ABSTRACT. Repellency of Euphorbia balsamifera, Lawsonia inermis, Mitracarpus hirtus andSenna obtusifolia along with permethrin powder against Sitophilus zeamais was evaluated in the laboratory at 28-32 o C and 60-75% RH. The botanicals were applied as powders, methanolic, ethanolic and aqueous extracts at the rate of 2.5, 5.0 and 10.0 x 10 4 ppm per 20 g of sorghum grains, while the permethrin powder was applied at 0.056 x 10 4 ppm. Percentage repellency was recorded at 1, 6, 12 and 24 hours after exposure (HAE). All the botanicals were found to have a repellent effect against Sitopholus zeamais at all three concentrations. The highest (82.22 ± 2.22%) repellency among the botanical powders was exhibited by 10.0 x 10 4 ppm of Euphorbia balsamifera within 24 HAE. Methanolic leaf extracts were found to be more effective than the other formulations, causing total repellency against the weevils at 10.0 x 10 4 ppm of all the botanicals, while the activities of the aqueous extracts were the least repellent (41.37 ± 7.39 to 60.14 ± 1.64%) after 24 hours of exposure. The repellent activities of the botanicals decreased with increasing exposure periods for powders and aqueous extracts, and increased with increasing duration for methanolic and ethanolic extracts. The results showed that the botanicals were good repellents against Sitopholus zeamais and could serve as stored sorghum protectants against maize weevil infestation. Grains protected with these botanicals could be used as seeds for planting. Meanwhile, studies on the toxicity of these botanicals against higher animals are recommended.

Background: Despite low rice yield levels in Tanzania, the country is the leading producer in Eastern and Southern Africa. Given that this business is dominated by smallholder farmers and that the country is endowed with extensive landscapes suitable for rice production coupled with a high domestic and foreign potential market, there is an urgent need to enhance the yield as a key to promote food security from household to national and international levels. This paper seeks to demonstrate the importance of empowering smallholder farmers as a strategy for identifying and applying improved rice husbandry technologies in a holistic and integrated manner by employing a Farmer Field School (FFS) approach. Methods: The study was conducted in two sample villages, namely Kipera Njiapanda in the Morogoro region and Bwawani Visegese in the Pwani region, where culturally and ecologically rice is grown. The FFS approach was applied with the involvement of smallholders and local authorities to develop innovative ways to increase yield and promote food security. Data and information on current rice farming practices were collected using FFS participants and qualitatively analyzed at each rice production stage. Results: Findings revealed that farmers' socioeconomic conditions varied, thus reflecting differences in farm size, crop husbandry and associated yield as well as in non-market production along with consumption and/or market exchange. The FFS approach demonstrated that community participatory processes have the capacity to create conducive conditions for empowering smallholders to identify their rice production problems and opportunities related to access to technical and financial support in the realm of seedbed preparation and irrigation, including pest and disease control and crop marketing. Conclusion: The FFS approach is a robust tool for the identification of problems/challenges as well as pertinent opportunities to increase rice yield and promote food security. The paper calls for support from development partners in managing the rice production systems at all stages in the production cycle given the current potential of both the smallholder farmers and the arable land to increase rice yield, reduce poverty and promote food security at household, national and international levels.

The sweetpotato whitefly, Bemisia tabaci (Gennadius) is the vector of the cassava mosaic geminiviruses (CMGs) that cause cassava mosaic disease (CMD). Synergistic interactions between B. tabaci and CMGs have been hypothesized as a cause of whitefly "super-abundance," which has been a key factor behind the spread of the severe CMD pandemic through East and Central Africa. The current study investigated this hypothesis by conducting experiments with CMD-susceptible cassava varieties infected with different CMGs in both the north-western Lake Zone region (pandemic affected) and the eastern Coast Zone where CMD is less severe. Male and female pairs of B. tabaci were placed in clip cages for 48 h on plants of three cassava varieties at each of the two locations. There were significantly more eggs laid on CMG-infected than on CMG-free plants in the Lake Zone, whereas in Coast Zone, there were no significant differences. There were no significant differences in proportions, mortality, and development duration of immature stages of B. tabaci among virus states and cassava variety in the two locations. The overall number of eggs was significantly higher with longer development duration of the immature stages in the Lake than in the Coast Zone, whereas mortality was significantly higher in the Coast than in the Lake Zone. Based on these results, it is concluded that there was no net positive synergistic interaction between CMGs and B. tabaci for either lowland coastal or mid-altitude inland populations. Consequently, other factors seem more likely to be the cause of the "super-abundance," and require further investigation.