Phenacoccus solenopsis (cotton mealybug)

Several countries require inspection of plant material imported from countries where P. solenopsis is known to occur. China has initiated a notice of inspection and quarantine for P. solenopsis (Ministry of Agriculture, 2009).

Use of sticky traps placed throughout the field is an effective means to monitor for the presence and population density of P. solenopsis, by catching the winged males.

It is important to cut infested stems or branches from plants and destroy the infested plant material by burning or deep burial; infested prunings must not be left lying in the field, as the mealybugs will walk onto nearby plants. After harvest, crop residue and weeds left in infested fields should be gathered up and buried or burned, as mealybugs on plant material left in the field can survive to infest the next crop. Field borders should be inspected for alternative host plants for the mealybug; these should be removed to prevent the mealybugs from overwintering and infesting the next crop. Trap plants like Hibiscus rosa-sinensis may be planted, to initially attract the mealybugs; these serve to alert farmers to the presence of P. solenopsis in the field, and can then be treated to protect the primary crop.

Small populations of P. solenopsis can be controlled by regular inspection of plants, removing loose bark where mealybugs might be difficult to observe and hand-picking or crushing specimens from newly-infested plants.  

When working in fields known to be infested with P. solenopsis, it is necessary to sanitize farm equipment and check clothing items before movement to uninfested fields, to prevent the transfer of the pest to new locations. Infested prunings should be destroyed on site, not transported elsewhere for disposal, as crawlers falling off transported material will infest plants along the route.

The use of biological control agents provides a cost-effective, non-toxic, self-perpetuating means of suppressing invasive pest populations of exotic mealybugs. Several parasitoids and predators have been identified that attack P. solenopsis and can control pest populations at low densities. Established parasitoids have been recorded parasitizing over 70% of the cotton mealybug population (Pala Ram et al., 2009). Other tactics suggested to suppress populations of P. solenopsis include allowing the parasitoids to build up their numbers prior to applying chemical insecticides, and to use pesticides that minimise parasitoid fatalities; to attach plant parts bearing parasitoid-infested mealybugs (mummies) onto the host plant to be protected; mass-rearing and releasing parasitoids into mealybug-infested areas; and using a combination of several natural enemies to control the exotic pest (Pala Ram et al., 2009). Predators are used to control P. solenopsis on cotton in several countries. The commercially available predatory ladybeetle, Cryptolaemus montrouzieri (Coleoptera: Coccinellidaae), has been imported into India and released in cotton-infested fields to help to control P. solenopsis.

Several species of ants are often associated with honeydew-producing mealybugs, and protect them from attack by their natural enemies. To increase the chances of success in using biological control agents against P. solenopsis, attendant ants need to be eradicated if at all possible (Helms and Vinson, 2002; Tanwar et al., 2007).

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources: