Crops > Roots & tubers > Potato > Dorylus orientalis, red ant, potato, Bhutan

Crops > Roots & tubers > Potato > Dorylus orientalis, red ant, potato, Bhutan

Crops Roots & tubers PotatoDorylus orientalis, red ant, potato, Bhutan

Dorylus orientalis, red ant, potato, Bhutan

February 2012. Red ant, Dorylus orientalis Westwood causes significant damage in potato in Bhutan. However, up till now there was no effective technique in controlling this pest. Information was requested on how it can be done.

From a quick look on the Internet, it is reported from Bihar, Assam, and other northern states of India that chlorpyriphos is the chemical of choice for this ant. It is also a problem in Nepal.

Look at this page of Mendeley and then in Google Scholar:

In Australia, chlorpyiphos is registered for ant control by the Australian Pesticides and Veterinary Medicines Authority.

However, a warning: PAN The Pesticide Network has been calling for a ban on chlorpyiphos for some time in the US, and here is why: It is banned in some countries for home and garden use.

Another member wrote, that Dorylus orientalis is one of the few ant species that attack the underground parts of crop plants (in Asia) – the tubers of potatoes (across northern India and Nepal) and developing pods of peanuts. They make 2-3 mm diameter holes in soft pods and clean out the soft kernels. They eat roots of many plants but this is likely to go unnoticed.

Chorpyriphos is a standard insecticide for their management and the rates will be on the container. Conventional spraying of the soil during crop development is recommended, but risky in terms of crop contamination; it would be better to treat pre-plant with a prill or granule formulation in known trouble spots.

In Thailand, peanut farmers have placed baits of coconut meat mixed with chlorpyriphos in the infested areas of their crops. If the ants form locatable nests, then it should be possible for farmers to be shown how to destroy them with insecticide, kerosene or diesel.

However, Bhutan said that they would prefer methods other than insecticides, and baits and barriers (used against the Andean potato weevil, Premnotrypes suturicallus) were a possibility.

Another member provided information on baits in response, as follows:

“I am not familiar with this species of ant; however, one of the important basic facts needed in any ant control program is to determine what the ants are attracted to – there are two broad groups of attractants based on the ants feeding – sugar feeders and protein feeders

“A simple way to find out is to place some sugar syrup or honey on cards and some protein (peanut butter, tinned fish) on similar cards within the crop. Check these after an hour and you should have the answer to this critical question for your ant.”

The reply went on to say that sticky bands might be considered which the ants would not cross (but how practical this was in Bhutan was not known). The plastic barriers for potato weevils could be treated with the sticky material as used for bird proofing, but entomologists the world over have adapted it for catching insects or excluding crawling insects. It goes under many trade names (Stikem is one). The bands would only be effective if the ants were forced to the surface. There would need to be some barriers placed to stop the ants tunnelling under the bands. As long as there is no soil or leaves bridging the gap then ants would be excluded by such bands. This would be very difficult to manage though, and possibly impractical in a field situation. It can be used in food storage facilities, which are undercover.

The baits can be used to dispense an insecticide, and this could be boron if a conventional insecticide was not wanted. An insect growth regulator could be considered also. If it is acceptable to use conventional pesticides then there are a range which you could consider, although the residues issues would need to be addressed for potatoes.

As a follow up on the issue of non-conventional insecticide, a member mentioned that boracic acid plus flour was recommended in the 1960s, and sodium borate, plus flour, plus sugar (1:1:1) is also used. (Dorylus is a root, tuber and pod eater, but how much is comes above ground was not known to the writer, but as it is related to the African driver ants that march across terrain en masse, it may well come above ground.

It was also mentioned that Spinosad 1 cc/liter is effective, although retreatment after 3 months is necessary.