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1.
Bull Entomol Res ; 108(6): 781-791, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29357962

RESUMO

Pyrethroid and carbamate resistance was evaluated in Helicoverpa armigera from 2008 to 2015. Insects were collected as eggs primarily from cultivated hosts in the major cropping areas of New South Wales and Queensland, Australia. Larvae reared from eggs were tested for resistance to fenvalerate, bifenthrin or methomyl in the F0 generation using a topical application of a discriminating dose of insecticide. In 2008-2009, resistance to fenvalerate was 71% and no resistance to bifenthrin was recorded. In the following two seasons, resistance to pyrethroids was relatively stable with fenvalerate resistance ranging from 63% to 67% and bifenthrin resistance ranging from 5.6% and 6.4% in 2009-2010 and 2010-2011, respectively. However, in 2011-2012, pyrethroid resistance had increased to 91% and 36% for fenvalerate and bifenthrin, respectively. Resistance remained above 90% for fenvalerate and above 35% for bifenthrin in the following three seasons from 2012 to 2015. In 2008-2009, methomyl resistance was 33% and declined to 22% and 15% in 2009-2010 and 2010-2011, respectively. Methomyl resistance remained at moderate levels from 2011-12 to 2014-15, ranging from 21% to 40%. Factors that influenced selection pressure of pyrethroid and carbamate insecticides and impacted resistance frequency in H. armigera may have been associated with changes in the composition of the cropping landscape. The rapid expansion of the pulse industry and the commensurate increased use of insecticide may have played a role in reselection of high-level pyrethroid resistance, and highlights the need for an urgent and strategic response to insecticide resistance management in the Australian grains industry.


Assuntos
Inseticidas/farmacologia , Metomil/farmacologia , Mariposas/efeitos dos fármacos , Nitrilos/farmacologia , Plantas Geneticamente Modificadas , Piretrinas/farmacologia , Animais , Bacillus thuringiensis/química , Gossypium/crescimento & desenvolvimento , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , New South Wales , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Queensland
2.
J Econ Entomol ; 110(2): 615-623, 2017 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28158628

RESUMO

Oxycarenus hyalinipennis Costa (Hemiptera: Lygaeidae) is an economic and key pest of the Malvaceae family widely distributed in the world. Significant field resistance to cypermethrin (26.69-fold), chlorpyrifos (32.60-fold), methomyl (10.87), acetamiprid (20.63-fold), fipronil (5.84-fold), and spirotetramat (116.02-fold) has been reported. Cypermethrin combined with methomyl and spirotetramat, methomyl with spirotetramat, acetamiprid with spirotetramat, and fipronil with spirotetramat had synergistic effects (combination index, (CI) in a laboratory population of O. hyalinipennis named Lab-PK. Methomyl combined with acetamiprid and acetamiprid with fipronil had synergistic effects on O. hyalinipennis in a field in Multan named Field-POP. Cypermethrin combined with methomyl and spirotetramat; chlorpyrifos with methomyl, acetamiprid, and spirotetramat; methomyl with acetamiprid and spirotetramat; and fipronil with spirotetramat also had synergistic effects on O. hyalinipennis in Field-POP. Enzyme inhibitors piperonyl butoxide and S,S,S-tri-n-butyl phosphorotrithioate significantly increased the toxicity of chlorpyrifos, methomyl, acetamiprid, and spirotetramat to O. hyalinipennis in Field-POP, suggesting a monooxygenase- and esterase-based resistance mechanism. However, fipronil did not synergize with PBO and DEF. This study suggests that insecticide mixtures showing synergism must be determined for insecticide resistance management and other strategies such as rotations, mosaics, and cultural control should also be considered for the management of O. hyalinipennis.


Assuntos
Heterópteros/efeitos dos fármacos , Resistência a Inseticidas/efeitos dos fármacos , Inseticidas/farmacologia , Sinergistas de Praguicidas/farmacologia , Animais , Compostos Aza/farmacologia , Clorpirifos/farmacologia , Proteção de Cultivos/métodos , Resistência a Inseticidas/fisiologia , Metomil/farmacologia , Neonicotinoides , Paquistão , Butóxido de Piperonila/farmacologia , Pirazóis/farmacologia , Piretrinas/farmacologia , Piridinas/farmacologia , Compostos de Espiro/farmacologia
3.
Pestic Biochem Physiol ; 135: 27-34, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28043327

RESUMO

Acetylcholinesterases (AChEs) from the infective juveniles (IJs) of entomopathogenic nematode (EPN) have been investigated with respect to their susceptibility to insecticides and immunological characteristics, aiming at nominating the most compatible insecticide(s) to be used in conjunction with the most insecticide-tolerant EPN strain before incorporation in integrated pest management (IPM) programs. The inhibition kinetics of two purified AChE isoenzymes, AChEAII and AChEBI isolated from Heterorhabditid bacteriophora EM2 strain, by different insecticides revealed that the insensitivity to inhibition by such insecticides could be arranged in a descending order as; methomyl>carbofuran>acetamiprid>oxamyl>malathion. Except for malathion, the insecticides competitively inhibited AChEs with Ki values ranging from 0.1 to 15mM and IC50 values from 1.25 to 23mM. The two AChE isoforms are several folds less sensitive to inhibition by methomyl and carbofuran compared to those previously reported for other insect species. AChEBI was used as an immunogen to raise anti-AChEBI antisera in rabbits. The prepared antisera cross-reacted with AChEs of five different heterorhabditid nematode strains implying the presence of common epitopes shared along all the examined strains. Such studies could aid in the rational selection of the compatible insecticide(s) and the prepared polyclonal anti-AChE antisera would be a valuable immunodiagnostic tool for evaluating the most insecticide-tolerant EPN strain(s) in IPM programs.


Assuntos
Acetilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Inseticidas/farmacologia , Nematoides/enzimologia , Acetilcolinesterase/imunologia , Animais , Carbamatos/farmacologia , Carbofurano/farmacologia , Malation/farmacologia , Metomil/farmacologia , Neonicotinoides , Controle Biológico de Vetores/métodos , Piridinas/farmacologia , Coelhos
4.
Cell Physiol Biochem ; 39(5): 1941-1954, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27771709

RESUMO

BACKGROUND/AIMS: In previous publications we were able to demonstrate the exposure of phosphatidylserine (PS) in the outer membrane leaflet after activation of red blood cells (RBCs) by lysophosphatidic acid (LPA), phorbol-12 myristate-13acetate (PMA), or 4-bromo-A23187 (A23187). It has been concluded that three different mechanisms are responsible for the PS exposure in human RBCs: (i) Ca2+-stimulated scramblase activation (and flippase inhibition) by A23187, LPA, and PMA; (ii) PKCα activation by LPA and PMA; and (iii) enhanced lipid flip flop caused by LPA. Further studies aimed to elucidate interconnections between the increased Ca2+ content, scramblase- and PKCα-activation. In addition, the role of the Ca2+-activated K+ channel (Gardos channel) activity in the process of PS exposure needs to be investigated. METHODS: The intracellular Ca2+ content and the PS exposure of RBCs have been investigated after treatment with LPA (2.5 µM), PMA (6 µM), or A23187 (2 µM). Fluo-4 and annexin V-FITC has been used to detect intracellular Ca2+ content and PS exposure, respectively. Both parameters (Ca2+ content, PS exposure) were studied using flow cytometry. Inhibitors of the scramblase, the PKCα, and the Gardos channel have been applied. RESULTS: The percentage of RBCs showing PS exposure after activation with LPA, PMA, or A23187 is significantly reduced after inhibition of the scramblase using the specific inhibitor R5421 as well as after the inhibition of the PKCα using chelerythrine chloride or calphostin C. The inhibitory effect is more pronounced when the scramblase and the PKCα are inhibited simultaneously. Additionally, the inhibition of the Gardos channel using charybdotoxin resulted in a significant reduction of the percentage of RBCs showing PS exposure under all conditions measured. Similar results were obtained when the Gardos channel activity was suppressed by increased extracellular K+ content. CONCLUSION: PS exposure is mediated by the Ca2+-dependent scramblase but also by PKCα activated by LPA and PMA in a Ca2+-dependent and a Ca2+-independent manner. Furthermore, we hypothesize that a hyperpolarisation of RBCs caused by the opening of the Gardos channel is essential for the scramblase activity as well as for a fraction of the LPA-induced Ca2+ entry.


Assuntos
Calcimicina/farmacologia , Cálcio/metabolismo , Lisofosfolipídeos/farmacologia , Fosfatidilserinas/metabolismo , Acetato de Tetradecanoilforbol/farmacologia , Anexina A5/genética , Anexina A5/metabolismo , Benzofenantridinas/farmacologia , Células Cultivadas , Charibdotoxina/farmacologia , Contagem de Eritrócitos , Eritrócitos , Regulação da Expressão Gênica , Humanos , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/antagonistas & inibidores , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/genética , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/metabolismo , Metomil/análogos & derivados , Metomil/farmacologia , Naftalenos/farmacologia , Fosfatidilserinas/química , Proteínas de Transferência de Fosfolipídeos/antagonistas & inibidores , Proteínas de Transferência de Fosfolipídeos/genética , Proteínas de Transferência de Fosfolipídeos/metabolismo , Proteína Quinase C-alfa/antagonistas & inibidores , Proteína Quinase C-alfa/genética , Proteína Quinase C-alfa/metabolismo , Transdução de Sinais
5.
Environ Sci Pollut Res Int ; 23(4): 3086-96, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26566611

RESUMO

Insecticides have long been used as the main method in limiting agricultural pests, but their widespread use has resulted in environmental pollution, development of resistances, and biodiversity reduction. The effects of insecticides at low residual doses on both the targeted crop pest species and beneficial insects have become a major concern. In particular, these low doses can induce unexpected positive (hormetic) effects on pest insects, such as surges in population growth exceeding what would have been observed without pesticide application. Methomyl and chlorpyrifos are two insecticides commonly used to control the population levels of the cotton leafworm Spodoptera littoralis, a major pest moth. The aim of the present study was to examine the effects of sublethal doses of these two pesticides, known to present a residual activity and persistence in the environment, on the moth physiology. Using a metabolomic approach, we showed that sublethal doses of methomyl and chlorpyrifos have a systemic effect on the treated insects. We also demonstrated a behavioral disruption of S. littoralis larvae exposed to sublethal doses of methomyl, whereas no effects were observed for the same doses of chlorpyrifos. Interestingly, we highlighted that sublethal doses of both pesticides did not induce a change in acetylcholinesterase activity in head of exposed larvae.


Assuntos
Comportamento Animal/efeitos dos fármacos , Clorpirifos/farmacologia , Poluentes Ambientais/farmacologia , Inseticidas/farmacologia , Metomil/farmacologia , Spodoptera , Acetilcolinesterase/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/enzimologia , Egito , Hemolinfa/metabolismo , Hormese , Resistência a Inseticidas , Larva/efeitos dos fármacos , Larva/metabolismo , Dose Letal Mediana , Spodoptera/efeitos dos fármacos , Spodoptera/metabolismo
6.
J Environ Sci Health B ; 50(7): 484-91, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25996812

RESUMO

The main objective of this work was to investigate the kinetic characteristics of acid and alkaline phosphatases isolated from different sources and to study the effects of the herbicide atrazine and insecticide methomyl on the activity and kinetic properties of the enzymes. Acid phosphatase (ACP) was isolated from the tomato plant (Solanum lycopersicum L. var. lycopersicum); alkaline phosphatase (ALP) was isolated from two sources, including mature earthworms (Aporrectodea caliginosa) and larvae of the Egyptian cotton leafworm (Spodoptera littoralis). The specific activities of the enzymes were 33.31, 5.56 and 0.72 mmol substrate hydrolyzed per minute per milligram protein for plant ACP, earthworms ALP and cotton leafworm ALP, respectively. The inhibition kinetics indicated that atrazine and methomyl caused competitive-non-competitive inhibition of the enzymes. The relationships between estimates of K(m) and V(max) calculated from the Michaelis-Menten equation have been explored. The extent of the inhibition was different, as estimated by the values of the inhibition constant Ki that were found to be 3.34 × 10(-3), 1.12 × 10(-2) and 1.07 × 10(-2) mM for plant ACP, earthworms ALP and cotton leafworm ALP, respectively, with methomyl. In the case of atrazine, K(i) were found to be 8.99 × 10(-3), 3.55 × 10(-2) and 1.36 × 10(-2) mM for plant ACP, earthworms ALP and cotton leafworm ALP, respectively.


Assuntos
Fosfatase Ácida/antagonistas & inibidores , Fosfatase Alcalina/antagonistas & inibidores , Atrazina/farmacologia , Metomil/farmacologia , Fosfatase Ácida/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Inibidores Enzimáticos/farmacologia , Herbicidas/farmacologia , Inseticidas/farmacologia , Cinética , Larva/enzimologia , Lycopersicon esculentum/enzimologia , Oligoquetos/enzimologia , Oligoquetos/metabolismo , Especificidade da Espécie , Spodoptera/efeitos dos fármacos
7.
J Egypt Soc Parasitol ; 43(1): 245-58, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23697030

RESUMO

This work monitored changes in some digestive enzymes (trypsin and aminopeptidase) associated with the building up of resistance in Cx. pipiens larvae to two chemical insecticides (methomyl and/or malathion) and one biological insecticide (Bacillus thuringiensis-H14 or B.t H 14). The LC50 value of methomyl for both field- and the 12th generation (F12) of the selected strain was 1.789 ppm and 8.925 ppm respectively. The LC50 value of malathion for both field and the F12 of the selected strain was 0.082 ppm and 0.156 ppm respectively, and those of B.t H14 of field strain and the F12 was 2.550ppm & 2.395ppm respectively. The specific activity of trypsin enzyme in control susceptible colony was 20.806 +/- 0.452micromol/min/mg protein; but at F4 and F8 for malathion and methomyl treated larvae were 10.810 +/- 0.860 & 15.616+/-0.408 micromol/min/mg protein, respectively. Trypsin activity of F12 in treated larvae with B.t.H14 was 2.097 +/- 0.587 microiol/min/mg protein. Aminopeptidase specific activity for susceptible control larvae was 173.05 +/- 1.3111 micromol/min/mg protein. This activity decreased to 145.15 +/- 4.12, 152.497 +/- 6.775 & 102.04 +/- 3.58a micromol/min/mg protein after larval (F 12) treatment with methomyl, malathion and B.t H 14 respectively.


Assuntos
Toxinas Bacterianas/farmacologia , Culex/efeitos dos fármacos , Culex/enzimologia , Resistência a Inseticidas/genética , Metomil/farmacologia , Precursores de Proteínas/farmacologia , Tripsina/metabolismo , Animais , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Larva/enzimologia , Dose Letal Mediana , Malation/farmacologia , Tripsina/genética
8.
Ying Yong Sheng Tai Xue Bao ; 23(7): 1933-9, 2012 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-23173470

RESUMO

To understand the resistance risks of Frankliniella occidentalis Pergande against phoxim, this paper studied the resistance mechanisms of phoxim-resistant F. occidentalis population against phoxim and the cross-resistance of the population against other insecticides. The phoxim-resistant population had medium level cross-resistance to chlorpyrifos, lambda-cyhalothrin, and methomyl, low level cross-resistance to chlorfenapyr, imidacloprid, emamectin-benzoate, and spinosad, but no cross-resistance to acetamiprid and abamectin. The synergists piperonyl butoxide (PBO), s, s, s-tributyl phosphorotrithioate (DEF), and triphenyl phosphate (TPP) had significant synergism (P < 0.05) on the toxicity of phoxim to the resistant (XK), field (BJ), and susceptible (S) populations, while diethyl maleate (DEM) had no significant synergism to XK and S populations but had significant synergism to BJ population. As compared with S population, the XK and BJ populations had significantly increased activities of mixed-functional oxidases P450 (2.79-fold and 1.48-fold), b, (2.88-fold and 1.88-fold), O-demethylase (2.60-fold and 1.68-fold), and carboxylesterase (2.02-fold and 1.61-fold, respectively), and XK population had a significantly increased acetylcholine esterase activity (3.10-fold). Both XK and BJ population had an increased activity of glutathione S-transferases (1.11-fold and 1.20-fold, respectively), but the increment was not significant. The increased detoxification enzymes activities in F. occidentalis could play an important role in the resistance of the plant against phoxim.


Assuntos
Resistência a Inseticidas , Inseticidas/farmacologia , Compostos Organotiofosforados/farmacologia , Tisanópteros/efeitos dos fármacos , Tisanópteros/crescimento & desenvolvimento , Acetilcolinesterase/metabolismo , Animais , Clorpirifos/farmacologia , Metomil/farmacologia , Nitrilos/farmacologia , Piretrinas/farmacologia , Tisanópteros/enzimologia
9.
Artigo em Inglês | MEDLINE | ID: mdl-22755542

RESUMO

The present study was designed to evaluate the toxic effects induced by different time intervals of methomyl exposure on liver antioxidant defense system, oxidative stress, liver function biomarkers and histopathology in CD-1 mice. Ten male mice per group were assigned to one of four treatment groups. Group one served as control while group 2, 3 and 4 were orally treated with one mg methomyl/kg BW for 10, 20 and 30 days, respectively. Results obtained showed that methomyl significantly induced TBARS and decreased the activity of antioxidant enzymes, glutathione S-transferase, superoxide dismutase and catalase and the levels of reduced glutathione in mice liver. Aminotransferases and alkaline phosphatase activities were significantly decreased in liver due to methomyl administration, while the activities of these enzymes were significantly increased in serum. In addition, liver lactate dehydrogenase activity was significantly increased. On the contrary, methomyl treatment caused a significant decrease in liver acid phosphatase. The histology of mice liver treated with methomyl for 10, 20 and 30 days of duration showed dilation of central vein, sinusoids between hypertrophied hepatocytes and nuclear degeneration with mononuclear cell infiltration. In conclusion, exposure to methomyl induced toxicity and oxidative stress in mice liver via free radicals mechanism. Also, methomyl might have affected cell metabolism, cell membrane permeability and the detoxification system in liver.


Assuntos
Fígado/efeitos dos fármacos , Fígado/metabolismo , Metomil/farmacologia , Animais , Antioxidantes/metabolismo , Catalase/metabolismo , Glutationa/metabolismo , Glutationa Transferase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo
10.
J Econ Entomol ; 105(2): 471-9, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22606817

RESUMO

Tests were conducted that evaluated efficacy of wax matrix bait stations for Ceratitis capitata (Wiedemann) adults in Guatemala. Bait stations were exposed to outdoor conditions to determine effect of weathering on longevity as indicated by bait station age. Results of laboratory tests found that bait stations with spinosad and ammonium acetate remained effective for at least 31 d compared with pesticide-free controls, although there was some loss of efficacy over time. Percentage mortality for bait station strips with 2% spinosad and 1% ammonium acetate decreased from 100 +/- 0.0% on day 0 to 70 +/- 7.1% after 31 d. Ammonia concentration had little effect on percentage mortality although there was some indication that ammonia concentration affected number of flies observed on the bait stations. Bait station strips (one per cage) were more effective than controls for 6-8 wk when tests were conducted in field cages (3 m diameter x 2 m), but only 2-3 wk when tests were conducted in large (2.5 m high and 6.0 m wide and 7.5 m long) field cages. Longevity was restored when multiple bait stations (3, 6, or 12) were deployed per cage. Bait stations containing methomyl were used for field tests of efficacy for wild flies. Dipped lure bait stations, which were made by coating two edges of commercial ammonium acetate and trimethylamine lures, killed six times more flies than corn cob bait stations dipped into a Nulure/malathion solution. They also killed more flies than pesticide-free controls for 8 wk.


Assuntos
Ceratitis capitata/efeitos dos fármacos , Controle de Insetos/métodos , Inseticidas/farmacologia , Feromônios/farmacologia , Acetatos/farmacologia , Animais , Bicarbonatos/farmacologia , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Feminino , Guatemala , Controle de Insetos/instrumentação , Macrolídeos/farmacologia , Masculino , Metomil/farmacologia , Metilaminas/farmacologia , Fatores de Tempo , Ceras/química
11.
J Econ Entomol ; 104(5): 1698-705, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22066201

RESUMO

Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is an important pest of several crops in the western hemisphere. This insect has genetically differentiated into two host-associated populations: the corn (Zea mays L.) and the rice (Oryza sativa L.) strains. The corn strain also is found in cotton (Gossypium hirsutum L.) and sorghum and the rice strain in Bermuda grass [Cynodon dactylon (L.) Pers.] and millet. In the United States and Brazil, lines from corn, rice, Bermuda grass, and millet were used to evaluate the resistance of both strains to various insecticides, and found that the corn strain is more resistant than the rice strain. However, in these studies the larvae were not genotyped. In Colombia, genotyping of fall armyworm is necessary because the rice strain also can be found in corn fields. In this work, collected larvae from corn and rice fields from Tolima (central Colombia) were genotyped and evaluated for the resistance to methomyl and lambda-cyhalothrin. We found that the rice strain does not significantly differ in resistance to methomyl compared with the corn strain but it develops tolerance more rapidly to lambda-cyhalothrin. The eggs viability of treated females also was significantly affected by methomyl on each generation. The realized heritability of resistance was higher for lambda-cyhalothrin (0.23-0.42) than for methomyl (0.04-0.14). The number of generations needed for 10-fold increase in resistance is approximately 11.5 generations for methomyl and 6.5 for lambda-cyhalothrin. Finally, the genetic basis of resistance to both insecticides involves few recessive autosomal genes. The results obtained here suggest that methomyl is a better option than lambda-cyalothin to control fall armyworm.


Assuntos
Resistência a Inseticidas , Inseticidas/farmacologia , Metomil/farmacologia , Nitrilos/farmacologia , Piretrinas/farmacologia , Spodoptera/efeitos dos fármacos , Spodoptera/genética , Animais , Colômbia , Feminino , Genótipo , Larva , Dose Letal Mediana , Masculino , Polimorfismo Genético
12.
Pest Manag Sci ; 67(5): 521-7, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21472970

RESUMO

BACKGROUND: Drip application of insecticides is an effective way to deliver the chemical to the plant that avoids off-site movement via spray drift and minimizes applicator exposure. The aim of this paper is to present a cascade model for the uptake of pesticide into plants following drip irrigation, its application for a soil-applied insecticide and a sensitivity analysis of the model parameters. RESULTS: The model predicted the measured increase and decline of residues following two soil applications of an insecticide to peppers, with an absolute error between model and measurement ranging from 0.002 to 0.034 mg kg fw(-1). Maximum measured concentrations in pepper fruit were approximately 0.22 mg kg fw(-1). Temperature was the most sensitive component for predicting the peak and final concentration in pepper fruit, through its influence on soil and plant degradation rates. CONCLUSION: Repeated simulations of pulse inputs with the cascade model adequately describe soil pesticide applications to an actual cropped system and reasonably mimic it. The model has the potential to be used for the optimization of practical features, such as application rates and waiting times between applications and before harvest, through the integrated accounting of soil, plant and environmental influences.


Assuntos
Capsicum/metabolismo , Frutas/metabolismo , Inseticidas/metabolismo , Irrigação Agrícola , Capsicum/química , Capsicum/efeitos dos fármacos , Frutas/química , Frutas/efeitos dos fármacos , Inseticidas/farmacologia , Metomil/metabolismo , Metomil/farmacologia , Modelos Biológicos
13.
Pest Manag Sci ; 67(5): 507-13, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21438120

RESUMO

BACKGROUND: Methomyl is a widely used carbamate insecticide that has traditionally been applied as a foliar spray. More recently, methomyl has been labeled as a soil application via drip chemigation. Not much is known about the insecticidal and nematicidal potential of soil-applied methomyl. Methomyl soil applications were evaluated for their potential to control soil nematodes and foliar insect pests in a series of lab and greenhouse tests. RESULTS: Methomyl showed rapid knockdown of Meloidogyne incognita (Kof. & White) Chitwood in aqueous assays, with EC50 and EC90 values that were similar to oxamyl and averaged 4.9 and 15.2 mg L(−1). In the greenhouse, soil applications of methomyl ranging from 0.56 to 4.0 kg ha(−1) provided significant M. incognita control similar to oxamyl during early growth (up to 25 days after planting) of pea and bean. Higher application rates and split applications improved nematode control, but also increased the risk of phytotoxicity. Methomyl soil applications were highly effective on several insects including Myzus persicae (Sulzer), Aphis gossypii (Glover), Frankliniella occidentalis Perg. and Spodoptera exigua (Hübner). Methomyl was about 5­9-fold more potent on M. persicae and A. gossypii when applied via soil drench as opposed to foliar spray. Potency on Bemisia tabaci Genn., S. exigua and Trichoplusia ni Hübner was about the same with the two application methods. CONCLUSION: Methomyl soil applications showed good potential for early control of various insect and nematode pests. Further testing is required to verify activity under field conditions.


Assuntos
Carbamatos/farmacologia , Insetos/efeitos dos fármacos , Metomil/farmacologia , Controle de Pragas/métodos , Praguicidas/farmacologia , Solo/parasitologia , Tylenchoidea/efeitos dos fármacos , Animais , Tylenchoidea/crescimento & desenvolvimento
14.
J Vector Ecol ; 35(1): 144-8, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20618660

RESUMO

In this study, the knockdown and mortality effects of imidacloprid and methomyl were investigated. The residual surface applications were carried out to determine the knockdown effects (KDt50 and KDt95) and mortality (LD50 and LD95) induced by each insecticide. For mortality comparisons, the susceptible house fly (Musca domestica L., Diptera: Muscidae) of a WHO population and three natural field-collected M. domestica populations from Turkey were used. In conclusion, it was found that the resistance to imidacloprid and methomyl was significantly higher in the field populations when compared to the susceptible population from WHO. The results showed that applicators and pest management decision-makers should control and conduct an integrated pest management strategy by including biological agents to prevent the development of high levels of resistance in the field populations.


Assuntos
Moscas Domésticas/efeitos dos fármacos , Imidazóis/farmacologia , Inseticidas/farmacologia , Metomil/farmacologia , Nitrocompostos/farmacologia , Animais , Resistência a Inseticidas , Neonicotinoides
15.
Med Vet Entomol ; 23(2): 167-9, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19493197

RESUMO

The housefly, Musca domestica L. (Diptera: Muscidae), is a pest of great veterinary and public health importance. In this study, the efficacy of metaflumizone granular fly bait was assessed on first generation (F1) housefly adults raised from flies collected at a cattle feedlot in Kansas. All bioassays were conducted as choice tests, with flies having ad libitum access to water, granular sugar and bait. A commercial methomyl-based bait (Golden Malrin) was used as positive control; no bait (water and granular sugar only) was used as negative control. Fly mortality was recorded on days 2, 7 and 14. The metaflumizone bait was significantly more slow-acting than the methomyl bait (mortality rates after 2 days of exposure were 49.9% and 57.9%, respectively). However, there were no significant differences in cumulative mortality later in the bioassays. Cumulative mortality rates on days 7 and 14 were 96.1% (metaflumizone), 91.4% (methomyl) and 99.0% (metaflumizone), 97.6% (methomyl), respectively. Our results demonstrate that the metaflumizone granular fly bait may be an effective modality for incorporation into management programmes for houseflies in and around livestock production facilities as well as in residential settings.


Assuntos
Moscas Domésticas/efeitos dos fármacos , Inseticidas/farmacologia , Semicarbazonas/farmacologia , Animais , Bovinos , Abrigo para Animais , Controle de Insetos/métodos , Metomil/farmacologia
16.
Pest Manag Sci ; 65(6): 672-7, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19306314

RESUMO

BACKGROUND: Development of attract-and-kill bait stations for pest fruit flies has been limited by the water solubility of sugar needed as a feeding stimulant and by the volatility of chemical attractants. A wax-based matrix was developed that provides the longevity needed for field use and is biodegradable. RESULTS: Laboratory bioassays with the Caribbean fruit fly, Anastrepha suspensa (Loew), confirmed the efficacy of bait stations containing avermectin, methomyl, spinosad and phloxine B. Field cage studies demonstrated that significant mortality occurred with either 1% (w/v) spinosad or 1% (w/v) methomyl bait stations versus pesticide-free bait stations. Bait stations were exposed to environmental conditions by placing them in trees at the ARS station in Miami, Florida, between tests. There was no loss in efficacy, in spite of exposure to over 360 mm of rainfall over the 56 days of the study, indicating that the bait stations could provide population suppression for at least 1-2 months when used in subtropical environments. CONCLUSION: A long-lasting, female-targeted fruit fly bait station, such as the one developed herein, could provide a cost-effective option for fruit fly population suppression that would be an important tool in tephritid pest management and control. Additional studies are needed to demonstrate efficacy against wild fruit fly populations and determine deployment strategies.


Assuntos
Controle de Insetos/métodos , Tephritidae/fisiologia , Animais , Combinação de Medicamentos , Azul de Eosina I/farmacologia , Feminino , Controle de Insetos/economia , Inseticidas/farmacologia , Macrolídeos/farmacologia , Metomil/farmacologia , Tephritidae/efeitos dos fármacos
17.
J Econ Entomol ; 100(1): 155-63, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17370823

RESUMO

The activity of spinosad, imidacloprid, and methomyl baits and technical actives were assessed against susceptible house flies, Musca domestica L. (Diptera: Muscidae). In a feeding assay, imidacloprid affected flies more rapidly than methomyl or spinosad, but spinosad was 2.7 times more potent than methomyl and 8 times more potent than imidacloprid. The profile of technical actives correlated with their respective fly bait formulations in laboratory assays. Although having the most rapid onset of activity in laboratory tests, up to 50% of flies remained alive after exposure to imidacloprid bait. In contrast, <5% of flies survived 24-h exposure to spinosad or methomyl baits. High temperature reduced the knockdown activity of imidacloprid bait and slowed the speed of kill for spinosad and methomyl baits over a 24-h exposure period. Spinosad and methomyl baits were also superior to imidacloprid when applied to the floors of environmentally controlled rooms at label recommended rates, providing good fly control for up to 21 d. The fact that a significant percentage of flies exposed to imidacloprid were rapidly knocked down but subsequently remained alive in all of the assays suggested that flies were recovering from initial exposure to this compound. Given its favorable safety profile, a high degree of initial and residual activity comparable with methomyl and lack of cross-resistance to other chemistries, spinosad bait may be a valuable component of house fly control programs to help control or delay the emergence of resistant populations.


Assuntos
Moscas Domésticas/efeitos dos fármacos , Imidazóis/farmacologia , Inseticidas/farmacologia , Macrolídeos/farmacologia , Metomil/farmacologia , Nitrocompostos/farmacologia , Animais , Combinação de Medicamentos , Controle de Insetos/instrumentação , Neonicotinoides , Fatores de Tempo
18.
J Mol Neurosci ; 30(1-2): 21-2, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-17192611

RESUMO

The cotton bollworm, Helicoverpa armigera, is a cosmopolitan, insecticide-resistant insect pest of food and fiber (Gunning et al., 1992). Acetylcholinesterase (AChE) is the insect target site for carbamate insecticides, and H. armigera has developed an insensitive form of AChE as a resistance mechanism (Gunning et al., 1996). Insensitive AChE is normally considered an intractable resistance mechanism in pests. The methenedioxphenyl compound, piperonyl butoxide (PBO), has a long history as an insecticide synergist in the control of resistant arthropod pests; it is known to inhibit mono-oxygenases and nonspecific esterases (Gunning et al., 1998). This work discusses PBO inhibition of AChE in H. armigera and explores synergism.


Assuntos
Carbamatos/farmacologia , Inibidores da Colinesterase/farmacologia , Sinergistas de Praguicidas/farmacologia , Butóxido de Piperonila/farmacologia , Animais , Inibidores da Colinesterase/isolamento & purificação , Cinética , Larva/efeitos dos fármacos , Metomil/farmacologia , Mariposas
19.
Neotrop. entomol ; 35(6): 818-822, Nov.-Dec. 2006. tab
Artigo em Inglês | LILACS | ID: lil-442250

RESUMO

The egg-larval parasitoid Chelonus insularis Cresson is a key parasitoid of the fall armyworm Spodoptera frugiperda (J. E. Smith) during the second field generation in the upper Magdalena River Basin, Colombia. In spite of selection pressure, the higher susceptibility of the second generation fall armyworm larvae to insecticides, compared with that of the first generation, suggests that the parasitism may be responsible for the apparent difference in susceptibility. Parasitized and non-parasitized 2nd-instar larvae of the fall armyworm were tested for susceptibility to chlorpyriphos, methomyl, cypermethrin, and Bacillus thuringiensis in the laboratory, using the leaf dip test. Parasitized larvae were up to 3.93 times more susceptible to chlorpyriphos, 3.71 times to methomyl, and 14.11 times to cypermethrin than non-parasitized larvae. The least effect of parasitism on susceptibility was found for B. thuringiensis. We discuss the negative influence of synthetic insecticide on the parasitoid population dynamics and its impact on insecticide resistance.


El parasitoide huevo-larva Chelonus insularis Cresson es un parasitoide clave del cogollero del maíz, Spodoptera frugiperda (J.E. Smith) durante la segunda generación de campo en el Valle Superior del Río Magdalena de Colombia. A pesar de la presión de selección se encuentra una susceptibilidad mayor a insecticidas en la segunda generación, comparado con la primera, siendo para esto la única diferencia aparente el parasitismo. Por esta razón, la susceptibilidad a clorpirifos, metomyl, cipermetrina y Bacillus thuringiensis de larvas parasitadas y no parasitadas del segundo instar del cogollero fueron evaluadas, utilizando el test de inmersión foliar. Las larvas parasitadas fueron 3,93 veces más suscptibles a clorpirifos, 3,71 veces más a metomyl y 14,11 veces más a cipermetrina que las no parasitadas. El menor efecto del parasitismo sobre la susceptibilidad se encontró con B. thuringiensis. Se discute la influencia negativa de las aplicaciones de insecticidas sintéticos sobre la dinámica poblacional del parasitoide, lo mismo que sus implicaciones en estudios de resistencia.


Assuntos
Animais , Clorpirifos/farmacologia , Himenópteros/fisiologia , Inseticidas/farmacologia , Metomil/farmacologia , Piretrinas/farmacologia , Spodoptera/efeitos dos fármacos , Spodoptera/parasitologia , Testes de Sensibilidade Parasitária
20.
Artigo em Inglês | MEDLINE | ID: mdl-16461013

RESUMO

The inhibitory effects of four carbamate insecticides, methomyl, thiodicarb, carbofuran and carbosulfan, on acetylcholinesterase of male and female Carassius auratus were investigated in the laboratory. Kinetic constants, biomolecular rate constant (k(i)), carbamylation rate constant (k2) and decarbamylation rate constant (k3) were determined in vitro. The ratios of bimolecular rate constant (female/male) for AChE reacting with methomyl, thiodicarb, carbofuran and carbosulfan were 1.03, 2.44, 1.03 and 1.106, respectively. The k(i) of AChE for thiodicarb was significantly higher in female fish than in male fish (P<0.05). The ratios of carbamylation rate constant (female/male) for methomyl, thiodicarb, carbofuran and carbosulfan were 1.18, 4.29, 3.53, and 2.07, respectively. The k2 values of AChE for the above four carbamates were significantly higher in females than in males. The ratios of the decarbamylation rate constant (female/male) for methomyl, thiodicarb, carbofuran and carbosulfan were 1.02, 1.39, 1.06, and 1.98, respectively. Only for carbosulfan, the decarbamylation rate of AChE was significantly higher in the female than in the male, indicating that AChE of females inhibited by carbosulfan recovered more quickly than that of males. The above results suggest that the female in the sensitivity of AChE to carbamates was different from the male fish.


Assuntos
Acetilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Carpa Dourada/metabolismo , Inseticidas/farmacologia , Acetilcolinesterase/análise , Animais , Carbamatos/farmacologia , Carbofurano/farmacologia , Feminino , Cinética , Masculino , Metomil/farmacologia , Tiocarbamatos/farmacologia
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