School of Pure and Applied Sciences

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Interaction between Phaedrotoma scabriventris Nixon and Opius dissitus Muesebeck (Hymenoptera: Braconidae): endoparasitoids of Liriomyza leafminer
(African Entomology, 2015) Foba, C.N; Langat, Z.O.; Gitonga, L.M.; Akutse, K.S.; Fiaboe, K.K.M.
The exotic parasitoid, Phaedrotoma scabriventris Nixon, was imported from Peru for the biological control of invasive Liriomyza species in vegetable and ornamental crops in Kenya where Opius dissitus Muesebeck is the most abundant indigenous Liriomyza parasitoid. Both species are solitary larva-pupal endoparasioids attacking the same larval stage. In order to assess whether these two species compete or co-exist, an interaction study involving sole, sequential and simultaneous releases of the two species on polyphagous Liriomyza huidobrensis (Blanchard) was conducted in the laboratory at the International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya. Simultaneous releases of 50 individuals each of the two parasitoids resulted in significantly higher total parasitism rate (61.96 ± 4.60) than in the single release of P. scabriventris (34.94 ± 8.50). Simultaneous release of 25 individuals of each species resulted in a parasitism rate (44.52 ± 2.75) similar to that obtained for single releases of 50 individuals of O. dissitus (42.57 ± 3.35) and P. scabriventris (34.94 ± 8.50). No significant effect was observed in total parasitism between sequential and single releases of 50 individuals of each species. The specific parasitism rate of each parasitoid species in the simultaneous release of 50 individuals of each species was not significantly different from when each species was released alone. The first introduced parasitoid in sequential releases achieved the same parasitism rate as when released alone. However, the second released species gave a significantly lower parasitism rate than when released alone and compared to the first released species. The F1 progeny sex ratio was balanced for P. scabriventris but male-biased in O. dissitus. The sex ratios of both parasitoid species were not significantly affected, neither in simultaneous nor sequential releases, except in one of the sequential release where P. scabriventris was released second, with its sex ratio significantly female-biased. Non-reproductive host mortality was not important for both parasitoids when used alone and in combined releases compared to the natural mortality observed in the control. These findings suggest that P. scabriventris has no detrimental effect on O. dissitus and its release into Kenya’s agricultural ecosystems will enhance the management of Liriomyza leafminer.
Interaction between Phaedrotomascabriventris Nixon and Opiusdissitus Muesebeck (Hymenoptera: Braconidae) : endoparasitoids of Liriomyza leafminer
(Sabinet African Journals, 2015-03-01) Foba, C.N.; Akutse, K.S.; Fiaboe, K.K.M.; Lagat, Z.O.; Gitonga, L.M.
The exotic parasitoid, Phaedrotoma scabriventris Nixon, was imported from Peru for the biological control of invasive Liriomyza species in vegetable and ornamental crops in Kenya where Opius dissitus Muesebeck is the most abundant indigenous Liriomyza parasitoid. Both species are solitary larva-pupal endoparasioids attacking the same larval stage. In order to assess whether these two species compete or co-exist, an interaction study involving sole, sequential and simultaneous releases of the two species on polyphagous Liriomyza huidobrensis (Blanchard) was conducted in the laboratory at the International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya. Simultaneous releases of 50 individuals each of the two parasitoids resulted in significantly higher total parasitism rate (61.96 ± 4.60) than in the single release of P. scabriventris (34.94 ± 8.50). Simultaneous release of 25 individuals of each species resulted in a parasitism rate (44.52 ± 2.75) similar to that obtained for single releases of 50 individuals of O. dissitus (42.57 ± 3.35) and P. scabriventris (34.94 ± 8.50). No significant effect was observed in total parasitism between sequential and single releases of 50 individuals of each species. The specific parasitism rate of each parasitoid species in the simultaneous release of 50 individuals of each species was not significantly different from when each species was released alone. The first introduced parasitoid in sequential releases achieved the same parasitism rate as when released alone. However, the second released species gave a significantly lower parasitism rate than when released alone and compared to the first released species. The F1 progeny sex ratio was balanced for P. scabriventris but male-biased in O. dissitus. The sex ratios of both parasitoid species were not significantly affected, neither in simultaneous nor sequential releases, except in one of the sequential release where P. scabriventris was released second, with its sex ratio significantly female-biased. Non-reproductive host mortality was not important for both parasitoids when used alone and in combined releases compared to the natural mortality observed in the control. These findings suggest that P. scabriventris has no detrimental effect on O. dissitus and its release into Kenya's agricultural ecosystems will enhance the management of Liriomyza leafminer.
Species Composition, Distribution, and Seasonal Abundance of Liriomyza Leafminers (Diptera: Agromyzidae) Under Different Vegetable Production Systems and Agroecological Zones in Kenya
(Environmental Entomology, 2015-02-03) Foba, C.N; Salifu, D.; Langat, Z.O.; Gitonga, L.M.; Akutse, K.S.; Fiaboe, K.K.M.
A longitudinal study to identify the species of Liriomyza leafminer, their distribution, relative abundance, and seasonal variation, including their host range, was conducted in vegetable fields at three altitudes in Kenya from November 2011 to November 2012. Three main species were identified: Liriomyza huidobrensis (Blanchard), Liriomyza sativae Blanchard, and Liriomyza trifolii (Burgess), of which L. huidobrensis was the most abundant across all altitudes irrespective of the cropping season and accounting for over 90% of the total Liriomyza specimens collected. Liriomyza species were collected from all infested incubated leaves of 20 crops surveyed belonging to seven families: Fabaceae, Solanaceae, Cucurbitaceae, Malvaceae, Brassicaceae, Amaranthaceae, and Amaryllidaceae. However, more than 87.5% of the Liriomyza species were obtained from only four of these crops: Pisum sativum L., Phaseolus vulgaris L., Solanum lycopersicum L., and Solanum tuberosum, thereby demonstrating that Fabaceae and Solonaceae crops are the most important hosts with regard to Liriomyza species richness and relative abundance. L. huidobrensis had the widest host range (20 crops), followed by L. sativae (18 crops) and L. trifolii (12 crops). Although L. trifolii has been considered the dominant Liriomyza leafminer in Kenya, this study suggests that this may not be the case anymore, as L. huidobrensis dominates at all altitudes.