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

Abstract

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.

The spread of the non-native pine tortoise scale Toumeyella parvicornis (Hemiptera: Coccidae) in Europe: a major threat to Pinus pinea in Southern Italy

“…Several aspects of PTS life history in Campania confirmed previous investigations carried out in USA and Turks and Caicos Islands (Malumphy et al 2012, Clarke 2013. Similarly, PTS behaviour here recorded is consistent with what was reported for the Southern range of the native area on Nearctic pines (Cooper & Cranshaw 2004, Clarke 2013, Camacho & Chong 2015. The noteworthy environmental plasticity of the species is exemplified by the variable number of generations completed per year coupled with the acceptance of new host species (Malumphy et al 2012).…”

A Review of White Mango Scale (Aulacaspis tubercularis Newstead; Hemiptera: Diaspididae) in Sub-Saharan Africa: Distribution, Impact and Management Strategies

“…The control threshold is expected to vary depending on the climate, season (off season versus on-season of production) and market (local versus international market). However, control practice should be initiated when at least 20 individual pests are recorded per twig sampled (Camacho and Chong, 2015).…”

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

“…Careful timing of control measures, informed by pest phenology, is critical to the management of landscape pests (Ascerno 1991, Raupp et al 1992, Mussey and Potter 1997, Robayo Camacho and Chong 2015. The crawlers and settled first instars of soft scale insects in the subfamily Coccinae is the only life stage without the protection of a waxy cover or deposit Braman 2004, Robayo Camacho andChong 2015). Consequently, it is the life stage most vulnerable to contact insecticide applications.…”