An organic remedy for mealybug infestation
Mealybugs can be a consistent nuisance to the organic orchardist and fruit producer. Being sap suckers, they rarely kill the trees directly but weaken to the point where fruit quality is lowered in addition to increasing general susceptibility to disease and other forms of pest infestation. Plant derived pesticides have rarely been successful, possibly on account of the protective wax which covers adult Mealybugs. The telltale signs of infestation are patches of sooty coloured mould. This grows on the honeydew secretions released by the Mealybugs.
The best natural predator of the Mealybug is Cryptolaemus Montrouzieri, a species of Ladybird found in Australia. Since it’s discovery, Cryptolaemus has been exported to organic citrus producers in many countries as an effective biological control against Mealybugs.
Adult specimens of Cryptolaemus are oval shaped, approximately 5mm in length, and distinctive in appearance with their orange head and black wings. Their larvae are covered in white filaments and pupate on the underside of leaves and other crevices. The larvae and mature Cryptolaemus feed directly on Mealybug eggs and it has been noted that some of the larger larvae will also prey on adult Mealybugs.
Beneficial insects like Cryptolaemus are generally sold in quantities of one hundred or more. The minimum recommended release rates for commercial orchards are one thousand beetles per hectare although most organic setups will benefit from an increase on this figure. Release conditions need to be optimum, protecting arrivals from extremes of temperature. It is also important to introduce Cryptolaemus into an environment where Mealybugs are present.
Upon release, the Cryptolaemus should disperse across the Mealybug infestation areas. An assessment should be conducted after approximately four weeks. Serious infestations will require additional treatments which should be interspersed at monthly intervals, throughout the early portion of spring and summer.