RESISTENSI KEPIK COKLAT (Riptortus linearis) TERHADAP JENIS INSEKTISIDA BRANTAS 25 EC PADA TANAMAN KACANG PANJANG

Kepik coklat (Riptortus linearis) merupakan hama utama pada tanaman kacang panjang, adapun cara hama R. linearis merusak tanaman kacang panjang dengan cara R. linearis menusuk stiletnya ke dalam polong dan biji, sehingga polong dan biji kacang panjang dapat gugur dan biji keriput. Populasi hama R. linearis pada semua stadium, dapat berpotensi merusak polong kacang panjang, untuk itu para petani melakukan tindakan pengendalian secara kimia yaitu dengan menggunakan penyemprotan insektisida kimia untuk mengendalikan hama, namun dalam pengendalian yang tidak efektif dapat mengalami resistensi hama, sehingga terjadinya kegagalan dalam pengendalian, selain itu dapat mengalami residu dan resurjensi. Saat ini belum terdapat data, terkait evaluasi resistensi hama R. linearis terhadap penggunaan insektisida kimia di Kabupaten Sumba Timur. Oleh karena itu, perlu di lakukan penelitian tentang uji resistensi hama R. linearis terhadap insektisida kimia (Brantas 25 EC) di laboratorium. Hasil penelitian meenunjukan bahwa aplikasih insektisida kimia brantas 25 EC, pada hama R. linearis dengan konsentrasi 0,25 ml/l, 0,5ml/l, 0,75 ml/l, 1,00ml/l dan 1,25ml/l dapat di lihat mortalitas R. linearis dalam waktu 24 jam, dengan mengakibatkan mortalitas tertinggi 66%. Hasil penelitian Estimated resistance ratio (ERR), menunjukan bahwa aplikasih insektisida kimia terhadap R.linearis dengan LC50, dapat mengakibatkan resistensi tertinggi yaitu 3,44% pengamatan dilakukan 28 jam setelah aplikasih insektisida kimia brantas 25 EC.

RESISTENSI KEPIK COKLAT (Riptortus linearis) TERHADAP JENIS INSEKTISIDA BRANTAS 25 EC PADA TANAMAN KACANG PANJANG

Kepik coklat (Riptortus linearis) merupakan hama utama pada tanaman kacang panjang, adapun cara hama R. linearis merusak tanaman kacang panjang dengan cara R. linearis menusuk stiletnya ke dalam polong dan biji, sehingga polong dan biji kacang panjang dapat gugur dan biji keriput. Populasi hama R. linearis pada semua stadium, dapat berpotensi merusak polong kacang panjang, untuk itu para petani melakukan tindakan pengendalian secara kimia yaitu dengan menggunakan penyemprotan insektisida kimia untuk mengendalikan hama, namun dalam pengendalian yang tidak efektif dapat mengalami resistensi hama, sehingga terjadinya kegagalan dalam pengendalian, selain itu dapat mengalami residu dan resurjensi. Saat ini belum terdapat data, terkait evaluasi resistensi hama R. linearis terhadap penggunaan insektisida kimia di Kabupaten Sumba Timur. Oleh karena itu, perlu di lakukan penelitian tentang uji resistensi hama R. linearis terhadap insektisida kimia (Brantas 25 EC) di laboratorium. Hasil penelitian meenunjukan bahwa aplikasih insektisida kimia brantas 25 EC, pada hama R. linearis dengan konsentrasi 0,25 ml/l, 0,5ml/l, 0,75 ml/l, 1,00ml/l dan 1,25ml/l dapat di lihat mortalitas R. linearis dalam waktu 24 jam, dengan mengakibatkan mortalitas tertinggi 66%. Hasil penelitian Estimated resistance ratio (ERR), menunjukan bahwa aplikasih insektisida kimia terhadap R.linearis dengan LC50, dapat mengakibatkan resistensi tertinggi yaitu 3,44% pengamatan dilakukan 28 jam setelah aplikasih insektisida kimia brantas 25 EC.

DETERMINACIÓN DE LA CONCENTRACIÓN EFECTIVA 50, 90 Y 99 DE IVERMECTINA SOBRE UNA CEPA DE GARRAPATA COMÚN DEL BOVINO (Rhipicephalus (Boophilus) microplus) PROVENIENTE DE LA PROVINCIA DE SANTA FE-ARGENTINA

The aim of this study was to obtain the sensitivity data of the native strains of R. microplus to ivermectin (IVM) in the province of Santa Fe-Argentina, in order to detect the emergence of resistant strains. Native (field isolation) and susceptible (reference) larvae of R. microplus were treated with increasing concentrations of IVM in order to determine its efficacy at different doses. The statistical treatment of the concentration-efficacy curves was performed by the PROBIT model, who is a standardized method proposed by FAO. The results obtained indicated that the larvae isolated were susceptible, being the values of LD50 (9.66 ppm) and LD90 (17.41 ppm), which were lower than those of the reference strain (LD50:13.58 ppm, LD90:19.31 ppm), and the RR (resistance ratio) were less than one (RR50: 0.711; RR90: 0.901). The DL99 (51.48 ppm) was only obtained in the reference strain to determine the discriminant dose (DL99x2), which is a parameter that could be used to easily discriminate susceptible and resistant larvae populations.

The oscillation resistance ratio (ORR) for understanding inelastic response

Single-storey systems with different hysteretic characteristic are subjected to impulse-type short duration and long duration earthquake records to investigate the effects of hysteretic behaviour and ground motion characteristics on the seismic response. EPP, bilinear, Takeda, SINA, and flag-shaped hysteretic models loops are considered and an energy approach is taken to explain the inelastic behaviour. The first part of the work is based on analyses of the single-storey systems without any torsion, however; torsional irregularity is considered in the later analyses. It is shown that structures with the same backbone curve, but different hysteretic characteristics, tend to experience the same maximum response under short duration earthquake records, where there is one major displacement excursion. The likelihood of further displacement in the reverse (i.e. negative) direction is characterized using energy methods and free vibration analyses along with a new proposed “oscillation resistance ratio (ORR)” are employed to improve the understanding of the seismic response. Hysteretic models with low ORR, such as SINA and flag-shaped, are shown to have a greater likelihood of higher absolute displacement response in the negative direction compared with those with fatter hysteretic loops. The understanding of the response in terms of energy reconciles some differences in the ability of initial stiffness versus secant stiffness based methods to predict peak displacement demands with account for different ground motion characteristics. The same peak displacements in the primary direction was also observed for structures with stiffness/strength eccentricities under an impulse-type earthquake record. However, during unloading, the elastic energy stored in the out-of-plane elements is released causing greater displacement on the weak side in the reverse direction.

Application of an Improved Empirical Model for Rheology Prediction of Cement Pastes Modified with Filler from Manufactured Sand

There is a need for simple but precise prediction models for proportioning concrete with manufactured sand, for use in ready-mix concrete production. For the last two decades, the particle-matrix model has been used in Norway for proportioning and prediction of concrete flow based on the properties and proportions of two concrete phases: coarse particles and filler modified cement paste (matrix). This paper presents experimental testing of 117 cement pastes of which 107 contain filler, i.e. particles < 125 microns, from manufactured sand. Based on compositions and properties of ingoing materials in these mixes, an empirical equation is developed that predicts the rheological properties plastic viscosity, yield stress, flow resistance ratio and mini slump flow. Optimization by regression analysis provides a practical microproportioning equation that readily can be used as input in concrete proportioning with the particle-matrix model. The equation provides a coefficient of determination R2 = 0.98 for plastic viscosity, R2 = 0.95 for mini slump flow, R2 = 0.91 for flow resistance ratio and R2 = 0.80 for yield stress.

Biological responses in Musca domestica to fipronil and chlorfenapyr exposures

Insect populations exist under acute and chronic exposures to lethal and sublethal insecticide concentrations. Among the sublethal effects of insecticides on insects are reductions in life span, development rates, population growth, fertility, fecundity, changes in sex ratio, deformities, changes in behaviour, feeding, searching, and oviposition. These effects may differ depending on the modes of action of insecticides, their doses, and developmental stage of application. This study evaluated the life-history parameters in Musca domestica Linnaeus, 1758 (Diptera:Muscidae) strains that were exposed to two insecticides (fipronil and chlorfenapyr) with different modes of action at sublethal concentrations in each generation up to tenth. Two approaches to each insecticide’s exposure were used in this study, particularly in one approach, only adults M. domestica were exposed to fipronil or chlorfenapyr and in another approach, only larvae were exposed to each insecticide. The susceptibility of adult flies to these insecticides was assessed by resistance ratio based on results of non-choice feeding bioassays. Fipronil exposure at the sublethal concentration in each generation did not affect the susceptibility of adult M. domestica (in the tenth generation) to fipronil. The resistance ratio values revealed tolerance to chlorfenapyr in adults of M. domestica strains that were exposed to this insecticide, independent of the approach used to insecticide exposure. Most of the life-history parameters (such as durations of separate developmental stages, the emergence duration, the adult emergence ratio, the female ratio, and the number of eggs per female per day) of the second, fourth, sixth, eighth, and tenth generations of the insecticide-exposed strains were similar to those of the control strain. At the same time, the sublethal effects of both insecticides fipronil and chlorfenapyr prolonged the larval duration (1.63–2.22 times) and the number of days from egg to adult (1.18–1.39 times) compared to the control strain. Further studies are needed to investigate a possible genetic variability in M. domestica in response to exposure of parental generation to sublethal doses of fipronil and chlorfenapyr.

STAPHYLOCOCCUS AUREUS RESISTANCE AGAINST CEPHALOSPORIN ANTIBIOTIC IN ADEN-YEMEN

The study was carried out to determine antibacterial resistance profiles of methicillin-resistant Staphylococcus aureus (MRSA), isolated from clinical samples (n: 352) of patients during the period, from January 2019 to July 2020 in five governmental and private medical laboratories of Aden governorate, Yemen. The results showed the percentage for resistance ratio is differentiated between samples and the category of cephalosporin antibiotic groups. The highest percentage of resistance was in the wound sample for Cefadroxil, Cefuroxime, and Ceftriaxone at (100%), in addition to 100% in the pus, CSF, and sputum samples for Ceftriaxone antibiotic. Moreover, Cefadroxil has 100 % of resistance in semen, ear, and sputum samples. However, the Staphylococcus aureus isolated from the pharyngeal sample not showed any resistance to all cephalosporin antibiotic groups.