Resumo: A conservação de inimigos naturais é um componente importante no manejo integrado de prag... more Resumo: A conservação de inimigos naturais é um componente importante no manejo integrado de pragas. Neste trabalho, estudou-se a seletividade de 11 inseticidas usados para manejar Leucoptera coffeella (Guérin-Méneville) aos predadores Protonectarina sylveirae ...
ABSTRACT Spinosad has been used to control Tuta absoluta in Brazil for more than a decade but wil... more ABSTRACT Spinosad has been used to control Tuta absoluta in Brazil for more than a decade but will eventually be replaced by spinetoram despite the risk of cross-resistance. Therefore, the susceptibility to both molecules and the activity of detoxification enzymes were determined for eight representative populations of T. absoluta to assess resistance and the risk of cross-resistance. The LC 50 values for spinosad varied from 0.007 (Pelotas) to 0.626 mg/L (Su-maré); the LC 50 values for spinetoram varied from 0.047 (Pelotas) to 0.308 mg/L (Sumaré). The LC 99 values for spinosad varied from 0.23 (Pelotas) to 11.56 mg/L (Venda Nova do Imigrante); the LC 99 values for spinetoram varied from 0.55 (Pelotas) to 6.71 mg/L (Iraquara). The resistance levels ranged from 1.0-to 93.8-fold (RR 50) and 1.0-to 51.5-fold (RR 99) for spinosad and from 1.0-to 6.5-fold (RR 50) and 1.0-to 12.1-fold (RR 99) for spinetoram. The concen-tration-mortality responses to spinetoram were more homogeneous than those to spinosad. A strong correlation between the susceptibilities of T. absoluta populations to spinosad and spinetoram was observed, showing the simi-larity of the mode of action of both molecules and producing cross-resistance between them. The b–esterase activity of T. absoluta populations was correlated with spinosyn suscep-tibility, suggesting a potential contribution of the enzyme to evolved spinosyn resistance. The evolution of resistance to spinosyns in T. absoluta observed in this study suggests that strategies to mitigate resistance must be carefully implemented over the short term and that rotation with other products is encouraged. Keywords Enhanced detoxification Á Cross-resistance Á Spinosad Á Spinetoram Á Tomato leafminer Key message • Insecticide resistance is an increasing phenomenon among pests and impairs the control of invasive pests, particularly to risk-reduced insecticides such as spinosyns. • High levels of resistance in field populations of Tuta absoluta to spinosyns are reported as well as cross-resistance to other spinosyns and detoxificative metabolism. • The reporting of Tuta absoluta resistance to spinosad will lead to further studies for generating tools of resistance monitoring to spinosyns, thus fine-tuning the insecticide resistance programs.
The introduction of an agricultural pest species into a new environment is a potential threat to ... more The introduction of an agricultural pest species into a new environment is a potential threat to agroecosystems of the invaded area. The phytosanitary concern is even greater if the introduced pest's phenotype expresses traits that will impair the management of that species. The invasive tomato borer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is one such species and the characterization of the insecticide resistance prevailing in the area of origin is important to guide management efforts in new areas of introduction. The spinosad is one the main insecticides currently used in Brazil for control of the tomato borer; Brazil is the likely source of the introduction of the tomato borer into Europe. For this reason, spinosad resistance in Brazilian populations of this species was characterized. Spinosad resistance has been reported in Brazilian field populations of this pest species, and one resistant population that was used in this study was subjected to an additional seven generations of selection for spinosad resistance reaching levels over 180,000-fold. Inheritance studies indicated that spinosad resistance is monogenic, incompletely recessive and autosomal with high heritability (h(2) = 0.71). Spinosad resistance was unstable without selection pressure with a negative rate of change in the resistance level ( = -0.51) indicating an associated adaptive cost. Esterases and cytochrome P450-dependent monooxygenases titration decreased with spinosad selection, indicating that these detoxification enzymes are not the underlying resistance mechanism. Furthermore, the cross-resistance spectrum was restricted to the insecticide spinetoram, another spinosyn, suggesting that altered target site may be the mechanism involved. Therefore, the suspension of spinosyn use against the tomato borer would be a useful component in spinosad resistance management for this species. Spinosad use against this species in introduced areas should be carefully monitored to prevent rapid selection of high levels of resistance and the potential for its spread to new areas.
The tomato leafminer, Tuta absoluta, is a major pest of tomato crops worldwide. This study survey... more The tomato leafminer, Tuta absoluta, is a major pest of tomato crops worldwide. This study surveyed the resistance of T. absoluta populations from four regions in Brazil to pyrethroid insecticides, the frequencies of L1014F, T929I and M918T Na channel mutations, and the role of detoxification metabolism in the resistance. Resistance ratios varied from 1- to 11-times among populations and insecticides, but control failure likelihood assays showed that all pyrethroids assessed exhibited no efficacy at all (and thus, 98-100% control failure likelihood) against all T. absoluta populations. The activity of glutathione S-transferase and cytochrome P450-mediated N-demethylation in biochemical assays was significantly correlated with the level of resistance to deltamethrin and permethrin suggesting that these enzymes may play a role in resistance. TaqMan assays were used to screen for the presence of knockdown resistance (kdr) mutations and revealed that the L1014F kdr mutation was fixed in all populations and associated with two super-kdr mutations, M918T and particularly T929I, at high frequency. Altogether, results suggest that control failures are because of mutations in the domain II of the sodium channel, as a prevailing mechanism of resistance to pyrethroids in populations of T. absoluta in Brazil. But, enhanced cytochrome P450-dependent monooxygenases and GST activities also play an important role in the resistance of some populations, which reinforce that pyrethroids must not be used overall to control T. absoluta.
This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyali... more This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyalinata (L.) (Lepidoptera: Pyralidae), Musca domestica (L.) (Diptera: Muscidae), Periplaneta americana (L.) (Blattodea: Blattidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). The plant species used were: basil (Ocimum selloi Benth.), rue (Ruta graveolens L.), lion's ear (Leonotis nepetaefolia L.), Jimson weed (Datura stramonium L.), 'baleeira' herb (Cordia verbenaceae L.), mint (Mentha piperita L.), wild balsam apple (Mormodica charantia L.) and billy goat weed (Ageratum conyzoides L.). Firstly, the insecticidal activities of hexane and ethanol plant extracts were evaluated against adults of R. dominica. Among them, only the hexane extract of A. conyzoides showed insecticidal activity. The hexane extract of this plant species was therefore fractionated by silica gel column chromatography to isolate and purify its bioactive chemical constituents. Three compounds were identified using IR spectra, (1)H NMR, (13)C NMR, HMBC and NOE after gel chromatography: 5,6,7,8,3', 4', 5'-heptamethoxyflavone, 5,6,7,8,3'-pentamethoxy-4', 5'-methylenedioxyflavone and coumarin. The complete assignment of (13)C NMR to…
The objective of this work was to screen plants with insecticide activity, in order to isolate, i... more The objective of this work was to screen plants with insecticide activity, in order to isolate, identify and assess the bioactivity of insecticide compounds present in these plants, against Coleoptera pests of stored products: Oryzaephilus surinamensis L. (Silvanidae), Rhyzopertha dominica F. (Bostrichidae) and Sitophilus zeamais Mots. (Curculionidae). The plant species used were: basil (Ocimum selloi Benth.), rue (Ruta graveolens L.), lion's ear (Leonotis nepetifolia (L.) R.Br.), jimson weed (Datura stramonium L.), baleeira herb (Cordia verbenacea L.), mint (Mentha piperita L.), wild balsam apple (Mormodica charantia L.), and billy goat weed or mentrasto (Ageratum conyzoides L.). The insecticide activity of hexane and ethanol extracts from those plants on R. dominica was evaluated. Among them, only hexane extract of A. conyzoides showed insecticide activity; the hexane extract of this species was successively fractionated by silica gel column chromatography, for isolation and p...
Page 1. Pesq. agropec. bras., Brasília, v. 37, n. 3, p. 237-242, mar. 2002 Seletividade fisiológi... more Page 1. Pesq. agropec. bras., Brasília, v. 37, n. 3, p. 237-242, mar. 2002 Seletividade fisiológica de inseticidas a Vespidae predadores 237 Seletividade fisiológica de inseticidas a Vespidae predadores de Ascia monuste orseis(1) ...
Chlorantraniliprole, a new anthranilic diamide, is an insecticide that has recently been register... more Chlorantraniliprole, a new anthranilic diamide, is an insecticide that has recently been registered in Brazil to control several lepidopterans, including the diamondback moth, Plutella xylostella (L.). Chemical control of this pest has been particularly difficult because of its evolution of resistance to previous insecticide classes. To deploy a chlorantraniliprole resistance-monitoring program, the susceptibility of P. xylostella populations from different regions of Brazil was assessed using concentration-mortality bioassays before the commercial release of chlorantraniliprole. Mortality data were subjected to Probit analysis to estimate lethal parameters. Dosing by immersion or by spraying in a Potter tower were both suitable but topical application was not. All of the P. xylostella populations were highly susceptible to chlorantraniliprole (LC 50 0.015e0.056 mg a.i./l of water) with those from the Northeast being the most tolerant. LC 99 values were also low (0.065e0.281 mg a.i./l). The susceptibility variation among the populations was notably low, with the highest tolerance ratio being 3.8 fold, indicating a low variability of response among the Brazilian populations to this insecticide. A discriminating concentration of 0.3 mg a.i./l was obtained from the baseline data and proved to be effective for evaluating other populations, causing 100% mortality. The baseline data reflect the natural variation of these P. xylostella populations to chlorantraniliprole, rather than variations caused by previous exposure.
Page 1. RESEARCH ARTICLE Biological performance of Diclidophlebia smithi (Hemiptera: Psyllidae), ... more Page 1. RESEARCH ARTICLE Biological performance of Diclidophlebia smithi (Hemiptera: Psyllidae), a potential biocontrol agent for the invasive weed Miconia calvescens Elisangela Gomes Fidelis de Moraisa,*, Marcelo Coutinho ...
A traça-do-tomateiro [Tuta absoluta (Meyrick)] é a praga mais importante em várias áreas de produ... more A traça-do-tomateiro [Tuta absoluta (Meyrick)] é a praga mais importante em várias áreas de produção de tomate no Brasil. Espécies silvestres de Lycopersicon, como L. hirsutum e L. peruvianum, têm mostrado possibilidades de utilização em programas de melhoramento visando à obtenção de variedades comerciais resistentes a pragas. Este trabalho teve como objetivo avaliar o desenvolvimento e a sobrevivência de lagartas recém-eclodidas de T. absoluta em oito genótipos de tomateiros: Santa Clara; L. pimpinellifolium (PI 126931); L. peruvianum (PI 306811; PI 128659; LA 444-1; BG 3286; CNPH 374); e L. hirsutum f. glabratum (PI 134417). Lagartas recém-eclodidas foram individualizadas em vidros contendo areia aos quais foram fixados pecíolos de folhas de tomate (um pecíolo por vidro). Em seguida, os vidros foram recobertos com filme plástico de PVC e colocados em BOD sob temperatura de 25 °C e umidade relativa de 70%. Acompanhou-se o desenvolvimento nas trocas de folhas, a cada três dias, até se obter a segunda geração do inseto. Houve efeito dos genótipos na mortalidade de lagartas somente na segunda geração (90,0% para PI 134417
The introduction of an agricultural pest species into a new environment is a potential threat to ... more The introduction of an agricultural pest species into a new environment is a potential threat to agroecosystems of the invaded area. The phytosanitary concern is even greater if the introduced pest's phenotype expresses traits that will impair the management of that species. The invasive tomato borer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is one such species and the characterization of the insecticide resistance prevailing in the area of origin is important to guide management efforts in new areas of introduction. The spinosad is one the main insecticides currently used in Brazil for control of the tomato borer; Brazil is the likely source of the introduction of the tomato borer into Europe. For this reason, spinosad resistance in Brazilian populations of this species was characterized. Spinosad resistance has been reported in Brazilian field populations of this pest species, and one resistant population that was used in this study was subjected to an additional seven generations of selection for spinosad resistance reaching levels over 180,000-fold. Inheritance studies indicated that spinosad resistance is monogenic, incompletely recessive and autosomal with high heritability (h 2 = 0.71). Spinosad resistance was unstable without selection pressure with a negative rate of change in the resistance level ( = 20.51) indicating an associated adaptive cost. Esterases and cytochrome P450-dependent monooxygenases titration decreased with spinosad selection, indicating that these detoxification enzymes are not the underlying resistance mechanism. Furthermore, the cross-resistance spectrum was restricted to the insecticide spinetoram, another spinosyn, suggesting that altered target site may be the mechanism involved. Therefore, the suspension of spinosyn use against the tomato borer would be a useful component in spinosad resistance management for this species. Spinosad use against this species in introduced areas should be carefully monitored to prevent rapid selection of high levels of resistance and the potential for its spread to new areas.
Chlorantraniliprole, a new anthranilic diamide, is an insecticide that has recently been register... more Chlorantraniliprole, a new anthranilic diamide, is an insecticide that has recently been registered in Brazil to control several lepidopterans, including the diamondback moth, Plutella xylostella (L.). Chemical control of this pest has been particularly difficult because of its evolution of resistance to previous insecticide classes. To deploy a chlorantraniliprole resistance-monitoring program, the susceptibility of P. xylostella populations from different regions of Brazil was assessed using concentration-mortality bioassays before the commercial release of chlorantraniliprole. Mortality data were subjected to Probit analysis to estimate lethal parameters. Dosing by immersion or by spraying in a Potter tower were both suitable but topical application was not. All of the P. xylostella populations were highly susceptible to chlorantraniliprole (LC 50 0.015e0.056 mg a.i./l of water) with those from the Northeast being the most tolerant. LC 99 values were also low (0.065e0.281 mg a.i./l). The susceptibility variation among the populations was notably low, with the highest tolerance ratio being 3.8 fold, indicating a low variability of response among the Brazilian populations to this insecticide. A discriminating concentration of 0.3 mg a.i./l was obtained from the baseline data and proved to be effective for evaluating other populations, causing 100% mortality. The baseline data reflect the natural variation of these P. xylostella populations to chlorantraniliprole, rather than variations caused by previous exposure.
Conservation of natural enemies is an important component of integrated pest management. In this ... more Conservation of natural enemies is an important component of integrated pest management. In this work, the selectivity of 11 insecticides used for management of Leucoptera coffeella (Guérin-Méneville) was studied to Protonectarina sylveirae (Saussure), Polybia scutellaris (White) and Protopolybia exigua (Saussure) (Hymenoptera: Vespidae). The insecticides were applied in concentrations corresponding to 50% and 100% of the field rates used for management of L. coffeella. The organophosphates (except to the 50% rate of ethion to P. scutellaris) were highly toxic to all three Vespidae species. Cartap was highly toxic to P. escutellaris and P. exigua but showed median selectivity to P. sylveirae. The pyrethroids cypermethrin, deltamethrin, betacyfluthrin, zetacypermethrin, and esfenvalerate were selective to at least one of wasp species. The mortality of P. scutelaris caused by ethion, cypermethrin, deltamethrin, betacyfluthrin and zetacypermethrin decreased when 50% of the recommended rates were used. This reduction was also observed for the mortality of P. exigua by permethrin and for the mortality of P. sylveirae by deltamethrin. P. sylveirae was the most tolerant species to cartap; P. scutellaris was the most tolerant to ethion, while P. exigua was more tolerant to pyrethroids than P. scutellaris and P. sylveirae. The results of this research indicate that pyrethroid insecticides are likely to be selective to predatory wasps in field settings given their overall selectivity in the conditions of extreme exposure of this study. The possible mechanisms underlying the selectivity of these compounds and the differential tolerance of the wasps are discussed.
This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyali... more This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyalinata (L.) (Lepidoptera: Pyralidae), Musca domestica (L.) (Diptera: Muscidae), Periplaneta americana (L.) (Blattodea: Blattidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). The plant species used were: basil (Ocimum selloi Benth.), rue (Ruta graveolens L.), lion's ear (Leonotis nepetaefolia L.), Jimson weed (Datura stramonium L.), 'baleeira' herb (Cordia verbenaceae L.), mint (Mentha piperita L.), wild balsam apple (Mormodica charantia L.) and billy goat weed (Ageratum conyzoides L.). Firstly, the insecticidal activities of hexane and ethanol plant extracts were evaluated against adults of R. dominica. Among them, only the hexane extract of A.
Insecticide lethal and sub-lethal effects on non-target species are a focus in pest management pr... more Insecticide lethal and sub-lethal effects on non-target species are a focus in pest management programs. However, such studies are usually centered in relatively few groups of natural enemies of insect pests. Earwigs, although insect pest predators of key importance in Neotropical maize fields, have received very little attention. The earwig Doru luteipes (Sccuder) (Dermaptera: Forficulidae) is one of the main predators of the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Both species were subjected to toxicity and selectivity studies with the insecticides chlorantraniliprole, chlorfenapyr, chlorpyrifos, l-cyhalothrin, deltamethrin, etofenprox, methomyl and spinosad. The behavioral locomotory response of D. luteipes to these compounds was also assessed. Concentration-response bioassays indicated very low potency of chlorantraniliprole (>550,000Â less toxic), followed by spinosad (>3,500Â less toxic) and etofenprox (>1,100Â less toxic) as compared to chlorpyrifos, the most toxic insecticide studied against this earwig species. These same three compounds exhibited the highest selectivity when comparing the earwig with its prey, the fall armyworm. Time-response bioassays using the insecticide label rates recommended against the fall armyworm confirmed the high selectivity of chlorantraniliprole and etofenprox, in addition to deltamethrin and methomyl. Again chlorpyrifos exhibited the lowest levels of selectivity. Exposure of the earwig to insecticide-treated surfaces indicated that spinosad reduced the locomotory activity of the adults probably increasing their insecticide exposure, while they avoided chlorfenapyr-, etofenprox-, and chlorpyrifos-treated surfaces. Chlorantraniliprole and etofenprox seem the most promising compounds for use against S. frugiperda whilst preserving populations of D. luteipes.
Resumo: A conservação de inimigos naturais é um componente importante no manejo integrado de prag... more Resumo: A conservação de inimigos naturais é um componente importante no manejo integrado de pragas. Neste trabalho, estudou-se a seletividade de 11 inseticidas usados para manejar Leucoptera coffeella (Guérin-Méneville) aos predadores Protonectarina sylveirae ...
ABSTRACT Spinosad has been used to control Tuta absoluta in Brazil for more than a decade but wil... more ABSTRACT Spinosad has been used to control Tuta absoluta in Brazil for more than a decade but will eventually be replaced by spinetoram despite the risk of cross-resistance. Therefore, the susceptibility to both molecules and the activity of detoxification enzymes were determined for eight representative populations of T. absoluta to assess resistance and the risk of cross-resistance. The LC 50 values for spinosad varied from 0.007 (Pelotas) to 0.626 mg/L (Su-maré); the LC 50 values for spinetoram varied from 0.047 (Pelotas) to 0.308 mg/L (Sumaré). The LC 99 values for spinosad varied from 0.23 (Pelotas) to 11.56 mg/L (Venda Nova do Imigrante); the LC 99 values for spinetoram varied from 0.55 (Pelotas) to 6.71 mg/L (Iraquara). The resistance levels ranged from 1.0-to 93.8-fold (RR 50) and 1.0-to 51.5-fold (RR 99) for spinosad and from 1.0-to 6.5-fold (RR 50) and 1.0-to 12.1-fold (RR 99) for spinetoram. The concen-tration-mortality responses to spinetoram were more homogeneous than those to spinosad. A strong correlation between the susceptibilities of T. absoluta populations to spinosad and spinetoram was observed, showing the simi-larity of the mode of action of both molecules and producing cross-resistance between them. The b–esterase activity of T. absoluta populations was correlated with spinosyn suscep-tibility, suggesting a potential contribution of the enzyme to evolved spinosyn resistance. The evolution of resistance to spinosyns in T. absoluta observed in this study suggests that strategies to mitigate resistance must be carefully implemented over the short term and that rotation with other products is encouraged. Keywords Enhanced detoxification Á Cross-resistance Á Spinosad Á Spinetoram Á Tomato leafminer Key message • Insecticide resistance is an increasing phenomenon among pests and impairs the control of invasive pests, particularly to risk-reduced insecticides such as spinosyns. • High levels of resistance in field populations of Tuta absoluta to spinosyns are reported as well as cross-resistance to other spinosyns and detoxificative metabolism. • The reporting of Tuta absoluta resistance to spinosad will lead to further studies for generating tools of resistance monitoring to spinosyns, thus fine-tuning the insecticide resistance programs.
The introduction of an agricultural pest species into a new environment is a potential threat to ... more The introduction of an agricultural pest species into a new environment is a potential threat to agroecosystems of the invaded area. The phytosanitary concern is even greater if the introduced pest's phenotype expresses traits that will impair the management of that species. The invasive tomato borer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is one such species and the characterization of the insecticide resistance prevailing in the area of origin is important to guide management efforts in new areas of introduction. The spinosad is one the main insecticides currently used in Brazil for control of the tomato borer; Brazil is the likely source of the introduction of the tomato borer into Europe. For this reason, spinosad resistance in Brazilian populations of this species was characterized. Spinosad resistance has been reported in Brazilian field populations of this pest species, and one resistant population that was used in this study was subjected to an additional seven generations of selection for spinosad resistance reaching levels over 180,000-fold. Inheritance studies indicated that spinosad resistance is monogenic, incompletely recessive and autosomal with high heritability (h(2) = 0.71). Spinosad resistance was unstable without selection pressure with a negative rate of change in the resistance level ( = -0.51) indicating an associated adaptive cost. Esterases and cytochrome P450-dependent monooxygenases titration decreased with spinosad selection, indicating that these detoxification enzymes are not the underlying resistance mechanism. Furthermore, the cross-resistance spectrum was restricted to the insecticide spinetoram, another spinosyn, suggesting that altered target site may be the mechanism involved. Therefore, the suspension of spinosyn use against the tomato borer would be a useful component in spinosad resistance management for this species. Spinosad use against this species in introduced areas should be carefully monitored to prevent rapid selection of high levels of resistance and the potential for its spread to new areas.
The tomato leafminer, Tuta absoluta, is a major pest of tomato crops worldwide. This study survey... more The tomato leafminer, Tuta absoluta, is a major pest of tomato crops worldwide. This study surveyed the resistance of T. absoluta populations from four regions in Brazil to pyrethroid insecticides, the frequencies of L1014F, T929I and M918T Na channel mutations, and the role of detoxification metabolism in the resistance. Resistance ratios varied from 1- to 11-times among populations and insecticides, but control failure likelihood assays showed that all pyrethroids assessed exhibited no efficacy at all (and thus, 98-100% control failure likelihood) against all T. absoluta populations. The activity of glutathione S-transferase and cytochrome P450-mediated N-demethylation in biochemical assays was significantly correlated with the level of resistance to deltamethrin and permethrin suggesting that these enzymes may play a role in resistance. TaqMan assays were used to screen for the presence of knockdown resistance (kdr) mutations and revealed that the L1014F kdr mutation was fixed in all populations and associated with two super-kdr mutations, M918T and particularly T929I, at high frequency. Altogether, results suggest that control failures are because of mutations in the domain II of the sodium channel, as a prevailing mechanism of resistance to pyrethroids in populations of T. absoluta in Brazil. But, enhanced cytochrome P450-dependent monooxygenases and GST activities also play an important role in the resistance of some populations, which reinforce that pyrethroids must not be used overall to control T. absoluta.
This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyali... more This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyalinata (L.) (Lepidoptera: Pyralidae), Musca domestica (L.) (Diptera: Muscidae), Periplaneta americana (L.) (Blattodea: Blattidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). The plant species used were: basil (Ocimum selloi Benth.), rue (Ruta graveolens L.), lion's ear (Leonotis nepetaefolia L.), Jimson weed (Datura stramonium L.), 'baleeira' herb (Cordia verbenaceae L.), mint (Mentha piperita L.), wild balsam apple (Mormodica charantia L.) and billy goat weed (Ageratum conyzoides L.). Firstly, the insecticidal activities of hexane and ethanol plant extracts were evaluated against adults of R. dominica. Among them, only the hexane extract of A. conyzoides showed insecticidal activity. The hexane extract of this plant species was therefore fractionated by silica gel column chromatography to isolate and purify its bioactive chemical constituents. Three compounds were identified using IR spectra, (1)H NMR, (13)C NMR, HMBC and NOE after gel chromatography: 5,6,7,8,3', 4', 5'-heptamethoxyflavone, 5,6,7,8,3'-pentamethoxy-4', 5'-methylenedioxyflavone and coumarin. The complete assignment of (13)C NMR to…
The objective of this work was to screen plants with insecticide activity, in order to isolate, i... more The objective of this work was to screen plants with insecticide activity, in order to isolate, identify and assess the bioactivity of insecticide compounds present in these plants, against Coleoptera pests of stored products: Oryzaephilus surinamensis L. (Silvanidae), Rhyzopertha dominica F. (Bostrichidae) and Sitophilus zeamais Mots. (Curculionidae). The plant species used were: basil (Ocimum selloi Benth.), rue (Ruta graveolens L.), lion's ear (Leonotis nepetifolia (L.) R.Br.), jimson weed (Datura stramonium L.), baleeira herb (Cordia verbenacea L.), mint (Mentha piperita L.), wild balsam apple (Mormodica charantia L.), and billy goat weed or mentrasto (Ageratum conyzoides L.). The insecticide activity of hexane and ethanol extracts from those plants on R. dominica was evaluated. Among them, only hexane extract of A. conyzoides showed insecticide activity; the hexane extract of this species was successively fractionated by silica gel column chromatography, for isolation and p...
Page 1. Pesq. agropec. bras., Brasília, v. 37, n. 3, p. 237-242, mar. 2002 Seletividade fisiológi... more Page 1. Pesq. agropec. bras., Brasília, v. 37, n. 3, p. 237-242, mar. 2002 Seletividade fisiológica de inseticidas a Vespidae predadores 237 Seletividade fisiológica de inseticidas a Vespidae predadores de Ascia monuste orseis(1) ...
Chlorantraniliprole, a new anthranilic diamide, is an insecticide that has recently been register... more Chlorantraniliprole, a new anthranilic diamide, is an insecticide that has recently been registered in Brazil to control several lepidopterans, including the diamondback moth, Plutella xylostella (L.). Chemical control of this pest has been particularly difficult because of its evolution of resistance to previous insecticide classes. To deploy a chlorantraniliprole resistance-monitoring program, the susceptibility of P. xylostella populations from different regions of Brazil was assessed using concentration-mortality bioassays before the commercial release of chlorantraniliprole. Mortality data were subjected to Probit analysis to estimate lethal parameters. Dosing by immersion or by spraying in a Potter tower were both suitable but topical application was not. All of the P. xylostella populations were highly susceptible to chlorantraniliprole (LC 50 0.015e0.056 mg a.i./l of water) with those from the Northeast being the most tolerant. LC 99 values were also low (0.065e0.281 mg a.i./l). The susceptibility variation among the populations was notably low, with the highest tolerance ratio being 3.8 fold, indicating a low variability of response among the Brazilian populations to this insecticide. A discriminating concentration of 0.3 mg a.i./l was obtained from the baseline data and proved to be effective for evaluating other populations, causing 100% mortality. The baseline data reflect the natural variation of these P. xylostella populations to chlorantraniliprole, rather than variations caused by previous exposure.
Page 1. RESEARCH ARTICLE Biological performance of Diclidophlebia smithi (Hemiptera: Psyllidae), ... more Page 1. RESEARCH ARTICLE Biological performance of Diclidophlebia smithi (Hemiptera: Psyllidae), a potential biocontrol agent for the invasive weed Miconia calvescens Elisangela Gomes Fidelis de Moraisa,*, Marcelo Coutinho ...
A traça-do-tomateiro [Tuta absoluta (Meyrick)] é a praga mais importante em várias áreas de produ... more A traça-do-tomateiro [Tuta absoluta (Meyrick)] é a praga mais importante em várias áreas de produção de tomate no Brasil. Espécies silvestres de Lycopersicon, como L. hirsutum e L. peruvianum, têm mostrado possibilidades de utilização em programas de melhoramento visando à obtenção de variedades comerciais resistentes a pragas. Este trabalho teve como objetivo avaliar o desenvolvimento e a sobrevivência de lagartas recém-eclodidas de T. absoluta em oito genótipos de tomateiros: Santa Clara; L. pimpinellifolium (PI 126931); L. peruvianum (PI 306811; PI 128659; LA 444-1; BG 3286; CNPH 374); e L. hirsutum f. glabratum (PI 134417). Lagartas recém-eclodidas foram individualizadas em vidros contendo areia aos quais foram fixados pecíolos de folhas de tomate (um pecíolo por vidro). Em seguida, os vidros foram recobertos com filme plástico de PVC e colocados em BOD sob temperatura de 25 °C e umidade relativa de 70%. Acompanhou-se o desenvolvimento nas trocas de folhas, a cada três dias, até se obter a segunda geração do inseto. Houve efeito dos genótipos na mortalidade de lagartas somente na segunda geração (90,0% para PI 134417
The introduction of an agricultural pest species into a new environment is a potential threat to ... more The introduction of an agricultural pest species into a new environment is a potential threat to agroecosystems of the invaded area. The phytosanitary concern is even greater if the introduced pest's phenotype expresses traits that will impair the management of that species. The invasive tomato borer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is one such species and the characterization of the insecticide resistance prevailing in the area of origin is important to guide management efforts in new areas of introduction. The spinosad is one the main insecticides currently used in Brazil for control of the tomato borer; Brazil is the likely source of the introduction of the tomato borer into Europe. For this reason, spinosad resistance in Brazilian populations of this species was characterized. Spinosad resistance has been reported in Brazilian field populations of this pest species, and one resistant population that was used in this study was subjected to an additional seven generations of selection for spinosad resistance reaching levels over 180,000-fold. Inheritance studies indicated that spinosad resistance is monogenic, incompletely recessive and autosomal with high heritability (h 2 = 0.71). Spinosad resistance was unstable without selection pressure with a negative rate of change in the resistance level ( = 20.51) indicating an associated adaptive cost. Esterases and cytochrome P450-dependent monooxygenases titration decreased with spinosad selection, indicating that these detoxification enzymes are not the underlying resistance mechanism. Furthermore, the cross-resistance spectrum was restricted to the insecticide spinetoram, another spinosyn, suggesting that altered target site may be the mechanism involved. Therefore, the suspension of spinosyn use against the tomato borer would be a useful component in spinosad resistance management for this species. Spinosad use against this species in introduced areas should be carefully monitored to prevent rapid selection of high levels of resistance and the potential for its spread to new areas.
Chlorantraniliprole, a new anthranilic diamide, is an insecticide that has recently been register... more Chlorantraniliprole, a new anthranilic diamide, is an insecticide that has recently been registered in Brazil to control several lepidopterans, including the diamondback moth, Plutella xylostella (L.). Chemical control of this pest has been particularly difficult because of its evolution of resistance to previous insecticide classes. To deploy a chlorantraniliprole resistance-monitoring program, the susceptibility of P. xylostella populations from different regions of Brazil was assessed using concentration-mortality bioassays before the commercial release of chlorantraniliprole. Mortality data were subjected to Probit analysis to estimate lethal parameters. Dosing by immersion or by spraying in a Potter tower were both suitable but topical application was not. All of the P. xylostella populations were highly susceptible to chlorantraniliprole (LC 50 0.015e0.056 mg a.i./l of water) with those from the Northeast being the most tolerant. LC 99 values were also low (0.065e0.281 mg a.i./l). The susceptibility variation among the populations was notably low, with the highest tolerance ratio being 3.8 fold, indicating a low variability of response among the Brazilian populations to this insecticide. A discriminating concentration of 0.3 mg a.i./l was obtained from the baseline data and proved to be effective for evaluating other populations, causing 100% mortality. The baseline data reflect the natural variation of these P. xylostella populations to chlorantraniliprole, rather than variations caused by previous exposure.
Conservation of natural enemies is an important component of integrated pest management. In this ... more Conservation of natural enemies is an important component of integrated pest management. In this work, the selectivity of 11 insecticides used for management of Leucoptera coffeella (Guérin-Méneville) was studied to Protonectarina sylveirae (Saussure), Polybia scutellaris (White) and Protopolybia exigua (Saussure) (Hymenoptera: Vespidae). The insecticides were applied in concentrations corresponding to 50% and 100% of the field rates used for management of L. coffeella. The organophosphates (except to the 50% rate of ethion to P. scutellaris) were highly toxic to all three Vespidae species. Cartap was highly toxic to P. escutellaris and P. exigua but showed median selectivity to P. sylveirae. The pyrethroids cypermethrin, deltamethrin, betacyfluthrin, zetacypermethrin, and esfenvalerate were selective to at least one of wasp species. The mortality of P. scutelaris caused by ethion, cypermethrin, deltamethrin, betacyfluthrin and zetacypermethrin decreased when 50% of the recommended rates were used. This reduction was also observed for the mortality of P. exigua by permethrin and for the mortality of P. sylveirae by deltamethrin. P. sylveirae was the most tolerant species to cartap; P. scutellaris was the most tolerant to ethion, while P. exigua was more tolerant to pyrethroids than P. scutellaris and P. sylveirae. The results of this research indicate that pyrethroid insecticides are likely to be selective to predatory wasps in field settings given their overall selectivity in the conditions of extreme exposure of this study. The possible mechanisms underlying the selectivity of these compounds and the differential tolerance of the wasps are discussed.
This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyali... more This work aimed at identifying plant compounds with insecticidal activity against Diaphania hyalinata (L.) (Lepidoptera: Pyralidae), Musca domestica (L.) (Diptera: Muscidae), Periplaneta americana (L.) (Blattodea: Blattidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). The plant species used were: basil (Ocimum selloi Benth.), rue (Ruta graveolens L.), lion's ear (Leonotis nepetaefolia L.), Jimson weed (Datura stramonium L.), 'baleeira' herb (Cordia verbenaceae L.), mint (Mentha piperita L.), wild balsam apple (Mormodica charantia L.) and billy goat weed (Ageratum conyzoides L.). Firstly, the insecticidal activities of hexane and ethanol plant extracts were evaluated against adults of R. dominica. Among them, only the hexane extract of A.
Insecticide lethal and sub-lethal effects on non-target species are a focus in pest management pr... more Insecticide lethal and sub-lethal effects on non-target species are a focus in pest management programs. However, such studies are usually centered in relatively few groups of natural enemies of insect pests. Earwigs, although insect pest predators of key importance in Neotropical maize fields, have received very little attention. The earwig Doru luteipes (Sccuder) (Dermaptera: Forficulidae) is one of the main predators of the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Both species were subjected to toxicity and selectivity studies with the insecticides chlorantraniliprole, chlorfenapyr, chlorpyrifos, l-cyhalothrin, deltamethrin, etofenprox, methomyl and spinosad. The behavioral locomotory response of D. luteipes to these compounds was also assessed. Concentration-response bioassays indicated very low potency of chlorantraniliprole (>550,000Â less toxic), followed by spinosad (>3,500Â less toxic) and etofenprox (>1,100Â less toxic) as compared to chlorpyrifos, the most toxic insecticide studied against this earwig species. These same three compounds exhibited the highest selectivity when comparing the earwig with its prey, the fall armyworm. Time-response bioassays using the insecticide label rates recommended against the fall armyworm confirmed the high selectivity of chlorantraniliprole and etofenprox, in addition to deltamethrin and methomyl. Again chlorpyrifos exhibited the lowest levels of selectivity. Exposure of the earwig to insecticide-treated surfaces indicated that spinosad reduced the locomotory activity of the adults probably increasing their insecticide exposure, while they avoided chlorfenapyr-, etofenprox-, and chlorpyrifos-treated surfaces. Chlorantraniliprole and etofenprox seem the most promising compounds for use against S. frugiperda whilst preserving populations of D. luteipes.
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