Nairobi, kenya
May 4, 2007
Scientists from the
Nairobi-headquartered ICIPE,
African Insect Science for Food and Health, the
Kenya Agricultural Research
Institute (KARI) and the
International Potato Centre (CIP), Peru, with funding from
BMZ, Germany, ha= ve joined forces to control the invasive
horticultural pests of the genus Liriomyza, in eastern
Africa.
Leafminer flies, as these pests are commonly known, cause crop
damage in their adult and larval stages. The females puncture
the plant leaves and in some instances the fruits with their
ovipositors. The flies mainly use these punctures for feeding,
but 10% of the time, they lay eggs in them, which then develop
into larvae. A heavy attack of leafminers leads to large-scale
destruction of leaf tissue, shrivelling of the leaves and
eventually, the complete defoliation of the entire plant. More
importantly, the presence of leafminer larvae on export produce
is of quarantine relevance in the European Union markets.
Liriomyza leafminers were restricted to the New World until the
1970s but have since then been spreading to other parts of the
world. In eastern Africa, three polyphagous species, L.
huidobrensis, L. sativae and L. trifoli, have been recorded on
French and runner beans, snow and sugar snap peas, okra,
aubergine, passion fruit and various species of cut flowers.
A significant area of concern is that in South America and
Southeast Asia, L. huidobrensis has been known to attack and
damage potato crops to crisis levels. Even though no attacks
have been noted on this crop in eastern Africa, it is important
to pre-empt such a possibility, which would be catastrophic as
potatoes provide a fallback in bad maize years, preventing
serious famines.
Overall, if not contained, the leafminer problem in East Africa
would threaten the livelihoods of the region’s small-scale
farmers, who produce 80% of vegetables for the local and export
markets. Leafminers easily develop resistance to synthetic
pesticides, thus necessitating the use of the newest plant
protection materials, which are often out of the reach of such
farmers. Synthetic chemicals also have an adverse effect on the
natural enemies, which are important in controlling the
leafminers. Moreover, while only L. huidobrensis is a listed
quarantine pest in the EU, there is currently no practicable
method for inspectors to distinguish between leafminer larvae on
import produce. As a result, whole consignments are usually
rejected when any leafminers are detected.
The work by icipe, KARI and CIP will build on the extensive
studies on leafminers already done in the developed countries.
Further, it will address existing research gaps towards
environmentally-friendly, affordable and sustainable management
of leaf miners in eastern Africa.
One of the priority areas will be to improve biocontrol of
leafminers. The researchers will also look at other control
techniques, which would be harmless to the natural enemies such
as trap crops and biopesticides.
The technologies generated through this study will be of benefit
to small, medium to large-scale farming units. In addition,
national research and extension services, non-governmental
organisations and the private sector enterprises could use the
results for producing and marketing biopes. |
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