Insects Associated with Terminalia brownii Growing in Kitui, Baringo and Homa Bay Counties, Kenya: Implications on Tree Species Domestication
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Abstract
Terminalia brownii Fresen (Combretaceae) is widely grown as an agroforestry tree species in dry lowlands of Eastern-Africa. A study aimed to identify insects that interact with T. brownii in Kitui, Baringo and Homa Bay Counties of Kenya was carried to highlight the implication of these insects on domestication of T. brownii in the drylands of Kenya. Ninety T. brownii trees were randomly selected; thirty from each of the three counties and their GPS locations recorded. Baited insect traps were erected on branches of selected trees to capture visiting insects. Sweep nets and pan traps were used to capture flying insects on site at the time of trap inspection during day time. A cutting test on randomly selected immature and mature fruits was carried out. Collected data was analyzed using GENSTAT version 18 and descriptive charts were used to inform the differences in insect interactions with T. brownii. The beneficial insects encountered included Diptera (Helina spp., Musca spp. and Orthellia spp.). Gall formation was frequent in Kitui region (70%) associated with Gall Wasps attack. Defoliation in Kitui County was higher, associated with Lepidoptera attack (60%). Cerambycidae and Curculionadae larvae were found in 58% of probed mature fruits in Kitui. Of the probed seeds, 12.8% had empty endosperms implying poor pollination levels. Baringo and Homa Bay had more full seeds (73% and 77% respectively) compared to Kitui (32%). This study informs on T. brownii-insect-interactions as one of the factors that influence successful tree domestication.
Keywords: Terminalia brownii, agroforestry, domestication, insects