Survey on Toxoptera citricidus and citrus tristeza in Central America and Caribbean
In order to evaluate the threat presented by Toxoptera citricidus (EPPO A1 quarantine pest) and citrus tristeza closterovirus (EPPO A2 quarantine pest), an extensive survey has been conducted from 1991 to 1993 in the citrus-producing regions of Central America, Mexico and Caribbean Basin. Commercial orchards, nurseries and dooryard citrus have been inspected and samples have been tested (ELISA) to detect citrus tristeza. This survey has showed that T. citricidus is well established in Costa Rica, Nicaragua, Panama and has recently spread throughout most of the Caribbean basin. However, during this survey, the pest has not been found in Belize, El Salvador, Guatemala, Honduras, Mexico, Bahamas, and Bermuda. [In this paper, a map also illustrates the spread of T. citricidus and shows in particular that it is present in Colombia and was there before 1980 (the EPPO Secretariat had previously no information on the situation in this country)]. The situation of T. citricidus in the countries studied is presented below.
- Central America
Costa Rica: T. citricidus is widespread in small plantings and dooryards near the east coast and central regions, and in commercial plantings in the north-west. It was first observed in 1989.
Nicaragua*: It was first found in 1991, as one population in a nursery (in the south near Costa Rica). But within a year, the pest spread throughout southern and central Nicaragua.
Panama*: T. citricidus was sporadic in 1991 but widespread in 1992. It was first found in 1989.
- Caribbean
Cuba: found in April 1993, in Guantanamo Bay.
Dominica*: First found in November 1991.
Dominican Republic: It was first found in January 1992 and large numbers were observed in citrus groves during 1992.
Guadeloupe: It was first detected in November 1991, and large numbers were found in citrus groves during 1992.
Haiti: found in December 1992.
Jamaica: found in July 1993.
Martinique: It was first detected in November 1991, and large numbers were found in citrus groves during 1992.
Puerto Rico: first detected in April 1992 and was already widespread.
St Lucia: First found in November 1991.
Trinidad and Tobago: widespread since 1985.
US Virgin Islands: T. citricidus was found in St Thomas and St Croix in April 1992.
In the same region, the incidence of citrus tristeza closterovirus is low (;15 %) and in certain areas it was not detected. CTV has been detected in Bahamas¨, Belize, Bermuda, Costa Rica, Dominican Republic, El Salvador, Guatemala¨, Honduras¨, Jamaica, Mexico¨, Nicaragua, Panama, Puerto Rico, Trinidad and Tobago. CTV was not detected in Cuba. Most of the isolates can be considered as mild. Severe tristeza symptoms were rare in Mexican lime and sweet orange grafted on sour orange and absent in grapefruit. However, some isolates reacted with the monoclonal antibody used to discriminate the severe strain of CTV, and have been found in Belize, Costa Rica, Panama, Bermuda, Dominican Republic, Jamaica, Puerto Rico and Trinidad.
The authors felt that the incidence of citrus tristeza is still low because most of the planted trees have been propagated from virus-free material. In addition, as the occurrence of its most efficient vector is only recent, the incidence of the disease had no sufficient time to reach detectable and significant levels. However, recent observations showed an increase of the disease in some areas (Costa Rica, Puerto Rico, Dominican Republic and Trinidad). The existence of potentially severe strains in latent conditions presents also a serious risk for this region. The authors concluded that the spread of citrus tristeza and its vector present a serious threat for the important citrus production of Caribbean, Central America, Mexico and United States. Further surveys will be carried out in this region, especially in areas at risk like Florida, Texas and Mexico.
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* New records for T. citricidus according to the EPPO Secretariat.
¨ New records for CTV according to the EPPO Secretariat
Sources
Yokomi, R.K.; Lastra, R.; Stoetzel, M.B.; Damsteegt, V.D.; Lee, R.F.; Garnsey, S.M.; Gottwald, T.R.; Rocha-Peña, M.A.; Niblett, C.L. (1994) Establishment of the brown citrus aphid (Homoptera: Aphididae) in Central America and the Caribbean Basin and transmission of citrus tristeza virus.
Journal of Economic Entomology, 87(4), 1078-1085.