Abstract:With the aim of developing tools for simultaneously managing Rhynchophorus palmarum and the coconut stem bleeding disease, we evaluated the effects of the insecticide thiamethoxam and the fungicide cyproconazole on R. palmarum larvae under laboratory conditions. Early-instar and intermediate-instar larvae were fed on an artificial diet containing 0.1% concentration of insecticide, fungicide or a mixture of both. Larval mortality was assessed daily during the 48 hours after the application of the treatments. Me… Show more
“…In this sense, exposure time to synthetic insecticides is likely shorter in individuals with wider pronotum. In accordance with this, some studies have reported that this pest can prevail in agricultural areas with high intensity of insecticide use [75]. This is related to the prediction that agricultural intensification can create insect pests from herbivores, which illustrates that frequent insecticide use provides conditions permissive or conducive to the emergence and spread of pests [3,8].…”
Insect pests show phenotypic plasticity as a function of resource availability and limiting conditions. Although Rhynchophorus palmarum displays high variation in certain morphological traits, it is still not clear how and which of these are being filtered along agricultural management gradients in palm plantations. This study assesses the influence of biophysical structure of ornamental palm plantations and agrochemical use on morphological traits of adults in 15 permanent plots of ornamental palm plantations in Veracruz, Mexico. A total of 4972 adults were and their body length, pronotum width, rostrum length, and mesothorax depth were measured. Body length and mesothorax depth of adults of both sexes were greater in plantations with a high diversity of palm species and frequency of fertilizer use. Rostrum length of females increased as a function of palm density, and pronotum width of both sexes was positively related with the use of insecticides. Local characteristics of agricultural management of palm plantations might filter integrated, adaptative, and environment-specific phenotypes. This is the first ecological study of the south American palm weevil that provides new insights on the current intensive management of ornamental palm plantations that far from controlling, benefits current geographic expansion, demographic outbreak, and economic impact of this pest.
“…In this sense, exposure time to synthetic insecticides is likely shorter in individuals with wider pronotum. In accordance with this, some studies have reported that this pest can prevail in agricultural areas with high intensity of insecticide use [75]. This is related to the prediction that agricultural intensification can create insect pests from herbivores, which illustrates that frequent insecticide use provides conditions permissive or conducive to the emergence and spread of pests [3,8].…”
Insect pests show phenotypic plasticity as a function of resource availability and limiting conditions. Although Rhynchophorus palmarum displays high variation in certain morphological traits, it is still not clear how and which of these are being filtered along agricultural management gradients in palm plantations. This study assesses the influence of biophysical structure of ornamental palm plantations and agrochemical use on morphological traits of adults in 15 permanent plots of ornamental palm plantations in Veracruz, Mexico. A total of 4972 adults were and their body length, pronotum width, rostrum length, and mesothorax depth were measured. Body length and mesothorax depth of adults of both sexes were greater in plantations with a high diversity of palm species and frequency of fertilizer use. Rostrum length of females increased as a function of palm density, and pronotum width of both sexes was positively related with the use of insecticides. Local characteristics of agricultural management of palm plantations might filter integrated, adaptative, and environment-specific phenotypes. This is the first ecological study of the south American palm weevil that provides new insights on the current intensive management of ornamental palm plantations that far from controlling, benefits current geographic expansion, demographic outbreak, and economic impact of this pest.
“…Em estudo similar, Chihaoui-Meridja et al (2019) observaram que adultos de Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) alimentados com dieta natural (maçã) tratada com o produto à base de tiametoxam (Renova 250 ® WG) na dose equivalente a 0,2 mL do p.c./inseto, tiveram mortalidade de 50% após 5 dias de exposição ao produto. Avaliando a mortalidade das larvas de R. palmarum alimentadas com dieta artificial contendo tiametoxam incorporado, Santos et al (2018) constataram que, na menor concentração (0,1% de i.a., equivalente a 1.000 ppm), o inseticida causou 100% de mortalidade nas larvas pequenas e 90% em larvas de tamanho intermediário, as quais apresentaram os mesmos sintomas verificados nos adultos do presente trabalho, após 48 horas. Ao compararmos ambos os estudos, fica evidenciado que as doses avaliadas por Santos et al (2018) estão além do espectro de letalidade capaz de determinar com maior precisão as doses letais (CL 50 e CL 90 ), como observado para adultos desta praga, observados no presente estudo.…”
Section: Resultsunclassified
“…Avaliando a mortalidade das larvas de R. palmarum alimentadas com dieta artificial contendo tiametoxam incorporado, Santos et al (2018) constataram que, na menor concentração (0,1% de i.a., equivalente a 1.000 ppm), o inseticida causou 100% de mortalidade nas larvas pequenas e 90% em larvas de tamanho intermediário, as quais apresentaram os mesmos sintomas verificados nos adultos do presente trabalho, após 48 horas. Ao compararmos ambos os estudos, fica evidenciado que as doses avaliadas por Santos et al (2018) estão além do espectro de letalidade capaz de determinar com maior precisão as doses letais (CL 50 e CL 90 ), como observado para adultos desta praga, observados no presente estudo. Assim, estudos futuros para determinação das doses letais para larvas desta praga são essenciais para melhor dimensionamento da aplicação deste inseticida a fim de otimizar o uso deste método de controle em possíveis aplicações em campo.…”
Due to the ability to locate the host plant over long distances, and the direct and indirect damage that are caused, Rhynchophorus palmarum L. (Coleoptera: Curculionidae) is considered a key pest of coconut crop. Therefore, the objective of this research was to evaluate the efficiency by contact of the insecticide thiamethoxam on adults of R. palmarum, determining the lethal concentrations (LC50 and LC90), under laboratory conditions. One mL of insecticide solution was applied to the insect body at concentrations of 1 ppm, 2 ppm, 3 ppm, 4 ppm and 5 ppm. Insect mortality in the treatments was evaluated after five days. The comparison of means was performed by the Tukey test at 5% significance. For determining the lethal concentrations of 50 and 90%, Probit analysis was performed. The LC50 (2.16 ppm) and LC90 (4.23 ppm) remained within the confidence interval. The concentration of 5 ppm caused 100% mortality, evidencing the efficiency of the insecticide by contact, demonstrating a promising alternative in controlling this pest.
“…Chemical control of APW with carbaryl, carbofuran, imidacloprid, abamectin, deltamethrin, fipronil, spinosad and phenylpyrazole often is not fruitful (Al-Dosary et al, 2013;Dos Santos et al, 2018;Martinez et al, 2019). The application of entomopathogenic fungi, such as Metarhizium anisopliae (Metschn.)…”
<p><strong>Background. </strong><em>Rhynchophorus palmarum </em>is the main insect pest in <em>Cocos nucifera</em><strong> </strong>orchards in the Pacific Centre of Mexico. The mass capture of adults is the strategy for control of this pest promoted by integrated pest management programs. It is essential to find an economic and efficient trap for farmers.<strong> Objective. </strong>The present study aimed to determine the efficacy and cost efficiency of five traps for capturing <em>R. palmarum</em> in a <em>C. nucifera</em> orchard and to correlate the capture with environmental parameters. <strong>Methodology.</strong> The bucket-trap (BT), trash-can trap (TCT), 20L-type trap (20LTT), bottle-type trap (BTT), and CSAT-type (Colegio Superior de Agricultura Tropical, a Spanish acronym) trap were evaluated. Total captured insects, number of males and females, cost of trapping, and cost-efficiency were measured.<strong> </strong>Total captured insects and environmental parameters were correlated using a Pearson model. <strong>Results. </strong>A total of 1065 insects were captured (60% females and 40% males). The TCT captured more (<em>P</em>=0.00001) insects than the BT, 20LTT and BTT. The CSAT ($540.5 USD) and TCT ($531.0 USD) were the most expensive traps during the period of the experiment (4.5 months), whereas the BTT was the cheapest ($515.5 USD). The cost of capture per insect in the TCT was $1.5 USD; therefore, this trap had the best cost efficiency overall of the studied traps (BT=2.6 USD, 20LTT=3.1 USD, CSAT=1.9 USD, and BTT=6.9 USD). The average (r=0.6115, <em>P</em>=0.0154) and maximum (r=0.6280, <em>P</em>=0.0122) wind speeds were correlated positively with the <em>R. palmarum</em> capture.<strong> Implications.</strong> This study demonstrates statistically that the TCT capture the same number of insects than the CSAT trap with lower cost. <strong>Conclusion. </strong>More females were caught than males, the TCT trap statistically captures the same amount of insects than the CSAT trap at a lower cost. Wind speed was positively correlated in the capture of <em>R. palmarum</em>. </p>
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