Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2006
Publication Date: 9/12/2006
Citation: Epsky, N.D., Amalin, D., Kendra, P.E., Puche, H., Mannion, C.M. 2006. Spacial and temporal factors in a local infestation of Paratatachardina Lobata Lobata (Hemiptera: kerriidae). Florida Entomologist 89:367-374.
Interpretive Summary: The lobate lac scale, Paratachardina lobata lobata (Chamberlin), an insect native to India and Sri Lanka, was first found in the U.S. in 1999 in Florida. Reported hosts include species native to Florida as well as commercial fruit and ornamental trees. Little is known about the population dynamics and invasive potential of this insect, therefore a study was conducted by USDA/ARS and USDA/APHIS scientists at the Subtropical Horticulture Research Station in collaboration with scientists at the University of Florida, TREC to determine the infestation levels and spatial distribution of lobate lac scale among the plant material at SHRS, and to monitor changes in population levels over a 36 month time period. There were 55 plants evaluated and infestation increased from 42% of sampled plants at the start to 75% at the end of the study. Individual host susceptibility appeared to be the primary factor regulating population level. Scale populations on some hosts fluctuated rapidly, with populations either building up or crashing very rapidly. Other plants had only low infestation levels or remained uninfested even though they have been reported as hosts for the scale and were located near infested plants. This information will be used to better understand the relationship between host susceptibility and population growth of this insect.
Technical Abstract: The lobate lac scale, Paratachardina lobata lobata (Chamberlin) first found in south Florida in 1999. Reported hosts are present in the germplasm collection located at the USDA/ARS Subtropical Horticulture Research Station in Miami. A study was initiated in July-August 2003 to determine the infestation levels and spatial distribution of lobate lac scale at SHRS, and changes in population levels were determined by sampling at ~ 6 month intervals (during January-February 2004, June-July 2004, January-February 2005, and June-July 2005). Number and percent viable adults, and reproductive success as indicated by ratio of nymphs to viable adults (< 2 cm diam and 30 cm long branch sample) were recorded. There were 55 plants evaluated over the 5 sampling periods. Infestation increased from 42% of sampled plants at the start to 75% at the end of the study, and most of the plants had low or moderate levels of infestation (between 0 and 100 adults per 30 cm branch). Percentage non-viable adults dropped from ~ 27% at the start of the study ~ 7% by the end of the study, and ratio of nymphs to viable adults dropped from ~ 9% to ~ 2%. Spatial analysis showed that initial infestations were along the eastern edge of the sampled area, with populations declining over the first year of the study but then increasing during the second year. Over the course of the study, heavy infestations (>= 100 scales per 30 cm branch) were found on only seven host plants. Individual host susceptibility appeared to be the primary factor regulating infestation level.