The Cotton Mealybug Is Spreading along the Mediterranean: First Pest Detection in Italian Tomatoes

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is an extremely polyphagous invasive pest that can cause serious damages to cultivated plants. The pest is native to America but invaded Asian and Mediterranean countries during the last decades. Tomato (Lycopersicon esculentum Mill., Solanaceae) is an economic relevant crop worldwide and its production can be threatened by numerous insect pests including P. solenopsis. We recorded for the first time P. solenopsis in association with tomato in greenhouse crops and urban landscapes in Sicily (Italy) during the fall season in 2020. The species was identified as P. solenopsis based on the morphological characters and DNA amplification of an ≈800 bp portion of mitochondrial cytochrome oxidase subunit I (mtCOI) gene. The phylogenetic analysis among the obtained P. solenopsis mtCOI sequences with those already available in GenBank suggests Asian countries as a potential source of new introduction. This is the first record of P. solenopsis attacking tomato plants in Italy and may represent a potential threat for tomato production in Europe and nearby countries. For this reason, actions should be taken to avoid the uncontrolled spread of this alien species.

Phenacoccus solenopsis (cotton mealybug).

This mealybug species has the ability to increase rapidly in population size and spread to cover vast areas where host plants occur, in a relatively short period of time. It has been reported from over 200 hosts. Since the original description of P. solenopsis from Atriplex canescens in New Mexico, USA in 1898, no reports on its presence were reported until 1967 (McKenzie, 1967; McDaniel, 1975). Later, Fuchs et al. (1991) reported small, sporadic populations on cotton in Runnels County, Texas, USA in 1988 that spread 75 to 200 miles from the original site with contiguous populations by 1990. With the increase in international trade over the last few decades, this invasive pest has been collected and identified on host material at international ports and in greenhouses outside its native range (Jansen, 2004). As such, P. solenopsis has become established in the Afrotropical, Australasian, Nearctic, Neotropical, and Oriental regions.

Survival, development and reproduction of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on kaolin-treated cotton

The mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is a cotton pest widespread in several cotton growing regions of Brazil, particularly in the semi-arid region of southwestern Bahia. The impact of kaolin on survival, development and reproduction of P. solenopsis was evaluated in the laboratory. The experiment was developed in a completely randomized design with two treatments: immature or newly emerged adults of P. solenopsis sprayed with kaolin and fed with cotton leaf discs treated with kaolin suspension (with kaolin) (T1) and immature or newly emerged adults of P. solenopsis sprayed with distilled water and fed with cotton leaf discs treated with distilled water (without kaolin) (T2). The kaolin suspension shortens the life cycle, increases the reproductive potential and population growth of the cotton mealybug, P. solenopsis and, therefore, it should be used with caution on cotton plants in regions with a history of occurrence of this pest.