Insect pests and beneficial arthropod populations under different hedgerow intercropping systems in semiarid Kenya

Published source details Girma H., Rao M.R. & Sithanantham S. (2000) Insect pests and beneficial arthropod populations under different hedgerow intercropping systems in semiarid Kenya. Agroforestry Systems, 50, 279-292.
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This study is summarised as evidence for the following.

	Action	Category
	Plant new hedges Action Link
	Use alley cropping Action Link

Plant new hedges

A randomised, replicated, controlled trial in 1995-1996 in Machakos, Kenya (Girma et al. 2000) found the type of hedge species affected the abundance of some but not all natural enemies and pests in bean Phaseolus vulgaris or maize Zea mays plots. During the dry season, there were more wasps (Hymenoptera) near hedges of croton Croton megalocarpus, gliricidia Gliricidia sepium, mulberry Morus alba, siamea Senna siamea and spectabilis Senna spectabilis (averaging 19-25 wasps/trap) compared to other hedge species (10-15 wasps). Spiders (Araneae) were more abundant near hedges of calliandra Calliandra calothyrsus, croton, grevillea Grevillea robusta, lantana Lantana camara and siamea than other hedge species. Hedge type did not affect ladybird (Coccinellidae) or aphid (Aphidoidea) abundance or levels of pest infestation in beans and maize. Hedges were planted 8 m upslope of 10 x 10 m plots in 1993 using nine tree/shrub species (as above, plus flemingea Flemingia macrophylla) and pruned to 0.5 m. Beans were grown in the short- and maize in the long-rain season. There were four replicates/hedge species. Two yellow pan traps and two pitfall traps were placed in each plot (one of each near the hedge, one of each 4 m away) and monitored every 10 days.
Use alley cropping

A randomised, replicated, controlled trial in 1995-1996 in Machakos, Kenya (Girma et al. 2000) found more wasps (Hymenoptera) (65 vs. 45) and spiders (Araneae) (96 vs. 71) but fewer ladybirds (Coccinellidae) (14 vs. 23) in alley cropped plots compared to conventional plots. Alley cropped plots had fewer aphids (Aphidoidea) (520 vs. 895 individuals). Maize Zea mays had lower aphid Rhophalosiphum maidis and stalk borer (maize stalk borer Busseola fusca and Chilo spp.) infestations in alley cropped than conventional plots (21% vs. 32% and 17% vs. 30% infestation, respectively). However, alley cropped beans Phaseolus vulgaris had higher beanfly Ophiomyia spp. infestation than conventional beans (35% vs. 25% plants infested). The proportion of aphid Aphis fabae infestations in beans was similar between plots (14% vs. 13%). The type of hedge species affected the abundance of some but not all pest and natural enemies studied. Hedges in alley cropped plots were planted 8 m upslope of crops in 1993 (using nine tree species) and pruned to 0.5 m. Beans were grown in the short- and maize in the long-rain season. Alley cropping was replicated 36 times and conventional cropping four times in 10 x 10 m plots. See also 'Plant new hedges'.