Understanding the beetle’s behaviour is necessary as a way to devise ecologically sound administration methods
India is the seventh largest producer of coffee, exporting 3,95,000 tonnes yearly. Of the two varieties of coffee grown broadly in India, particularly, arabica (Coffea arabica) and robusta (Coffea canephora), the arabica vegetation endure infestation by a spread of longhorn beetle referred to as the coffee white stem borer (Xylotrechus quadripes).
The lifecycle of the beetle lasts between 142 and 390 days. The feminine lays about 50-100 eggs in the cracks in the bark of coffee vegetation. Once the larvae hatch and develop, they chew the bark and tunnel into the stem the place they find yourself obstructing the circulation of meals, which can even kill the plant. The injury executed by the coffee white stem borer quantities to $17-40 million misplaced yearly.
Coffee White Stem Borer laying eggs in the bark gaps.
| Photo Credit: Santosh Rajus
Managing this pest is a troublesome drawback. The larvae burrow deep into the wooden, subsequently, it’s troublesome to kill them utilizing pesticides. Several methods are being tried to handle the pest. These embrace putting shady bushes at strategic factors, as the beetles desire open, sunlit areas; utilizing pesticides to kill adults; bark scrubbing to get rid of the eggs laid in the cracks; stem wrapping to stop adults from laying eggs in the stems; mass trapping of adults utilizing pheromones and even getting rid of affected vegetation. “Though these methods are effective, for various compounding reasons the coffee white stem borer has become one of the toughest pests to control,” says Shannon Olsson from the National Centre for Biological Sciences, Tata Institute of Fundamental Research (NCBS) Bengaluru.
Prof. Olsson and a group of researchers have been finding out the coffee white stem borer. Their intention is to review the insect and the method it approaches numerous vegetation and its response to plant volatiles so {that a} ecologically derived administration technique will be labored out. According to her, traditionally, it has been famous that the beetle assaults solely arabica until the space is closely infested. However, latest research by the group, printed in the journal Frontiers in Ecology and Evolution, have proven that this isn’t as a result of the beetle is extra attracted to at least one selection than the different.
“We found that [the beetle] is attracted to both varieties and uses the volatiles released by the host plants to locate them,” she says. Further, the research confirmed that the beetles most well-liked to strategy robusta over arabica. “Subsequent experiments in our lab have also shown that the beetle can and will lay eggs on robusta, but that robusta apparently can partially defend itself against the beetle as it begins to bore through the wood,” Prof. Olsson explains. “However, it is important to note that this defence is not absolute – not all plants we examined prevented the beetle from developing into an adult and emerging.”
Recent stories have proven proof of infestation in robusta, though not at ranges seen in arabica. Hence, a whole shift in cropping from arabica to robusta can probably face an analogous infestation drawback until totally different administration practices are adopted, she explains. “While it should not be a total replacement for arabica, the lower infestation rates of [the beetle] in robusta, indicate that it could serve a suitable trap host plant if organised strategically.”
The paper additionally offers the fascinating statistic that coffee plantation space in India has elevated by 56% in the previous 25 years, changing the various forest areas of Western Ghats. In this, the planted space of robusta has elevated by 810% from 1950 to 2019, changing arabica farms that have extreme injury from pests.
