Prospects for the development of odour baits to control the tsetse flies Glossina tachinoides and G. palpalis s.l.

Field studies were done of the responses of Glossina palpalis palpalis in Côte d'Ivoire, and G. p. gambiensis and G. tachinoides in Burkina Faso, to odours from humans, cattle and pigs. Responses were measured either by baiting (1.) biconical traps or (2.) electrocuting black targets with natural host odours. The catch of G. tachinoides from traps was significantly enhanced (~5×) by odour from cattle but not humans. In contrast, catches from electric targets showed inconsistent results. For G. p. gambiensis both human and cattle odour increased (>2×) the trap catch significantly but not the catch from electric targets. For G. p. palpalis, odours from pigs and humans increased (~5×) the numbers of tsetse attracted to the vicinity of the odour source but had little effect on landing or trap-entry. For G. tachinoides a blend of POCA (P = 3-n-propylphenol; O = 1-octen-3-ol; C = 4-methylphenol; A = acetone) alone or synthetic cattle odour (acetone, 1-octen-3-ol, 4-methylphenol and 3-n-propylphenol with carbon dioxide) consistently caught more tsetse than natural cattle odour. For G. p. gambiensis, POCA consistently increased catches from both traps and targets. For G. p. palpalis, doses of carbon dioxide similar to those produced by a host resulted in similar increases in attraction. Baiting traps with super-normal (~500 mg/h) doses of acetone also consistently produced significant but slight (~1.6×) increases in catches of male flies. The results suggest that odour-baited traps and insecticide-treated targets could assist the AU-Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) in its current efforts to monitor and control Palpalis group tsetse in West Africa. For all three species, only ~50% of the flies attracted to the vicinity of the trap were actually caught by it, suggesting that better traps might be developed by an analysis of the visual responses and identification of any semiochemicals involved in short-range interaction

Tracking the Feeding Patterns of Tsetse Flies (Glossina Genus) by Analysis of Bloodmeals Using Mitochondrial Cytochromes Genes

Tsetse flies are notoriously difficult to observe in nature, particularly when populations densities are low. It is therefore difficult to observe them on their hosts in nature; hence their vertebrate species can very often only be determined indirectly by analysis of their gut contents. This knowledge is a critical component of the information on which control tactics can be developed. The objective of this study was to determine the sources of tsetse bloodmeals, hence investigate their feeding preferences. We used mitochondrial cytochrome c oxidase 1 (COI) and cytochrome b (cytb) gene sequences for identification of tsetse fly blood meals, in order to provide a foundation for rational decisions to guide control of trypanosomiasis, and their vectors. Glossina swynnertoni were sampled from Serengeti (Tanzania) and G. pallidipes from Kenya (Nguruman and Busia), and Uganda. Sequences were used to query public databases, and the percentage identities obtained used to identify hosts. An initial assay showed that the feeds were from single sources. Hosts identified from blood fed flies collected in Serengeti ecosystem, included buffaloes (25/40), giraffes (8/40), warthogs (3/40), elephants (3/40) and one spotted hyena. In Nguruman, where G. pallidipes flies were analyzed, the feeds were from elephants (6/13) and warthogs (5/13), while buffaloes and baboons accounted for one bloodmeal each. Only cattle blood was detected in flies caught in Busia and Uganda. Out of four flies tested in Mbita Point, Suba District in western Kenya, one had fed on cattle, the other three on the Nile monitor lizard. These results demonstrate that cattle will form an integral part of a control strategy for trypanosomiasis in Busia and Uganda, while different approaches are required for Serengeti and Nguruman ecosystems, where wildlife abound and are the major component of the tsetse fly food source

Symmetry Group Approach to the Solution of Generalized Burgers Equation: U t + UU x = λU xx

Abstract Symmetry of a system of differential equations is a transformation that maps any solution to another solution of the system. In Lie's framework such transformations are groups that depend on continuous parameters and consist of point transformations (point symmetries), acting on the system's space of independent and dependent variables, or, more generally, contact transformations (contact symmetries), acting on independent and dependent variables as well as on all first derivatives of the dependent variables. Lie groups, and hence their infinitesimal generators, can be naturally prolonged to act on the space of independent variables, dependent variables, and derivatives of the dependent variables. We present a Lie symmetry approach in solving Burgers Equation:U t + UU x = λU xx which is a nonlinear partial differential equation, which arises in model studies of turbulence and shock wave theory. In physical application of shock waves in fluids, coefficient λ, has the meaning of viscosity. So far in both analytic and numerical approaches the solutions have only been established for 0 ≤ λ ≤ 1. In this paper, we give a global solution to the Burgers equation with no restriction on λ i.e. for λ ∈ (−∞, ∞)

BIOACTIVITY OF OCIMUM AMERICANUM L. ESSENTIAL OILS AGAINST FOUR INSECT PESTS OF STORED FOOD COMMODITIES

Laboratory studies were conducted to evaluate the fumigant and repellent properties of Ocimum americanum L. essential oils against adult Sitophilus oryzae L., Rhyzopertha dominica F., Tribolium castaneum (Herbst) and Callosobruchus chinensis F. Each essential oil was tested at four (0, 1, 5, 10 µl/L air) and five (0, 0.5, 1.0, 1.5, 2.0 µl oil/ g grain) rates in space fumigation and choice bioassay studies, respectively, with four replicates per treatment. Corrected percent mortality and PR were arcsine transformed before ANOVA and means separated by Tukey’s HSD test [1, 2]. Dose-responses were further subjected to Probit analysis and LC50 values computed [3]. Leaf essential oil at 10 µl/L air 24 h after treatment, caused 88.8, 87.5, 11.3 and 100% adult mortality of S. oryzae, R. dominica, T. castaneum and C. chinensis, respectively (LC50 values of 0.38, 0.49, NS and 0.18 µl/L air, respectively). The LC50 values varied with plant part assayed. Leaf essential oil was most efficacious (LC50 values: 0.18-0.49 µl/L air) followed by fruit (1.15-15.07 µl/L air) and stem (3.70-34.68 µl/L air) essential oils, respectively. In the choice bioassay studies, fruit essential oil (at 2.0 µl oil/ g grain and 24 h) produced highest PR values of 81 and 94% against S. oryzae and R. dominica, respectively. Similarly, the leaf oil repelled 51 and 83% of T. castaneum and C. chinensis, respectively. Clear intra-species variations in essential oil compositions and inter-insect species differences form the basis of differential bioactivity observed. Leaf oil was high in monoterpenes whereas stem and fruit oil were high in sesquiterpenes. Results show that plant volatiles are potential alternative grain fumigants and further validation studies required for compatibility with tropical agriculture. Refrerences: [1] Rajendran, S. and Muralidharan, N. Effectiveness of allyl acetate as a fumigant against five stored grain beetle pests. Pest Management Science 61: 97-101 (2005). [2] Rozman et al. Toxicity of naturally occuring compounds of Lamiaceae and Lauraceae to three stored-product insects. Journal of Stored Products Research 43(4): 347-355 (2007). [3] Finney, D.J. Probit Analysis, 3rd ed. Cambridge Univ. Press, London (1971)

QUALITY, EFFICACY AND SAFETY OF PHYTOMEDICINES AND PHYTOCOSMETICS

Laboratory studies were conducted to evaluate the fumigant and repellent properties of essential oils extracted from the leaves of Ocimum americanum L. against five storage insects, Sitophilus oryzae L., Rhyzopertha dominica F., Tribolium castaneum (Herbst) and Callosobruchus chinensis F. Each essential oil was tested at four (0, 1, 5 and 10 µl/L air) and five (0, 0.5, 1.0, 1.5 and 2.0 µl oil/ g grain) rates in space fumigation and choice bioassay studies, respectively, with four replicates per treatment. In space fumigation studies, leaf essential oil at 10 µl/L air 24 h after treatment, caused 88.8, 87.5, 11.3 and 100% kill of S. oryzae, R. dominica, T. castaneum and C. chinensis insects, respectively, whose corresponding LC50 values were 0.38, 0.49, NS and 0.18 µl/L air, respectively. The LC50 values varied with plant part from which the essential oil was extracted. Leaf essential oil was most efficacious (0.18-0.49 µl/L air) followed by fruit (1.15-15.07 µl/L air) and stem (3.70-34.68 µl/L air) essential oils, respectively. In the choice bioassay studies, fruit essential oil (at 2.0 µl oil/ g grain and 24 h) produced highest repellence against S. oryzae and R. dominica with PR values of 81 and 94%, respectively. Under the same conditions, the leaf essential oil had PR values of 51 and 83% against adult T. castaneum and C. chinensis insects, respectively. Results of this study demonstrate the potential use of plant volatiles as alternatives to the synthetic fumigants and their applicability for preservation of stored food commodities in subsistence agriculture. Key words: Callosobruchus chinensis, Oryzaephilus surinamensis, Rhyzopertha dominica, Sitophilus oryzae, Tribolium castaneum, Ocimum americanum, Essential oil, Fumigant toxicity, Repellence, *Corresponding author: Email: [email protected] (J.O. Ogendo) Fax: +254-51-62145/62442 Cell phone: +254-722-892504; +254-738-41221