Research Publications
https://karuspace.karu.ac.ke/handle/20.500.12092/1797
2024-03-29T15:53:17Zpopular dynamics of megalurothrips sjostedti and frankliniela occidentalis (Thysanoptera: thripidae) in a French bean (Phaseolus vulgaris L. agroecosystem
https://karuspace.karu.ac.ke/handle/20.500.12092/3057
popular dynamics of megalurothrips sjostedti and frankliniela occidentalis (Thysanoptera: thripidae) in a French bean (Phaseolus vulgaris L. agroecosystem
Gitonga, L. M.; Lohr, B.
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Research article on megalurothrips sjostedti and frankliniela occidentalis (Thysanoptera: thripidae) in a French bean
2008-01-01T00:00:00ZEvaluation of feed for rearing corcyracephalonica and optimisation of host and parasitoid ages for mass-production of trichogramatid parasitoids
https://karuspace.karu.ac.ke/handle/20.500.12092/3056
Evaluation of feed for rearing corcyracephalonica and optimisation of host and parasitoid ages for mass-production of trichogramatid parasitoids
Migiro, L. N.; Gitonga, L. M.; Sithanantham, S.
Research article on mass-production of trichogramatid parasitoids
2008-01-01T00:00:00ZMacroinvertebrate metrics and lipid profiles as potential indicators of land use influence in a high altitude tropical highland stream (Sagana River Basin, Kenya)
https://karuspace.karu.ac.ke/handle/20.500.12092/3055
Macroinvertebrate metrics and lipid profiles as potential indicators of land use influence in a high altitude tropical highland stream (Sagana River Basin, Kenya)
Odhiambo, Charles O.; Ngugi, Charles C.; Sharma, Rekha R.; Oyoo-Okoth, Elijah
Land use practices near river ecotones result in numerous inputs of terrestrial materials into the
river ecosystem. While macroinvertebrates population metrics is widely used in monitoring
water quality changes, including those induced by humans, the use of lipid profiles in these
organisms to monitor influence of land use practices is rather ignored. The aim of this study was
to determine lipid profile in macroinvertebrates as potential indicator of human influence in
Sagana River Basin, a high altitude tropical highland stream in Kenya. Sites were selected based
on differences in land use activities delineated: forest with minimal land use activities, while
cropland and saw milling areas had varying degrees of land use activities, with urban areas
designated as sites with most human impacts. The macroinvertebrate metrics such as
occurrence, abundance, diversity, percentage of oligo chaetes and chironomids (%OC), as well
as the Ephemeroptera, Plecoptera and Trichoptera (%EPT) index differed relative to land use
changes. Variation in the Fatty Acids (FAs), alcohols and sterols in benthic mac roinvertebrates
was related to the land use activities along the stream. Evidently, streams traversing the urban
areas had higher concentrations of Phospholipid fatty acids (PLFA), while streams traversing
croplands had the highest neutral lipid fatty acids (NLFA). The dominance of monounsaturated
FAs (MUFAs) in forest, shortchain FAs (SCFAs) and polyunsaturated FAs (PUFAs) in croplands and
longchain FAs (LCFAs) near urban areas clear indicate different sources of these materials, mainly
from terrestrial sources. Individual fatty acids, alcohols and sterols profiles discerned difference
in land use changes. The concentrations of SCFAs, MUFAs, LCFAs, TeoH, 27Δ5.22, 28Δ5,24,
28Δ5,22, 29Δ5,22 and 29Δ5,22 in the benthic macroinvertebrates samples were positively
associated with OC%, EPT, total abundance and eH’. Meanwhile the concentration of phytol,
AqOH, 27Δ5 and SCOH were associated with Simpson index. The current findings support the
combination of macroinvertebrates species composition, abundance, diversity and lipids profiles
to detect land use activities at the riverine scale. While implementing catchment-based river
management and conservation activities should incorporate lipid analysis as a management tool.
There is need for continuous monitoring of long term trends in land use activities on the changes
in lipid content of the macroinvertebrates
Research article on Macroinvertebrate metrics and lipid profiles
2024-01-01T00:00:00ZThe Critical Onion Growth Stages For Selective Protection From Thrips Tabaci Lindeman (Thysanoptera:Thripidae) Infestation
https://karuspace.karu.ac.ke/handle/20.500.12092/3052
The Critical Onion Growth Stages For Selective Protection From Thrips Tabaci Lindeman (Thysanoptera:Thripidae) Infestation
Waiganjo, M. M.; Sithanantham, S.; Mueke, J. M.; Gitonga, L. M.
Field trials were conducted during 2000-2001 at KARIandrsquo;s Mwea-Tebere and Kiboko farms to establish the effect of onion thrips, Thrips tabaci Lindeman on onion bulb yields and to identify the critical onion growth stage for selective protection from the pest infestation. Yield reductions of 59 and 27% were recorded in the first and second crops respectively at Mwea-Tebere, but no significant yield reductions were observed in a third crop grown at Kiboko with low thrips infestation. A significant onion yield response to thrips infestation was observed during the 2nd month after transplanting (bulb-formation) and 3rd month after transplanting (bulb-enlargement), but no significant response was observed during the 1st month (pre-bulbing) and 4th month (maturation stage). Onion protection during bulb-formation and enlargement stages only, resulted in higher marginal returns than full season pesticide application. The studies suggest that control recommendations for onion could be refined to optimize need-based protection.
Conference proceedings
2006-01-01T00:00:00Z