ABSTRACT
@#Abstract: Objective To investigate the population densities composition and seasonal change of mosquitoes, and resistance of Culex pipiens quinquefasciatus and Aedes albopictus several commonly used insecticides in Zigong, so as to provide a theoretical basis for guiding the scientific rational selection and use of chemical insecticides, as well as the prevention and control of mosquito-borne diseases. Methods The surveillance data on mosquitoes by traps were collected from 2018 to 2020 in Zigong. The wild Culex pipiens quinquefasciatus and Aedes albopictus were collected throughout the city and reared to F1 generation in lab. The resistance of adult Culex pipiens quinquefasciatus and Aedes albopictus to these commonly insecticides was detected by contact tube method recommended. The statistical analysis on the monitoring results was used by Excel 2010. Results The annual average mosquito densities of monitoring sites were 1.11, 10.71, and 4.81 mosquitoes/(lamp·h), respectively from 2018 to 2020. The seasonal density of mosquitoes showed a single peak curve distribution throughout the year from 2018 to 2020 in Zigong, with the highest in July. There were obvious differences in mosquito density between different habitats, with the highest density of mosquitoes in barn. The 24 h mortality of Aedes albopictus and Culex pipiens quinquefasciatus to beta-cypermethrin, lambda-cyhalothrin, deltamethrin, permethrin, malathion, fenitrothion, chlorpyrifos, propoxur, and bendiocarb were 70.71% and 3.85%, 26.53% and 1.68%, 19.79% and 1.94%, 40.80% and 0.81%, 97.98% and 3.85%, 100.00% and 7.52%, 100.00% and 66.34%, 96.15% and 33.60%, 100.00% and 71.43%, respectively. The adult Aedes albopictus larvae in Zigong was sensitive to fenitrothion, chlorpyrifos, bendiocarb, showed resistance to beta-cypermethrin, lambda-cyhalothrin, deltamethrin, permethrin, and showed resistance dubiously to malathion and propoxur. The adult Culex pipiens quinquefasciatus larvae in Zigong have developed certain resistance to these commonly insecticides. Conclusion Both Culex pipiens quinquefasciatus and Aedes albopictus had high resistance to pyrethroid insecticides, which suggested that we should strengthen the patriotic hygiene campaigns, reduce pyrethroid insecticides, use alternately different types of insecticides for delay the development of resistance and better mosquito prevention and control.
ABSTRACT
Objective To explore the sensitivity of Culex pipiens pallens to common chemical insecticides in the southwestern region of Shandong Province, so as to provide a theoretical basis for the development of reasonable and effective mosquito control measures. Methods The resistance of Cx. pipiens pallens larvae to 5 chemical insecticides, such as cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate were tested by using the WHO biological test method in 2018, and the co-toxicity coefficients after compounding the above-mentioned insecticides were tested by using a drug compounding method. Results The resistance indexes of Cx. pipiens pallens to cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate in 3 cities were 144.43–557.54, 118.17–445.33, 6.44–19.00, 2.37–8.10, and 0.88–2.98, respectively, and expect the difference between the DDVP resistances of Cx. pipiens pallens in Jining City and Heze City was not statistically significant (P > 0.05), all the other differences were statistically significant (all P < 0.05). The synergistic coefficients of cypermethrin + DDVP, cypermethrin + propoxur, DDVP + acetofenate, and propoxur + acetofenate were 199.58 – 456.95, 190.56 – 292.37, 123.32 – 319.24, and 192.31 – 367.32, respectively. The lower synergism was observed by using the mixture of DDVP + propoxur (synergistic coefficient: 99.87–108.36) . Conclusions After decades of chemical control, Cx. pipiens pallens in the southwestern region of Shandong Province has produced different degrees of resistance to common chemical insecticides. Therefore, comprehensive control measures should be taken to control mosquito breeding and prevent the development of insecticide resistance.
ABSTRACT
The banana weevil borer (Cosmopolites sordidus) is the main pest of banana crops, causing significant losses in productivity, being recommended control by chemical insecticides which cause several environmental impacts. On the other hand, entomopathogenic nematodes can be an alternative to the pest control, mainly because of their habits. Thus, this study aimed at evaluating isolated entomopathogenic nematodes under laboratory conditions and also their interaction with a chemical insecticide (carbofuran), aiming at their use for the weevil borer control. Sixteen Sterinernematidae and Heterorhabditidae isolates were evaluated, applied over the banana tree pseudo stem (100 JIs/cm²) and they were compared to one another concerning mortality caused in adults individual of C. sordidus. The most infective isolates were subjected to in vivo multiplication at the host Galleria mellonella and interaction with the insecticide carbofuran, including in this case, viability and infectivity analysis of the entomopathogenic nematodes exposed to the product, as well as the effect of the insecticide on the symbiotic bacteria of the entomopathogenic nematodes. The experiments at this stage were conducted in completely randomized design and the data were subjected to ANOVA, with application of the Tukey test (p 0.05). The most virulent isolates were IBCBn24 and IBCBn40 [...]
A broca-da-bananeira (Cosmopolites sordidus) é a principal praga dos cultivos de banana, acarretando perdas significativas na produtividade da cultura, sendo recomendados inseticidas químicos para seu controle, os quais causam impacto ambiental. Por outro lado, os nematoides entomopatogênicos podem ser uma alternativa para o controle da praga, principalmente devido aos seus hábitos. Assim, este trabalho teve como objetivo avaliar isolados de nematoides entomopatogênicos em condições de laboratório e a interação com inseticida químico (carbofurano), visando a sua utilização no controle da broca. Foram testados 16 isolados das famílias Sterinernematidae e Heterorhabditidae, aplicados sobre pseudocaule de banananeira (100 JIs/cm²) e comparados entre si quanto à mortalidade causada em indivíduos adultos de C. sordidus. Os isolados mais infectivos foram submetidos a experimentos de multiplicação in vivo no hospedeiro Galleria mellonella e de interação com o inseticida carbofurano incluindo, neste caso, análise de viabilidade e infectividade dos nematoides expostos ao produto, bem como o efeito do inseticida sobre as bactérias simbiontes dos nematoides entomopatogênicos. Os experimentos dessa fase foram conduzidos em delineamento inteiramente casualizado, sendo os dados submetidos à ANOVA, com aplicação do teste de Tukey (p 0,05). Os isolados mais virulentos foram o IBCBn24 [...]