Detectability of Hibiscus Mealybug, Nipaecoccus viridis (Hemiptera: Pseudoccocidae), DNA in the Mealybug Destroyer, Cryptolaemus montrouzieri (Coleoptera: Coccinellidae), and Survey of Its Predators in Florida Citrus Groves.

Abstract

The Hibiscus mealybug, Nipaecoccus viridis (Newstead), has recently established in Florida citrus and become a pest of concern given secondary pest outbreaks associated with management of citrus greening disease. Chemical controls used to manage other citrus arthropod pests are not as effective against N. viridis due to its waxy secretions, clumping behavior, and induced cellular changes to host plant tissue which increase microhabitats. Populations of this mealybug pest are regulated by natural enemies in its native region, but it remains unclear if resident natural enemies in Florida citrus could similarly suppress N. viridis populations. This investigation: 1) established species-specific primers for N. viridis based on the mitochondrial gene Cytochrome-oxidase 1 (COI), 2) determined duration of N. viridis DNA detectability in a known predator, the mealybug destroyer (Cryptolaemus montrouzieri Mulsant), by using identified primers in molecular gut content analysis, and 3) screened field-collected predators for the presence of N. viridis DNA. The detection rate of N. viridis DNA was >50% at 36 h after adult C. montrouzieri feeding but DNA was no longer detectable by 72 h after feeding. Field-collected predators were largely comprised of spiders, lacewings, and C. montrouzieri. Spiders, beetles (primarily C. montrouzieri), and juvenile lacewings were the most abundant predators of N. viridis, with 17.8, 43.5, and 58.3 of field-collected samples testing positive for N. viridis DNA, respectively. Our results indicate that Florida citrus groves are hosts to abundant predators of N. viridis and encourage the incorporation of conservation or augmentative biological control for management of this pest.