The virulence of eight isolates of Metarhizium anisopliae and four isolates of Beauveria bassiana (Ascomycota: Hypocreales) to adult Cylas puncticollis (Coleoptera: Curculionidae) was tested in the laboratory. Insects were sprayed with a standard concentration of 1.0 × 107 conidia mL−1 using Burgerjon’s spray tower. All the isolates tested were pathogenic to C. puncticollis. Mortality varied between 77.5% and 84.2% with isolates of B. bassiana and between 62.5% and 89.2% with isolates of M. anisopliae, 26 days post‐treatment. The lethal time to 50% mortality for the 12 isolates varied between 9.7 and 18.5 days. Four isolates, M. anisopliae International Centre of Insect Physiology and Ecology (ICIPE) 18 and ICIPE 62 and B. bassiana ICIPE 275 and ICIPE 114 were selected for dose–response mortality [lethal concentration to 50% mortality (LC50)] bioassays. Five concentrations (1.0 × 106, 3.0 × 106, 1.0 × 107, 3.0 × 107 and 1.0 × 108 conidia mL−1) of both fungal species were used. B. bassiana ICIPE 275 was the most active isolate with LC50 value of 0.7 × 106 conidia mL−1. The effect of fungal infection on feeding, fecundity and egg viability of C. puncticollis adult females was also investigated under laboratory conditions. M. anisopliae isolate ICIPE 18 and B. bassiana isolate ICIPE 114 were tested for feeding experiment using six concentrations (0, 1.0 × 106, 3.0 × 106, 1.0 × 107, 3.0 × 107 and 1.0 × 108 conidia mL−1). For reproduction potential (fecundity and egg viability) bioassays, five concentrations (0, 1.0 × 106, 3.0 × 106, 1.0 × 107 and 3.0 × 107 conidia mL−1) of M. anisopliae isolate ICIPE 18 were used. Adult sweet potato weevils (SPWs) treated with M. anisopliae at the concentrations of 3.0 × 107 and 1.0 × 108 conidia mL−1 consumed significantly less food than weevils in the control and B. bassiana treatments at all the concentrations, except at the higher concentration of 1.0 × 108 conidia mL−1, 14 days post‐treatment. Female weevils in the control treatments laid more eggs than fungus‐treated females. Percentage egg viability differences between controls and fungus treatments were significant at all the concentrations tested, 10 days post‐treatment. These results show that B. bassiana and M. anisopliae are pathogenic to SPWs and infection can reduce feeding, fecundity and egg viability.

A field experiment was carried out in 2004 and 2005 to identify the diversity of sunflower (Helianthus annuus L.) pollinators and their influence on seed yield in Makueni district, a semi-arid area in Eastern Kenya. Insect flower visitors were recorded, pollen counted from their body and pollination efficiency index for each visitor determined. Seed yield from plots where insect visitors had access to and where they were denied access was compared. The proportional difference of yield from this pollination scenario was used to estimate monetary net-gain by farmers that could be attributed to insect pollination. In total, individuals belonging to 14 insect species were observed visiting sunflower floral heads. These included six Lepidopteran species, five Hymenopteran species, two Dipteran species, and one Coleopteran species. Apis mellifera L. was the most frequent visitor and had the highest pollination efficiency index. Plots where insect visitors had access produced on average 53% more seed yield compared with plots where insect visitors were excluded. This translates to a net monetary benefit of 51% of the total annual market value of sunflower, accruing to farmers in Makueni district in 2005 due to insect pollination.Additional key words: Apis mellifera, non-Apis bees, pollination efficiency index, pollination value. Resumen Diversidad de polinizadores de girasol y sus efectos en el rendimiento de semillas en el Distrito Makueni, este de KeniaSe condujo un experimento de campo entre 2004 y 2005 para determinar la diversidad de polinizadores de girasol (Helianthus annuus L.) y su influencia en el rendimiento de semillas en el distrito Makueni, una región semi-árida del Este de Kenia. Se identificaron los insectos vectores de polinización y se contó el polen adherido a sus cuerpos, a fin de determinar el índice de eficiencia de polinización de cada especie. Se comparó el rendimiento de semillas entre las parcelas visitadas y no visitadas por los vectores de polinización. Se estimó la ganancia monetaria neta de los campesinos atribuida a la polinización por insectos. En total, se observaron 14 especies de insectos visitando girasoles, que incluyeron 6 especies de Lepidópteros, 5 de Himenópteros, 2 de Dípteros y un Coleóptero. Apis mellifera L. fue la especie visitante más frecuente y obtuvo el mayor índice de eficiencia de polinización. Las parcelas a las que los insectos tuvieron acceso produjeron como promedio un 53% más semillas que las parcelas de las que los insectos fueron excluidos. Esto implica un beneficio monetario neto del 51% del valor total del mercado anual de girasol, debido a polinización por insectos, para los campesinos del distrito Makueni en 2005.Palabras clave adicionales: abejas no Apis, Apis mellifera, índice de eficiencia de polinización, valor de la polinización.

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A survey for entomopathogenic nematodes in the central Rift valley region of Kenya was conducted at altitudes between 1800 and 3000 m above sea level and from croplands and noncropland habitats. The sampling depth was 0–30 cm. GPS (global positioning system) was used to measure site positions. One hundred and twelve soil samples were collected and entomopathogenic nematodes trapped through Galleria mellonella. Entomopathogenic nematode presence was demonstrated by G. mellonella mortality and viable ones bulked through the same host. Nematode recoveries from two consecutive extractions were 30% per extraction and 52% for cumulative extractions. Recoveries from agro ecological zones ranged between 18% and 71%. Recovery frequency was higher from disturbed cropland habitats than the stable noncrop habitats. Steinernema species were more frequent than Heterorhabditis (9 : 1). Nematode occurrence clustered at 2–3% carbon and pH 5.3–6.3 with no specific pattern demonstrated from soil types. Nematode species of the two genera from high altitudes lost their culturing ability within 1 month of isolation. There was a tendency for recovering both nematode genera at the shores of water bodies. This is the first report of Steinernema yirgalemense and S. weiseri in Kenya and of S. karii in the central Rift valley region. The Heterorhabditis species has not been confirmed yet. This has widened the genetic base of entomopathogenic nematodes from Kenya. The entomopathogenic nematodes are available for developement as biological control agents of athropod pests.

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