HORTICULTURAL ENTOMOLOGY Pheromone-Baited Traps for Assessment of Seasonal Activity and Population Densities of Mealybug Species (Hemiptera: Pseudococcidae) in Nurseries Producing Ornamental Plants REBECCAH A. WATERWORTH, 1 RICHARD A. REDAK, AND JOCELYN G. MILLAR Department of Entomology, University of California, Riverside, CA 92521 J. Econ. Entomol. 104(2): 555Ð565 (2011); DOI: 10.1603/EC10317 ABSTRACT Operational parameters of traps baited with the pheromones of three mealybug species were optimized in nurseries producing ornamental plants. All pheromone doses (1Ð320 g) attracted Pseudococcus longispinus (Targioni Tozzetti) and Pseudococcus viburni (Signoret) males, with the lowest dose (1 g) attracting the fewest males for both species. Doses of 3.2Ð100 g were as attractive to male P. longispinus as the highest dose (320 g); doses from 10 to 320 g were equally attractive for P. viburni males. Lures containing 25-g doses of either pheromone had effective Þeld lifetimes of at least 12 wk. Experiments were performed to test the efÞcacy of combining multiple pheromones to attract several species of mealybugs simultaneously. Lures loaded with a mixture of the pheromones of P. longispinus, P. viburni, and Planococcus citri (Risso) were as attractive to P. viburni and P. citri as lures with their individual pheromones. Response of P. longispinus to the blend was decreased by 38% compared with its pheromone as a single component. A subsequent trial with two-component blends showed that the pheromone of P. citri was responsible for this modest decrease in P. longispinus response. This should not affect the overall efÞcacy of using these lures for monitoring the presence of all three mealybug species simultaneously. Pheromone traps were used to detect infestations of P. longispinus throughout the season and to track population cycles. When pheromone-baited traps for P. longispinus were compared with manual sampling, trap counts of male mealybugs were signiÞcantly correlated with mealybugs counted on plants in the vicinity of the traps. KEY WORDS mealybugs, pheromone trap, detection, sampling, ornamental plants The wholesale value of California nursery and ßori- culture crops in 2007 was US$1 billion for nurseries with annual sales of US$10,000 (California Agricul- tural Production Statistics 2009 Ð2010), which trans- lated into a market value of US$3.6 billion (Census of Agriculture 2007). With crop values and revenue so high and a low tolerance for aesthetic damage to ornamental plants (Raupp et al. 1992, Sadof and Sclar 2002), nursery managers are under intense pressure to control insects and other pests to minimize damage to production- stage plants. Regardless of how crops are grown, mealybugs are chronic pests of ornamental plants throughout tem- perate regions of the world, including California (Laf- lin et al. 2004). In a survey conducted in 19 of Cali- forniaÕs production nurseries, 12 mealybug species were found on a wide assortment of host plants (Laßin et al. 2004). The most common mealybug species were citrus mealybug, Planococcus citri (Risso); longtailed mealybug, Pseudococcus longispinus (Targioni Toz- zetti); and obscure mealybug, Pseudococcus viburni (Signoret) (Laßin et al. 2004). P. citri was found most often on annual crops, with the exception of Rosa species, whereas P. longispinus was most common on perennial species. P. viburni was found on both an- nuals and perennials. The remaining nine species of mealybugs listed in the survey were specialists on a single or a few host plant species at one nursery lo- cation (Laßin et al. 2004). Mealybug damage to plant tissues is primarily aes- thetic. These insects use their mouthparts to pierce a plantÕs phloem to extract photosynthates (Gullan and Martin 2003), resulting in distorted plant tissues, leaf yellowing, defoliation, and reduced plant growth, but rarely plant death. Adaptations in mealybugs (and other phloem feeders) allow excess sugar to be pro- cessed into longer-chain oligosaccharides that are ex- creted as honeydew (Douglas 2006). Accumulations of sticky honeydew not only contaminate plant foliage but also result in the growth of black sooty mold fungi that further greatly reduces the marketability of in- fested plants. Management strategies for mealybugs primarily in- volve the use of insecticides, including organophos- phates, insect growth regulators (IGRs), pyrethroids, and neonicotinoids (e.g., imidacloprid) (Bethke 2010). Nonetheless, mealybugs can be difÞcult to control ef- 1 Corresponding author, e-mail: rebeccah.waterworth@ucr.edu. 0022-0493/11/0555Ð0565$04.00/0  2011 Entomological Society of America Downloaded from https://academic.oup.com/jee/article/104/2/555/2199634 by guest on 30 April 2023