (CONTE et al., 2019CONTE, O. et al. Resultados do manejo integrado de pragas da soja na safra 2018/19 no Paraná. Londrina: Embrapa Soja, n.416, 63p., 2019. Available from: <Available from: https://www.embrapa.br/busca-de-publicacoes/-/publicacao/1111771/resultados-do-manejo-integrado-de-pragas-da-soja-na-safra-201819-no-parana >. Accessed: Sep. 20, 2020.
https://www.embrapa.br/busca-de-publicac...
). It is because non-Bt soybean was still cropped in 13.7 million of hectares during the 2017/2018 Brazilian crop season. Moreover, even at the maximum of Bt soybean adoption in Brazil, 7.2 millions of hectares of non-Bt soybean are still expected (COUNCIL BIOTECHNOLOGY INFORMATION, 2018COUNCIL BIOTECHNOLOGY INFORMATION, C. B. 20 Years of GMOs: environmental, economic and social benefits in Brazil, 20 p., 2018. Available from: <Available from: https://croplifebrasil.org/publicacoes/20-years-of-gmos-environmental-economic-and-social-benefits-in-brazil/ >. Accessed: Sep. 20, 2020.
https://croplifebrasil.org/publicacoes/2...
), keeping pest management in non-Bt fields an important issue.

Anticarsia gemmatalis control is carried out, predominantly, with the use of synthetic insecticides (PLATA-RUEDA et al., 2020PLATA-RUEDA, A. et al. Side-effects caused by chlorpyrifos in the velvetbean caterpillar Anticarsia gemmatalis (Lepidoptera: Noctuidae). Chemosphere, v.259, p.127530, 2020. Available from: <Available from: https://doi.org/10.1016/j.chemosphere.2020.127530 >. Accessed: Sep. 13, 2020. doi: 10.1016/j.chemosphere.2020.127530.
https://doi.org/10.1016/j.chemosphere.20...
; STACKE et al., 2020STACKE, R. F. et al. Inheritance of lambda-cyhalothrin resistance, fitness costs and cross-resistance to other pyrethroids in soybean looper, Chrysodeixis includens (Lepidoptera: Noctuidae). Crop Protection , v.131, p.105096, 2020. Available from: <Available from: https://doi.org/10.1016/j.cropro.2020.105096 >. Accessed: Sep. 20, 2020. doi: 10.1016/j.cropro.2020.105096.
https://doi.org/10.1016/j.cropro.2020.10...
). However, its overuse triggers impactful negative effects (BUENO et al., 2020BUENO, A. F. et al. Challenges for adoption of Integrated Pest Management (IPM): the Soybean Example. Neotropical Entomology, n.1959, p.1-16, 2020. Available from: <Available from: https://www.embrapa.br/busca-de-publicacoes/-/publicacao/1129115/challenges-for-adoption-of-integrated-pest-management-ipm-the-soybean-example >. Accessed: Jan. 09, 2020. doi: 10.1007/s13744-020-00792-9.
https://www.embrapa.br/busca-de-publicac...
; SONG & SWINTON, 2009SONG, F.; SWINTON, S. M. Returns to integrated pest management research and outreach for soybean aphid. Journal of Economic Entomology , v.102, n.6, p.2116-2125, 2009. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/20069840/ >. Accessed: Sep. 13, 2020. doi: 10.1603/029.102.0615.
https://pubmed.ncbi.nlm.nih.gov/20069840...
), among which the selection of resistant pest strains (DIEZ-RODRÍGUEZ & OMOTO, 2001DIEZ-RODRÍGUEZ, G. I.; OMOTO, C. Herança da Resistência de Spodoptera frugiperda (J. E. Smith ) a Lambda-Cialotrina. Proteção de plantas, v.30, n.2, p.311-316, 2001. Available from: <Available from: https://www.scielo.br/pdf/ne/v30n2/a16v30n2 >. Accessed: Sep. 20, 2020. doi: 10.1590/s1519-566x2001000200016.
https://www.scielo.br/pdf/ne/v30n2/a16v3...
; KOCH et al., 2018KOCH, R. L. et al. Management of insecticide-resistant soybean aphids in the upper midwest of the United States. Journal of Integrated Pest Management, v.9, n.1, p.1-7, 2018. Available from: <Available from: https://academic.oup.com/jipm/article/9/1/23/5075325 >. Accessed: Sep. 17, 2020. doi: 10.1093/jipm/pmy014.
https://academic.oup.com/jipm/article/9/...
) and the death of biological control agents (CARMO et al., 2010CARMO, E. L.; BUENO, A. F.; BUENO, R. C. O. F. Pesticide selectivity for the insect egg parasitoid Telenomus remus. BioControl, v.55, n.4, p.455-464, 2010. Available from: <Available from: https://link.springer.com/article/10.1007/s10526-010-9269-y >. Accessed: Sep. 26, 2020. doi: 10.1007/s10526-010-9269-y.
https://link.springer.com/article/10.100...
; HATT et al., 2018HATT, S. et al. Spatial diversification of agroecosystems to enhance biological control and other regulating services: An agroecological perspective. Science of the Total Environment , v.621, p.600-611, 2018. Available from: <Available from: https://doi.org/10.1016/j.scitotenv.2017.11.296 >. Accessed: Sep. 29, 2020. doi: 10.1007/s12571-010-0108-x.
https://doi.org/10.1016/j.scitotenv.2017...
; VAN LENTEREN & BUENO, 2003______; BUENO, V. H. P. Augmentative biological control of arthropods in Latin America. BioControl, v.48, n.2, p.123-139, 2003. Available from: <https://link.springer.com/article/10.1023%2FA%3A1022645210394>. Accessed: Sep. 17, 2020. doi: 10.1023/A:1022645210394.
https://link.springer.com/article/10.102...
) are the most relevant. Thus, a better alternative to the exclusive use of chemical pesticides in caterpillar pest management is the adoption of Integrated Pest Management (IPM). Not only can IPM offer a more profitable soybean yield due to the reduction of pest control costs but also assures equitable, secure, sufficient, and stable flows of yield and ecosystem services throughout the use of less harmful pest control strategies (BUENO et al., 2020).

The major IPM principle is to control pests throughout different tools combined in a compatible strategy. Moreover, environmentally safe management tool should be prioritized (BUENO et al., 2011BUENO, A. F. et al. Effects of integrated pest management, biological control and prophylactic use of insecticides on the management and sustainability of soybean. Crop Protection, v.30, n.7, p.937-945, 2011. Available from: <Available from: http://dx.doi.org/10.1016/j.cropro.2011.02.021 >. Accessed: Sep. 27, 2020. doi: 10.1016/j.cropro.2011.02.021.
http://dx.doi.org/10.1016/j.cropro.2011....
; TORRES & BUENO, 2018TORRES, J. B.; BUENO, A. De F. Conservation biological control using selective insecticides - A valuable tool for IPM. Biological Control, v.126, p.53-64, 2018. Available from: <Available from: https://doi.org/10.1016/j.biocontrol.2018.07.012 >. Accessed: Jan. 20, 2021. doi: 10.1016/j.biocontrol.2018.07.012.
https://doi.org/10.1016/j.biocontrol.201...
). Among the most environment-friendly and sustainable pest management tools available, biological control stands out (VAN LENTEREN et al., 2018LENTEREN, J. C. VAN et al. Biological control using invertebrates and microorganisms: plenty of new opportunities. BioControl , v.63, n.1, p.39-59, 2018. Available from: <Available from: https://link.springer.com/article/10.1007/s10526-017-9801-4 >. Accessed: Sep. 17, 2020. doi: 10.1007/s10526-017-9801-4.
https://link.springer.com/article/10.100...
) in which the Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) is the world’s most successful viral bioinsecticide (MOSCARDI, 1999MOSCARDI, F. Assessment of the application of baculoviruses for control of Lepidoptera. Annual Review of Entomology, v.44, n.1, p.257-289, 1999. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/15012374/ >. Accessed: Sep. 19, 2020. doi: 10.1146/annurev.ento.44.1.257.
https://pubmed.ncbi.nlm.nih.gov/15012374...
; DEL-ANGEL et al., 2018DEL-ANGEL, C. et al. Anticarsia gemmatalis Nucleopolyhedrovirus from soybean crops in Tamaulipas, Mexico: Diversity and insecticidal characteristics of individual variants and their co-occluded mixtures. Florida Entomologist, v.101, n.3, p.404-410, 2018. Available from: <Available from: https://bioone.org/journals/florida-entomologist/volume-101/issue-3/024.101.0319/Anticarsia-gemmatalis-Nucleopolyhedrovirus-from-Soybean-Crops-in-Tamaulipas-Mexico/10.1653/024.101.0319.full >. Accessed: Sep. 29, 2020. doi: 10.1653/024.101.0319.
https://bioone.org/journals/florida-ento...
). Considering that A. gemmatalis often occurs in soybean crops at the same periods of important weeds and plant pathogens (HARTMAN et al., 2011HARTMAN, G. L.; WEST, E. D.; HERMAN, T. K. Crops that feed the world. Soybean-worldwide production, use, and constraints caused by pathogens and pests. Food Security, v.3, n.1, p.5-17, 2011. Available from: <Available from: https://link.springer.com/article/10.1007/s12571-010-0108-x >. Accessed: Sep. 29, 2020. doi: 10.1007/s12571-010-0108-x.
https://link.springer.com/article/10.100...
) it is of theoretical and practical interest to study the mixture compatibility of AgMNPV with different herbicides and fungicides. This study will allow knowing which herbicide or fungicide can be mixed with AgMNPV in the same spray’s operation. The use of combined pesticides in a single spray is a desired practice in the management of soybean fields due to less soil compaction, decreased machinery’s cost, and increased safety to growers due to reduced time spent spraying pesticides in the field (GANDINI et al., 2020GANDINI, E. M. M. et al. Compatibility of pesticides and/or fertilizers in tank mixtures. Journal of Cleaner Production, v.268, p.122-152, 2020. Available from: <Available from: https://www.sciencedirect.com/science/article/abs/pii/S0959652620321995 >. Accessed: Sep. 19, 2020. doi: 10.1016/j.jclepro.2020.122152.
https://www.sciencedirect.com/science/ar...
; HENRY et al., 2011HENRY, R. S.; JOHNSON, W. G.; WISE, K. A. The impact of a fungicide and an insecticide on soybean growth, yield, and profitability. Crop Protection , v.30, n.12, p.1629-1634, 2011. Available from: <Available from: http://dx.doi.org/10.1016/j.cropro.2011.08.014 >. Accessed: Sep. 17, 2020. doi: 10.1016/j.cropro.2011.08.014.
http://dx.doi.org/10.1016/j.cropro.2011....
; PETTER et al., 2012PETTER, F. A. et al. Incompatibilidade física de misturas entre herbicidas e inseticidas. Planta Daninha, v.30, n.2, p.449-457, 2012. Available from: <Available from: https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582012000200025 >. Accessed: Sep. 09, 2020. doi: 10.1590/S0100-83582012000200025.
https://www.scielo.br/scielo.php?script=...
). Not only is it important to evaluate the efficacy of pesticides immediately after the mixture but also at different time after products mixture since in field conditions, it might take hours for growers to spray the whole crop after preparing the sprayer with pesticides. Therefore, this research verified the mixture compatibility of AgMNPV with herbicides and fungicides commonly used in soybean crops both immediately and one and two hours after the mixture of those pesticides. This was carried out in order to point out which products might and might not be mixed in the field, considering possible effects of time after the mixture into the product`s compatibility.

MATERIALS AND METHODS:

Eight independent bioassays were carried out evaluating A. gemmatalis mortality caused by herbicides or fungicides alone (bioassays 1 and 2), AgMNPV mixed with herbicides and fungicides immediately (bioassays 3 and 4) and both one (bioassays 5 and 6) and two hours (bioassays 7 and 8) after the mixture (Table 1). The bioassays were carried out under controlled conditions of temperature (25 ± 2°C), relative humidity (70 ± 10%) and photoperiod (14:10 h Light/Dark) at the Laboratory of Entomology from Embrapa Soja, located in Londrina, Paraná, Brazil.

Table 1
Herbicides and fungicides evaluated for mixture compatibility with AgMNPV (Baculovirus Soja WP® 20 g.150 L H2O-1) under controlled laboratory conditions (temperature of 25 ± 2°C, relative humidity of 70 ± 10% and photoperiod of 14:10 h Light/Dark) and commercial dosage.

Laboratory rearing of A. gemmatalis

Anticarsia gemmatalis caterpillars, used in the bioassays, originated from insect colonies kept at Embrapa Soybean (one of the units of the Brazilian Agricultural Research Corporation), Londrina, State of Paraná, Brazil. Colony was kept under controlled environmental conditions inside Biochemical Oxygen Demand (BOD) climate chambers (ELETROLab®, model EL 212, São Paulo, SP, Brazil) set at 70 ± 10% humidity, temperature of 25 ± 2°C, and a 14:10 h (L:D) photoperiod according to methodologies previously described in literature (SILVA et al., 2012SILVA, D. M. et al. Biological characteristics of Anticarsia gemmatalis (Lepidoptera: Noctuidae) for three consecutive generations under different temperatures: understanding the possible impact of global warming on a soybean pest. Bulletin of Entomological Research, v.102, n.3, p.285-292, 2012. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/22112586/ >. Accessed: Sep. 13, 2020. doi: 10.1017/S0007485311000642.
https://pubmed.ncbi.nlm.nih.gov/22112586...
) and briefly summarized in the followings.

Anticarsia gemmatalis were originally collected in soybean fields in Embrapa Soybean Experimental Farm, Londrina, State of Paraná, Brazil (23° 11’ 11.7” S and 51° 10’ 46.1” W). These populations were kept in the laboratory for approximately 3 yr during which new field insects were introduced each year to maintain colony quality.

Caterpillars were individually kept in 50-mL plastic cups (Plasvale Ltda., Gaspar, State of Santa Catarina, Brazil) sealed with cardboard caps, containing an artificial diet developed by GREENE et al. (1976GREENE, G. L.; LEPPLA, N. C.; DICKERSON, W. A. Velvetbean Caterpillar: A Rearing Procedure and Artificial Medium. Journal of Economic Entomology, v.69, n.4, p.487-488, 1976. Available from: <Available from: https://academic.oup.com/jee/article-abstract/69/4/487/2212175 >. Accessed: Sep. 18, 2020. doi: 10.1093/jee/69.4.487.
https://academic.oup.com/jee/article-abs...
). Adults were placed in cages (PVC tubes of 10 cm in diameter x 21.5 cm high) and fed with solution (10 g of honey, 60 g of sugar, 1 g of sorbic acid, 1 g of methylparaben / 1 liter of distilled water) and beer. Cages walls were covered with A4 paper for moth oviposition. Eggs were removed and cages cleaned daily. Eggs were placed into 200-mL plastic cups (Plasvale Ltda., Gaspar, State of Santa Catarina, Brazil) containing 20 mL of artificial diet (GREENE et al., 1976). The caterpillars were kept in these containers until they reached the 3rd instar when they were then used for trials.

Different pesticides alone (bioassay 1 and 2) and AgMNPV mixture with different herbicides and fungicides (bioassay 3 and 4) mortality of Anticarsia gemmatalis.

Different herbicides and fungicides (Table 1) used alone or in association with the entomopathogenic baculovirus AgMNPV (Baculovirus Soja WP® 20g.150 L H2O-1) were evaluated in the dosage recommended by the manufacturers. As a control, sterilized distilled water was used. Artificial diet (GREENE et al. 1976GREENE, G. L.; LEPPLA, N. C.; DICKERSON, W. A. Velvetbean Caterpillar: A Rearing Procedure and Artificial Medium. Journal of Economic Entomology, v.69, n.4, p.487-488, 1976. Available from: <Available from: https://academic.oup.com/jee/article-abstract/69/4/487/2212175 >. Accessed: Sep. 18, 2020. doi: 10.1093/jee/69.4.487.
https://academic.oup.com/jee/article-abs...
) was cut into cubes (1 cm3) and immersed in the treatments for 5 seconds, then placed in plastic containers with a volume of 50 mL (sample unit), containing 2 caterpillars of 3rd instar. The diet cubes with the treatments were offered for caterpillars for 24 hours and later exchanged for cubes of a diet free of any pesticide.

The bioassay was conducted in a completely randomized design. Each treatment consisted of four repetitions containing 20 caterpillars each, which were packed in pairs in the sample units, totaling 80 caterpillars per treatment. The evaluation was performed daily, quantifying the number of dead caterpillars. The specimen was considered dead when it was immobile and insensitive to mechanical touch using a forceps.

Anticarsia gemmatalis mortality due to AgMNPV in mixture with different herbicides and fungicides after one (bioassay 5 and 6) and two (bioassay 7 and 8) hours of the mixture.

Treatments formed by the products (Table 1) and their association with AgMNPV (Baculovirus Soja WP® 20 g.150 L H2O-1) were evaluated in a completely randomized design. As previously described for bioassays 1, 2, 3 and 4 each treatment consisted of four repetitions containing 20 caterpillars each, which were packed in pairs in the sample units, totaling 80 caterpillars per treatment. The evaluation was performed daily, quantifying the number of dead caterpillars. The specimen was considered dead when it was immobile and insensitive to mechanical touch using a forceps.

Statistical analysis

The data obtained in the bioassays were analyzed for normality (SHAPIRO & WILK, 1965SHAPIRO, S.; WILK, M. B. An analysis of variance test for normality. Biometrika, v.52, p.591-611, 1965. Available from: <Available from: https://www.jstor.org/stable/2333709?seq=1 >. Accessed: Aug. 13, 2020. doi: 10.2307/2333709.
https://www.jstor.org/stable/2333709?seq...
) and homogeneity of variance for each treatment (BURR & FOSTER, 1972BURR, I. W.; FOSTER, L. A. A test for equality of variances. Mimeo Series. West Lafayette: [s.n.], 1972.) and, if necessary, transformed to perform ANOVA. The treatment means were then compared by Tukey test at the 5% probability level (SAS, 2001SAS. Institute. SAS user’s guide: statistics. 2001.).

RESULTS:

The caterpillars treated only with herbicides and fungicides, without association with AgMNPV (bioassays 1 and 2) triggered similar mortality (%) to control without the virus (8.74% and 10.23%, respectively). Those results were lower than mortality caused by AgMNPV (98.62% and 97.75%, respectively). Only the fungicides metconazole + pyraclostrobin caused a higher mortality of A. gemmatalis (40.95%) compared to the respective control (10.23%) (Table 2).

Table 2
Anticarsia gemmatalis mortality (%) due to ingestion of different pesticides alone (bioassays 1 and 2) or in mixture (bioassay 3 and 4) with AgMNPV (Baculovirus Soja WP® 20 g.150 L H2O-1).

Regarding herbicides and fungicides, when associated with AgMNPV (bioassays 3 and 4), they did not differ from the mortality (%) caused by the AgMNPV alone (95.22% and 93.45%, respectively), where the mortality rates ranged from 89.29% (clethodim) to 99.31% (chlorimuron-ethyl). Low mortality rates were observed in controls without AgMNPV (6.80% and 2.89%, respectively) (Table 2).

When evaluating the mixture compatibility of AgMNPV with herbicides and fungicides one hour after mixing the products (bioassays 5 and 7), it was reported that the herbicides and fungicides did not reduce the mortality of A. gemmatalis compared to AgMNPV alone (95.76% and 80.11%, respectively). Mortality ranged from 80.60% (azoxystrobin + benzovindiflupyr) to 99.31% (imazapic + imazapir). The mortality values caused by the pesticides were all higher than the values registered for the respective controls (2.83% and 6.67%) (Table 3).

Table 3
Anticarsia gemmatalis mortality (%) due to ingestion of AgMNPV (Baculovirus Soja WP® 20 g.150 L H2O-1) in mixture with different pesticides after 1 hour (bioassays 5 and 6) and two hours (bioassays 7 and 8) of the mixture.

Likewise, when checking the AgMNPV mixture compatibility with herbicides and fungicides two hours after mixing (bioassays 6 and 8), A. gemmatalis mortality caused by all the tested pesticides were higher than the mortality caused by the respective controls (1.36% and 2.00%). Although, azoxystrobin + benzovindiflupyr mixed with AgMNPV caused lower mortality of the caterpillars (69.27%) compared to the herbicide Bentazone (97.93%), both led to mortalities similar to that caused by the respective control (84.89%), as well as the other evaluated pesticides, when compared to the respective controls (96.40% and 84.89%) (Table 3).

DISCUSSION:

The efficiency of the entomopathogenic virus AgMNPV has been proven since the 1980s (MOSCARDI, 1999MOSCARDI, F. Assessment of the application of baculoviruses for control of Lepidoptera. Annual Review of Entomology, v.44, n.1, p.257-289, 1999. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/15012374/ >. Accessed: Sep. 19, 2020. doi: 10.1146/annurev.ento.44.1.257.
https://pubmed.ncbi.nlm.nih.gov/15012374...
) to the present date, with high levels of control even after three decades (DEL-ANGEL et al., 2018DEL-ANGEL, C. et al. Anticarsia gemmatalis Nucleopolyhedrovirus from soybean crops in Tamaulipas, Mexico: Diversity and insecticidal characteristics of individual variants and their co-occluded mixtures. Florida Entomologist, v.101, n.3, p.404-410, 2018. Available from: <Available from: https://bioone.org/journals/florida-entomologist/volume-101/issue-3/024.101.0319/Anticarsia-gemmatalis-Nucleopolyhedrovirus-from-Soybean-Crops-in-Tamaulipas-Mexico/10.1653/024.101.0319.full >. Accessed: Sep. 29, 2020. doi: 10.1653/024.101.0319.
https://bioone.org/journals/florida-ento...
). However, soybean production in this period increased exponentially, from 15 million tonnes in the 1980s to 114 million in 2017 (CATTELAN & DALL’AGNOL, 2018CATTELAN, A. J.; DALL’AGNOL, A. The rapid soybean growth in Brazil. OCL - Oilseeds and fats, Crops and Lipids, v.25, n.1, p.1-12, 2018. Available from: <Available from: https://www.embrapa.br/busca-de-publicacoes/-/publicacao/1091243/the-rapid-soybean-growth-in-brazil >. Accessed: Sep. 20, 2020. doi: 10.1051/ocl/2017058.
https://www.embrapa.br/busca-de-publicac...
), this significant increase was also due to the increase of cropped area that was followed by higher incidence of weeds and plant pathogens.

Mixing different pesticides (insecticides with herbicides or fungicides) was started as an alternative to reduce the costs of the increased need to control both insects and weeds or plant pathogens ate the same time (GANDINI et al., 2020GANDINI, E. M. M. et al. Compatibility of pesticides and/or fertilizers in tank mixtures. Journal of Cleaner Production, v.268, p.122-152, 2020. Available from: <Available from: https://www.sciencedirect.com/science/article/abs/pii/S0959652620321995 >. Accessed: Sep. 19, 2020. doi: 10.1016/j.jclepro.2020.122152.
https://www.sciencedirect.com/science/ar...
; ZANDONADI et al., 2018ZANDONADI, C. H. S. et al. Tank-mix of chlorantraniliprole and manganese foliar fertilizers: Impact on rheological characteristics, deposit properties and cuticular penetration. Crop Protection , v.106, p.50-57, 2018. Available from: <Available from: https://doi.org/10.1016/j.cropro.2017.12.011 >. Accessed: Sep. 20, 2020. doi: 10.1016/j.cropro.2017.12.011.
https://doi.org/10.1016/j.cropro.2017.12...
). However, the mixture of different molecules can reduce control of these substances. Studies verifying compatibility between molecules are essential to assess the feasibility of those pesticide mixture with the same quality as the isolated use. Studies evaluating the compatibility of synthetic chemical insecticides and herbicides were carried out, which verified that most of the molecules are compatible, demonstrating the efficiency of the mixture of substances in pest control (GANDINI et al., 2020; MA et al., 2016MA, X. Y. et al. Weed and insect control affected by mixing insecticides with glyphosate in cotton. Journal of Integrative Agriculture, v.15, n.2, p.373-380, 2016. Available from: <Available from: http://dx.doi.org/10.1016/S2095-3119(15)61188-1 >. Accessed: Sep. 17, 2020. doi: 10.1016/S2095-3119(15)61188-1.
http://dx.doi.org/10.1016/S2095-3119(15)...
; PETTER et al., 2012PETTER, F. A. et al. Incompatibilidade física de misturas entre herbicidas e inseticidas. Planta Daninha, v.30, n.2, p.449-457, 2012. Available from: <Available from: https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582012000200025 >. Accessed: Sep. 09, 2020. doi: 10.1590/S0100-83582012000200025.
https://www.scielo.br/scielo.php?script=...
); however, as far as we know this is the first research evaluating the mixture compatibility of chemical pesticides with AgMNPV.

In the present study, the entomopathogenic virus AgMNPV was compatible with tested fungicides and herbicides, allowing its concomitant use, maintaining the control efficiency of A. gemmatalis, with mortality rates above 89%. Similar compatible association of pesticides with biological control had been previously published with Roundup Ready® and the parasitoid Palmistichus elaeisis Delvare & LaSalle, 1993 (Hymenoptera: Eulophidae) (DE LA CRUZ et al., 2017LA CRUZ, R. A. DE et al. Side-effects of pesticides on the generalist endoparasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae). Scientific Reports, v.7, n.1, p.1-8, 2017. Available from: <Available from: https://www.nature.com/articles/s41598-017-10462-3 >. Accessed: Sep. 17, 2020. doi: 10.1038/s41598-017-10462-3.
https://www.nature.com/articles/s41598-0...
). Differently, the mixture of oxyfluorfen, glufosinate-ammonium, metribuzin and linuron impaired the entomopathogenic nematodes Rhabditida: Steinernematidae and Heterorhabditidae (LAZNIK & TRDAN, 2017LAZNIK, Ž.; TRDAN, S. The influence of herbicides on the viability of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae). International Journal of Pest Management, v.63, n.2, p.105-111, 2017. Available from: <Available from: https://doi.org/10.1080/09670874.2016.1227882 >. Accessed: Sep. 20, 2020. doi: 10.1080/09670874.2016.1227882.
https://doi.org/10.1080/09670874.2016.12...
). Fungicides also showed different results depending on the tested products and biological control. Azoxystrobin, chlorothalonil and thi-ophanate-methyl reduced the growth of Beauveria bassiana and Metarhizium anisopliae (FIEDLER & SOSNOWSKA, 2017FIEDLER, Z.; SOSNOWSKA, D. Side effects of fungicides and insecticides on entomopathogenic fungi in vitro. Journal of Plant Protection Research, v.57, n.4, p.355-360, 2017. Available from: <Available from: http://www.plantprotection.pl/Side-effects-of-fungicides-and-insecticides-on-entomopathogenic-fungi-in-vitro,85272,0,2.html >. Accessed: Sep. 19, 2020. doi: 10.1515/jppr-2017-0048.
http://www.plantprotection.pl/Side-effec...
). However, for Orius insidiosus Say, 1832 (Hemiptera: Anthocoridae), myclobutanil, potassium bicarbonate and cyprodinil + fludioxonil were harmless (GRADISH et al., 2011GRADISH, A. E. et al. Effect of reduced risk pesticides on greenhouse vegetable arthropod biological control agents. Pest Management Science, v.67, n.1, p.82-86, 2011. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/21162147/ >. Accessed: Sep. 19, 2020. doi: 10.1002/ps.203.
https://pubmed.ncbi.nlm.nih.gov/21162147...
). In addition to the tank mix of synthetic and biological products, the mix also occurs in seed treatments. The treatment of soybean seed with Bradyrhizobium spp mixed with fungicides pyraclostrobin and thiophanate-methyl and the insecticide fipronil, caused a decrease in the efficiency of the bacteria immediately and over time (RODRIGUES et al., 2020RODRIGUES, T. F. et al. Impact of pesticides in properties of Bradyrhizobium spp. and in the symbiotic performance with soybean. World Journal of Microbiology and Biotechnology, v.36, n.11, p.1-16, 2020. Available from: <Available from: https://doi.org/10.1007/s11274-020-02949-5 >. Accessed: Sep. 13, 2020. doi: 10.1007/s11274-020-02949-5.
https://doi.org/10.1007/s11274-020-02949...
). The use of Thichoderma spp combined with the fungicide Fludioxonil to treat soybean seed, caused an increase in crop production (ZANDONÁ et al., 2019ZANDONÁ, R. R. et al. Chemical and biological seed treatment and their effect on soybean development and yield. Revista Caatinga, v.32, n.2, p.559-565, 2019. Available from: <Available from: https://www.scielo.br/scielo.php?script=sci_arttext&pid=S1983-21252019000200559 >. Accessed: Jan. 20, 2021. doi: 10.1590/1983-21252019v32n229rc.
https://www.scielo.br/scielo.php?script=...
). Those differences recorded for different biological control agents and chemicals studied illustrate the importance of studying each scenario in order to offer growers the most precise information about what could and could not be mixture.

Only the fungicide (metconazole + pyraclostrobin), caused 40% mortality for A. gemmatalis, the effect is possibly linked to the metconazole molecule, which fits into chiral pesticides, in this class the way of action to other organisms is not yet elucidated, in addition 40% of insecticides belong to the chiral class (BIELSKÁ et al., 2021BIELSKÁ, L.; HALE, S. E.; ŠKULCOVÁ, L. A review on the stereospecific fate and effects of chiral conazole fungicides. Science of the Total Environment, v.750, p.1-10, 2021. Available from: <Available from: https://www.sciencedirect.com/science/article/abs/pii/S0048969720351299 >. Accessed: Jan. 09, 2021. doi: 10.1016/j.scitotenv.2020.141600.
https://www.sciencedirect.com/science/ar...
; JESCHKE, 2018JESCHKE, P. Current status of chirality in agrochemicals. Pest Management Science , v.74, n.11, p.2389-2404, 2018. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/29704299/ >. Accessed: Jan. 10, 2021. doi: 10.1002/ps.5052.
https://pubmed.ncbi.nlm.nih.gov/29704299...
). The fungicide (azoxystrobin + benzovindiflupyr) caused a reduction in mortality of A. gemmatalis after two hours of mixing (69.27%), compared to one hour of mixing (80.60%), it is possible to infer that this reduction is linked to the increase in pH caused by presence of the fungicide in suspension (LANDIM et al., 2019LANDIM, T. N. et al. Interactions between adjuvants and the fungicide azoxystrobin + benzovindiflypyr in hydraulic spraying. Engenharia agrícola, v.39, n.5, p.600-606, 2019. Available from: <Available from: https://www.scielo.br/scielo.php?pid=S0100-69162019000500600&script=sci_arttext >. Accessed: Jan. 20, 2021. doi: 10.1590/1809-4430-Eng.Agric.v39n5p600-606/2019.
https://www.scielo.br/scielo.php?pid=S01...
). Thus, exceeding optimal conditions for virus action. In addition, the substances present in the fungicide formulation, such as surfactants or adjuvants, which have detergent properties and with the longest exposure time, may have caused a deleterious action of the entomopathogen. Molecules with detergent action have hydrophilic and lipophilic portions in their structure, which increases the solubility of the products in water, as well as can denature proteins, which can interfere in the interaction with the virus, reducing the mortality of caterpillars (RAFIKOVA et al., 2004RAFIKOVA, E. R. et al. Low sodium dodecyl sulfate concentrations inhibit tobacco mosaic virus coat protein amorphous aggregation and change the protein stability. Biochemistry (Moscow), v.69, n.12, p.1372-1378, 2004. Availabe from: < Availabe from: https://pubmed.ncbi.nlm.nih.gov/15627393/ >. Accessed: Mar. 25, 2021. doi: 10.1007/s10541-005-0083-6.
https://pubmed.ncbi.nlm.nih.gov/15627393...
; PETTER et al., 2012PETTER, F. A. et al. Incompatibilidade física de misturas entre herbicidas e inseticidas. Planta Daninha, v.30, n.2, p.449-457, 2012. Available from: <Available from: https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582012000200025 >. Accessed: Sep. 09, 2020. doi: 10.1590/S0100-83582012000200025.
https://www.scielo.br/scielo.php?script=...
). Impact of differences regarding formulation on pesticide selectivity had also been previously reported in the literature for macro-organisms (GIOLO et al., 2006GIOLO, F. P. et al. Toxicidade de pesticidas utilizados na cultura do pessegueiro para estádios imaturos deTrichogramma pretiosu Riley (Hymenoptera: Trichogrammatidae). BioAssay, v.1, n.4, p.1-7, 2006. Available from: <Available from: http://www.bioassay.org.br/articles/1.4/BA1.4.pdf >. Accessed: Jun. 1, 2018.
http://www.bioassay.org.br/articles/1.4/...
).

The compatibility of AgMNPV with herbicides and fungicides has been proven to occur immediately after mixing and also after two hours of mixing, maintaining the same efficacy with caterpillar mortality close to or above 80%. Therefore, AgMNPV can be mixed with all pesticides tested under laboratory conditions. These laboratory results are essential indications for developing recommendations for use in the field, mainly assessing the quality of the biological agent and following the current legislation on the practice of mixing in a tank.

ACKNOWLEDGEMENTS

This study was financed in part by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (grants 402797/2016-7 and 302645/2018-7) and by Embrapa Soja.

REFERENCES

  • CR-2021-0027.R1

  • 1
    Editors: Leandro Souza da Silva (0000-0002-1636-6643) Uemerson Silva da Cunha (0000-0001-8005-4647)

Publication Dates

  • Publication in this collection
    20 Aug 2021
  • Date of issue
    2022

History

  • Received
    13 Jan 2021
  • Accepted
    20 Apr 2021
  • Reviewed
    10 June 2021
Universidade Federal de Santa Maria Universidade Federal de Santa Maria, Centro de Ciências Rurais , 97105-900 Santa Maria RS Brazil , Tel.: +55 55 3220-8698 , Fax: +55 55 3220-8695 - Santa Maria - RS - Brazil
E-mail: cienciarural@mail.ufsm.br