Ladybird beetles to fight Croton Scale Disease

by Linda Straker

• 30,000 Cryptolaemus Ladybird beetles imported
• Full effect of beetles will be observed in about 6 months
• Croton Scale Disease was spotted in Grenada in 2020

The Ministry of Agriculture through the Pest Management Unit (PMU) has adopted biological measures to deal with the Croton Scale Disease. Several fruit trees have died while others produce fewer fruits if they continue to survive.

“In an effort to further control the effects of the Croton Scale Disease, the Ministry of Agriculture’s Pest Management Unit has now taken a biological measure approach through the breeding and releasing of Ladybird Beetles that are expected to feed on and significantly minimise the effects of the pest,” the Ministry disclosed in a Facebook post on Thursday, 2 November 2021.

This disease was spotted in Grenada in 2020 and has since been wreaking havoc on crops like soursop, plums, guavas, mangoes, and sugar apples.

Agriculture Minister Peter David disclosed to Parliament when he made his contribution to the 2022 Budget debate, that the Pest Management Unit will be purchasing thousands of ladybird beetles to be released onto trees, because these beetles are natural predators.

The beetles were brought into the island on Wednesday and the team at the Pest Management Unit has already started the process of releasing them in areas prone to heavy infestation of Croton Scale.

“30,000 of the Cryptolaemus Ladybird beetles which are also known as the Mealybug destroyer was procured and we will be using them to mitigate the effects of the Croton Scale Disease. This is the same approach we adopted in the 90s when we had to deal with the mealybug infestation,” said Thaddeus Peters, Head of the PMU.

Peters travelled to the USA to purchase the beetles and returned with them. The beetles were purchased from an insectary in California, which coincidentally also supplied the country during the height of the mealybug outbreak. The total cost was US$3,000 as each beetle is priced at ten cents. The ministry is expected to import more beetles because the limited number will not be sufficient to release throughout farms and areas affected by the Croton Scale.

Peters said that once feeding is available for the beetles they are expected to survive and multiply. “And that will be a good thing because they are eating the pest away.” Peters pointed out that once the mealybug infestation was under control the beetles were no longer observed. “When the beetles can no longer get the required feeding they will die naturally, so we don’t have to worry that they will cause or develop another problem. We use them in the 90s and if they were around now, they will naturally deal with the Croton Scale,” he said. “From the success we had then, we do expect the population of the pest to go down as we release more and more of the beetles,” he said. “The full effect of the beetles will be observed in about 6 months.”