Mosquito bug now threatens to steal flavour from tea farmers

Tea farmers from Kapkatet are grappling with Helopeltis (mosquito bug) that has attacked their cash crops. 

Tea Research Institute (TRI) report has indicated that the affected farms have serious leaf spots on clone PMC 51 series and clone TRFK 31/8 and EPK TN14-3. 

TRI Director Samson Kamunya said the affected shoots/leaves were stunted and distorted. “The Genus, Helopeltis, also known as mosquito bug, is a group of heteropterans in the family Miridae (cuspid bug). They include pests of various crops, including cocoa, cashews, cotton, and tea,” said Dr Kamunya.

Kamunya said the tea mosquito bug and the red spider mite were the most dreaded polyphagous pests in plantation crops. 

“Particularly, these are the most damaging pests of tea. If the population of these pests is not controlled, they can cause a total loss of tea,” he said.

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Kamunya added that Helopeltis species was associated with moist climates and found where the equatorial forest had been cleared and crops planted.  

“The bug is very sensitive to plant health, especially those planted in waterlogged soils. Mosquito bug is a big problem in Kericho, Bomet, and Kisii,” he said. The life cycle of this insect, starting from egg to adult, is that of complete metamorphosis and takes five to 11 weeks, depending on the season. 

On average, a female will lay 50 to 60 eggs, but as many as 100 may be laid. 

“The mosquito bug breeds throughout the year and there is considerable overlapping in generations, which makes it difficult to separate different stages,” said Kamunya.

The TRI director added that the female Helopeltis is slightly longer than the male one, and is generally crimson or reddish-brown.

On the other hand, the male is paler than the female and is red or orange. 

“Adults can live for nearly two months in captivity, but possibly do not survive for more than a few weeks in the field. Mosquito bug damage is serious in both nymphs and adults stages, and is very active during the early hours of the morning, in the late afternoon, and at night,” said Kamunya. To deal with the situation, Kamunya told tea farmers to gradually uproot the old clones of tea and plant new ones that are high yielding and resistant to diseases and pests.

The new clones of tea the farmers can plant include Tea Research Foundation-TRF-K 31/8 and TRF-K 704/2. 

“The high yielding clones take about three years to mature. The clones are good for producing black or green orthodox teas,” he said. 

Kamunya added: “Famers can gradually start uprooting their tea bushes, starting with the numbers they are comfortable with, even if it is replacing 100 bushes until the entire field is covered.”

He advised farmers who cannot uproot the affected bushes to practice short plucking intervals of about four times per month to interrupt the breeding cycle of Helopeltis, in addition to denying the pest the young soft succulent leaves that they prefer. 

“In severe damage, when there is no active production of the tea bushes as a result of Helopeltis damage, hard plucking or skiffing to be practiced for the time being until the problem subsides,” he said.

Kamunya explained that skiffing was a very light pruning operation. The bushes are also cut across using a pruning knife at some level within the maintenance layer of the top 5cm to 8cm, thereby removing new growth.

Other methods include clearing bushes at the edges of tea fields, which act as hiding or breeding sites for the pest, avoidance of inter-cropping, since the inter-crop acts as an alternative host for the pest.