Abstract: The spider mites Tetranychus urticae Koch and Tetranychus evansi Baker and Pritchard are important pests of horticultural crops. They are infected by entomopathogenic fungi naturally or experimentally. Fungal pathogens known to cause high infection in spider mite populations belong to the order Entomophthorales and include Neozygites spp. Studies are being carried out to develop some of these fungi as mycoacaricides, as standalone control measures in an inundative strategy to repla...
Abstract: A two-host–two-parasitoid model was constructed to assess the effects of the introduced larval parasitoid, the braconid Cotesia flavipes, on its primary target host, the invasive crambid Chilo partellus, and on secondary host species, in inter-specific competition with Cotesia sesamiae, the main native parasitoid species of stemborers in Kenya. The model assumed that: (1) there was no host iscrimination by either parasitoid species; (2) Cotesia flavipes was the superior competito...
Abstract: The stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is a major pest of maize,Zea mays L.,and sorghum,Sorghum bicolor (L.) Moench (both Poaceae), in sub-Saharan Africa. Like in many other lepidopteran insects, the success of B. fusca in recognizing and colonizing a limited variety of plants is based on the interaction between its sensory systems and the physicochemical characteristics of its immediate environment. The sensilla on the maxillary galeae of B. fusca larvae a...
Abstract: The susceptibility of third instar Helicoverpa armigera to seven strains of three entomopathogenic fungal species, i.e. Metarhizium anisopliae, Beauveria bassiana and Paecilomyces fumosoroseus , was tested under laboratory conditions using the larval immersion method. High efficacies ranging from 68 to 100% corrected mortality were recorded with more profound effects in treatments with B. bassiana and P. fumosoroseus strains. The median lethal concentration (LC50) for L3 was 6.0 10...
Abstract: Diachasmimorpha longicaudata (Ashmead), a solitary koinobiont larval– prepupal endoparasitoid of fruit flies, was introduced into Kenya for testing and final release against the recently discovered invasive species, Bactrocera invadens Drew, Tsuruta and White in Africa. Laboratory experiments were conducted to determine host preference, host acceptability for oviposition and physiological suitability of B. invadens and five other indigenous tephritid fruit fly species – Ceratit...
Abstract: A survey was carried out between 2005 and 2006 in two ecologically different localities, Suam and Mtito Andei, to assess diversity and abundance of wild host plants of lepidopteran stem borers during the cropping and non-cropping seasons. Suam in western Kenya is situated in the moist high tropics and is characterised by an Afromontane vegetation mosaic, while Mtito Andei is located in the dry mid-altitudes characterised by a Somalia Masai vegetation mosaic. In Suam, wild host plan...
Abstract: In response to emerging interest in commercial mass production of Trichogramma for Helicoverpa armigera biocontrol in eastern Africa, laboratory experiments were undertaken to assess the scope for genetic enhancement of the parasitisation potential of native strains of the local common trichogrammatid species, Trichogrammatoidea sp. nr. lutea . Four promising strains (ex-Kilifi Kilifi District, ex-Kwa Chai Kibwezi District, ex-Rarieda Bondo District and ex-Ebuhayi, Kakamega Distric...
Abstract: A liquid diet for rearing Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) was developed. Several yeast-based products were evaluated as diet ingredients, and a combination of whole cell yeast (LBI2240) and hydrolyzed yeast (such as FNILS65) in 1:1Ð3:1 ratio was selected for use in the study. Larvae reared in a liquid diet with LBI2240:FNILS65 ratios of either 1:1 or 3:1 resulted in the same pupal recovery as to those reared in the conventional mill fee- based control diet. L...
Abstract: Controlled crosses in bambara groundnut were attempted between a range of thirty-six bambara groundnut landraces (thirty domesticated (V. subterranea var. subterranea) and six wild (V. subterranea var. spontanea)). Ten F1 seed were produced. Of these, eight germinated producing F2 populations. On seed set, four populations could be unambiguously confirmed as true crosses by F3 seed coat colour. A single F2 population, derived from a domesticated landrace from Botswana (DipC; female...
Abstract: Bactrocera invadens Drew, Tsuruta & White (Diptera: Tephritidae), an invasive fruit ßy species of Asian origin, was detected in Kenya in 2003, and is now well established in several parts of the country. We assessed the host range of this major quarantine pest in Kenya by collecting a wide range of cultivated and wild host plants from December 2004 to April 2006. Fruit were collected from 90 plant species representing 40 families from the Coast, Eastern, and Rift Valley provinces ...
Abstract: The development, survival and reproductive potential of diamondback moth Plutella xylostella (Linnaeus) were studied at 25 ^ 1 8C in the laboratory in response to two cultivated Brassica oleracea cultivars (cabbage B. oleracea var. capitata and kale B. oleracea var.acephala) and four wild crucifer species Erucastrum arabicum, Raphanus raphanistrum,Rorippa nudiuscula and Rorippa micrantha. Rorippa micrantha was the most preferred species in oviposition choice tests, while cabbage an...
Abstract: Tetranychus evansi Baker and Pritchard and Tetranychus urticae Koch (Acari: Tetranychidae) are important pests of Solanaceae in many countries. Several studies have demonstrated that T. urticae is an acceptable prey to many predatory mites, although the suitability of this prey depends on the host plant. T. evansi, has been shown to be an unfavorable prey to most predatory mites that have been tested against it. The predator Phytoseiulus fragariae Denmark and Schicha (Acari: Phytos...
Abstract: Two correlative approaches to the challenge of ecological niche modeling (genetic algorithm, maximum entropy) were used to estimate the potential global distribution of the invasive fruit fly, Bactrocera invadens, based on associations between known occurrence records and a set of environmental predictor variables. The two models yielded similar estimates, largely corresponding to Equatorial climate classes with high levels of precipitation. The maximum entropy approach was somewha...
Abstract: The tomato red spider mite, Tetranychus evansi Baker and Pritchard, is an invasive species in Africa causing considerable damage to Solanaceous crops. The fungal pathogen Neozygites Xoridana Weiser and Muma from Brazil has been considered a potential candidate for introduction into Africa for the control of T. evansi. To be incorporated in the tomato production system, N. Xoridana has to be compatible with the pesticides used for the control of other pests and diseases. Pesticides ...
Abstract: Interspecific competition between an introduced parasitoid species aimed at controlling a herbivorous pest species and a native parasitoid parasitising the same host may influence the success of classical biological control programmes. In Kenya, interspecific competition between an introduced and a local parasitoid on two diamondback moth populations (DBM, Plutella xylostella) was investigated on two different host plants. We tested simultaneous and delayed competition of the local...