Life History of Parthenolecanium spp. (Hemiptera: Coccidae) in Urban Landscapes of the Southeastern United States.

This study was conducted to better understand the life history of Parthenolecanium corni (Bouché) and Parthenolecanium quercifex (Fitch) (Hemiptera: Coccidae), and to develop degree-day models for crawler emergence of the two soft scale species in Georgia, North Carolina, South Carolina, and Virginia. Both species were univoltine in the southeastern United States. In South Carolina, eggs hatched from mid-April to early June; second instars began to appear in September and migrated to twigs to overwinter in October; and third instars and adults appeared in mid-March to early April. Each parthenogenetic female produced on average 1,026 ± 52 eggs. Fecundity was positively correlated to the fresh weight, length, width, and height of gravid females. Gross reproductive rate (GRR) was 695.98 ± 79.34 ♀/♀, net reproductive rate (Rº) was 126.36 ± 19.03 ♀/♀, mean generation time (TG) was 52.61 ± 0.05 wk, intrinsic rate of increase (rm) was 0.04 ♀/♀/wk, and finite rate of increase (λ) was 1.04 times per week. Crawlers first occurred across Georgia, North Carolina, South Carolina, and Virginia in 2011-2013 when 524-596 Celsius-degree-days (DDC) had been accumulated with the single sine estimation method, or 411-479 DDC with the simple average method, at the base temperature of 12.8 °C and the start date of 1 January. These regional models accurately predicted the date of crawler emergence within 1 wk of the actual emergence in 2014.

General Biology and Current Management Approaches of Soft Scale Pests (Hemiptera: Coccidae).

We summarize the economic importance, biology, and management of soft scales, focusing on pests of agricultural, horticultural, and silvicultural crops in outdoor production systems and urban landscapes. We also provide summaries on voltinism, crawler emergence timing, and predictive models for crawler emergence to assist in developing soft scale management programs. Phloem-feeding soft scale pests cause direct (e.g., injuries to plant tissues and removal of nutrients) and indirect damage (e.g., reduction in photosynthesis and aesthetic value by honeydew and sooty mold). Variations in life cycle, reproduction, fecundity, and behavior exist among congenerics due to host, environmental, climatic, and geographical variations. Sampling of soft scale pests involves sighting the insects or their damage, and assessing their abundance. Crawlers of most univoltine species emerge in the spring and the summer. Degree-day models and plant phenological indicators help determine the initiation of sampling and treatment against crawlers (the life stage most vulnerable to contact insecticides). The efficacy of cultural management tactics, such as fertilization, pruning, and irrigation, in reducing soft scale abundance is poorly documented. A large number of parasitoids and predators attack soft scale populations in the field; therefore, natural enemy conservation by using selective insecticides is important. Systemic insecticides provide greater flexibility in application method and timing, and have longer residual longevity than contact insecticides. Application timing of contact insecticides that coincides with crawler emergence is most effective in reducing soft scale abundance.