Rapid species-level hemolymph color test for all life stages of Nipaecoccus viridis (Newstead) (Hemiptera: Pseudococcidae), an invasive and regulatory pest in the United Sates

Authors: Ahmed, Muhammad; DETER, LILY - Florida Department Of Agriculture And Consumer Services

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2022
Publication Date: 4/26/2022
Citation: Ahmed, M.Z., Deter, L.A. 2022. Rapid species-level hemolymph color test for all life stages of Nipaecoccus viridis (Newstead) (Hemiptera: Pseudococcidae), an invasive and regulatory pest in the United Sates. Journal of Applied Entomology. 2022;00:1-7. https://doi.org/10.1111/jen.12985.
DOI: https://doi.org/10.1111/jen.12985

Interpretive Summary: Lebbeck mealybug, an invasive species worldwide. Its first occurrence in the commercial citrus area, associated with heavy damage, was misidentified in the field as cottony cushion scale in 2018 and was correctly identified in 2019. Lebbeck mealybug is a polyphagous pest that has been reported from 144 genera of 51 host plant families, including several citrus species, from at least 63 countries worldwide. Its feeding damage includes distorted fruit and leaves, branch dieback, and even tree death in young and recently planted trees. Citrus orchards were burned due to its extensive damage in Jordan in an effort to eradicate it. Premature fruit drop has been documented to cause up to 50% of crop losses in citrus orchards. At low populations or as individuals, this pest can be easily misidentified since its species based on eggs, first instars, and other immature stages is hard to distinguish from those of other mealybugs. In addition, immatures can be missed during plant inspections as individuals tend to feed in cryptic locations, including under the sepals on citrus fruit. Slide-mounting is a mandatory step in accurate species-level identification of mealybugs; unfortunately, the typical slide-mounting protocol is a resource- and time-consuming process. In addition, the chemicals used can be corrosive, flammable, and carcinogenic or can produce toxic fumes. Our study presents a hemolymph color metrics test for the first time in mealybugs and suggests it as a rapid and relatively safe tool for species-level identification of lebbeck mealybug. We discuss implementing this test in the field to help growers, researchers, and regulators make preliminary identifications.

Technical Abstract: Slide-mounting is mandatory for accurate morphological identification of mealybug species (Hemiptera: Pseudococcidae). A typical slide-mounting process is performed in laboratory settings and requires several tedious and technical steps that can take up to two hours. Moreover, most of the taxonomic literature on mealybugs is based on adult females, whereas it can be difficult to find adult females in good condition in field samples. We tested 2,635 specimens of 57 mealybug species from 26 genera of Pseudococcidae collected from all over Florida for two consecutive years to discover an alternative to slide-mounting Nipaecoccus viridis (Newstead). Nipaecoccus viridis is an emerging polyphagous pest of regulatory concern in the USA, and its distribution is limited to Florida. Recent exceptionally high infestations in commercial citrus growing areas have activated regulatory agencies to implement quarantine and regulatory measures in efforts to halt its further spread within and outside of Florida. A five-minute hemolymph color test of eggs, immatures and adults is species-specific to N. viridis. This test will allow the identification of all life stages even when an adult female is not available. We discuss implementing this test in the field to help growers, researchers, and regulators make preliminary identifications.