Complete our Tamarixia Release Form to request parasitoids for release on your property to reduce Asian citrus psyllid populations.
ACP has a native range in tropical and subtropical Asia and can now be found throughout many of the tropical and subtropical fruit-producing regions of the world. They feed on all varieties of citrus and a few closely related ornamental plants in the family Rutaceae, including Chinese box orange ( Severinia buxifolia), Indian curry leaf ( Murraya koenigii) and orange jasmine ( Murraya paniculata). Adult ACP measure 3 to 4 mm long and are mottled white and brown, with a distinctive dark band along the apical margin of the forewing that is interrupted by a white gap at the apex. Nymphs are 0.25 to 1.7 mm, yellowish orange with prominent wing pads, and advance through five instars before emerging as adults. ACP adults reach reproductive maturity two to three days after emergence and can lay over 800 eggs in a lifetime. The yellowish-orange, tear-shaped eggs are laid on the unfolded leaves, flower buds, leaf axils, and the tips of newly expanding leaves (flush). Nymphs begin to feed on sap of soft new flush and may feed on harder stems as they mature. Adults are capable of feeding on mature, hardened leaves in the absence of new flush. While resting or feeding, adults generally sit on the undersides of leaves where they maintain their body at a 45 degree angle relative to the leaf surface. The life cycle can vary greatly depending on the season, from 15-47 days, with adults living as long as several months.
Citrus greening, also known as Huanglongbing, HLB, and yellow dragon disease, is one of the most serious citrus diseases in the world. It is widespread in Asia, Africa and the Saudi Arabian Peninsula. In August 2005 it was found for the first time in the U.S. in south Miami-Dade County. Citrus greening is a bacterial disease that attacks the vascular system of plants. The disease has no cure, and in areas where the disease is endemic, infected citrus trees decline and die within a few years. There are three known forms: Asian, African and Brazilian. The bacteria responsible for citrus greening is transmitted primarily by insect vectors (ACP) but can also be spread through plant grafting and movement of infected plant material. The disease does not spread by casual contamination of personnel and tools or by wind and rain.
Psyllids acquire the bacteria when they feed on infected plants, and the disease spreads when a bacteria-laden psyllid flies to a healthy plant and injects the bacteria into it as it feeds. Citrus greening causes dieback of foliage and roots, stunted growth, discoloration of leaves, distorted and bitter fruit, and tree death in as little as five years. The only way to protect trees and prevent the spread of citrus greening is by controlling psyllid populations and destroying infected trees.
In Florida’s citrus groves, management of citrus greening depends primarily on controlling ACP with regular pesticide applications. However, insecticides are not used to control ACP everywhere in Florida. If ACP populations are not controlled, they can serve as a reservoir for the disease, which can then spread and threaten commercial citrus groves. Many homeowners rarely use pesticides and have dooryard citrus trees and susceptible ornamentals that can support large populations of ACP. Dooryard citrus and orange jasmine hedges are especially problematic because they are often trimmed and irrigated. This induces frequent leaf flushing that is used by ACP for egg-laying, promoting population increases. Adult ACP move frequently between host plants in search of new growth; they can fly over a mile and move even greater distances in strong winds. Therefore, it is important that homeowners monitor their citrus trees and susceptible ornamentals for ACP and take the necessary management actions.
Biological control is an environmentally sound and effective means of reducing or mitigating pests and pest effects through natural enemies. In cooperation with the University of Florida’s Institute of Food and Agricultural Sciences (UF/IFAS), two parasitoids of ACP, Diaphorencyrtus aligarhensis (Shafee, Alam, & Agarwal) (Hymenoptera: Encyrtidae) and Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), were introduced into our quarantine laboratory from Southeast Asia in 1998. A permit for field release of D. aligarhensis was granted in March of 2000. However, Diaphorencyrtus aligarhensis is not known to have established in Florida. Therefore, mass production of this biocontrol agent ceased in 2021.
A permit for field release of T. radiata was granted in July of 1999. Tamarixia radiata has been reported to effectively suppress ACP populations in locations such as Réunion Island, India, Puerto Rico and Guadeloupe. After release, the parasitoid quickly established in Florida and now occurs widely throughout the state and provides varying levels of ACP control. Millions of T. radiata are distributed by FDACS every year.
Tamarixia radiata females lay an egg on the ventral surface of the ACP nymph, usually one egg per nymph. The resulting larval wasp consumes the body fluid of the ACP nymph, eventually killing it and turning the empty psyllid casing into a “mummy” where the wasp pupates, undergoing a major physical change called metamorphosis and developing to adulthood. The now-adult wasps chew an exit hole through the dorsal surface of the mummy, emerge, and fly off to attack other psyllids. Female T. radiata also destroy ACP nymphs by feeding on them. Over her lifetime of approximately 28 days, a T. radiata female can kill over 500 nymphs. Tamarixia radiata attacks and kills ACP and has no negative impact on any organism other than ACP. These wasps are very tiny and will not sting humans.
If you are not a commercial citrus grower and would like to request parasitoids for release on your property to reduce ACP populations in citrus or ornamental plantings, please fill out the Tamarixia Release Form (see link at the top). Forms will be sent automatically to FDACS ACP biocontrol project coordinators. Your information is kept confidential. Supplies of T. radiata are limited, but program staff will respond to all inquiries and send wasps to as many requesters as possible. Tamarixia radiata will be shipped overnight at no cost with instructions for releasing the insects, which is fun and easy and is extremely important for protecting our citrus industry.
The FDACS, Division of Plant Industry has two rearing facilities for the mass production of Tamarixia radiata. One located in Gainesville and the other one in Dundee. Each facility is run by a biological scientist and approximately five additional laboratory technicians and plant care specialists that assist in insect production and plant care, respectively.
Several organisms are involved in the rearing process. To mass-produce the parasitoid wasps, we must mass-produce ACP; to mass-produce ACP, we must first grow suitable host plants. Our program uses Murraya paniculata, orange jasmine, for this purpose. These plants require one to two years of growth before they can be incorporated into ACP/wasp production. When plants are mature, ACP adults are introduced to the plants in large oviposition cages where they mate and lay eggs on the young fresh tissues of the plant. After several days of egg laying, the plants are removed and placed in a development cage where eggs can eclose (hatch) and nymphs can grow to the appropriate size. This takes about a week.
Tamarixia radiata adults are then released into the cages with the ACP nymphs, where they select nymphs as hosts and lay their eggs. Adult T. radiata also eat the ACP nymphs, so these adults are removed after two days. The T. radiata eggs hatch, and the larvae feed on the ACP nymphs from within until they pupate; after a few days they emerge as adult wasps, which the team collects and ships to citrus growers in need.
The entire operation requires a minimum of 17,000 plants in various growth stages at any given time. The process of introducing the ACP and moving the orange jasmine into and out of the production cycle stresses the plants; after repeated exposure the stress can cause plant death, and each year we acquire and plant thousands of seeds to make up for these losses. These two facilities produce hundreds of thousands of wasps each year!
