Sex pheromone and period gene characterization of Lutzomyia longipalpis sensu lato (Lutz & Neiva) (Diptera: Psychodidae) from Posadas, Argentina

Lutzomyia longipalpis s.l. is the primary vector of Leishmania (L.) infantum in the New World. In this study, male Lutzomyia longipalpis specimens from Posadas, Argentina were characterized for two polymorphic markers: the male sex pheromone and the period (per) gene. The male sex pheromone was identified as (S)-9-methylgermacrene-B, the same compound produced by Lu. longipalpis from Paraguay and many populations from Brazil. The analysis of per gene sequences revealed that the population from Argentina is significantly differentiated from previously studied Brazilian populations. Marker studies could contribute to the understanding of the distribution and spread of urban American visceral leishmaniasis, thus aiding in the design of regional surveillance and control strategies.     

Response of wheat genotypes to sowing date and boron fertilization aimed at controlling sterility in a rice-wheat rotation in Nepal

Spikelet sterility in wheat (Triticum aestivum L.) is emerging as a production threat in different parts of Nepal. This study was aimed at determining the effects of sowing date and boron application in controlling spikelet sterility in four different genotypes of spring wheat in a rice-wheat system in the western hills of Nepal. Four genotypes of known different responses to boron were planted on 21 November, 6 December and 21 December, 1994 with or without boron application at 1 kg B ha-1 (i.e. 9 kg borax ha-1) on a soil that was known to be deficient in boron.The effect of sowing date was significant for the phenology, yield components, percentage sterility and grain yield. Sterility was significantly increased in the crop planted on 21 December, which had also the lowest 1000 seed weight and grain yield; there was an almost 50% grain yield reduction compared to the crop planted on 21 November. Terminal moisture stress (i.e. lack of moisture during the later part of the development) was observed in the late sown crop which also amplified the extent of sterility associated with boron deficiency. Genotypes differed in response to sowing dates and boron treatment for all of the phenological events measured, yield components, grain yield and percentage sterility. SW-41 and BL-1022 had significantly higher sterility at all sowing dates. BL-1249 showed a consistently lower% sterility over all sowing dates and boron treatments. The addition of boron significantly increased the number of grains set per spike thereby decreasing the total sterility in boron responsive genotypes SW-41 and BL-1022 while those not susceptible did not respond. The boron concentration in the flag leaf at anthesis was increased in treatments with added B in the soil but genotypes did not differ in boron concentration for any soil treatment.     

山东地区药用植物染色体数目的观察(Ⅲ)

本文对17科35种药用植物体细胞染色体作了计数,并就有关的细胞学和分类学问题略作了讨论。     

Seasonal fluctuation, phenology and turnover of chafer assemblages – insight to the structural plasticity of insect communities in tropical farmlands

1 Studies on chafer assemblages were conducted on two farmland sites in the Terai lowland of Nepal (200 m above sea level) using light traps. During the course of a 2-year field monitoring program, a total of 4503 specimens was captured and an unexpectedly high number of syntopically co-occurring species was found: 52 from Gunganagar (GN) and 36 from Gaindakot (GK), respectively. Highest species abundances and species numbers were found during April and May.
2 Species occurrence was strongly correlated with air temperature and the maximum soil temperature, at least during the pre-monsoon season. However, assemblage structure from the two sites showed significant qualitative and quantitative changes seasonally, as well as from 1 year to the next. Turnover rates between adjacent months were in the range 26–62% (GN) and 37–70% (GK), whereas the turnover from 2004 to 2005 was 25.8% (GN) and 21.4% (GK) respectively.
3 When only dominant and subdominant taxa are considered, the seasonal change in species composition was even more striking.
4 Strong fluctuation in chafer assemblage over time suggests: (i) a possible influence of patchy habitat types and soil working on seasonal assemblage structure and (ii) colonization of suitable habitats (fields) in great part by chance.     

Joint modeling of DNA sequence and physical properties to improve eukaryotic promoter recognition

We present an approach to integrate physical properties of DNA, such as DNA bendability or GC content, into our probabilistic promoter recognition system McPROMOTER. In the new model, a promoter is represented as a sequence of consecutive segments represented by joint likelihoods for DNA sequence and profiles of physical properties. Sequence likelihoods are modeled with interpolated Markov chains, physical properties with Gaussian distributions. The background uses two joint sequence/profile models for coding and non-coding sequences, each consisting of a mixture of a sense and an anti-sense submodel. On a large Drosophila test set, we achieved a reduction of about 30% of false positives when compared with a model solely based on sequence likelihoods.     

Efficacy of natural products against Callosobruchus chinensis (Coleoptera: Bruchidae) in Nepal

This study was conducted to determine the efficacy of local natural products against the beetle, Callosobruchus chinensis L. (Coleoptera: Bruchidae), in stored chickpea Cicer arietinum L. (Fabaceae) in Chitwan, Nepal. Five natural products and one synthetic pesticide (Malathion) and two storage regimes (aluminum sheet bin vs. jute bags with plastic lining) were tested for their effect on stored pulse with respect to damage by C. chinensis. The five natural products included Xanthoylum armatum DC (Rutaceae) fruit powder, Acorus calamus L. (Araceae) rhizome powder, Cinnamom camphora L. (Lauraceae) balls, oil of Sesamum indicum L. (Pedaliaceae), and leaf powder of Azadirachta indica A. Juss. (Meliaceae). Treatments of stored pulses with natural products or with Malathion all caused significantly higher mortality of C. chinensis at 15 d after treatment (DAT) than stored pulses receiving no treatments. The balls of C. camphora, rhizome powder of A. calamus and sesame oil outperformed all other treatments, including the Malathion at 45 and 75 DAT and resulted in significantly reduced damage or deterioration of stored pulses compared with other treatments. Storage regimes performed similarly, although the jute bags did protect seed integrity for some treatments. Our results indicate that incorporating these natural products into stored pulses can protect the seeds from C. chinensis for up to two generations, something that Malathion cannot do. These products are readily available to most farmers in the region and their use will lead to 1) reduction of losses to significant stored product pests, and 2) a reduction of contamination of foodstuffs and the environment by synthetic pesticides like Malathion.