Life History and Natural Enemy Associations of Calico Scale (Homoptera: Coccidae) in Kentucky

Abstract

Seasonal phenology of calico scale, Eulecanium cerasorum (Cockerell), was monitored for 3 yr on various deciduous tree species in central Kentucky. Infestations were found on 16 host species in six plant families. Calico scale is a univoltine parthenogenic species that overwinters as second instars on bark. Nymphs molted to adult females around mid-April and began producing eggs in late April. Mean fecundity ranged from 3,728 to 4,654 eggs per female, depending on host plant species. Date of first crawler hatch in 2001-2003 ranged from 21 to 26 May, corresponding to a mean accumulation of 818 +/- 2 Celsius degree-days (DDC), calculated from 1 January and a base of 4.4 degrees C. This value predicted crawler hatch within 2 d in Lexington, KY, in 2004. Crawler dispersal lasted 2 to 3 wk. Upon hatching, crawlers move to leaves where they feed during summer. Crawlers primarily settled on the abaxial side of leaves and their within-leaf distribution varied between different tree species. Settled crawlers molted in mid-July and second instars remained on leaves until late September through mid-October, when they returned to bark to overwinter. On hackberry, Celtis occidentalis L., they were concentrated toward the basal end of shoots, primarily because leaf flush continued beyond the end of the crawler dispersal period. Crawler distribution did not differ between upper and lower canopy zones. Fourteen species of parasitoids and a coccinellid beetle were reared from individual scales. Monitoring with sticky traps in tree canopies confirmed that targeting crawlers with insecticides during late May or June would not coincide with peak flight activity of the scale's primary parasitoids.

Ant-Exclusion to Promote Biological Control of Soft Scales (Hemiptera: Coccidae) on Woody Landscape Plants

“…axyridis, too, consumed E. cerasorum in laboratory trials but only during the scalesÕ active crawler stage. Crawler dispersal only lasts Ϸ19 d (Hubbard and Potter 2005), so predation by H. axyridis likely has less impact on the scale population compared with C. rufilabris larvae, which presumably consume scales at least from June through September. Furthermore, when harassed by the ant Myrmica sp., H. axyridis pulled its legs beneath the protection of its well-armored body and waited for the ants to retreat.…”

“…Calico scale, a univoltine invasive pest, reaches high densities on many species of deciduous shade and landscape trees in both urban and rural (e.g., horse farm) settings in Kentucky (Hubbard and Potter 2005). Females mature in spring, each laying several thousand eggs during May.…”

“…First instars (crawlers) emerge from lateMay to mid-June, settling mainly on leaf undersides. Second instars migrate back to overwintering sites on twigs and branches shortly before leaf drop in autumn (Hubbard and Potter 2005).…”

“…In addition, 400 nymphs (200 each from banded or control trees) were removed with a razor blade and examined under a binocular microscope with backlight for the presence of parasitoid larvae or pupae. Parasitism of settled nymphs was evaluated in autumn because Hubbard and Potter (2005) reported increased parasitism rates from mid-August to early October.…”

Relative resistance or susceptibility of maple (Acer) species, hybrids and cultivars to six arthropod pests of production nurseries

“…They include two exotic species, calico scale ( Eulecanium cerasorum Cockerell) and Japanese beetle ( Popillia japonica Newman), and four native pests, potato leafhopper ( Empoasca fabae Harris), maple shoot borer ( Proteoteras aesculana Riley), flatheaded appletree borer ( Chrysobothris femorata Olivier) and maple spider mite ( Oligonychus aceris Shimer). Different pesticides and treatment timings are needed to control such a wide range of pests, and growers who fail to protect their young trees can incur significant economic losses …”