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. 2015 Oct 28;6(1):17.
doi: 10.1093/jipm/pmv016. eCollection 2015.

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

Affiliations

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

Ernesto Robayo Camacho et al. J Integr Pest Manag. .

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.

Keywords: biological control; chemical control; crawler emergence; cultural control; voltinism.

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Figures

Fig. 1.
Fig. 1.
Eggs within the brood chamber (left) of the oak lecanium scale, Parthenolecanium quercifex (Fitch).
Fig. 2.
Fig. 2.
Crawlers of the oak lecanium scale emerging and dispersing from adult female.
Fig. 3.
Fig. 3.
First-instar oak lecanium scales settled on their feeding sites, in proximity to a leaf vein of willow oak.
Fig. 4.
Fig. 4.
Second instars of the oak lecanium scale, after moving from the leaves to the branches to overwinter.
Fig. 5.
Fig. 5.
By spring, the second instars of oak lecanium turn to third instars. A second instar that was in the process of shedding the silvery exuvia could be seen in the middle of the twig.
Fig. 6.
Fig. 6.
Adult female oak lecanium scales on a willow oak twig. Their bodies swell and turn reddish color as they mature.

References

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