Field evaluation of the efficacy of copper nanoparticles against mites associated with orange trees.

Phytophagous mites are dangerous pests, causing economic losses to the world's crops. Nanotechnology is a promising field for pests and disease management, and enhancement of agricultural productivity. The aim of the study was to evaluation of the effectiveness of copper nanoparticles (CuNP) against all stages of eriophyid mite, the citrus rust mite, Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae) and tetranychid mite, the citrus brown mite Eutetranychus orientalis (Klein) (Acari: Tetranychidae), and Tenuipalpid mite, the false spider mite, Brevipalpus obovatus Donnadieu (Acari: Tenuipalpidae). This includes its impacts on predacious mites, Amblyseius swirskii Athias-Henriot and Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae), on orange trees under field conditions. Five different concentrations of copper nanoparticles (40, 80, 160, 240, and 320 ppm), as well as the control (well water) were examined. The obtained results indicated that the mortality rate of both phytophagous and predacious mites was associated with an increase in the concentrations of copper nanoparticles. Copper nanoparticles were significantly effective in killing P. oleivora, E. orientalis and B. obovatus with minimal effects on A. swirskii and E. scutalis. The mortality percentage was 15.24, 20.32, 46.32, 78.97 and 86.37% for P. oleivora, 6.87, 9.86, 28.91, 56.30 and 77.52% for E. orientalis and 8.38, 23.50, 48.83, 68.80 and 84.08% for B. obovatus while the mortality percentage was 0.00, 0.56, 5.83, 9.91 and 15.19% for A. swirskii and 0.44, 3.96, 6.93, 8.63 and 21.39% for E. scutalis one week after exposure to 40, 80, 160, 240 and 320 ppm of copper nanoparticles, respectively. Moreover, the results showed that copper nanoparticles caused a reduction in the percentage of eggs hatching. The percentages of larvae hatching from eggs were 96.29, 80.00, 64.13, 45.66 and 32.17% for P. oleivora, 97.38, 83.28, 69.41, 48.01 and 35.29 for E. orientalis and 96.60, 76.92, 56.38, 40.55 and 33.28% for B. obovatus one week after exposure to copper nanoparticles at 40, 80, 160, 240 and 320 ppm respectively, compared with the control (well water). According to the results, the use of copper nanoparticles significant effect on reducing the population of phytophagous mites associated with orange trees, with low detrimental effects on predatory mites.

Side effects of abamectin and hexythiazox on seven predatory mites / Efeitos colaterais da abamectina e hexitiazox em sete ácaros predadores

Use of acaricides has become a common practice to control pests all over the world including Saudi Arabia. In spite of killing the targeted pests, such insecticides also effect growth of predatory mites. Present study has been conducted to evaluate the impact of two acaricides, abamectin and hexythiazox, on seven species of predatory mites. Standard solutions of abamectin (8.4% w/v) and hexythiazox (10% w/w) were purchased and prepared for direct spray. Acaricides were tested at three serial concentrations of recommended dose (RD), half of the recommended dose (HRD) and double the recommended dose (DRD). Trials were made on eggs, nymphs and adults of the seven species of predatory mites under laboratory conditions. Effect of the applied acaricides was determined one week after the application. The results of the study revealed that all doses of hexythiazox and abamectin are toxic to the nymphs and adults of all seven species of predatory mites but to the variable extent. Furthermore, it was observed that hexythiazox and abamectin reduced the percentage of egg hatching for all seven species of predatory mites. Hexythiazox was found to be more toxic than abamectin to all seven predatory mites. Higher mortality was recorded at DRD and RD, while minimum mortality was recorded at HRD. Acaricidal effect is less severe on hatching eggs than on immatures and adults of the predatory mites. Species vary in susceptibility to acaricides and in some populations resistance has been observed. Based upon this study, it is recommended that the frequent use of acaricides against phytophagous mites should be avoided and feasibility of biological control programs should be promoted to protect the environment, health of living individuals and the non-target organisms.

O uso de acaricidas se tornou prática comum para o controle de pragas em todo o mundo, incluindo a Arábia Saudita. Apesar de matar as pragas-alvo, esses inseticidas também afetam o crescimento de ácaros predadores. O presente estudo foi conduzido para avaliar o impacto de dois acaricidas, abamectina e hexythiazox, em sete espécies de ácaros predadores. Soluções padrão de abamectina (8.4% w/v) e hexitiazox (10% w/w) foram adquiridas e preparadas para pulverização direta. Os acaricidas foram testados em três concentrações seriais de dose recomendada (RD), metade da dose recomendada (HRD) e o dobro da dose recomendada (DRD). Os ensaios foram feitos em ovos, ninfas e adultos das sete espécies de ácaros predadores em condições de laboratório. O efeito dos acaricidas aplicados foi determinado uma semana após a aplicação. Os resultados do estudo revelaram que todas as doses de hexitiazox e abamectina são tóxicas para as ninfas e adultos de todas as sete espécies de ácaros predadores, mas em extensão variável. Além disso, foi observado que hexitiazox e abamectina reduziram a porcentagem de eclosão de ovos para todas as sete espécies de ácaros predadores. Verificou-se que o hexitiazox é mais tóxico do que a abamectinapara todos os sete ácaros predadores. A mortalidade mais alta foi registrada no DRD e RD, enquanto a mortalidade mínima foi registrada no HRD. O efeito acaricida é menos severo em ovos para incubação do que em imaturos e adultos de ácaros predadores. As espécies variam em suscetibilidade a acaricidas, e em algumas populações foi observada resistência. Com base neste estudo, recomenda-se que o uso frequente de acaricidas contra ácaros fitófagos seja evitado e a viabilidade de programas de controle biológico seja promovida para proteger o meio ambiente, a saúde de indivíduos vivos e de organismos não visados.

Side effects of abamectin and hexythiazox on seven predatory mites

Abstract Use of acaricides has become a common practice to control pests all over the world including Saudi Arabia. In spite of killing the targeted pests, such insecticides also effect growth of predatory mites. Present study has been conducted to evaluate the impact of two acaricides, abamectin and hexythiazox, on seven species of predatory mites. Standard solutions of abamectin (8.4% w/v) and hexythiazox (10% w/w) were purchased and prepared for direct spray. Acaricides were tested at three serial concentrations of recommended dose (RD), half of the recommended dose (HRD) and double the recommended dose (DRD). Trials were made on eggs, nymphs and adults of the seven species of predatory mites under laboratory conditions. Effect of the applied acaricides was determined one week after the application. The results of the study revealed that all doses of hexythiazox and abamectin are toxic to the nymphs and adults of all seven species of predatory mites but to the variable extent. Furthermore, it was observed that hexythiazox and abamectin reduced the percentage of egg hatching for all seven species of predatory mites. Hexythiazox was found to be more toxic than abamectin to all seven predatory mites. Higher mortality was recorded at DRD and RD, while minimum mortality was recorded at HRD. Acaricidal effect is less severe on hatching eggs than on immatures and adults of the predatory mites. Species vary in susceptibility to acaricides and in some populations resistance has been observed. Based upon this study, it is recommended that the frequent use of acaricides against phytophagous mites should be avoided and feasibility of biological control programs should be promoted to protect the environment, health of living individuals and the non-target organisms.

Resumo O uso de acaricidas se tornou prática comum para o controle de pragas em todo o mundo, incluindo a Arábia Saudita. Apesar de matar as pragas-alvo, esses inseticidas também afetam o crescimento de ácaros predadores. O presente estudo foi conduzido para avaliar o impacto de dois acaricidas, abamectina e hexythiazox, em sete espécies de ácaros predadores. Soluções padrão de abamectina (8.4% w/v) e hexitiazox (10% w/w) foram adquiridas e preparadas para pulverização direta. Os acaricidas foram testados em três concentrações seriais de dose recomendada (RD), metade da dose recomendada (HRD) e o dobro da dose recomendada (DRD). Os ensaios foram feitos em ovos, ninfas e adultos das sete espécies de ácaros predadores em condições de laboratório. O efeito dos acaricidas aplicados foi determinado uma semana após a aplicação. Os resultados do estudo revelaram que todas as doses de hexitiazox e abamectina são tóxicas para as ninfas e adultos de todas as sete espécies de ácaros predadores, mas em extensão variável. Além disso, foi observado que hexitiazox e abamectina reduziram a porcentagem de eclosão de ovos para todas as sete espécies de ácaros predadores. Verificou-se que o hexitiazox é mais tóxico do que a abamectina para todos os sete ácaros predadores. A mortalidade mais alta foi registrada no DRD e RD, enquanto a mortalidade mínima foi registrada no HRD. O efeito acaricida é menos severo em ovos para incubação do que em imaturos e adultos de ácaros predadores. As espécies variam em suscetibilidade a acaricidas, e em algumas populações foi observada resistência. Com base neste estudo, recomenda-se que o uso frequente de acaricidas contra ácaros fitófagos seja evitado e a viabilidade de programas de controle biológico seja promovida para proteger o meio ambiente, a saúde de indivíduos vivos e de organismos não visados.

The miticidal activity of silver nanoparticles towards date palm mite (Oligonychus afrasiaticus (McGregor)): efficacy, selectivity, and risk assessment.

Promising bioactivities of silver nanoparticles SNP urged researchers of different specialties to evaluate their field-respective activities. Bioactivity towards agricultural pests were the subject of limited publications. In the current study, SNP were synthesized and miticidal activity was evaluated towards old world date mite Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae) and an associated predatory mite Neoseiulus barkeri Hughes (Phytoseiidae). Under laboratory conditions, SNP displayed significantly higher activity towards O. afrasiaticus (LC50 was 39.7 µg/mL) than N. barkeri (LC50 was 1587.9 µg/mL) which accounts for about 40 folds of selectivity against the pest. SNP exhibited ovicidal activity against laid eggs of O. afrasiaticus (LC50 was 67.8 µg/mL). In field, SNP (at 216 µg/mL) achieved slightly higher efficiency than in laboratory study, 86.5% of population reduction of O. afrasiaticus was achieved and only 18.5% of N. barkeri population was affected. SNP suppressed hatching of 57.1% of laid eggs of O. afrasiaticus. Residues of silver were determined using ICP-OES spectrometry. Initial residues reached 1.83 µg/mL after application then declined with time passing. Estimated daily intake (EDI) reached 1.28 µg/kg/day, calculated for the highest residues obtained and the highest consumption rate of date in the world. Hazard index (Hi) was 0.17 in average. The obtained level of residues appeared to be safe in terms of acute and chronic toxicity references.

Evaluation of the effectiveness of Neoseiulus cucumeris (Oudemans) as a predator of Tuta absoluta (Meyrick).

The leaf miner, Tuta absoluta is continue to be a serious threat to solanaceous plants, especially tomato plant worldwide. Tomato crop in Saudi Arabia has been recently affected by T. absoluta, which is difficult to control due to its unique biological features, such as high fecundity and its potential to develop resistance to chemical pesticides. In this article, the suitability and effectiveness of the predatory mite, Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), an indigenous species usually found in tomato greenhouses of northcentral Saudi Arabia, has been evaluated on eggs and 1st instar larvae of T. absoluta in the laboratory. All experiments were conducted in an incubator at three constant temperatures of 22, 27 and 32°C ± 1°C, 50 ± 4% R.H. and L12:D12 h photoperiod. Adult females and males of N. cucumeris were able to feed and sustain oviposition on eggs and 1st instar larvae of T. absoluta, and could be an effective biocontrol agent against T. absoluta. The N. cucumeris had a clear preference for eggs compared to 1st instar larvae of T. absoluta. The results showed the obvious effect of the temperature on the consumption rate of the predatory mite. The maximum daily consumption rate occurred during the oviposition period, when the females of the predatory mite consumed an average of 4.26 eggs and 2.44 1st instar larvae of T. absoluta. In general, total fecundity was high with T. absoluta eggs as a food source when temperature increased from 22 to 32°C. The highest fecundity rate (42.92 and 20.97 eggs /female) was recorded at 32°C, while the lowest one (26.77 and 10.12 eggs / female) was recorded at 22°C, when N. cucumeris female fed on eggs and 1st instar larvae of T. absoluta, respectively. The results of this study indicated that the predatory mite, N. cucumeris can be considered a promising potential candidate for controlling the leaf miner T. absoluta, and further research is required to assess its effectiveness under greenhouse conditions.

Evaluation of the effectiveness of Neoseiulus cucumeris (Oudemans) as a predator of Tuta absoluta (Meyrick) / Avaliação da eficácia de Neoseiulus cucumeris (Oudemans) como predador de Tuta absoluta (Meyrick)

The leaf miner, Tuta absoluta is continue to be a serious threat to solanaceous plants, especially tomato plant worldwide. Tomato crop in Saudi Arabia has been recently affected by T. absoluta, which is difficult to control due to its unique biological features, such as high fecundity and its potential to develop resistance to chemical pesticides. In this article, the suitability and effectiveness of the predatory mite, Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), an indigenous species usually found in tomato greenhouses of northcentral Saudi Arabia, has been evaluated on eggs and 1st instar larvae of T. absoluta in the laboratory. All experiments were conducted in an incubator at three constant temperatures of 22, 27 and 32°C ± 1°C, 50 ± 4% R.H. and L12:D12 h photoperiod. Adult females and males of N. cucumeris were able to feed and sustain oviposition on eggs and 1st instar larvae of T. absoluta, and could be an effective biocontrol agent against T. absoluta. The N. cucumeris had a clear preference for eggs compared to 1st instar larvae of T. absoluta. The results showed the obvious effect of the temperature on the consumption rate of the predatory mite. The maximum daily consumption rate occurred during the oviposition period, when the females of the predatory mite consumed an average of 4.26 eggs and 2.44 1st instar larvae of T. absoluta. In general, total fecundity was high with T. absoluta eggs as a food source when temperature increased from 22 to 32°C. The highest fecundity rate (42.92 and 20.97 eggs /female) was recorded at 32°C, while the lowest one (26.77 and 10.12 eggs / female) was recorded at 22°C, when N. cucumeris female fed on eggs and 1st instar larvae of T. absoluta, respectively. The results of this study indicated that the predatory mite, N. cucumeris can be considered a promising potential candidate for controlling the leaf miner T. absoluta, and further research is required to assess its effectiveness under greenhouse conditions.

A traça-do-tomateiro, Tuta absoluta, continua sendo uma séria ameaça às plantas solanáceas, especialmente ao tomateiro em todo o mundo. A safra de tomate na Arábia Saudita foi recentemente afetada por T. absoluta, o qual é de difícil controle por causa de suas características biológicas únicas, como alta fecundidade e potencial para desenvolver resistência a pesticidas químicos. Neste artigo, a adequação e a eficácia do ácaro predador Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), uma espécie indígena geralmente encontrada em estufas de tomate no centro-norte da Arábia Saudita, foram avaliadas em ovos e larvas de 1º instar de T. absoluta em condições de laboratório. Todos os experimentos foram conduzidos em uma incubadora em três temperaturas constantes de 22, 27 e 32°C ± 1°C, 50 ± 4% UR e fotoperíodo L12: D12 h. Fêmeas e machos adultos de N. cucumeris foram capazes de se alimentar e sustentar a oviposição em ovos e larvas de 1º instar de T. absoluta, podendo ser um agente de biocontrole eficaz contra T. absoluta. Neoseiulus cucumeris teve uma clara preferência por ovos em comparação com larvas de 1º instar de T. absoluta. Os resultados mostram que mais presas foram consumidas conforme a temperatura aumentou de 22°C para 32°C. A taxa máxima de consumo diário ocorreu durante o período de oviposição, quando as fêmeas consumiram em média 4,26 ovos e 2,44 larvas de 1º instar de T. absoluta. Em geral, a fecundidade total foi maior com ovos de T. absoluta como fonte alimentar e com o aumento da temperatura. A maior taxa de fecundidade (42,92 e 20,97 ovos por fêmea) foi registrada a 32°C, enquanto a mais baixa (26,77 e 10,12 ovos por fêmea) foi a 22°C, quando N. cucumeris se alimentou de ovos e larvas de 1º instar de T. absoluta, respectivamente. Os resultados deste estudo indicam que o ácaro predador N. cucumeris pode ser considerado um potencial candidato para o controle da traça-do-tomateiro T. absoluta, e mais pesquisas são necessárias para avaliar sua eficácia em condições de estufa.

Evaluation of the effectiveness of Neoseiulus cucumeris (Oudemans) as a predator of Tuta absoluta (Meyrick)

Abstract The leaf miner, Tuta absoluta is continue to be a serious threat to solanaceous plants, especially tomato plant worldwide. Tomato crop in Saudi Arabia has been recently affected by T. absoluta, which is difficult to control due to its unique biological features, such as high fecundity and its potential to develop resistance to chemical pesticides. In this article, the suitability and effectiveness of the predatory mite, Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), an indigenous species usually found in tomato greenhouses of northcentral Saudi Arabia, has been evaluated on eggs and 1st instar larvae of T. absoluta in the laboratory. All experiments were conducted in an incubator at three constant temperatures of 22, 27 and 32°C ± 1°C, 50 ± 4% R.H. and L12:D12 h photoperiod. Adult females and males of N. cucumeris were able to feed and sustain oviposition on eggs and 1st instar larvae of T. absoluta, and could be an effective biocontrol agent against T. absoluta. The N. cucumeris had a clear preference for eggs compared to 1st instar larvae of T. absoluta. The results showed the obvious effect of the temperature on the consumption rate of the predatory mite. The maximum daily consumption rate occurred during the oviposition period, when the females of the predatory mite consumed an average of 4.26 eggs and 2.44 1st instar larvae of T. absoluta. In general, total fecundity was high with T. absoluta eggs as a food source when temperature increased from 22 to 32°C. The highest fecundity rate (42.92 and 20.97 eggs /female) was recorded at 32°C, while the lowest one (26.77 and 10.12 eggs / female) was recorded at 22°C, when N. cucumeris female fed on eggs and 1st instar larvae of T. absoluta, respectively. The results of this study indicated that the predatory mite, N. cucumeris can be considered a promising potential candidate for controlling the leaf miner T. absoluta, and further research is required to assess its effectiveness under greenhouse conditions.

Resumo A traça-do-tomateiro, Tuta absoluta, continua sendo uma séria ameaça às plantas solanáceas, especialmente ao tomateiro em todo o mundo. A safra de tomate na Arábia Saudita foi recentemente afetada por T. absoluta, o qual é de difícil controle por causa de suas características biológicas únicas, como alta fecundidade e potencial para desenvolver resistência a pesticidas químicos. Neste artigo, a adequação e a eficácia do ácaro predador Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), uma espécie indígena geralmente encontrada em estufas de tomate no centro-norte da Arábia Saudita, foram avaliadas em ovos e larvas de 1º instar de T. absoluta em condições de laboratório. Todos os experimentos foram conduzidos em uma incubadora em três temperaturas constantes de 22, 27 e 32°C ± 1°C, 50 ± 4% UR e fotoperíodo L12: D12 h. Fêmeas e machos adultos de N. cucumeris foram capazes de se alimentar e sustentar a oviposição em ovos e larvas de 1º instar de T. absoluta, podendo ser um agente de biocontrole eficaz contra T. absoluta. Neoseiulus cucumeris teve uma clara preferência por ovos em comparação com larvas de 1º instar de T. absoluta. Os resultados mostram que mais presas foram consumidas conforme a temperatura aumentou de 22°C para 32°C. A taxa máxima de consumo diário ocorreu durante o período de oviposição, quando as fêmeas consumiram em média 4,26 ovos e 2,44 larvas de 1º instar de T. absoluta. Em geral, a fecundidade total foi maior com ovos de T. absoluta como fonte alimentar e com o aumento da temperatura. A maior taxa de fecundidade (42,92 e 20,97 ovos por fêmea) foi registrada a 32°C, enquanto a mais baixa (26,77 e 10,12 ovos por fêmea) foi a 22°C, quando N. cucumeris se alimentou de ovos e larvas de 1º instar de T. absoluta, respectivamente. Os resultados deste estudo indicam que o ácaro predador N. cucumeris pode ser considerado um potencial candidato para o controle da traça-do-tomateiro T. absoluta, e mais pesquisas são necessárias para avaliar sua eficácia em condições de estufa.