About Asian Citrus Psyllid
The Asian Citrus Psyllid (ACP) is an invasive pest that causes serious damage to citrus plants and citrus plant relatives through its feeding activities. Burned tips and twisted leaves result from an infestation of psyllids on new growth. Even more serious is that psyllids act as a carrier of the bacterium that causes Huanglongbing (HLB) disease, also known as citrus greening disease, spreading the disease to healthy citrus plants as they feed. Citrus greening is one of the most serious citrus plant diseases in the world. Once a tree is infected, there is no cure. HLB is now a serious threat to the U.S. citrus industry. Infected trees produce fruit that are green, misshapen and bitter, unsuitable for sale as fresh fruit or for juice. Most infected trees die within a few years.
Once the Asian citrus psyllid picks up the disease, it carries it for the rest of its life. HLB is then spread by moving infected plant material, such as potted plants, bud wood and even leaves.
The pest is found in tropical and subtropical climates in Southern Asia, Afghanistan and parts of Central and South America. The ACP was first found in California in 2008 in both San Diego and Imperial Counties, where control and quarantine activities are underway.
What Does the Asian Citrus Psyllid Look Like?
Asian citrus psyllids are most likely to be found on new shoots, and the insect population increases during periods of active plant growth. The tiny adults are aphid-like in appearance, measuring about 1/8 inch in size. The bodies are grayish-tan with brown markings and mottled brown wings. The last two segments of antennae are black. ACPs feed with the posterior of their bodies raised at a 45° angle. When approached, they jump or fly.
Nymphs have yellow to brown oval bodies. They are often found on new growth and feed on leaves and stems. They move slowly, cannot fly and can be very difficult to see. However, the white, waxy excretions given off by the nymphs can be noticeable.
ACP eggs are almond-shaped and range from yellow to orange in color.
What is the Asian Citrus Psyllid’s Life Cycle?
Eggs are laid on tips of growing shoots and between unfurling leaves. Females lay 300 to 800 eggs during their lifetime. Nymphs pass through five developmental stages. Adult ACPs may live for more than one month. The total life cycle requires from 15 to 47 days, depending on environmental factors such as temperature and season. Populations are typically low in the winter or during dry periods. There are nine to 10 generations a year, with up to 16 found under observation in field cages.
What Damage does the Asian Citrus Psyllid Cause?
The ACP threatens citrus plants and citrus relatives in two ways: it damages new plant growth as it feeds but, even worse, it is a host to the deadly citrus disease Huanglongbing (HLB).
HLB is a bacterial disease that greatly reduces production, destroys the economic value of fruit and eventually kills trees. Although the disease poses no threat to humans or animals, it has devastated the citrus crops in Asia, Africa, the Arabian Peninsula and Brazil. Once infected, there is no cure for a tree with HLB: within a few years, infected trees decline and die. A number of citrus plants host HLB, including:
- Chinese box-orange
- Finger-lime
- Grapefruit
- Kumquat
- Lemon
- Mandarin orange
- Pomelo
- Sour orange
- Sweet orange
- Tangerine
ACP can be found on those plants and more, including orange jasmine, other varieties of lime and some cherry-oranges.
The ACP damages new plant growth because it removes large amounts of sap from the plant as it feeds. This causes the ACP to produce a large amount of honeydew, which coats the leaves of plants and trees and encouraged sooty mold to grow.
The ACP is a sturdy pest: it can withstand freezing temperatures and hurricane-force winds. Because of its hardiness, ACP has the potential to devastate California’s $1.2 billion citrus industry if HLB is picked up by the pest and spread to healthy trees. A California Department of Food and Agriculture (CDFA) analysis based on Florida’s experience with the pest and HLB suggests it could cost $224 million annually—20 percent of total production—if ACP and HLB become established in California.
Where is the Asian Citrus Psyllid Found in California?
Since August 28, 2008, the United States Department of Agriculture’s Animal and Plant Health Inspection Service has confirmed small populations of ACP in portions of San Diego and Imperial counties. Agriculture officials have implemented an aggressive control and quarantine program to protect California from this invasive pest.
No HLB has been found in California at this time. A map of current quarantine areas can be found here.
What Happens in Quarantined Areas?
Quarantines are designed to try to keep the pest away from citrus-producing regions. Regulations specify:
- All harvested citrus in the quarantine area must be commercially cleaned and packed before it can be moved out of the quarantined areas
- Nursery host plants may not be moved out of the quarantined area
- The movement of cut greens, green waste and citrus fruit will be regulated and enforced by federal, state and county quarantine officials
- Cut flower producers in quarantined areas are not affected unless they utilize Murraya, a host plant that is closely related to citrus
The quarantine currently in effect in San Diego and Imperial counties does not affect the supply of fruit. It is okay to continue consuming citrus fruit because the fruit has not been harmed nor has the quality of the fruit changed. Agriculture officials request people within the quarantine area to consume home-grown citrus fruit at home and not transport home-grown citrus or citrus plants out of the area.
What Can We Do?
Although no HLB has yet been found in California, it is important to be able to identify citrus greening and the Asian Citrus Psyllid pest. Evidence of citrus greening includes:
- Lopsided, bitter, hard fruit with small, dark aborted seeds
- Asymmetrical blotchy mottling of leaves
- Yellow shoots
If you suspect you’ve seen the Asian Citrus Psyllid or signs of HLB in California, call the CDFA hotline: 800-491-1899.
Resources List
Asian Citrus Psyllid (ACP) and Huanglongbing (HLB)
United States Department of Agriculture: Animal and Plant Health Inspection Service
http://www.saveourcitrus.org
Asian Citrus Psyllid (ACP) and Huanglongbing (HLB)
California Department of Food and Agriculture
http://www.cdfa.ca.gov/phpps/acp/
Citrus Greening Hosts
United States Department of Agriculture: Animal and Plant Health Inspection Service
http://www.aphis.usda.gov/plant_health/plant_pest_info/citrus_greening/hosts.shtml
Citrus Research Board
http://www.californiacitrusthreat.org/
