25 research outputs found

    Mitochondrial DNA Variation Among Populations of Rhynchophorus ferrugineus (Coleoptera: Curculionidae) From Pakistan.

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    The Red Palm Weevil (RPW) Rhynchophorus ferrugineus (Olivier) is a voracious pest of palm species. In recent decades its range has expanded greatly, particularly impacting the date palm industry in the Middle East. This has led to conjecture regarding the origins of invasive RPW populations. For example, in parts of the Middle East, RPW is commonly referred to as the "Pakistani weevil" in the belief that it originated there. We sought evidence to support or refute this belief. First reports of RPW in Pakistan were from the Punjab region in 1918, but it is unknown whether it is native or invasive there. We estimated genetic variation across five populations of RPW from two provinces of Pakistan, using sequences of the mitochondrial cytochrome oxidase subunit I gene. Four haplotypes were detected; two (H1 and H5) were abundant, accounting for 88% of specimens across the sampled populations, and were previously known from the Middle East. The remaining haplotypes (H51 and H52) were newly detected (in global terms) and there was no geographic overlap in their distribution within Pakistan. Levels of haplotype diversity were much lower than those previously recorded in accepted parts of the native range of RPW, suggesting that the weevil may be invasive in Pakistan. The affinity of Pakistani haplotypes to those reported from India (and the geographical proximity of the two countries), make the latter a likely "native" source. With regards the validity of the name "Pakistani weevil", we found little genetic evidence to justify it

    Study on Desiccant and Evaporative Cooling Systems for Livestock Thermal Comfort: Theory and Experiments

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    The present study considers evaporative cooling and desiccant unit-based air-conditioning (AC) options for livestock AC application. In this regard, proposed systems are investigated by means of experiments and thermodynamic investigations. Air-conditioning requirements for animals are theoretically investigated and temperature-humidity index (THI) is estimated. A lab-scale heat mass exchanger based on the Maisotsenko-cycle evaporative cooling conception (MEC) is set up and its performance is evaluated at different ambient air conditions. In addition, a desiccant-based air-conditioning (DAC) unit is thermodynamically evaluated using a steady-state model available in the literature. The study focuses on the ambient conditions of Multan which is the 5th largest city of Pakistan and is assumed to be a typical hot city of southern Punjab. The study proposed three kinds of AC combination i.e., (i) stand-alone MEC, (ii) stand-alone desiccant AC, and (iii) M-cycle based desiccant AC systems. Wet bulb effectiveness of the stand-alone MEC unit resulted in being from 64% to 78% whereas the coefficient of performance for stand-alone desiccant AC and M-cycle based desiccant AC system was found to be 0.51 and 0.62, respectively. Results showed that the stand-alone MEC and M-cycle based desiccant AC systems can achieve the animals’ thermal comfort for the months of March to June and March to September, respectively, whereas, stand-alone desiccant AC is not found to be feasible in any month. In addition, the ambient situations of winter months (October to February) are already within the range of animal thermal comfort

    Combined Effect of Entomopathogens against Thrips tabaci Lindeman (Thysanoptera: Thripidae): Laboratory, Greenhouse and Field Trials

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    Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae) is one of the most damaging insect pests of onions, Allium cepa L., which is an economically important agricultural crop cultivated worldwide. In this study, the combined application of entomopathogenic nematodes with entomopathogenic fungi against different soil dwelling stages of T. tabaci was evaluated. The nematodes included Heterorhabditis bacteriophora (VS strain) and Steinernema feltiae (SN strain), and fungi included Beauveria bassiana (WG-11) and Metarhizium anisopliae (WG-02); all four paired combinations (nematode + fungus) were included. In a small cup bioassay, only the combined application of H. bacteriophora and B. bassiana (WG-11) caused a synergistic interaction against pre-pupae, while all other combinations were compatible in an additive manner against pupae and late second instars. In a larger arena, a potted soil bioassay, again, combined applications of both pathogens produced greater mortality compared to single applications of each pathogen; all the combinations exhibited additive interactions, with the highest mortality observed in pre-pupae, followed by pupae and late second instar larvae using H. bacteriophora and B. bassiana (WG-11). Additionally, in the potted plant bioassay, lower adult emergence was observed from treated groups compared to control groups. Under field conditions, lower numbers of adults and larvae were found in treated groups relative to controls. Overall, the pre-pupal stage was more susceptible to the pathogen treatments, followed by pupae and late second instar larvae, and also combined applications of both pathogens suppressed the adult population. Combined application of entomopathogenic nematodes and fungi could be used for integrated pest management (IPM) of T. tabaci in onion production systems

    Inducción de resistencia en garbanzo (Cicer arietinum L.) contra Ascochyta rabiei por la aplicación de productos químicos y extractos vegetales.

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    Since new fungicides are scarce in the market and because of environmental problems, researchers are now emphasizing other alternatives, such as the genetic potential of plants, resistance against pathogens, and the use of biotic and abiotic agents to develop induced or acquired resistance. We investigated the role of resistance-inducing substances (chemicals and plant extracts) in three chickpea cvs. C-44, Pb-91, and Bittle-98 in field experiments against Ascochyta blight disease. These cultivars were selected on the basis of better yield potential shown in previous experiments. Aqueous solution of salicylic acid (SA) at 0.5, 1.0, and 1.5 mM; acibenzolar-S-methyl (Bion®, ASM) at 0.4, 0.8, and 1.2 mM; and KOH at 25, 50, and 75 mM were applied, whereas Azadirachta indica A. Juss., Datura metel L., and Allium sativum L. plant extracts were applied at 5, 10, and 15%. Disease reduction data was recorded at different intervals from 4 to 14 d after being induced and inoculated with the pathogen. Overall results revealed that significant disease reduction (79.3%) was provided by ASM in the cv. C-44 at 1.2 mM compared with SA, whereas the least significant was KOH. Maximum disease reduction (43.5%) against disease in the plant extracts was observed by applying A. indica leaf extract, but D. metel and A. sativum extracts were not effective. Our findings suggest that enhancing resistance before infecting chickpea plants could be an innovative control method for Ascochyta blight of chickpea.Debido a la escasez de nuevos fungicidas en el mercado y problemas ambientales, los investigadores están ahora enfatizando otras alternativas, tales como potencial genético de las plantas, resistencia contra patógenos y uso de agentes bióticos y abióticos para el desarrollo de resistencia inducida y adquirida. Investigamos el rol de sustancias inductoras de resistencia (químicos y extractos vegetales) en tres cultivares de garbanzo ‘C-44’, ‘Pb-91’, ‘Bittle-98’, en experimentos de campo contra tizón por Ascochyta. Estos cultivares se seleccionaron basado en el mejor potencial de rendimiento mostrado en experimentos previos. Solución acuosa de ácido salicílico (SA) a 0,5; 1,0; y 1,5 mM, acibenzolar-S-metil (Bion®) a 0,4; 0,8; y 1,2 mM y KOH a 25, 50, y 75 mM se aplicaron mientras los extractos vegetales de Azadirachta indica A. Juss., Datura metel L. y Allium sativum L. se aplicaron a 5, 10, y 15%. Datos de reducción en la enfermedad se registraron con diferentes intervalos desde 4 a 14 d después de inducción e inoculación con el patógeno. Los resultados revelaron que ASM 1,2 mM provocó una reducción significativa de la enfermedad (79,3%) en el cv. C-44 comparado con SA; sin embargo, la menor reducción fue observada para KOH. Entre los extractos vegetales, la máxima reducción de la enfermedad (43,5%) se observó con la aplicación de extracto foliar de A. indica y los extractos de D. metel y A. sativum no fueron efectivos para la reducción de la enfermedad. Los presentes hallazgos sugieren que el aumento de la resistencia antes de la infección de plantas de garbanzo pudo ser un método de control innovador para tizón del garbanzo por Ascochyta

    Fungal-Based Biopesticide Formulations to Control Nymphs and Adults of the Desert Locust, <i>Schistocerca gregaria</i> Forskål (Orthoptera: Acrididae): A Laboratory and Field Cage Study

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    This is the first field study in which we have tested the efficacy of four different entomopathogenic fungal (EPF) formulations together in single study—i.e., Green Muscle, Green Guard, Metarhizium anisopliae, and an isolate of Beauveria bassiana (isolate WG-11)—against nymphs and adults of the desert locust, Schistocerca gregaria Forskål (Orthoptera: Acrididae). We conducted several different studies: (a) lethal bioassay against the 3rd, 5th, and adult stages under laboratory conditions; (b) sublethal effects on the reproduction, diet consumption, fecal production, and weight gain; (c) a greenhouse trial; and (d) a field cage trial. Under laboratory conditions, all EPF formulations caused significant mortality, and the highest efficacy was observed with Green Muscle, followed by Green Guard, B. bassiana, and M. anisopliae. Susceptibility was found to be greatest in 3rd-instar nymphs, followed by 5th instars, and then adults. Along with lethal effects, sublethal doses of EPF reduced the number of egg pods per female, total eggs per pod, and egg hatching, while extending nymphal developmental time and reducing adult longevity; again, Green Muscle performed better. Sublethal doses not only retarded reproduction, but also caused behavioral changes, including reductions in food consumption, fecal production, and weight gain. All EPF formulations not only produced significant mortality in laboratory conditions, but also performed very well under the greenhouse and field conditions. The maximum mortality against 3rd-instar (81.7% and 74.0%), 5th-instar (73.3% and 65.1%), and adult locusts (67.5% and 58.9%) was observed when using Green Muscle under greenhouse and field trials, respectively. The current study showed that all of the EPF formulations have the potential to reduce pest populations, and could be used in the integrated pest management program

    INSECTICIDAL EFFICACY OF Azadirachta indica , NUCLEOPOLYHEDROVIRUS AND CHLORANTRANILIPROLE SINGLY OR COMBINED AGAINST FIELD POPULATIONS OF Helicoverpa armigera HÃœBNER (LEPIDOPTERA: NOCTUIDAE)

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    The development of resistance in cosmopolitan insect Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) forced the researchers for alternative control measures. In the present study, insecticidal efficacy of formulations of Azadirachta indica , a Nucleopolyhedrovirus (NPV), and new anthranilic diamide insecticide (chlorantraniliprole) formulations was determined against 2nd, through 5th larval instars of H. armigera collected from diverse geographical locations in the Punjab province, Pakistan. Azadirachta indica was applied at 5 μL L-1; NPV at 2.1 × 105 polyhedral occlusion bodies (POB) mL-1 and chlorantraniliprole at 0.01 μL L-1, either alone or in combinations with each other. The bioassays were conducted at 27 ± 1 °C and 65 ± 5% relative humidity. The mortality varied greatly among treatments, larval instars, and locations. The combinations of NPV with A. indica and chlorantraniliprole caused higher mortality, pupation and produced an additive effect compared to their application singly in all the tested populations. The population from Rawalpindi was always susceptible while the Gujranwala was the resistant. The results herein suggest that the effectiveness of NPV and A. indica can be improved by the presence of chlorantraniliprole against the larvae of H. armigera
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