| dc.description.abstract | The tomato leafminer (Tuta absoluta) (Meyrick) (Lepidoptera: Gelechiidae) is an invasive
insect pest of tomato crops in many parts of Africa. It causes substantial economic losses to
tomato crops in Kenya. Majority of farmers have resulted to intensive insecticide
application that has led to development of insecticide resistance. It is therefore critical to
develop sustainable management strategies that can be used in Integrated Pest
Management (IPM) programmes against the tomato leaf miner. Genetic breeding against
the tomato leaf miner can be promising since effective cultural control is difficult. The
objective of this study was to evaluate level of resistance of popular tomato varieties to
tomato leaf miner in Kirinyaga County, Kenya. The four tomato varieties Rambo F1, Pesa
F1, RiograndeVF and Cal J were evaluated for resistance against T. absoluta under field
conditions. Mwea East Sub-County is characterised by intensive tomato production,
diverse cultural practises and high usage of synthetic pesticides against the tomato leaf
miner. The experiment was laid out in a randomized complete block design in two locations
(Kariithi and Kimbimbi), which have irrigation schemes that allows tomato production
throughout the year. Presence of mines was assessed on leaves obtained from the lower,
intermediate and upper canopy of tomato plants at days 20, 40, 60 and 80 after planting.
Fruit damage was estimated at the end of the cropping cycle. Data was subjected to arcsin
square root transformation and analysis of the level of pest damage on different tomato
varieties, was done using general linear mixed effects models, performed using the lme
function in the nlme package in R 3.4.2.The results of this study show that larvae mining
damage on the leaves was observed in all the evaluated tomato varieties, but it was
significantly higher on Pesa F1 hybrid variety (p > 0.001) than Riogrande VF and Cal J.
Fruit damage was also significantly higher on Pesa F1 variety (p > 0.01) than Riogrande
VF and Cal J. These results suggest that most of the commercially grown tomato varieties
are susceptible to T.absoluta infestation. However, Riogrande VF and Cal J can be
incorporated in IPM programs. Further studies need to be done for introgression of
resistance genes from wild varieties into cultivated tomato varieties. | en_US |
