Phenacoccus solenopsis, Tinsley, 1898

Phenacoccus solenopsis View in CoL

(solenopsis mealybug)

was described originally from the U.S. in 1898 and it remained known only in the U.S., where it is widespread, until 1992 (Ben­Dov 2004d). In 1992, it was reported in Central America, the Caribbean, and Ecuador ( Williams & Granara de Willink 1992). Larraín (2002) recently noted the species as a pest of Solanum muricatum in Chile, and we now record P. solenopsis for the first time in Brazil. It is uncertain if this sequence represents a true, recent expansion in geographic distribution of the species from North America to South America or is simply a coincidence of collection and identification efforts. The species has been found previously on a relatively wide variety of host plants including species in economically important families such as Cucurbitaceae and Fabaceae as well as Solanaceae , however, the present work is the first published record of tomato as a host for P. solenopsis (R.J. Gill, California Department of Food and Agriculture, personal communication, indicates that he has unpublished records of this species from tomato).

Williams & Granara de Willink (1992) note that P. solenopsis is very similar in appearance (microscopically) to Phenacoccus solani Ferris and Phenacoccus defectus Ferris. However , the live appearance of P. solenopsis differs from these other two species in that the adult female of P. solenopsis generally has paired dark spots and/or stripes dorsally ( Fig. 1 View FIGURE 1 ), whereas the females of the other two species appear to be uniformly white dorsally ( Miller et al. 2005a). P. solenopsis usually has short lateral wax filaments and slightly longer terminal wax filaments (less than half as long as the body).

Although P. solenopsis was described originally from specimens collected from plant roots ( Ben­Dov 2004d) and is referred to as a “soil mealybug” by Lorraín (2002), in the present study the species was observed only on stems and leaves of plants (although no attempt was made to determine if roots of plants were infested). Infestations on tomato plants were associated with noticeable deformation and distortion of the terminal growth, consisting of twisting and curling of stems and leaves, and leaf wrinkling and puckering ( Fig. 1 View FIGURE 1 ). Osborne (2005) demonstrates similar damage caused by P. solenopsis to hibiscus. P. solenopsis was first noticed on the tomato plants examined in this study because of the very distinct distortions of the foliage.

Although symptoms of stem twisting and leaf puckering initially were very noticeable on infested tomato plants, the extent to which P. solenopsis otherwise affects plant growth and production is not clear. In Vitória, after the initial infestation was noticed on three young plants beginning to flower and set fruit in January 2005, control was attempted by pruning out heavily infested stems and leaves and removing the mealybugs by hand. By the end of February, the mealybug infestation was again noticeable, but the plants had continued to grow vigorously, flower, and set fruit until early March (when observations ended); overall, the plants appeared to be healthy despite the mealybug infestation. The extent to which P. solenopsis may have affected the health and production of the tomato plants at Manguinhos is also unclear because the plants were stressed by many other factors (low soil fertility, shade, lack of water). These tomato plants had mostly died by 1 March 2005, apparently due to stem borers and otherwise poor growing conditions at the site.

Tomato plants exhibiting symptoms similar to those associated with P. solenopsis (stem curling and leaf puckering) and that appeared to be infested with this insect have been observed in the commercial tomato growing region of EspÌrito Santo (J.A. Ventura, INCAPER, personal communication), but additional research is needed to verify the distribution and potential impact of this pest. Phenacoccus solenopsis was found on common weeds in Manguinhos indicating that crops may become infested by mealybugs originating from nearby weeds.

The records reported here indicate that the mealybugs D. boninsis , P. solenopsis , and P. viburni are common and potentially important pests in Espírito Santo. The fact that the cosmopolitan species D. boninsis and P. viburni were found with relatively little effort in apparently well established populations suggests that the lack of previous records of these species in Espírito Santo reflects a lack of study of this group of insects in this area. Since P. solenopsis has not been noted previously as a pest of tomato, further research on this species and its effects on this economically important crop is especially warranted.