Phenacoccus solenopsis Tinsley
Common name: Cotton mealybug.
Geographic Distribution: This pest, of North American origin, is now of almost cosmopolitan distribution, due to international trade.
Morphology: The yellow body of the adult female is 2-5 mm long, covered with a powdery, waxy secretion; dorsum with dark bars on the thorax; abdomen with a pair of long terminal waxy filaments. Body with 18 pairs of cerarii, each with two spinose setae, located around the marginal area. Antennae 9-segmented. The first instar nymphs have a 6-segmented antennae and lack the circulus , and the third instar nymph has 7-segmented antennae and a circulus.
Host plants: About 200 species, especially cotton.
Life history: A female produces about 200-500 eggs in an ovisac. The emerging nymphs (crawlers) settle on the leaves, stems, and leaf petioles as well as around cotton bolls. In dry regions the mealybugs are often found on the lower stems and foliag and roots, whereas in more humid areas they settle on the upper plant parts. The pest excretes much honeydew and move between sites, thus spreading rapidly under favorable conditions. Adult females can live for up to 3 months and withstand starvation up to 12 days at 28ºC and 50.6% RH; they can be dispersed by visiting birds and rodents.
Economic importance: This mealybug recently invaded the Indian subcontinent, where it has become a major pest of cotton, severely reducing (by around 35%) yields. Infested plants are stunted, leaves become distorted, turn yellow and drop, and only a few small bolls may be produced. In addition, the honeydew is colonized by sootymold, which inhibits photosynthesis and further retards cotton growth and reduces market value. The honeydew also attracts ants that protect the mealybugs from natural enemies. Recently the pest has been found attacking many crops in Egypt, especially tomatoes. Phenacoccus solenopsis is now considered to be a major economic threat to cotton in Asia and other parts of the world.
Chemical control: Spinosad and spirotetramat controlled the pest and caused the least reduction in parasitization by natural enemies. An organophosphate, carbamates and imidacloprid were also very effective.
Biological control: The pest is attacked by the encyrtyd endoparasitoid Aenasius arizonensis which may kill 60-70% or more of the mealybug population, thus being a major pest control agent. The coccinellid predators Brumoides suturalis (Fabricius) and Nephus regularis Sicard also attack the pest.
Abbas, G., Arif, M.J., Ashfaq, M., Aslam, M. and Saeed, S. 2010. Host plants distribution and overwintering of cotton mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae). International Journal of Agriculture and Biology 12: 421-425.
Aheer, G.M., Shah, Z. and Saeed, M. 2009. Seasonal history and biology of cotton mealybug Phenacoccus solenopsis Tinsley. Journal of Agricultural Research 47: 423-431.
El-Zahi, E.S., Aref, S.A. E. and Korish, S.K. 2016. The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) as a new menace to cotton in Egypt, and its chemical control. Journal of Plant Protection Research 56: 111-115.
Beshr, S.M., Badr, S.A., Ahmad, A.A. and Mohamed, G.H. 2016. New record of host plants of invasive mealybug Phenacoccus solenopsis Tinsley (Tinsley, 1898), (Hemiptera: Pseudococcidae) in Alexandria and Behaira Governorates. Journal of Entomology 13: 155-160.
Hodgson, C.J., Abbas, G., Arif, M.J., Saeed, S. and Karar, H. 2008. Phenacoccus solenopsis Tinsley (Sternorrhyncha: Coccoidea: Pseudococcidae), an invasive mealybug damaging cotton in Pakistan and India, with a discussion on seasonal morphological variation. Zootaxa 1913: 1-35.
Ibrahim, S.S., Moharum, F.A. and Abd El-Ghany, N.M, 2015. The cotton mealybug Phenacoccus Solenopsis Tinsley (Hemiptera: Pseudococcidae) as a new insect pest on tomato plants in Egypt. Journal of Plant Protection Research 55: 48-51.
Kumar, R., Kranthi, K.R., Monga, D. and JAT, S.L. 2009. Natural parasitization of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) on cotton by Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae). Journal of Biological Control 23: 457–460.
Pala Ram, P. and Saini, R.K. 2010. Biological Control of Solenopsis mealybug, Phenacoccus solenopsis Tinsley on cotton: A typical example of fortuitous biological control. Journal of Biological control 24: 104-109.
Spodek, M., Ben-Dov, Y.,Mondaca, L.,Protasov, A., Erel,E. and Mendel, Z. 2018. The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) in Israel: pest status, host plants and natural enemies. Phytoparasitica 46: 45-55.
Wang, Y.P., Watson, G.W. and Zhang, R.Z. 2010. The potential distribution of an invasive mealybug Phenacoccus solenopsis and its threat to cotton in Asia. Agricultural and Forest Entomology 12: 403-416.