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The diversity and abundance of natural enemies of insect pests is often higher in agroforestry plantations than in sun-exposed monocultures, and it is often assumed that this will lead to improved pest suppression. The effect that incorporating trees in cropping systems will have on pest populations, however, also depends on the habitat requirements of the pests themselves. In Eastern Uganda, we studied how shade level (full [50 trees per acre, moderate 21-50 trees per acre, and low 0-20 trees per acre) and altitude (high 1,717-1,840 m.a.s.l. and low 1,511-1,605 m.a.s.l.) influenced the abundance of the white stem borer Monochamus leuconotus and the coffee berry borer Hypothenemus hampei. We found that the effect of shade trees differed between the two pest species. The coffee berry borer was more common on sun-exposed plantations, whereas the white stem borer was more common in shaded plantations. Furthermore, the effect of shade level on the white stem borer depended on altitude, with the differences between shade levels being most pronounced in plantations at low altitudes. This implies that the impact of agroforestry on pest regulation both under current conditions and in a global warming scenario will be highly context dependent; it will depend on the identity of the most important pests in the area, and on environmental factors such as altitude.Keywords Agroforestry Á Climate change Á Hypothenemus hampei Á Monochamus leuconotus Á Sunexposure Á Uganda Key message• We studied how agroforestry influenced infestations of two key coffee pests in Uganda: the coffee berry borer and the white stem borer. • Agroforestry decreased incidence of coffee berry borers, but increased white stem borers. • The effect of agroforestry on the white stem borer was larger at low altitudes. • The overall impact of agroforestry on pest regulation will therefore be context dependent; it will depend on the identity of the most important pests in an area, and on environmental factors such as altitude.

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Efforts to promote sustainable production and processing of Ruspolia differens Serville (Orthoptera: Tettigoniidae) as a viable agribusiness model for enhancing food and nutrition security have gained momentum. However, the inexistence of rearing techniques adapted to this insect creates uncertainty regarding the effectiveness of up-scaling production. This study evaluated the effect of five temperatures (26, 28, 30, 32 and 34 °C) on egg development time, percentage hatchability and nymphal weight at hatching. It also evaluated the average weekly wet weight attained by R. differens and percentage survival during growth when reared at 30 °C on four different food plant diets. The diets composed of (1) star grass Cynodon dactylon (L.) Pers.; (2) wild millet Eleusine indica (L.) Gaertn.; (3) guinea grass Panicum maximum Jacq.; and (4) a mixture of the three food plants. The highest hatchability (89.33±3.06%) was observed for egg clusters that were not detached from the leaf sheaths and incubated at 30 °C. At the same temperature, the hatchability of eggs detached from the leaf sheath was 43.33±4.16%. The wet nymphal weight at hatching varied significantly across the different incubation temperatures. For eggs that were not detached from the leaf sheath, it ranged between 3.12±1.20 mg at 30 °C to 4.15±0.98 mg at 34 °C, while for eggs that were detached, it ranged between 2.96±1.14 at 32 °C to 6.0±2.0 mg at 26 °C. The highest wet nymphal weight (586.4 mg) and growth rate (10.47 mg/day) of adult R. differens after 8 weeks was recorded on wild millet, followed by the mixture of the three food plants (553.7 mg; 9.9 mg/day). Food plants significantly influenced survival of nymphs, with C. dactylon and P. maximum associated with the highest survival rate (53.3%). These findings are central to upscaling R. differens production.

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