New to nature No 97: Ferrisia uzinuri

http://www.guardian.co.uk/science/2013/jan/20/mealybug-ferrisia-uzinuri-new-to-nature

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Mealy bugs are small, soft-bodied scale insects that attach themselves to plants where they feed on fluids, weakening or damaging the host and sometimes transmitting disease. Their common name derives from dense cottony wax secretions with which they enrobe their body. Sexual dimorphism is extreme in mealybugs with "wasp-like" winged males that lack functional mouthparts and live only days, just long enough to mate, and flightless females that are largely sedentary once they attach to a host plant.

In 1893, a mealy bug known today as Ferrisia virgata was found in Jamaica, attacking a wide variety of plants. Soon, it became apparent that this was a serious pest in many tropical areas including India, Sri Lanka, Madagascar, West Africa and Java. It seems that the species had originated in South America and been transported around the world by the shipping trade. The genus Ferrisia was named in 1923 to accommodate this species. In spite of additional species being described, to this day most mealy bugs detected at ports are identified as F virgata, often mistakenly. And although a couple of species have been introduced to tropical countries around the globe, the genus is natively endemic to the New World.

In the 1970s, electrophoresis revealed gaps in enzymes present in various populations of F virgata, leading Dr Uzi Nuri to speculate this might be a complex of closely related cryptic species. As the phrase suggests, cryptic species are so similar morphologically that they are easily taken to be one and the same. Cryptic species are often discovered based on non-morphological evidence. Vocalisations, for example, have alerted biologists to multiple cryptic species of crickets, frogs and birds.

In 2010, a team at the University of California at Davis reopened the question of cryptic species of Ferrisia using DNA sequence data. Recently, two of those investigators, MB Kaydan of Çukurova Üniversity in Turkey and PJ Gullan of the Australian National University in Canberra, completed a monograph of the genus describing eight new species and bringing the total number of known species to 18.

In this case, five of the new species were based on a combination of DNA and morphological evidence and three on morphology alone. One of the new species isolated, F uzinuri, was named in honour of Dr Nuri for his pioneering work.

Pinpointing different species, including host plants, is of obvious significance to agricultural security, particularly in the New World, where Ferrisia are commonly intercepted at ports of entry. Females are ovoviparous, retaining eggs until maturity before depositing them on a plant surface. In the case of F virgata, the most extensively studied species in the genus, females can lay up to 700 eggs which hatch in about half an hour. Beyond the damage imposed by such large numbers, the species is a known vector of swollen-shoot virus in cacao as well as tristeza virus in citrus.

In addition to DNA, F uzinuri differs from closely related species by anatomical details observable only from cleared, stained and slide-mounted specimens, including the presence, absence, size, density and distribution of various ducts, pores, and setae. The new species occurs in the Bahamas, Haiti, Dominican Republic, Saint Barthélemy and Florida, and has been collected from plants representing at least five families including Euphorbiaceae (cassava, castor oil, rubber and other spurges), Fabaceae (soy, peas, beans and other legumes), Polygonaceae (buckwheat and other knotweeds), Cannabaceae (hemp, cannabis and hops), and Combretaceae.

Quentin Wheeler is director of the International Institute for Species Exploration, Arizona State University