Abstract:
Liriomyza huidobrensis (Blanchard), Liriomyza sativae (Blanchard) and Liriomyza trifolii (Burgess) are multivoltine flies, which are highly polyphagous, prolific and invasive. They are currently important pests in areas where horticultural crops are grown in Kenya. Both the adult flies and larvae cause considerable damage to crops. Infestation results to reduced photosynthetic potential of plants, which translates to reduction of the expected yield and loss of the aesthetic value. In addition, these pests are of quarantine importance and stringent measures have been put in place to prevent movement of infested plant materials in the export markets. Controlling these agromyzid pests is difficult. Most of the chemicals available locally are ineffective and highly toxic to natural parasitoids. Economically important crops in Kenya such as French beans, snow peas, brassicas, tomatoes, potatoes among others, are at potential risk of infestation by these agromyzids. In an attempt to contain the Liriomyza menace, a study was conducted to determine the effect of host type and cropping (choice) system on survival, development, feeding and oviposition of Liriomyza huidobrensis, Liriomyza sativae and Liriomyza trifolii. Egg staining technique using lactophenol-acid fuchsin solution was done to enable observation of the leafminer eggs. Liriomyza huidobrensis referred Lycopersicon esculentum M. (producing feeding punctures per cm2 of as high as 11.59±1.36), Vicia faba L. and Phaseolus vulgaris L. for feeding and oviposition, while L. sativae and L. trifolii favoured P. vulgaris and L. esculentum. Results showed that all the three Liriomyza leafminer species followed the Hopkins’ Host Selection Principle (HHSP), but with no consistency. Correlation analyses showed lack of consistencies both regarding the association between punctures and eggs. The study further revealed the potential of mixed cropping as a way of controlling Liriomyza leafminer infestations and faba bean as a promising crop for host diversification. Highest numbers of offsprings were produced from V. faba for L. huidobrensis, and from P. vulgaris and V. faba for L. sativae and L. trifolii. Survival vii was at its lowest on L. esculentum for L. sativae and L. trifolii, and on P. vulgaris and L. esculentum for L. huidobrensis. The results of this study are discussed in the context of their relevance for sustainable management of Liriomyza leafminers in subsistence agriculture.
