December 2013. A mealybug with ovisacs heavily infesting eggplant in a field on Guam. Can it be identified?
It is posted at: http://guaminsects.myspecies.info/node/2623.

A member said that Phenacoccus solenopsis infests eggplant in Queensland and this is a possibility. It has been recorded on eggplant, hibiscus, tomato, cucurbits and several weeds. A fact sheet has been written.

However, another member said that the dark pigment is in the wrong positions on the body for P. solenopsis, which is already recorded in Guam. Later, the same person recognized the pigmentation pattern, and suspected that the mealybug was Coccidohystrix insolita(Green), but a study of slide-mounted material would be necessary to confirm the identification.

According to the literature, in the Pacific region C. insolitahas only been recorded from Western Samoa before, so it may be a new introduction to Guam. More information about this species is available at:

http://www.sel.barc.usda.gov/catalogs/pseudoco/Coccidohystrixinsolita.htm.

The identification of the mealybug resulted in the development of a fact sheet. Guam put out the following message:

The eggplant mealybug, Coccidohystrix insolita, has been detected on Guam. This species has potential to become a major pest on Guam. This is the first occurrence record for Guam, the Mariana Islands, and Micronesia. Guam is an unincorporated territory of the United States of America.”

For more information, please download a fact sheet. This fact sheet will be updated as new information evolves.

http://guaminsects.myspecies.info/content/guam-new-invasive-species-alert-no-2013-01-eggplant-mealybug.

A comment from Ethiopia thought the mealybug was the same as that on cotton, which was Phenacoccus solenopsis. However, it is different. It usually has a longitudinal row of 4 or more spots down the length of the body, one each side of the midline, and produces an ovisac shorter than the length of the female’s body. Coccidohystrix insolita produces an ovisac up to 6 times as long as the body of the adult female, and when dark spots are present they are only on a 3 body segments and are situated near the margin of the body.

It was suggested to look again at Aubrey’s (see above) photographs at http://guaminsects.myspecies.info/node/2623, especially picture no. 5, and pictures of P. solenopsisat: