NEW PEST ON WAY TO FIGHT BLACKFLY

 

By Kim Boodram

Central Bureau

Express

January 27, 2000

Page 11

Blackfly - Frequently Asked Questions

 

One year after recovering from the devastation of a sugarcane froghopper invasion, Caroni (1975) Ltd is preparing to do battle with a new pest that is threatening to wipe out their citrus division.

 

The citrus blackfly is being seen as a serious threat to the local citrus industry.

 

The Ministry of Agriculture is currently spearheading efforts to import the pest's natural biological enemies, before it goes the way of the dreaded froghopper.

 

Te blackfly has already made its way to Caroni (1975) Ltd's Citrus Division, Todd's Road, Caparo.

 

In South and Central Trinidad, citrus farmers have begun to cut their losses, as both trees and fruits continue to shrivel up from the deadly blackfly larvae, and the sooty mould their faecal matter attracts.

 

Caroni's Research Entomologist Graham White said the Todd's Road fields bear evidence of attack, and they are hoping to introduce a biological control element in the next few weeks.      

 

"No trees have died, but it is considered a serious threat," White said.  "The solution is on the horizon, but that is no reason to be complacent.  Farmers elsewhere are already feeling the pinch."

 

The insect may very well spell disaster for the citrus industry if the ministry does not act fast, but White said the company was "very comfortable with their efforts."

 

Currently, farmers have turned to chemical warfare to save their crops.

 

But depending on the severity of infection, White said this method is not always a blessing.

 

The expenditure can sometimes outweigh the profits that will eventually be turned out.

 

After thousands of dollars have been spent, he said, and the remaining fruit are not saleable, it makes more economic sense to allow the flies to finish their feast.

 

Also, insecticides have the potential to disrupt other predator-prey relationships.  That could create a new potential disaster.

 

In all likelihood, the blackfly may warrant the introduction of an entirely new species of insect to T&T.

 

White said this does not have to be hazardous, since the predators are usually bent on one particular prey.

 

"Bio-control is often more cost effective as well as long-term," White said.

 

"In most cases, the predator is particular about the pest, and does not pose a threat to other benign insects.  Chemicals, on the other hand, are indiscriminate, and they can upset delicate balances that are beneficial to the crops."

 

For this reason, White said that people should not be too quick to start blanket-spraying their crops.

 

White added that the company does not intend to allow the blackfly to reach the uncontrollable stage, where crops would have become too far gone to salvage.

 

Last year, Caroni enjoyed tremendous success with their bio-control treatment of the froghopper, which had claimed a large portion of the previous year's sugarcane crop.

 

ABOUT THE BLACKFLY

 

This tiny insect actually belongs to the whitefly family, and is a relative of the mayflies and the so-called "sour-flies."

 

It looks somewhat like an aphid, but is dark bluish-black in colour.

 

The citrus blackfly is not indigenous to Trinidad, but it has been around the region and middle-America for some time.

 

It appeared in this country in late 1997, but having gone unchecked, it has only now become a source of concern.

 

It is thought to have migrated from India, and the ministry of Agriculture is looking in that direction for a biological solution.

 

There are no known natural blackfly enemies in this country.

 

The fly's larval stage is its most deadly.  The larvae, which look like tiny black pyramids in the first stage, stick to the underside of the citrus leaves, where they suck the sap of the plant.

 

In the process, they excrete a sweet substance, similar to the ant-attracting excreta of aphids.

 

This substance encourages the growth of sooty mould (so named for its soot-like texture and black colour), which in turn obstructs the plants' ability to photosynthesise and replenish itself.

 

"It literally blocks the sunlight, so the plan cannot manufacture more food," Graham White said.

 

The larvae remain the same in appearance, but continue to grow.  Nor do they move much.  The adult is winged, and shortly after emerging, it mates, flies to a suitable spot, and lays.  It then dies.

 

Eventually, after a few months of infestation, the plant literally dries up.

TOP