Toxicity of quinones against two-spotted spider mite and three species of aphids in laboratory and greenhouse conditions

Toxicities of the eight quinones were evaluated through leaf dip bioassays conducted against Tetranychus urticae, Myzus persicae, Myzocallis walshii, and Illinoia liriodendri. Based on LC₅₀ values, plumbagin (LC₅₀ = 0.001%) was the most active compound against T. urticae and ubiquinone Q₀ (LC₅₀ = 0.005%), plumbagin (LC₅₀ = 0.010%), and dibromothymoquinone (LC₅₀ = 0.012%) were the most active compounds against M. persicae. The most active compounds against M. walshii were juglone (LC₅₀ = 0.011%) and ubiquinone Q₀ (LC₅₀ = 0.019%), whereas dibromothymoquinone (LC₅₀ = 0.030%), plumbagin (LC₅₀ = 0.033%) and ubiquinone Q₀ (LC₅₀ = 0.058%) were the most toxic to I. liriodendri. Ecotrol (positive control) was the least toxic compound (LC₅₀ = 0.39%) against T. urticae and M. persicae (LC₅₀ = 0.447%). Although the majority of the compounds tested were toxic to all four test species in residual bioassays, there was little overlap among the test species in terms of susceptibility to the compounds and interspecific differences were observed. Regarding structure-activity relationships for quinones, the addition of a hydroxyl group resulted in a significant increase in the toxicity of the 1,4-naphthoquinones, and those possessing a methyl group exhibited the highest levels of activity in T. urticae. The bromine atom at the 2- and 5-positions of the benzoquinone ring is crucial to the toxicity of the compounds against I. liriodendri. Toxicity was greatly affected not only by the number of hydroxyl groups, but also by their positions in the ring in the case of M. walshii. Juglone and plumbagin as residual toxins in the laboratory also reduced the population of two-spotted spider mites compared to EcoTrol™ (positive control) and the negative control in the greenhouse experiment. Some quinones tested may have potential as commercial insecticides and miticides, or alternatively, could serve as lead compounds for the development of more potent crop protection agents.     

Methyl donors potentiates growth, metabolic status and neurotransmitter enzyme in Labeo rohita fingerlings exposed to endosulfan and temperature

A 2-month preliminary study was conducted to delineate the effect of dietary methyl donors (choline, betaine, and lecithin) on the growth performance and metabolic status of Labeo rohita fingerlings subjected to endosulfan alone and in combination with elevated temperature. Four iso-caloric and iso-nitrogenous diets viz. basal diet, betaine-supplemented diet, choline-supplemented diet and lecithin-supplemented diet were prepared and fed to the different experimental groups throughout the experimental period as per the design. Two hundred and seventy fingerlings (average weight 7.95?±?0.04?g) were randomly distributed in six treatment groups each having three replicates. The experimental groups were as follows: fish subjected to normal water (without endosulfan) and fed with control diet (control group T(0)), fish subjected to endosulfan-treated water and fed with control diet (T(1)), fish subjected to concurrent exposure of endosulfan and elevated temperature and fed with control diet (T(2)), fish subjected to endosulfan and elevated temperature and fed with choline-supplemented diet (T(3)), fish subjected to endosulfan and temperature and fed with betaine-supplemented feed (T(4)), and fish subjected to endosulfan and temperature and fed with lecithin-supplemented feed (T(5)). The result shows that in both the groups, that is, endosulfan exposed and concurrent exposure to endosulfan and elevated temperature group of L. rohita the growth performance like percentage weight gain, feed conversion ratio and specific growth rates were significantly different (P?相似文献   

Relationship between rhizosphere acidification and phytoremediation in two acacia species

Purpose

Phytoremediation is the most sustainable and economical strategy for reclamation of the salt-affected soils. In order to investigate the relationship between phytoremediation and rhizosphere acidification, two experiments (greenhouse and field) were conducted using two acacia species viz. Acacia ampliceps and Acacia nilotica.

Materials and methods

In greenhouse experiment, both the species were exposed to 100 and 200 mM NaCl concentrations in solution culture. The release of organic acids from plant roots was determined after 14 and 28 days of the salt treatment. Shoot and root ash alkalinity was determined after harvesting the plants. In field experiment, both the species were grown on a saline sodic soil for 2 years. After every 6 months, plant growth data were recorded and soil samples were collected from different soil depths for physicochemical analyses.

Results and discussion

The results of greenhouse study indicated higher rhizosphere acidification by A. ampliceps than A. nilotica in terms of release of citric acid, malic acid, and tartaric acid along with ash alkalinity. The comparison of both the species in the field indicated higher amelioration in the soil properties like pH_s, EC_e, SAR, bulk density, and infiltration rate by A. ampliceps than A. nilotica.

Conclusions

It is concluded from these studies that A. ampliceps is more suitable species than A. nilotica for the phytoremediation of the salt-affected soils due to its higher rhizosphere acidification potential.

     

Maize production under risk: The simultaneous adoption of off-farm income diversification and agricultural credit to manage risk

Farmers in Pakistan continue to produce maize under various types of risks and adopt several strategies to manage those risks. This study is the first attempt to investigate the factors affecting the concurrent adoption of off-farm income diversification and agricultural credit which the farmers use to manage the risk to maize production. We apply bivariate and multinomial probit approaches to the primary data collected from four districts of Punjab Province in Pakistan. The results show that strong correlations exist between the off-farm diversification and agricultural credit which indicates that the use of one risk management strategy leads to another. The findings demonstrate that education, livestock number, maize farming experience, perceptions of biological risks and risk-averse nature of the growers significantly encourage the adoption of diversification as a risk management tool while farm size inversely affects the adoption of diversification. Similarly, in the adoption equation of credit, maize farming experience, farm size, perceptions of price and biological risks and risk attitude of farmers significantly enhance the chances of adopting agricultural credit to manage farm risks. These findings are important for the relevant stakeholders who seek to offer carefully designed risk minimizing options to the maize farmers.     

Genotypic variation in rice for grain yield and quality as affected by salt-affected field conditions

A field experiment was conducted under two natural field conditions at the Research Farm (normal soil) and Proka Farm (salt-affected soil) of The Institute of Soil and Environmental Sciences (ISES), University of Agriculture, Faisalabad, Pakistan, to evaluate the performance of 11 rice genotypes in normal and salt-affected conditions. The experiment was laid out in randomized complete block design (RCBD) with three replications. The gas exchange attributes were measured at vegetative stage whereas the grain and straw yields and the yield components were recorded at maturity. After harvesting, the ionic parameters including sodium (Na⁺) and potassium (K⁺) were determined. Afterward, grain quality in terms of length, width, milling recovery, broken fraction, and chalkiness was also determined for the selected genotypes. Salt-affected conditions adversely affected the physiology, yield, and quality of the tested genotypes. The genotypes KS-282 followed by Shaheen Basmati showed significantly higher photosynthetic rate, transpiration rate, and stomatal conductance under both normal and salt-affected conditions, whereas the genotypes 99404 followed by 99417 showed minimum values of gas exchange attributes. The grain and straw yields were the highest in the case of KS-282 at both sites, whereas the lowest grain and straw yields were observed in the case of 99440 followed by 99417 under both normal and salt-affected conditions. Regarding the quality attributes, Super Basmati produced longer grains but with higher broken fraction and lower milling recovery, whereas the reverse was observed in the case of KS-282.     

Antibody Prevalence and Risk Factors for Toxoplasma gondii Infection in Women from Multan,Pakistan

Toxoplasma gondii infections are prevalent in humans and warm‐blooded animals. Maternal infections during pregnancy may have devastating consequences for transplacentally infected neonates. This study was conducted to examine the seroprevalence of antibodies to T. gondii in pregnant women of childbearing age and determine risk factors associated with pregnancy history, pet ownership, social and cultural factors at Nishtar Hospital, Multan. Samples were collected from 403 women and examined using a commercially available enzyme‐linked immunosorbent assay (ELISA). The overall prevalence of antibodies to T. gondii was 17.6% (71) in the 403 samples collected from women. Antibodies to T. gondii were present in 19.4% (45) of 232 pregnant women and 15.2% (26) of the samples from 171 non‐pregnant women. This study identified miscarriage history, pet ownership, type of residence, marital status, source of drinking water and eating habits as significant (P < 0.05) risk factors associated with the presence of antibodies to T. gondii infection. Seroprevalence was not significantly different (P > 0.05) in women from different ethnic groups based upon lifestyle and culture.     

Performance of mono‐sex tilapia (Oreochromis niloticus) in rice field with different ditch size

The effects of ditch size on growth and production of mono‐sex tilapia, Oreochromis niloticus in rain fed concurrent rice–fish system were technically and economically evaluated for a period of 4 months. Three different ditch sizes were tried: 5%, 10% and 15% of the total cultivable rice field. The fish fingerlings stocking density (5000 ha^?1) and management practices were similar in all plots. The water temperature, dissolve oxygen, pH, Secchi disc visibility, ortho‐phosphate, ammonia nitrogen and alkalinity were found to be in the range of 31.5–31.9°C, 5.10–5.27 mg L^?1, 7.56–7.62, 34.81–35.41 cm, 0.88–0.96 mg L^?1, 0.014–0.021 mg L^?1 and 66.23–69.76 mg L^?1, respectively, and all the values were found suitable for tilapia fish farming. Sediment organic matter, available nitrogen and phosphorous were increased significantly (P < 0.05) in all plots after cultivating the fish. Larger ditch size (15% of the total land area) resulted in significantly (P < 0.05) higher specific growth rate, survival and fish production compared with the smaller (5%) and medium (10%) ditch sizes. However, significantly (P < 0.05) higher net income and benefit–cost ratio were obtained in medium ditch size with the values of 2.6% and 3.6% higher than the smaller and larger ditch sizes respectively. It is concluded that rice–fish farming in a rain fed ecosystem of Bangladesh with medium ditch size and stocking density of 5000 ha^?1 mono‐sex tilapia can achieve better economic return.     

Vegetation structure of subtropical forest of Tabai,South Waziristan,Pakistan

Phytosociological parameters, soil and temperature conditions, importance values of species, life form, leaf size, and biomass were investigated at the village Tabai during autumn 2006. There was very little difference in air and soil temperature due to similar elevation. There was a great difference in biomass production for various stands. The original vegetation structure has been altered due to deforestation and overgrazing. There is a need for restoration of the habitat.     

Genetic analysis and identification of SSR marker linked to Phomopsis blight resistance in eggplant (Solanum melongena L.)

The present investigation was carried out to decipher inheritance of resistance and to identify linked SSR markers for Phomopsis blight resistance in eggplant. An F₂ population comprising 161 plants was developed from the cross of Pusa Kranti and BR-40-7. Genetic analysis was carried out using Chi square test. Artificial inoculation of fruits was carried out using pin prick method, and scoring was done as per the standard scoring scale. The F₂ plants segregated into 92 susceptible (77—highly susceptible, 15—susceptible): 69 resistant (17—highly resistant, 27—resistant, 25—moderately resistant) suggesting complimentary epistasis with ratio of 9:7. To identify the putatively linked markers to resistance gene, parental polymorphic markers were subjected to bulk segregant analysis (BSA), and two markers (emk03O04 and emf11A03) could differentiate resistant and susceptible bulk and co-segregated with resistance gene. The genetic distance between the identified markers was found to be 18.12 cM using QTL IciMapping V3.2 software depicting two new QTLs on chromosome number 6. The identified QTLs have great significant importance in marker assisted breeding programme.