Monitoring Resistance of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) to Insecticides by Using Encapsulated Artificial Diet Bioassay

The novel ingestion bioassay method was developed for detecting and monitoring resistance of Euschistus heros by encapsulating an artificial liquid diet using Parafilm®. This methodology was compared with the tarsal contact (vial test) and topical application methods for thiamethoxam, imidacloprid, and lambda-cyhalothrin. The best bioassay method for the neonicotinoid insecticides thiamethoxam and imidacloprid was ingestion. For pyrethroid insecticide lambda-cyhalothrin, the best result was obtained by topical application. Using the best bioassay method for each insecticide, the susceptibility to these insecticides was monitored in 30 populations of E. heros collected from soybean crops in Brazil from 2018 to 2020. High variations in susceptibility to thiamethoxam (resistance ratios, 1.6–22 times), imidacloprid (resistance ratios, 1.6–22 times), and lambda-cyhalothrin (resistance ratios, 5–40 times) were detected among the evaluated E. heros populations. In order to monitor the susceptibility of E. heros to insecticides, diagnostic concentrations were defined based on the LC99 of the susceptible reference population: 5.65 µL of a.i./mL for thiamethoxam, 12.45 µL of a.i./mL for imidacloprid, and 0.20 µg of a.i./insect for lambda-cyhalothrin. Subsequently, we select an E. heros strain resistant to neonicotinoid insecticides and another to lambda-cyhalothrin. The resistance ratios obtained after seven selection cycles were 66, 41 and 44 times for thiamethoxam, imidacloprid and lambda-cyhalothrin, respectively.

Status Resistensi Nyamuk Aedes aegypti dari Wilayah Kerja Puskesmas Salido terhadap Malathion 5% dan Alfa-sipermethrin 0,025%

Background: Insecticides resistance status in Aedes aegypti population is one of the factors that influence the successful control efforts of dengue vector. Objectives:To determine the resistance status of Aedes aegypti from Salido Health Center towards malathion 5% and alpha-cypermethrine 0,025%. Methods: This was a descriptive study and collected during December 2019 – June 2020. Those samples were then observed with larval survey and from the ovitrap placed in 100 houses and then maintained in laboratory of parasitology, faculty of medicine Andalas University. To determine the resistance status of Aedes aegyptiusing the bioassay method with the susceptibility test by referring to the guidance of the Ministry of Health based on the 2016 WHO standard using impregnated paper malathion 5% and alpha-sipermethrin 0.025%. Observations were made by recording the number of mosquito deaths in the 15, 30, 45, 60 and 1440 minutes. The percentage of mosquito deaths is calculated after 24 hours of maintenance it is categorized as resistant if the mortality rate is less than 90%, supected to be resistant if the mortality is between 90-97%, and categorized as vunerable if the mortality rate is between 98-100%.Result: The mortality rate of Aedes aegypti for 24 hours by malathion 5% was 95%, the LT50 and the LT90 were 624 minutes and 1.247 minutes respectively. The percentage of mosquito deaths by alpha-sipermetrin 0,025% after 24 hours was 96,25% the LT50 and the LT90 were 526 minutes and 1.163 minutes respectively.Conclusion: that the resistance status of Aedes aegypti from Salido Health Center is resistant towards malathion 5% and alpha-cypermethrine 0,025%.

KLT BIOAUTOGRAFI HASIL PARTISI EKSTRAK ETANOL HERBA BANDOTAN (Ageratum conyzoides L.) TERHADAP Shigella dysentriae

Penelitian uji daya hambat dan analisis KLT bioautografi hasil partisi ekstrak etanol herba bandotan (Ageratum conyzoides L.) terhadap Shigella dysentriae telah dilakukan. Penelitian ini bertujuan untuk mengetahui kemampuan ekstrak tersebut dalam menghambat pertumbuhan S.dysentriae dan membandingkan daya hambat ekstrak dengan tingkat kepolaran yang berbeda yaitu pada ekstrak n-heksana, larut etil asetat, dan tidak larut etil asetat berdasarkan pengukurandiameter hambatan yang terbentuk. Herba tersebut diekstraksi dengan etanol menggunakan metode maserasi, lalu dipartisi dengan pelarut n-heksana dan etil asetat. Pengukuran dilakukan dengan menggunakan metode difusi pada medium Miller Hinton Agar (MHA) dengan waktu inkubasi 24 jam pada suhu 37oC dan memberikan diameter daerah hambatan terbesar pada ekstrak tidak larut etil asetat herba bandotan yaitu 9,3 dan 10,3 mm. Pemisahan secara KLT pada ekstrak n-heksana, ekstrak etil asetat, dan ekstrak tidak larut etil asetat dengan cairan pengelusi berturut-turut, n-heksana:etil asetat (3:1), n-heksana:etil asetat (1:1), dan etil asetat:etanol (10:1) dengan jumlah bercak noda berturut-turut 4, 5, dan 2. Nilai Rf pada ekstrak n-heksana 0.25, 0.41, 0.52, dan 0.71 sedangkan pada ekstrak etil asetat 0.34, 0.53, 0.65, 0.81, dan 0.92 pada ekstrak tidak larut etil asetat 0.33 dan 0.64. Hasil KLT bioautografi diperoleh komponen antibakteri yang diidentifikasi ekstrak n-heksana adalah golongan steroid dan pada tidak larut etil asetat golongan polifenol ABSTRACTInhibition test research and TLC bioautographic bioassay method of the partition results of the ethanol extract of bandotan (Ageratum conyzoides L.) herb against Shigella dysentriae have been conducted. This study aims to determine the ability of these extracts to inhibit S.dysentriae growth and to compare the inhibition of extracts with different polarity levels, n-hexane soluble, ethyl acetate soluble, and ethyl acetate insoluble extracts based on the diameter measurement of the formed resistance. The herbs were extracted with ethanol using the maceration method, then partitioned with n-hexane and ethyl acetate solvents. Measurements were carried out using the diffusion method on Miller Hinton Agar (MHA) medium with an incubation time of 24 hours at 37oC and gave the largest diameter area of resistance to the ethyl acetate insoluble extract of bandotan herb, value 9.3 and 10.3 mm. Separation by TLC on n-hexane extract, ethyl acetate extract, and ethyl acetate insoluble extract with elusive liquid respectively, n-hexane: ethyl acetate (3: 1), n-hexane: ethyl acetate (1: 1), and ethyl acetate: ethanol (10: 1) with the number of stains 4, 5, and 2, respectively. 0.81, and 0.92 in ethyl acetate insoluble extracts 0.33 and 0.64. The results of the bioautography TLC bioassay method showed that the antibacterial component identified in the n-hexane extract was a steroid compound and ethyl acetate insoluble was a polyphenol compound.

INSECTICIDAL AND INHIBITORY POTENTIAL OF TWO CHITIN SYNTHESIS INHIBITORS, BUPROFEZIN AND LUFENURON ON OKRA SHOOT AND FRUIT BORER, EARIAS VITTELLA

In this laboratory study, insecticidal and inhibitory potential of two chitin synthesis inhibitors (CSIs) viz. Buprofezin and Lufenuron were evaluated against okra shoot and fruit borer (OSFB). CSIs were applied on three days old larvae through different bioassay methods like topical or direct, okra-dip or indirect and combined (topical + leaf-dip). Data were collected on larval mortality, weight reduction and deformations of larvae and adults. Results showed that larval mortality and weight reduction were clearly dose, application methods and time dependent. In case of both CSIs, the highest mortality was found @ 1.0 ml/L that was followed by 0.75 ml and 0.50 ml/L respectively. Likewise, the highest body weight reduction was also found from 1.0 ml/L. In both cases, the concentration 0.5 ml/L was found less effective. In case of application methods, combined bioassay method was found superior than that of rest of the two methods. Moreover, a significant percentage of deformed larvae and adults were developed when 3 days old larvae were treated with either Buprofezin or Lufenuron @ 1.0 ml/L through combined bioassay method. The concentration 0.5 ml/L had very less efficacy on the development of deformed larvae or adults. Therefore, based on the laboratory findings Buprofezin and Lufenuron may be the potential component in IPM programmed, rather than their individual application, for controlling okra shoot and fruit borer as well as production of safe okra.

Study on the Bioassay of Anti-Inflammatory Effects of Fuke Qianjin Capsule Based on COX-2 Inhibiting Activity

Fuke Qianjin Capsule (FKQJ) is a common TCM compound formula in the treatment of gynecological inflammation-related diseases. This study intends to explore and establish a bioassay method to further improve its quality control. The bioassay method for the determination of anti-inflammatory biopotency was established based on its inhibitory activity on recombinant human cyclooxygenase-2 (COX-2), an active target of FKQJ in the treatment of female pelvic inflammatory disease. We firstly established chemical fingerprint of 20 batches of FKQJ by ultra-high-performance liquid chromatography to identify the components and analyze the chemical similarities. The similarity within different batches of FKQJ was relatively high. The values of similarity of the 19 batches were between 0.973 and 0.995, while one batch’s similarity value was 0.813. Celecoxib, a selective inhibitor of COX-2, was chosen as the positive control drug in COX-2 activity assay to establish an anti-inflammatory biopotency detection method based on parallel line test of qualitative response. The methodological investigation showed that the method possessed good repeatability and precision. Secondly, the anti-inflammatory biopotency of 20 batches of FKQJ for inhibiting COX-2 was determined. The results showed that the biopotency of different batches of FKQJ ranged from 676 U/μg to 1310 U/μg, with average value of 918 U/μg and RSD of 16.7%. Based on multiple linear regression analysis, we found that three contents were highly correlated with the anti-inflammatory biopotency, while chlorogenic acid was validated of the strongest anti-inflammatory activity in vitro. Compared with chemical detection, bioassay can better reflect the quality fluctuation of different batches of products and correlate the known pharmacodynamic targets. The supplement of the bioassay method based on chemical evaluation is helpful to improve the quality control ability of Chinese patent medicine and ensure its clinical efficacy is stable and controllable.

Study of Detoxifying Ability of Oxidized Humic Substances under the Conditions of Oil Pollution of Soils

The article presents the results of research on the oxidative modification of humic substances of brown coal of the Tyulgan deposit. The detoxifying effect of the obtained substances in relation to petroleum hydrocarbons was studied using the bioassay method. During the evaluation, a noticeable increase in the detoxifying ability was found in the result of chemical modification of humic substances. The greatest detoxifying effect in relation to oil pollution of the soil was observed for humic substances modified by oxidation and amounted to 19 and 42% at doses of 0.01 and 0.1% by weight. accordingly. The detoxifying effect of native humic substances is significantly lower: 9 and 2 % at doses of 0.01% and 0.1% by weight. accordingly. Thus, the prospects of using oxidized humic substances as sorbents-detoxicants during phytoremediation of oil-contaminated soil are shown.