Parabemisia myricae. [Distribution map].

A new distribution map is provided for Parabemisia myricae (Kuwana). Hemiptera: Aleyrodidae. Hosts: polyphagous. Information is given on the geographical distribution in Africa (Algeria, Côte d'Ivoire, Egypt, Morocco, Tunisia), Asia (China, Guangxi, Hong Kong, India, Karnataka, Iran, Israel, Japan, Honshu, Shikoku, Lebanon, Malaysia, Peninsular Malaysia, Sarawak, Sri Lanka, Taiwan, Turkey, Vietnam), Europe, (Croatia, Cyprus, France, Corsica, Greece, Crete, Italy, Sardinia, Sicily, Portugal, Spain, Canary Islands), North AMerica (Dominica, Guadeloupe, Honduras, Mexcio, Trinidad and Tobago, United States, California, Florida, Hawaii), Oceania (Papua New Guinea), South America (Brazil, Mato Grosso do Sul, Colombia, Ecuador, French Guiana, Venezuela).

The Whitefly Dialeurodes citri: A New Pest on Citrus in Tunisia?

Whiteflies invaded citrus orchards in Tunisia in the 90’s. Two species: Aleurothixus floccosus and Parabemisia myricae have been recorded successively infesting citrus and causing severe damage in Cap-Bon (North-East of Tunisia). These pests were first controlled by several insecticidal applications but with a relative efficiency. Then two biological control programs have been deployed completing the action of native natural enemies especially for P. myricae. The result was a very satisfactory control of both whitefly species, to a point that they almost disappeared from orchards for about 30 years. In 2017, a third whitefly species, identified as Dialeurodes citri, was observed during a prospection in citrus orchards in Takelsa region (Cap-Bon). It was a common species in Algeria, but never caused damage in Tunisia. In 2020, D. citri was found again with very high population densities in the regions of Menzel Bou Zelfa (Cap-Bon) and Tunis. These observations confirmed its change of status and spread in Tunisia. The main morphological and biological traits to distinguish between D. citri and the other two whitefly species, already recorded in Tunisia, were described and first observations on its infestation were reported. Some recommendations to manage this new pest are given.

First records of the bayberry whitefly, Parabemisia myricae (Kuwana) in Greece

Citrus groves of Corfu had been attacked during the last decade by citrus whitefly Dialeurodes citri (Ashmead). It presumably expanded later, and it was found to cause a serious infestation on lemon trees of Achaia region during summer of 1986, while it disappeared later existing today only in very small pockets on ornamental citrus species in Attica area. Late in August 1988, the leaves of citrus trees, and to a lesser extent of grapevines, in the region of Corinthia, NE Peloponnesos, in South Greece were covered by larvae, pupae and adults of a whitefly that was different from D. citri. In autumn of the same year, it was noticed that the infestation of this new whitefly had expanded to other parts of Peloponnese such as Argos, Patras and Ilia region. Samples of citrus and grapevine leaves with nymphs of the insect were sent for identification to British Museum of Natural History. Dr. J. H. Martin identified the species as Parabemisia myricae (Kuwana) (Homoptera: Aleyrodidae), making the first record of the species in Greece. The species is a native of Japan and possibly of other eastern asian countries such as Taiwan and West Malaysia. Today, the insect has been recorded in USA (California), Cyprus, Israel and Turkey, Egypt (Martin personal communication) and it is a pest of woody plants, especially citrus trees and grapevines. The damage caused to the plants by this insect, as a feeder, can be serious in cases of large populations accompanied with problems associated with the development of sooty mould on the excreted honeydew. In the autumn of 1988, infestation was high (more than 20 nymphs/leaf) in Achaia and Corinthia regions of N. Peloponnese, causing great concern to citrus growers. This species of whitefly was not included in the lists of known plant pests of Greece. It is probable that it invaded Greece from Israel. P. myricae is a newly introduced pest in citrus growing countries and there is little information available on its biology and control. Most of the published data comes from Israel and California on the biology and biological control of the insect. Additional data have been published on flight behaviour, oviposition behaviour, and survival of young nymphs on leaves of different age citrus leaves. The adults of P. myricae are smaller than D. citri adults and they have a dusty blue gray or lavender appearance. The females oviposit on very young leaves, often in circles. Preference for oviposition on very young leaves seems to be related to properties of the leaf cuticle. Leaf age is a critical factor for survival of nymphs. This gives a good explanation for the observed high rates of mortality in spring for nymphs growing on rapidly maturing leaves. It has been observed that on orange trees less eggs are layed on the lower surface of the leaves, while on lemon trees they tend to be layed equally on both surfaces. Initially eggs are off-white, while after about one day they gradually turn to brownish and finally black, before they hatch. First instar crawlers settle on the surface of the young leaves with a preference to the lower surface. First flights of adults were noticed in this area in late February of 1989. By end of March early April the emergence of adults of the first 1989 generation had been completed. It seems that it produces a quite large number of generations during the year, as it requires only 21 days at temperatures fluctuating between 210oC and 17.3oC and 65-100 percent relative humidity, to complete its cycle in glasshouse. Being a pest of Citrus and grapevines (Vitis vinifera) it has also been found on hosts like Ficus, Persea, Prunus, Psidium and Thea. As a matter of fact it has also been found in small colonies on Prunus cerasi in Northern Peloponnese in autumn 1988. Work on the control of Parabemisia myricae with the insect growth regulator Buprofezin has started in Greece in 1988 and is expected to be concluded in 1990.

Toxicity of some pesticides to Eretmocerus debachi (Hymenoptera: Aphelinidae), an important parasitoid of Parabemisia myricae (Homoptera: Aleyrodidae)

The effects of nine pesticides commonly used in citrus orchards were tested on adults, larvae and pupae of the parasitoid Eretmocerus debachi Rose & Rosen in the laboratory. All pesticides caused immediate mortality to adult parasitoid females and significant losses in efficiency, if applied to larvae of E. debachi in its host Parabemisia myricae (Kuwana). Only the fungicide captan and the insecticide Mercathion (malathion) were slightly harmful and harmless to the parasitoid larva. Gramoxone (paraquat), Dursban 4 (chlopyrifos-ethyl), Mercathion and Supracide (methidathion) were harmful to E. debachi pupae, while five other pesticides were only moderately harmful or harmless.

Parabemisia myricae. [Distribution map].

A new distribution map is provided for Parabemisia myricae (Kuwana) Homoptera: Aleyrodidae (Japanese bayberry whitefly). Attacks mulberry, Citrus, avocado, Gardenia, Cinnamomum camphora, Prunus, Salix, Morus alba and tea. Information is given on the geographical distribution in Europe, Crete, Cyprus, Greece, Italy, Sicily, Spain, Turkey, Africa, Egypt, Tunisia, Ivory Coast, Asia, Hong Kong, Israel, Japan, Malaysia, Taiwan, North America, USA, California, Florida.