The need for sustainable intensification in Eastern and Southern Africa (ESA) is widely recognized as a requirement to achieve food security with minimum negative social and environmental consequences. In current Research & Development programs, much emphasis is placed on increasing the efficiency with which land, water and nutrients are used, whereas farm power appears to be a 'forgotten resource'. This is a major concern when farm power in ESA countries is declining due to the collapse of most tractor hire schemes, the decline in number of draught animals and the growing shortage of human labour. A consequence of low levels of farm mechanization is high labour drudgery, which makes farming unattractive to the youth and disproportionally affects women. Undoubtedly, sustainable intensification in ESA will require an improvement in access to farm power. In this paper, we suggest this can be achieved through the use of small, multipurpose and inexpensive power sources such as two-wheel tractors (2WTs) coupled with the promotion of energy saving technologies such as conservation agriculture (CA), whilst ensuring the profitability for farmers, service providers and other private sector actors in the supply chain. We argue that appropriate mechanization in Africa, a paradigm largely abandoned three decades ago, may be re-examined through the combination of these three elements.

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Hatching experiments were carried out on a population of Brachionus plicatilis (Dor strain) resting eggs produced in batch laboratory cultures under controlled conditions and then stored for at least one month at 4 ° C in the dark . Light was found to be obligatory for termination of dormancy . Over the temperature range of 10-30 ° C (at 9 .0% 0 salinity), hatching was optimal (40-70%) at 10-15 ° C and decreased linearly with the rise in incubation temperature . Resting eggs incubated over a salinity range of 9-40% 0 (at 15 °C) showed optimal hatching at 16% 0 . Incubation of resting eggs in distilled water permitted normal embryonic development, but neonates died at eclosion . Presence of algae, Chlorella stigmatophora (0 .5 X 106 cell ml -1 ), was found to aid hatching .

Free-living nematodes-Panagrellus sp., Turbatrix aceti, Caenorhabditis elegans and C.hriggsae-were each fed to the fish Danio sp. and the process of their digestion, in the fish alimentary canal, was studied by light and electron microscope.Almost no identifiable nematodes were found in the fish gut when the digestion period was 3 h or more, except for buccal capsules of the four studied species, males' spicules of Panagrellus sp. and Turbatrix aceti and egg-capsules of the Caenorhabditis species. These structures could serve as indicators that the nematodes had been preyed on and digested by the fish.Differences in the mode of digestion were noticed between the various species of nematodes studied, after a period of0.5-I h, in the fish gut. In Panagrellus sp. and T. aceti disintegration of the soft inner tissues occurred mostly at the anterior or posterior ends of the nematode's body, while in Caenorhabditis the majority of digested nematodes were affected at both ends or evenly along the entire body. Digestion seemed to be initiated mostly at the nematodes' body apertures: mouth, anus or cloaca, and vulva which could be due to a more vulnerable cuticle around those areas. Disintegration proceeded from the soft inner parts to the more resistant cuticle that was finally disintegrated. Ofthe three layers of cuticle the most resistant were the external cortex and the basal layers.