Effects of herbivory on the reproductive effort of 4 prairie perennials

Background  

There is an urgent need to explore and utilize naturally occurring products for combating harmful agricultural and public health pests. Secondary metabolites in the leaves of the Tree of Heaven, Ailanthus altissima L. have been reported to be herbicidal and insecticidal. The mode of action, however, of the active compounds in A. altissima are not understood. In this paper, we report the chemical characteristics of the herbicidal and insecticidal components in this tree, and will discuss the effect of light on the bioactivity of the active components.     

Effects of soil disinfection on health status,growth and yield of strawberry stock plants

Two strawberry nursery field trials comparing soil disinfection with different fumigants (metam sodium, dazomet, chloropicrin, chloropicrin +1,3D) and a steaming system exploiting the exothermic reaction between steam and CaO (Bioflash System™) were conducted in 2010–2012 to evaluate the effect of treatments on Verticillium dahliae Kleb. inhabiting the soil, and on plant health, growth and yield of strawberry daughter plants. Chemical fumigants and the Bioflash System™ decreased the number of V. dahliae colonies in the soil, which corresponded to reduced incidence of Verticillium wilt (efficacy about 80%). The use of chemical fumigants had a positive impact on the size of the mother plants. The surface area covered by plants grown on the treated plots was 1.1–1.7 times larger than plants grown on non-fumigated control plots. The number of runners, as well as daughter plants, produced from plants grown on plots treated with all chemical fumigants was significantly higher than in the non-fumigated control or in the plots treated with the Bioflash System™. The disinfection treatments significantly increased the yield of marketable daughter plants, approximately 1.5–3 times higher in comparison to plants grown on control plots. Steam disinfection with the Bioflash System™ was the least effective treatment in this respect. The differences in marketable plants yield among the chemical fumigants significantly affected the net marginal return and the return on investment of the crop. In this respect, the steam disinfection was economically efficient only in one season. The efficacy in controlling Verticillium wilt even with low doses of metam sodium and dazomet and their influence on yield and quality of daughter plants is confirming the feasibility of these fumigants for strawberry nursery management.     

Are traditional neem extract preparations as efficient as a commercial formulation of azadirachtin A?

Neem seeds contain many substances with insecticidal properties, the main insecticidal ingredient being azadirachtin A. In developing countries such as Mali, a neem seed water extract is prepared by soaking ground seeds in water for three or seven days. The aim of this study was to check the effectiveness of this extract in terms of azadirachtin A extraction yield and insecticidal activity. The yield of extraction was 0.19 g azadirachtin A/100 g seeds. The concentration of azadirachtin A in the seed extract was approximately 200 mg l⁻¹, eight times higher than the recommended concentration of commercial products (25 mg l⁻¹). A comparison of the extractive capacity of different solvents indicated that the best solvents were water and methanol. The azadirachtin A concentration declined in extracts stored for more than 3 days at a temperatures higher than 30 °C. Bioassays were performed on target insects (the leafhopper Macrosteles quadripunctulatus, the moth Spodoptera littoralis and the tobacco whitefly Bemisia tabaci) in order to compare the insecticidal activity of the neem extract with that of the commercial product Neemazal T/S and of a solution of pure azadirachtin A. The bioassays conducted on the leafhopper and the moth demonstrated that the neem extract at the recommended concentration (25 mg l⁻¹ active ingredient) was as effective as the azadirachtin-based commercial product at the same concentration, while for the control of the whitefly B. tabaci a higher concentration of the water extract was needed.     

Fumigant persistence and emission from soil under multiple field application scenarios

Chemical fumigants are routinely used for soil disinfestation of high value crops. Good agricultural practices (GAPs) are needed to reduce their human health risks, environmental impacts, and improve their cost-effectiveness. This study investigated the effect of fumigant application methods on soil persistence and emission of 1,3-dichloropropene (1,3-D) and chloropicrin (CP). Field experiments were conducted to measure the individual and combined effects of pre-application tillage practices, fumigant application technology, and plastic films on 1,3-D soil concentrations to obtain a numerical index (CT value) to estimate their potential for pest control efficacy and to compare soil persistence, atmospheric flux rate, and cumulative emission of CP and 1,3-D under two diverse application scenarios. Greater 1,3-D soil vapor concentrations were observed by combining a pre-application soil seal with low soil disturbance application technology when compared to pre-application soil tillage and the use of back-swept application shanks. Under high density polyethylene plastic, the low disturbance scenario resulted in time weighted exposure concentration (CT) values ranging from 6.8 to 12.2 μg h cm⁻³ of soil as compared to CT values ranging from 2.9 to 5.4 μg h cm⁻³ under the conventional application scenario. Cumulative atmospheric emission of 1,3-D was decreased by 18% under the low disturbance scenario and atmospheric emission of CP by 21% when compared to a conventional application scenario. This study identified GAPs that can be readily implemented in the field to reduce the human and environmental impacts of soil fumigants and improve their cost-effectiveness under solid-tarp (broadcast) applications.     

Repellency of dimethyl disulfide to Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) under laboratory and field conditions

The mirid bug, Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae), is a major pest of cotton, fruit trees, and many other crops in China. While previous trials have found relatively low infestation levels of A. lucorum in fields treated with the acaricide dimethyl disulfide (DMDS), its mode of action has not been determined. In this study, we assessed the insecticidal and repellent action of DMDS against A. lucorum under laboratory and field conditions. DMDS did not cause mortality of A. lucorum adults or nymphs at concentrations of 10.6 and 170.9 mg a.i./1. In Y-tube olfactometer tests, both male and female A. lucorum adults preferred clean air over DMDS odors. In choice and no-choice cage trials, feeding damage and the number of A. lucorum eggs were lower on mungbean plants treated with DMDS than on control plants. Under field conditions, adult A. lucorum density was lower in DMDS-treated mungbean and cotton fields than in untreated fields, and this effect lasted 6 d, but nymph populations were not affected. Under field conditions, adult A. lucorum were repelled at a distance of up to 6 m from DMDS-sprayed cotton plants for 6 d after application. This study demonstrates the non-lethal repellent action of DMDS against adult A. lucorum and suggests its potential inclusion in integrated pest management (IPM) schemes.     

Effects of microcosm scaling and food resources on growth and survival of larval Culex pipiens

Background  

We used a simple experimental design to test for the effects of microcosm scaling on the growth and survival of the mosquito, Culex pipiens. Microcosm and mesocosm studies are commonly used in ecology, and there is often an assumption that scaling doesn't affect experimental outcomes. The assumption is implicit in the design; choice of mesocosms may be arbitrary or based on convenience or cost. We tested the hypothesis that scale would influence larvae due to depth and surface area effects. Larvae were predicted to perform poorly in microcosms that were both deep and had small openings, due to buildup of waste products, less exchange with the environment, and increased competition. To determine if the choice of scale affected responses to other factors, we independently varied leaf litter quantity, whose effects on mosquitoes are well known.     

Mating rhythms of Drosophila: rescue of tim01 mutants by D. ananassae timeless

Background  

It is reported that the circadian rhythms of female mating activity differ among Drosophila species and are controlled by an endogenous circadian clock. Here, we found that the mating rhythm of D. ananassae differed from that of D. melanogaster. Moreover, to evaluate the effect of clock gene products on mating activities, we examined the mating activity of D. melanogaster timeless (tim ⁰¹) transgenic fly harboring heat-shock promotor driven-D. ananassae timeless (tim) gene (hs-AT tim ⁰¹).     

CLOCK is suggested to associate with comorbid alcohol use and depressive disorders

Background  

Depression and alcohol abuse or dependence (AUD) co-occur in the general population more frequently than expected by chance. Alcohol use influences the circadian rhythms generated by the central pacemaker in the suprachiasmatic nucleus, and circadian rhythm alterations in turn are common in depressive disorders as well as among persons addicted to alcohol.     

Clock mutation affects circadian regulation of circulating blood cells

Background  

Although the number of circulating immune cells is subject to high-amplitude circadian rhythms, the underlying mechanisms are not fully understood.     

Measuring specialization in species interaction networks

Background  

Network analyses of plant-animal interactions hold valuable biological information. They are often used to quantify the degree of specialization between partners, but usually based on qualitative indices such as 'connectance' or number of links. These measures ignore interaction frequencies or sampling intensity, and strongly depend on network size.     

Insecticidal activities of crude extracts and phospholipids from Chenopodium ficifolium against melon and cotton aphid, Aphis gossypii

Several organic solvent extracts of Chenopodium ficifolium were tested for their insecticidal activity against melon and cotton aphid, Aphis gossypii, on cucumber plants. Both methanol and ethanol extracts, at 5000 μg ml⁻¹, were highly active giving over 80% control. The other crude extracts displayed moderate or weak insecticidal activity giving control in the range of 16–69%. Two phospholipids were isolated as insecticidal active substances from C. ficifolium. Their chemical structures were identified as 1-palmitoyl-2-(3-trans)-hexadecenoyl-sn-glycero-3-phosphoglycerol and 1-palmitoyl-2-linoleoyl-3-glycerophosphocholine by GC–MS, EDS, mass and NMR spectral analyses. Both compounds displayed a dose-dependent mortality of A. gossypii. Furthermore, the liquid formulation that was obtained by partitioning with n-hexane from the methanol extract of C. ficifolium controlled melon and cotton aphid on cucumber plants effectively. These results indicate that extracts of C. ficifolium have potential for development as botanical insecticides for controlling A. gossypii infesting cucumber plants.     

Simrank: Rapid and sensitive general-purpose k-mer search tool

Background  

Terabyte-scale collections of string-encoded data are expected from consortia efforts such as the Human Microbiome Project . Intra- and inter-project data similarity searches are enabled by rapid k-mer matching strategies. Software applications for sequence database partitioning, guide tree estimation, molecular classification and alignment acceleration have benefited from embedded k-mer searches as sub-routines. However, a rapid, general-purpose, open-source, flexible, stand-alone k-mer tool has not been available.     

Insecticidal effect of two novel pyrrole derivatives against two major stored product insect species

Several pyrrole compounds exhibit insecticidal properties against a wide range of insect pest species. In the present work, the insecticidal effect of the two new pyrrole derivatives, ethyl 3-(benzylthio)-4,6-dioxo-5-phenyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrrole-carboxylate (3i) and isopropyl 3-(benzylthio)-4,6-dioxo-5-phenyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrrole-carboxylate (3k) were studied as stored-grain protectants (maize and barley) against two major stored-product insect species, the confused flour beetle, Tribolium confusum Jaquelin du Val (Coleoptera: Tenebrionidae) adults and larvae and the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) larvae at three doses (0.1, 1 and 10 ppm) and five exposure intervals (1, 2, 7, 14 and 21d). All T. confusum adults were dead at all doses on barley treated with 3i after 21d of exposure, while for 3k mortality was >92%. Progeny production was very low (≤1 individual per vial) at all doses for both pyrrole derivatives. Mortality of T. confusum larvae was not complete with any dose of both pyrrole derivatives but it exceeded 96% with 3k at 10 ppm after 21d of exposure on maize. For barley, all exposed larvae were found dead at all doses of both pyrrole derivates after 7d of exposure. Mortality of E. kuehniella larvae was complete at 1 and 10 ppm of 3i and all doses of 3k at 7d of exposure. After 14d of exposure, all E. kuehniella larvae were dead at 0.1 ppm of 3i. The results of the present study indicate that the tested compounds have elevated insecticidal effect against both species tested on certain combinations of dose, exposure interval and type of commodity.     

Wildlife reintroduction: considerations of habitat quality at the release site

Background  

Assessing the suitability of a habitat prior to the release of animals is vital. Proper assessment of the flora will allow reintroduction programmes to determine whether the area will be capable of supporting the released animals in the long-term. Here data are presented from an island in Central Kalimantan, Indonesia which has been used as a release site for agile gibbons (Hylobates agilis albibarbis) since January 2003.     

Insomnia in chronic renal patients on dialysis in Saudi Arabia

Background  

Studies have shown that insomnia is a common sleep disorder among patients with end-stage renal disease (ESRD). This study aimed to assess the prevalence of insomnia in Saudi patients with ESRD who are on maintenance dialysis.     

Cytochrome P450 diversity and induction by gorgonian allelochemicals in the marine gastropod Cyphoma gibbosum

Background  

Intense consumer pressure strongly affects the structural organization and function of marine ecosystems, while also having a profound effect on the phenotype of both predator and prey. Allelochemicals produced by prey often render their tissues unpalatable or toxic to a majority of potential consumers, yet some marine consumers have evolved resistance to host chemical defenses. A key challenge facing marine ecologists seeking to explain the vast differences in consumer tolerance of dietary allelochemicals is understanding the biochemical and molecular mechanisms underlying diet choice. The ability of marine consumers to tolerate toxin-laden prey may involve the cooperative action of biotransformation enzymes, including the inducible cytochrome P450s (CYPs), which have received little attention in marine invertebrates despite the importance of allelochemicals in their evolution.     

Efficacy of fumigant treatments and inoculum placement on control of Macrophomina phaseolina in strawberry beds

Soil disinfestation is one of the main concerns of strawberry growers. The phased-out of methyl bromide (MeBr) and the lack of equally effective fumigants has increased the difficulty in controlling soilborne pathogens such as Macrophomina phaseolina, causal agent of charcoal rot. Soil fumigant treatments were tested in Dover, Florida during the 2012–13, 2013–14 and 2014–15 seasons. The treatments included MeBr as a standard and common alternatives such as chloropicrin (PIC), 1,3-dichloropropene (1,3D), dimethyl disulfide (DMDS), potassium N-methyldithiocarbamate (Kpam) and sodium methyldithiocarbamate (Vapam). The efficacy of different fumigation rates and application methods was also investigated. Treatment effects were evaluated using sclerotia of M. phaseolina buried in bags 7.6 and 20.3 cm deep in the center of the bed, or 7.6 cm deep on the side of the bed (7.6 s). Additionally, strawberry crowns infected with M. phaseolina were buried 7.6 cm deep in the center of the bed during the 2012–13 and 2013–14 growing seasons. At the end of the 2013–14 and 2014–15 growing seasons, plant mortality and charcoal rot incidence (%) were also determined. Except for 1,3-dichloropropene:chloropicrin 39/60, most treatments were effective in reducing the colony forming units (CFUs) of M. phaseolina in buried bags or crowns buried at the center of the bed and reduced percent of charcoal rot incidence each season. Most treatments applied by shank produced similar reductions in inoculum levels at the center and sides of the bed, whereas drip treatments effectively reduced inoculum in bags buried at both depths in the center of the bed, but not at the side of the bed. Thus, one of the main problems of the current fumigants is poor distribution in the soil beds and strawberry growers should consider application methods that will achieve a more uniform distribution of the fumigants.     

3种熏蒸剂对椰心叶甲的熏蒸效果及寄主切叶的影响

分别利用磷化钙、3%高效氯氰菊酯烟雾剂(烟魁)和溴甲烷3种熏蒸剂熏蒸处理椰心叶甲[Brontispalongissima(Gestro)]各虫态及散尾葵切叶,观察椰心叶甲各虫态的死亡情况和对散尾葵叶片的影响.结果表明:烟魁使用时灼伤散尾葵切叶,不适合处理散尾葵切叶.其他2种熏蒸剂对切叶没有明显影响,影响熏蒸剂对椰心叶甲各虫态致死的主要因素是熏蒸剂的浓度和熏蒸时间.磷化钙处理而言,其分解为磷化氢气体需要时间,需要熏蒸24 h,使用0.3 mg/m~3即可达到完全杀死椰心叶甲的目的;而对于溴甲烷处理而言,用量相对较大,但熏蒸时间较短,20g/m~3的浓度2 h才可以满足生产上对椰心叶甲除害的需要.研究结果对处理棕榈植物鲜切叶或苗木有重要的借鉴意义.     

The role of soil factors and leaf protein in the utilization of mopane plants by elephants in northern Botswana

Background  

Mopane (Colophospermum mopane) plants form monotypic woodlands that cover extensive areas in northern Botswana. Mopane is also a principal food item in the diet of elephants. Obtrusive damage to mopane plants as a result of elephant feeding may alter the structure of mopane woodlands. Some mopane woodland areas in northern Botswana are subjected to heavy elephant utilization rates whereas other mopane areas are less affected. However, the underlying reason for the concentrated elephant utilization is unknown.