Pest Control: Mealybugs

Mealybug is a pest which can have a considerable negative economic impact on a wide range of ornamental and agricultural crops. Since there are many species of mealybugs, scouting and identification are crucial.

                      

              

                                                                               

Sexually dimorphic, adult female mealybugs are much larger, retain the appearance of younger stages and lack wings while the adult males are much smaller and develop into mosquito-like insects with wings. Mealybugs have a mutualistic relation with some ants: mealybugs produce honeydew, which the ants harvest for the sugar and in return, the ants protect the mealybugs from potential natural enemies and may even move them from one plant to the other, increasing the number of infested plants.

Mealybugs can inflict various kinds of damage on a crop.

Retarded plant growth & malformations

Mealybug females feed on plant sap, secreting a powdery wax layer over their body, for protection. Their feeding causes stunting, chlorosis, defoliation, and wilting. Adult male mealybugs, on the other hand, do not feed at all, they only live shortly to fertilize the females. A high mealybug population can lead to fruit drop, fruit deformation (‘high shoulders’) and development of discolored welts on the rind of the fruit. Mealybugs are phytosanitary pests in some export markets (USA, Japan) and if found on fruit destined for these markets can result in rejection of the consignment and could place these important markets at risk for the future.

Black fungal mold

Mealybugs secrete copious quantities of honeydew, which is a substrate for a group of fungi, sooty mold. Sooty mold is black in color and may stain the fruit decreasing pack out percentages as well as causing a delay in fruit color development. Photosynthetic potential, especially of young trees, may be negatively affected if the sooty mold coverage is severe.      

   

Natural Enemies

There are specific natural enemies for different species of thrips.

The primary beneficial insects that are natural enemies of whiteflies are as follows: 

(Click the name of the beneficial insect for additional information) 

BioAnagyrus (Anagyrus vladimiri) is a solitary endoparasitoid of mealybugs in greenhouses, open fields, and fruit crops worldwide. The female wasp prefers to lay its eggs singly, inside the third instar larvae and young adult female mealybugs. When the parasitoid larva hatches, it feeds on the internal organs of its host and develops within it. The pupal stage appears within a “mummy” (which is the hardened skin of the dead mealybug), when the adult emerges it gnaws an irregular exit hole at the posterior end of the “mummy”.

BioCryptolaemus (Cryptolaemus montrouzieri) is a predatory beetle, also known as the “Mealybug destroyer” because it is a voracious predator of multiple species of mealybugs in both greenhouses and open fields.

In addition to these insects, the following insects also target mealybugs along with their primary enemies:

BioLacewing - (Chrysoperla rufilabris) also known as the red-lipped green lacewing, is an insect of the Chrysopidae family. The delicate looking adult feeds on nectar and pollen while the larvae of BioLacewing is the active predator. The three larval instars are the voracious ones.