Datasheet

Enhanced

30 November 2019

Blighia sapida (akee apple)

Author: F Areces-BerazainAuthors Info & Affiliations

Publication: CABI Compendium

9345

https://doi.org/10.1079/cabicompendium.9345

Datasheet Types: Tree, Host plant, Crop, Documented species

Abstract

This datasheet on Blighia sapida covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Dispersal, Diagnosis, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Management, Genetics and Breeding, Food Quality, Food Safety, Economics, Further Information.

Identity

Preferred Scientific Name: Blighia sapida K. D. Koenig
Preferred Common Name: akee apple
Other Scientific Names: Akea solitaria Stokes; Akeesia africana Tussac; Bonannia nitida Raf.; Cupania akeesia Cambess. ex Spach; Cupania sapida (K.D. Koenig) Oken; Cupania sapida J. Voigt; Cuponia sapida VOIGT
International Common Names: English
ackee
akee tree
vegetable brains; Spanish
aki
huevo vegetal
seso vegetal; French
akée d’Afrique
arbre à fricasser; German
Akipflaume
Akipflaumenbaum
Local Common Names: Brazil
castanheiro do Africa; Burkina Faso
arbre sarriette
blighia savoureuse
finzan
pommier finsam
ris de veau; Cameroon
abale
ndamba; Colombia
bien me sabe
pan y quesito; Cuba
akee de África
árbol del seso
arbre à fricassé
arbre fricassé; Côte d'Ivoire
baza
finzan
kaha
kaka
sugo; Dominican Republic
akee de África
árbol del seso; Gabon
ekom
ichi
ngwin; Germany
Akee; Ghana
achin
adza
atsa
ayigbe atia
takwadua; Guatemala
arbol de huevo
fruto de huevo; Guinea-Bissau
cuiema
féso
m’butchiri
otau; Italy
akee dell'Africa; Lesser Antilles
cervelle végétale
ris-de-veau
yeux de crabe; Mexico
huevo de gato
pera roja; Nigeria
abikotor
awai
feso
gwanja kusa
iIshin
ila
ilipa
isin
okpu
otusi
ukpe
ukpe rerhen; Panama
arbol de huevo
fruto de huevo; Senegal
finza; Sierra Leone
maiyosundo
Sundo; Suriname
akie; Togo
adza
keka
peso; Venezuela
merey del diablo; Vietnam
a kê
EPPO code: BLISA (Blighia sapida)

Pictures

Ripe fruits
Blighia sapida (Akee apple); open, ripe fruits. Locally known as 'seso vegetal' in Colombia. June 2005.
©Michael Hermann/http://www.cropsforthefuture.org/via wikipedia - CC BY-SA 3.0

Mature fruit
Blighia sapida (akee apple); Mature fruit split apart showing shiny black seeds. November 2016.
©Cerlin Ng/via Flickr - CC BY-NC-SA 2.0

Fruits and foliage
Blighia sapida (Akee apple); fruits and foliage, locally known as seso vegetal in Colombia. June 2005.
©Michael Hermann/http://www.cropsforthefuture.org/via wikipedia - CC BY-SA 3.0

Fruits
Blighia sapida (Akee apple); fruits and foliage. October 2005.
©Jerome Walker-2005/via wikipedia - CC BY-SA 3.0

Fruits and foliage
Blighia sapida (Akee apple); fruis and foliage. The fruits are poisonous if eaten before fully ripe. They are typically eaten with salted cod. Jamaica. December 2004.
©Jesper Rautell Balle-2004/via wikipedia - CC BY 3.0

Immature fruit
Blighia sapida (akee apple); Fruit. Ouagadougou University Campus, Burkina Faso. January 2010.
©Marco Schmidt/via Wikimedia Commons - CC BY-SA 3.0

Inflorescence
Blighia sapida (akee apple); Inflorescence. Jamaica. May 2006.
©Jerome Walker/via Wikimedia Commons - CC BY-SA 2.5

Habit
Blighia sapida (Akee apple); tree habit, in a private yard in Honolulu, Hawaii, USA. December 2015.
©Wendy L. Cutler-2015/via flickr - CC BY-SA 2.0

Fruits
Blighia sapida (Akee apple); fruits on display. Fruit & Spice Park, Homestead, Florida, USA. June 2008
©Asit K. Ghosh/Thaumaturgist/via wikipedia - CC BY-SA 3.0

Inflorescence
Blighia sapida (akee apple); Inflorescence. Santo Domingo, Dominican Republic. January 2016.
©Karen Blix/via Flickr - CC BY-NC-SA 2.0

Open fruit
Blighia sapida (Akee apple); open fruit, showing seeds. nr. Bobo Dioulassu, Burkina Faso. November 2013.
©Rik Schuiling/TropCrop-Tropical Crops Services/via wikipedia - CC BY-SA 3.0

Habit
Blighia sapida (akee apple); Habit. Puerto Viejo, Limon, Costa Rica. January 2013.
©Leonora (Ellie) Enking/via Flickr - CC BY-SA 2.0

Habit
Blighia sapida (akee apple); Habit - note the poisonous fruit warning signs. Fruit & Spice Park, Homestead, Florida, USA. March 2017.
Public Domain - Released by Daderot/via Wikimedia Commons - CC0

Foliage
Blighia sapida (akee apple); Foliage. Fruit & Spice Park, Homestead, Florida, USA. March 2017.
Public Domain - Released by Daderot/via Wikimedia Commons - CC0

Seeds
Blighia sapida (akee apple); Ripe akee seeds with their arils, one whole (dorsal view), one in longitudinal section. Bobo-Dioulasso, Burkina Faso. November 2013.
©Rik Schuiling/TropCrop - Tropical Crops Services/via Wikimedia Commons - CC BY-SA 3.0

Seeds
Blighia sapida (akee apple); Seeds embedded in aril. November 2016.
©Cerlin Ng/via Flickr - CC BY-NC-SA 2.0

Overview

The ackee, Blighia sapida Koenig (syn. Cupania sapida Voigt.), belongs to the Sapindaceae family, is a tropical/subtropical tree native to West African tropical forests and has been spread in the tropics as a curiosity and as an ornamental tree. The shiny dark-green leaves and beautiful, red-coloured mature fruit make the ackee primarily an ornamental tree. It was introduced in the late 18th century and became naturalized throughout the Caribbean and Central America from Brazil to Florida. Although widely grown, it is consumed mainly in Jamaica, where commercial orchards of more than 1000 ha exist. The fleshy cream aril of the ripe fruit is eaten. It is often boiled or fried, avoiding the pink tissue between the seeds and the arils. The fruit contains a potent poison that has to be removed before eating. In many places it is more known for its poisonous properties than for its useful aspects. The name ackee or akee derives from the West African akye and other common names include akee apple, vegetable brain, polo do seso (Cuba), huevo vegetal castanha (Port) and elsewhere baha or finza in parts of Nigeria. Other common names include akee apple and vegetable brain.

Principal sources: Janick and Paull (2008); Paull and Duarte (2012)

Summary of Invasiveness

Blighia sapida, commonly known as ackee, is a tree species native to the Guinean forests of West Africa that has been introduced to the Americas, Australia and a small number of countries in Asia and Oceania. It is cultivated as an ornamental and fruit tree despite the arils being deadly poisonous if improperly prepared. It has been reported as naturalized in Jamaica, where has become an important food crop, and in Cuba and Australia although it does not appear to constitute an immediate problem in these countries.

Taxonomic Tree

Notes on Taxonomy and Nomenclature

Blighia is a small genus of three species in the Sapindaceae, or the soapberry family (Acevedo-Rodríguez et al., 2011). Two species are native in tropical East Africa and one, Blighia sapida, is native to West Africa (Davies and Verdcourt, 1998). The genus is named after Captain William Bligh of the HMS Bounty who brought samples of ackee back to England in 1793. The fruit had apparently been taken to Jamaica from West Africa, probably on slave ships sometime earlier. The specific epithet comes from the Latin sapidus meaning savory in reference to the edible arils surrounding the seeds which are consumed as a vegetable in several countries (Stair and Sidrak, 1992, Paull and Duarte, 2012).

Plant Type

Broadleaved

Perennial

Seed propagated

Tree

Vegetatively propagated

Woody

Description

The following description is adapted from Little et al. (1974), Stair and Sidrak (1992), Davies and Verdcourt (1998), Janick and Paull (2008) and PROTA (2019):

The tree has a moderately dense round to oval crown and stiff branches. It is a medium to large tree that can reach 8-24 m in height and 60-80(-120) cm in trunk diameter. The bark is smooth to slightly rough, grey to pale brown, with lenticels in horizontal lines. The trees are very variable in plant form and height, colour, size and shape of capsules, quality of arils, yield, and flowering time and intensity.

Leaves Alternate and pinnate with short petioles and three to five pairs of glossy green leaflets, 6-20(-25) cm long and up to 7 cm wide, with the upper leaves being the longest. Margins entire. Leaflets are opposite or sub-opposite, elliptical to oblong–obovate and shortly acuminate. Leaves glabrate and lustrous above, slightly hairy below at least on the midrib.

Flowers The tree is described as andro-monoecious. The flowers are borne together in pendulous compound racemes (4-15 cm long) from pseudo-terminal shoots with both male and hermaphrodite flowers on the same plant. The proportion of male and hermaphrodite flowers varies with each flowering, tree and climatic conditions. The calyx is five- (or six-)parted and light green; the five petals are cream and a nectary disc is present at the base. The fragrant flowers are small, about 5 mm long.

Fruit The pear-shaped fruit is a fleshy, dehiscent, usually three-lobed (sometimes one-, two- or four-lobed) capsule (70-150 g) with a leathery skin. It measures 6-10 cm in length. Initially green, it turns to a red or to a yellow–orange colour at maturity. The time from anthesis to maturity is about 50-60 days. The fruit doubles in size during the first 2-3 weeks; fruit drop can be very high during this period. Approximately 5.6% of hermaphrodite flowers set fruit and 44% of fruit mature. At maturity the three lobes split longitudinally apart, with each showing a partially embedded seed in a kidney-shaped, cream-coloured, fleshy, glossy aril (usually 3.0-4.5 cm long and 2.5-3.5 cm wide) that is waxy in texture, attached to shiny black seeds.

Seeds The seeds are about 1 cm in diameter, almost round, black,hard, shiny and very poisonous. There are usually three seeds, although one or two may abort. The aril is attached to the stem end of the capsule by a pink or orange- to red-coloured fibrous membrane (sometimes called a raphe) that extends into the groove between the two lobes of the aril attaching it to the placenta. The red tissue and veins that attach the aril to the seed and the capsule must be removed before eating.

Distribution

The ackee tree is native to the forests of the Ivory and Golden Coasts of tropical West Africa, from Senegal to Gabon. It has been introduced to many American countries, and to India, Vietnam, Australia, Guam, Hawaii and French Polynesia.

In Ghana, it is often used as an ornamental street tree. In Jamaica trees are frequently found in backyards, along fence-rows or in small groves, especially on marginal land. The tree was introduced into many Caribbean islands and to the Atlantic coast of Central America by Jamaican slaves fleeing the island. However, it was outlawed in Trinidad after causing some fatalities. It has further spread to other parts of America such as Brazil and Florida. (Paull and Duarte, 2012).

Distribution Map

Distribution Table

History of Introduction and Spread

Blighia sapida was introduced to the Caribbean islands in the 1700s as a result of the slave trade from West Africa. It was introduced to Jamaica with the name akee in 1778, before the species was formally described in 1806 (Broughton, 1794). In Hortus Eastensis, a catalogue of exotic plants cultivated in the Botanic Garden of Liguanea in Jamaica, Broughton (1794) mentioned that: “this plant was brought here in a slave ship from a coast of Africa, and now grows very luxuriant producing every year large quantities of fruit”. In 1859 the species was recorded by Grisebach as naturalized. At present, B. sapida is found island-wide and is one of the most common trees around Jamaican houses (Rashford, 2001).

The first mention of B. sapida in Cuba seems to be from Grisebach (1860). Oviedo Prieto et al. (2012) and Oviedo Prieto and González-Oliva (2015) list it as potentially invasive in the island, but do not give any further details. In Puerto Rico the species was introduced around 1904 and is presently found only in cultivation (Little et al., 1974).

Blighia sapida was reported as naturalizing along the footslopes of the MacAlister Range in Queensland in 2001 (Werren, 2001). The oldest herbarium collections of B. sapida in Australiaare from 1980 and belong to cultivated plants in Cairns (AVH, 2019). No information on the extent of spread or impacts could be found. The species is not listed on the ‘Weeds of Australia’ website (Queensland Government, 2018).

Introductions

Introduced to	Introduced from	Year	Reasons	Introduced by	Established in wild through		References	Notes
Introduced to	Introduced from	Year	Reasons	Introduced by	Natural reproduction	Continuous restocking	References	Notes
Jamaica	West Africa	1778	Food (pathway cause)		Yes	No	Rashford (2001)	Very common, an important food crop in the island
Puerto Rico		1904			No	No	Little et al. (1974)	Uncommon, rarely cultivated

Risk of Introduction

Seeds of Blighia sapida can be purchased online and so it is possible for this species to be intentionally introduced into new areas in the future. However, outside Jamaica, there seems to be relatively little interest in this plant, likely due to its poisonous nature. In most countries where Blighia is already present it is generally considered as uncommon or rare.

Means of Movement and Dispersal

Natural Dispersal

The arillate seeds of ackee are likely dispersed by birds and monkeys (PROTA, 2019), and possibly also by rodents (Iplantz, 2019). In Côte d'Ivoire the fruits are consumed by the Maxwell’s duiker (Philatomba maxwellii) (Hofmann and Roth, 2003).

Intentional Introduction

Blighia sapida has been intentionally introduced to many tropical countries as a fruit crop.

Pathway Causes

Pathway cause	Notes	Long distance	Local	References
Botanical gardens and zoos (pathway cause)	Cultivated in botanic gardens	Yes	Yes	Rashford (2001)
Crop production (pathway cause)	Grown as a fruit crop	Yes	Yes	PROTA (2019) Rashford (2001)
Food (pathway cause)	Consumed as a vegetable and intentionally introduced to many countries for this purpose	Yes	Yes	PROTA (2019) Rashford (2001)
Habitat restoration and improvement (pathway cause)	Used for erosion control and soil improvement		Yes	PROTA (2019)
Horticulture (pathway cause)	Used as an ornamental and shade tree	Yes	Yes	PROTA (2019)
Internet sales (pathway cause)	Seeds available for purchase online	Yes
Medicinal use (pathway cause)	Used medicinally	Yes	Yes	PROTA (2019)
Nursery trade (pathway cause)	Plants are sold in nurseries	Yes	Yes
Ornamental purposes (pathway cause)	Used as an ornamental and shade tree	Yes	Yes	PROTA (2019)
Seed trade (pathway cause)	Seeds sold online	Yes

Pathway Vectors

Pathway vector	Notes	Long distance	Local	References
Germplasm (pathway vector)	Cultivated in nurseries and botanic gardens	Yes	Yes	Rashford (2001)

Similarities to Other Species/Conditions

Blighia sapida can be distinguished from the other two species of Blighia by its larger fruits with rounded or blunt lobes (PROTA, 2019). Blighia unijugata has fruits less than 3 cm long whereas B. welwitschii has fruits with sharp or winged angles (Davies and Verdcourt, 1998).

Habitat

In its native range, B. sapida occurs in semi-deciduous forests and seasonally dry lowland woodlands. It is also usually seen planted around villages from where it can further spread into the surrounding forest (PROTA, 2019).

In Jamaica, this species grows along roadsides and in fields and pastures, from sea-level to 900 m. It is a common tree around Jamaican homes, found growing in gardens and along fences (Rashford, 2001).

Habitat List

Category	Sub category	Habitat	Presence	Status
Terrestrial	Terrestrial – Managed	Cultivated / agricultural land	Present, no further details	Productive/non-natural
Terrestrial	Terrestrial – Managed	Managed forests, plantations and orchards	Present, no further details	Productive/non-natural
Terrestrial	Terrestrial – Managed	Rail / roadsides	Present, no further details	Productive/non-natural
Terrestrial	Terrestrial – Managed	Urban / peri-urban areas	Present, no further details	Productive/non-natural
Terrestrial	Terrestrial ‑ Natural / Semi-natural	Natural forests	Present, no further details	Natural

Biology and Ecology

Genetics

The chromosome number of B. sapida is 2n=32 (Sarkar et al., 1982). A preliminary study testing 12 microsatellite markers developed in Litchi, reported a higher number of alleles and higher heterozygosity in natural stands in Benin compared to planted stands (Ekué et al., 2009).

Reproductive Biology

The whitish, fragrant flowers of B. sapida are bee-pollinated. They are also visited by Polistes wasps but these are not as efficient pollinators as the honeybees (Free and Williams, 1976). In Benin, bees of the genera Dactylurina and Braunsapis have been also recorded visiting the flowers (Pauly et al., 2009). Only around 4-5.6% of hermaphroditic flowers develop into fruits and 44% of fruit mature (Janick and Paull, 2008; PROTA, 2019). Fruit development takes 50-60 days from fruit set to open capsule stage (70-150 g final weight), with fruit doubling in size during the first 14-21 days. Fruit shed is particularly high up to 21 days, and adverse weather can cause total loss.

Blighia sapida propagates relatively easily by seeds. The seeds are recalcitrant (short-lived) and it is recommended they are planted within a few days of collection. Germination percentage is reduced significantly with storage time. Seeds stored for seven days have a germination percentage of 33.3% while seeds stored for 14 days have only 3.3% (Olayode and Osuji, 2016). Germination starts after 2-3 weeks (Olayode and Osuji, 2016; PROTA, 2019) but may take up to two or three months (Crane et al., 2008). The trees start producing flowers and fruits at about three to six years (Crane et al., 2008).

Cuttings are effective as a means of vegetative propagation and quickly produce roots if planted under the right conditions. Grafting and air layering have also been used as alternative methods to propagate this species (PROTA, 2019). In a study to determine the effect of the rooting hormone indole-3-butyric acid (IBA) on the air layering propagation, the highest rooting success was obtained with 3500 ppm IBA (Maurya et al., 2013).

Physiology and Phenology

In Jamaica, Cuba, Florida, and perhaps other tropical locations, B. sapida flowers and fruits twice a year. Flowering occurs generally from March to June and from September to November. The heaviest crop is harvested during the summer. In some areas, the trees may produce flowers and fruits year-round (Crane et al., 2008, PROTA, 2019).

In tropical regions flowering seems to be induced by a dry period where plants slow their vegetative growth, enabling the buds to develop into flowers. In subtropical areas, flowering may be stimulated by relatively low temperatures which also suppress vegetative growth (Crane et al., 2008).

Population Size and Structure

Although not formally described, there are several forms or varieties of B. sapida that can be distinguished by the color and texture of the arils. The two more common are “butter” with soft and yellow arils, and “cheese” with hard and cream arils (Crane et al., 2008; Iplantz, 2019). The latter is preferred in food preparation because does not disintegrate in cooking (Rashford, 2001).

Environmental Requirements

Blighia sapida is a tropical/subtropical tree found from sea level to 900 m in Jamaica and Honduras and is regarded as a forest climax tree in West Africa. Its native range has annual lows of 17-25°C and annual highs of 26-35°C (Iplantz, 2019). Mature trees are moderately cold tolerant and, if mature, may withstand brief periods at –3.3°C. Its native range has a dry season of 2-7 months, but B. sapida can also grow well in subtropical frost-free areas and wetter climates with no dry season, but flowering and fruiting in these regions is often poor due to fungal attack (Iplantz, 2019).

Blighia sapida grows well on soils ranging from fertile to stony, but seems to flourish best on fertile, slightly alkaline, well-drained soils at elevations up to 600 m. It does well in sands and oolitic limestone (Crane and Balerdi, 2011). It is drought tolerant, and can tolerate moderately windy areas. If pruned regularly to limit tree size and open the canopy to wind movement then B. sapida can withstand hurricane-force winds without toppling, but it is susceptible to defoliation and desiccation from high winds. The tree is not flood tolerant and may decline in waterlogged or poor draining soil (Iplantz, 2019; PROTA, 2019).

The tree thrives in places with 1500-2000 mm annual rainfall. It can withstand prolonged dry periods once established, but fruit production will be low. Trees usually flush after any extended period of rain. With two main rainy seasons in the Caribbean, there are two distinct fruiting peaks: January–March and July–September. However, considerable variability occurs in time and extent of flowering between trees even at the same site. A period of regeneration seems necessary before flowering recurs on a particular branch. At each flowering, the proportion of hermaphrodite to male flowers varies (Stair and Sidrak, 1992). B. sapida can flower throughout the year and may produce three or more crops annually, with the heaviest bloom during spring. In Florida, flowering occurs in the spring and fruit in midsummer, although there may be a light flowering during the autumn and fruit during the winter.

In subtropical areas, trees probably respond to wet–dry periods and cool temperatures, which also inhibit vegetative growth. The major flower-inducing trigger in the tropics is probably wet weather after a pronounced dry period. During the dry period the tree’s vegetative growth slows or stops, allowing the buds in the leaf axils to mature and form flowers. Subsequently, under natural conditions, the tree flowers when the rainy season begins. Ackee flowers are easily cross-pollinated. The main pollinators are insects, especially bees (Suah, 1975) and the wind (Paull and Duarte, 2012).

Climate

Climate type	Description	Preferred or tolerated
Af - Tropical rainforest climate	> 60mm precipitation per month	Tolerated
Am - Tropical monsoon climate	Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))	Tolerated
As - Tropical savanna climate with dry summer	< 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])	Preferred
Aw - Tropical wet and dry savanna climate	< 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])	Preferred
Cs - Warm temperate climate with dry summer	Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers	Tolerated

Latitude/Altitude Ranges

Latitude North (°N)	Latitude South (°S)	Altitude lower (m)	Altitude upper (m)
30	24

Air Temperature

Parameter	Lower limit (°C)	Upper limit (°C)
Absolute minimum temperature	-3
Mean annual temperature	20	30
Mean maximum temperature of hottest month	26	35
Mean minimum temperature of coldest month	17	25

Rainfall

Parameter	Lower limit	Upper limit	Description
Dry season duration	2	7	number of consecutive months with <40 mm rainfall
Mean annual rainfall	800	6000	mm; lower/upper limits

Rainfall Regime

Winter

Bimodal

Uniform

Soil Tolerances

Soil texture > heavy

Soil texture > light

Soil texture > medium

Soil texture

Soil reaction > acid

Soil reaction > alkaline

Soil reaction > neutral

Soil drainage > free

Notes on Pests

Although no major pests and diseases are reported from Jamaica (Lindsay, 2000), stem galls caused by an unknown agent are common and can cause serious damage. Infestations of pustule scales, Asterolecanium pustulans, produce smaller galls on stems and petioles (Naylor, 1974). Mealy bugs (Lindsay, 2000) and black beetles, Macraspis tetradactyla, are reported and the fruit hosts fruit fly (Anastrepha acidusa and Anastrepha suspensa) (Williams, 2000). Some tree varieties seem to be particularly susceptible to fruit rot, which has been associated with Botryoplodia sp., Glomerella cingulata, Phomopsis sp. and Pyrenochaeta sp. Other diseases include Colletotrichum and Cercospora leaf spot (Didymosphaeria and Coniothyrium fuckelii leaf spot), Phaeosacchardinula anomala sooty mould (Williams, 2000) and Verticillium dieback (McMillan et al., 2002). Plant parasitic nematodes have not been recorded as serious pests, but small numbers of several species have been found (Hutton et al., 1982). Manual weeding is normally practiced for young plants, while bush cutters and herbicides are more commonly used in older plantations (Paull and Duarte, 2012).

List of Pests

Notes on Natural Enemies

Blighia sapida is susceptible to several fungal diseases including sooty mold (Aithaloderma setosum), black mildew (Meliola capensis), leaf spots (Phyllosticta sp.), wilt disease (Verticillium dahliae), anthracnose disease (Colletotrichum gloeosporioides), fruit rot (Cladosporium oxysporum, Rhizopus stolonifer, Phoma sp.) and root disease (Armillaria mellea) among others (Farr et al., 2008).

The wilt disease, caused by Verticillium dahliae, was reported in a commercial planting in Florida. The fungus appears to spread rapidly from infected trees to healthy trees causing branch death and leaf necrosis (McMillan et al., 2003).

Insects that have been reported to affect this species include at least 15 different scale species (Ceroplastes newsteadi, Chrysomphalus aonidum, Formicococcus njalensis, Howardia biclavis, Maconellicoccus hirsutus, Milviscutulus mangiferae, Morganella longispina, Nipaecoccus jonmartini, Paratachardina pseudolobata, Pseudococcus jackbeardsleyi, Pulvinaria psidii, Rastrococcus invadens, Russellaspis pustulans, Saissetia coffeae, S. oleae and Udinia catori) (García Morales et al., 2019), and seven tephritid fruit flies (Anastrepha suspensa, Bactrocera aquilonis, B. dorsalis, B. tryoni, Ceratitis capitata, C. cosyra and Trirhithrum nigerrimum) (White and Elson-Harris, 1992; Goergen et al., 2011; Thomas et al., 2013; Badii et al., 2015).

Natural enemies

Natural enemy	Type	Life stages	Specificity	Biological control in
Armillaria mellea (armillaria root rot)	Pathogen	Roots	not specific	N
Cladosporium oxysporum (seedlings blight of passion fruit)	Pathogen	Fruits/pods	not specific	N
Colletotrichum gloeosporioides	Pathogen	Leaves Fruits/pods	not specific	N
Phoma sp.	Pathogen	Fruits/pods	not specific	N
Phomopsis	Pathogen	Leaves Stems	not specific	N
Phyllosticta	Pathogen	Leaves	not specific	N
Rhizopus stolonifer (bulb rot)	Pathogen	Fruits/pods	not specific	N
Verticillium dahliae (verticillium wilt)	Pathogen	Leaves Stems Roots	not specific	N
Anastrepha suspensa (Caribbean fruit fly)	Herbivore	Fruits/pods	not specific	N
Bactrocera aquilonis	Herbivore	Fruits/pods	not specific	N
Bactrocera dorsalis (Oriental fruit fly)	Herbivore	Fruits/pods	not specific	N
Bactrocera tryoni (Queensland fruit fly)	Herbivore	Fruits/pods	not specific	N
Ceratitis capitata (Mediterranean fruit fly)	Herbivore	Fruits/pods	not specific	N
Chrysomphalus aonidum (circular scale)	Herbivore	Leaves	not specific	N
Howardia biclavis (mining scale)	Herbivore	Stems Leaves	not specific	N
Maconellicoccus hirsutus (pink hibiscus mealybug)	Herbivore	Stems Leaves	not specific	N
Paratachardina pseudolobata (lobate lac scale)	Herbivore	Stems	not specific	N
Pseudococcus jackbeardsleyi (Jack Beardsley mealybug)	Herbivore	Stems Leaves	not specific	N
Saissetia oleae (olive scale)	Herbivore	Stems Leaves	not specific	N

Impact Summary

Category	Impact
Cultural/amenity	Positive
Economic/livelihood	Positive
Environment (generally)	Positive
Human health	Positive and negative

Impact: Environmental

Blighia sapida has been listed as naturalized in Jamaica and as a potentially invasive species in Cuba. It has also escaped cultivation in Queensland, Australia, where it was reported as naturalizing in creek banks and forest edges of the foot slopes of the MacAlister Range (Werren, 2001). However, no information on the extent of spread and impact on these ecosystems could be found.

Impact: Social

The arils of B sapida are highly toxic if not harvested and cooked properly. They contain hypoglycin A, an amino acid derivative responsible for ‘Jamaican vomiting sickness’ or ‘toxic hypoglycemic syndrome’. The ingestion of unripe arils, even if cooked, results in severe vomiting and headache, hypoglycemia, seizures, and even coma and death (Morton, 1987; McTague and Forney, 1994). Due to public health concerns, ackee importation into the US was banned in the 1970s but was resumed in 2000 after the safety issues were addressed by the Jamaican government, the Jamaican industry, and the US Food and Drug Administration (Gordon et al., 2015).

Risk and Impact Factors

Invasiveness

Long lived

Fast growing

Has high reproductive potential

Reproduces asexually

Impact outcomes

Negatively impacts human health

Impact mechanisms

Poisoning

Rapid growth

Likelihood of entry/control

Highly likely to be transported internationally deliberately

Uses

Economic Value

The ripe arils of B. sapida are widely consumed in Jamaica, and to a lesser extent in Africa and other parts of the Neotropics. The fruit is sold year-round at roadsides and in markets across Jamaica (Rashford, 2001). Canned and frozen ackee is also exported to the United Kingdom, Canada, USA, and other countries (Morton, 1987). Ackee exports from Jamaica rose to $20,000,000 USD in 2016, and this number is expected to increase as the demand for the crop has grown in recent years (Bennett, 2017). The industry is very important to the island because it employs workers in many rural areas where opportunities are limited (Gordon et al., 2015).

Ackee plants are also cultivated along streets as an ornamental and shade tree for its attractive foliage and colorful fruits. Seeds and potted plants are sold in nurseries and gardening websites. The medium-weight wood, called achin in Ghana, is hard and durable and is used for light construction and furniture, for casks, containers, tool handles, and paddles, among other applications, but is mostly used locally and has little commercial importance (PROTA, 2019).

Social Benefit

Localized medicinal uses, reported from both sides of the Atlantic, have included ingested aril mixtures for dysentery and seed extracts against parasites. Topical treatments use ripe arils, crushed leaves, leaf, seed or bark extracts for such diverse disorders as headaches, severe pain, conjunctivitis and ulcers (Lindsay, 2000; Paull and Duarte, 2012).

Ackee is highly appreciated in Jamaica where is considered the national fruit. The only edible part of the fruit, the aril, is fried with seasonings or in pastry. In preparation, the aril is usually first cooked by boiling in salt water and this water discarded. The popular ‘Ackee and saltfish’ is Jamaica’s national dish and one of the island’s culinary delicacies. In West Africa, the aril is eaten raw, fried or roasted.

The green, unripe fruits produce lather in water and are used as a soap substitute. The ashes of dried capsules are rich in potash and can also be used to make soap. In northern Nigeria soap is made by mixing the oil from the seed is with dried, high potash husks. The wood is used for construction, furniture, firewood and charcoal. The flowers have been extracted for perfume. Different parts of the plant are employed medicinally to treat a variety of conditions (Morton, 1987; PROTA, 2019). The crushed unripe fruits are used for poison fishing (Neuwinger, 2004).

In Africa, ackee trees are considered useful for soil improvement and erosion control, and are valued by farmers as a multipurpose component of agro-ecosystems.

Uses List

Materials > Wood/timber

Medicinal, pharmaceutical > Source of medicine/pharmaceutical

General > Botanical garden/zoo

General > Ritual uses

General > Sociocultural value

Environmental > Agroforestry

Environmental > Erosion control or dune stabilization

Environmental > Soil conservation

Environmental > Soil improvement

Fuels > Fuelwood

Medicinal, pharmaceutical > Traditional/folklore

Human food and beverage > Emergency (famine) food

Human food and beverage > Vegetable

Ornamental > Seed trade

Ornamental > garden plant

Fuels > Charcoal

Wood Products

Sawn or hewn building timbers > For light construction

Railway sleepers

Containers > Crates

Containers > Boxes

Containers > Cases

Woodware > Tool handles

Woodware > Wood carvings

Woodware > Turnery

Furniture

Cultivation

The normal field-preparation procedures as for any fruit tree are followed. Ackee trees should be planted on a square, 6-10 m apart. Trees planted too close to other trees or structures may not grow normally or produce as much fruit because of shading or competition.

Irrigation

Irrigation is not usually practiced. The ideal is to plant at the beginning of the rainy season and to improve tree-establishment water using a bucket if no irrigation system is available. In ackee trees more than 4 years old, irrigation is beneficial to plant growth and crop yields during prolonged dry periods. The specific water requirements for mature trees have not been determined. However, as with other tree crops, the period from bloom and through fruit development is important. Drought stress should be avoided at this time, with periodic watering to ensure proper yields.

Pruning

The tree exhibits vigorous growth and pruning is recommended. In Florida or subtropical places with frost, pruning should be done soon after this danger has passed. Pruning may reduce fruit production for one to several seasons. Formation pruning should include topping the main stem at 80-90 cm when it reaches 1-1.2 m. The ideal is to keep three or a maximum of four main branches as evenly distributed as possible around the main trunk and at different heights so that the weight of the canopy is evenly distributed. Selectively removing a few upper limbs back to their origins (crotches) each year will help prevent the loss of the lower tree canopy due to shading by the upper canopy. Topping the tree at 4-5 m is suggested to facilitate harvesting and minimise wind damage. In addition, maintaining a small tree will facilitate tree care and make spraying easier.

Fertilization

A generalized recommendation is for 450 g of 10:10:10, 4 weeks following transplanting, followed by 400-500 g of ammonium sulfate after 6 months and 500 g 10:10:10 in year 2; the application rate should be increased by 450 g/year until the tree is 5 years old (Royes and Baccus, 1988). Specific recommendations are not available and Jamaican orchards use a variety of regimes. A small fertilizer trial with transplanted seedlings in Jamaica found that a per plant treatment of 112 g NPK (8:21:32) in two applications (56 g in the planting hole and 56 g broadcast after 6 months) increased growth in the first year compared to a similar treatment of 224 g per plant broadcast or no fertilization (Williams, 1993). Ackee trees are susceptible to iron deficiency under alkaline soil conditions; this can be prevented or corrected by soil applications of iron chelates. Periodic applications of ferrous (iron) sulfate may be made to trees growing in low-pH soils (Crane and Balerdi, 2011, Paull and Duarte, 2012).

Harvesting

For domestic use, fruit are usually picked when they open on the tree. Ackee fruit production data are not available; however, observations suggest that well-cared for mature trees can produce 45-68 kg/year. Some reports indicate that production can vary from 300 to 2000 fruit/tree/year. Ackee fruit should be harvested after the lobules have split longitudinally. It is important not to wait too long after this opening as the fruit will become overripe and poisonous. Immature fruit and those that have not split open naturally, or where the aril is soft or discoloured, are extremely poisonous. Ripe fruit can be separated by cutting with knives or pruning shears, but are usually just pulled by hand. In Jamaica, the main bearing seasons are between January to March and June to August. Fruit for home consumption are harvested after they have split open. Fruit for canning are harvested while still closed, laid on racks in the sun or allowed to split in the holding area of the canning plant. Fruit that do not split open within 3 days are discarded (Paull and Duarte, 2012)

Postharvest Treatment

The arils are usually extracted, cleaned and consumed within 1-3 days, keeping them under refrigeration. Canning is the only method of prolonging the life of arils (Paull and Duarte, 2012).

Genetic Resources and Breeding

Little is known about the cytogenetics and genetics of this tree. Selection or breeding programmes for this semi-domesticated species should focus on traits important for consumer needs (Ekue et al., 2010). Preferred fruit traits include size and shape, and aril colour, size and taste. Some selections have been made in Jamaica based on productivity, fruit quality and time of harvest. A collection of ackee exists near St. Catherine, Jamaica, with two main accessions types (both with bright red capsules) identified by the colour of the aril. The type with a soft yellow aril is known as ‘Butter’; and fruit with more flesh around the seed, hard yet with a smooth texture and cream-coloured aril, is known as ‘Cheese.’ Ease of cross-pollination has produced types with intermediate characteristics (Royes and Baccus, 1988).

Propagation

Traditionally ackee has been propagated by seeds that germinate readily if sown fresh without any special pre-germination treatment. The seeds are short-lived, and should be sown a few days after removal from the fruit. Seeds can take 2-3 months to germinate and seedlings will bear fruit after 3-4 years. In Jamaica, the main producer of ackee, most of the trees originate from seeds. This explains the large variability in tree characteristics, fruit quality, production and seasonality found on that island.

Cutting propagation has produced very promising results and vegetative propagation is encouraged (Lindsay, 2000). Vegetative propagation of selected, desirable types has been attempted with limited success (Stair and Sidrak, 1992). Treatment of stem cuttings with rooting formulations containing auxin may not be necessary as rooting occurs readily under good conditions. Success has been reported with grafting and air layering. Superior types may be propagated by grafting (side-veneer or cleft) or budding (patch) onto seedling rootstock. The tree begins to bear after 1-2 years with vegetative propagation (Paull and Duarte, 2012).

Nutritional Value

The fruit arils are a moderate source of calcium, iron, potassium and ascorbic acid. A 100 g edible portion of raw ackee arils contains: 57.6 g water, 8.75 g protein, 18.78 g fat, 3.45 g fibre, 9.55 g carbohydrate, 1.87 g ash, 83 mg calcium, 5.52 mg iron, 98 mg phosphorus, 65 mg ascorbic acid, 0.1 mg thiamine, 0.18 mg riboflavin, 3.74 mg niacin. They also possess a small amount of antioxidants (IC50 value = 6.6 μg/ml). The major fatty acids observed are linoleic (55% of the total), palmitic and stearic acids; ackee contributes to the fatty acid intake of many Jamaicans (Crane and Balerdi, 2011). Arils from unripe fruit have a high concentration of a heat-stable, water-soluble amino acid called hypoglycin A and hypoglycin B (the gamma-glutamyl derivative), that is half as toxic. Fruit that split naturally have safe levels of hypoglycin.

The seeds contain 1000 mg/kg hypoglycin. The lipid content is between 12.5 and 17.4% of the fresh aril. Mature aril oil is nutritive, having about 57% linoleic, 25% palmitic and 12% stearic acids.

Phytosanitary Issues/Food Safety

Unripe fruit arils contain the heat-stable, water-soluble amino acid hypoglycin that can induce vomiting, convulsions and coma in 6-48 h for children (Henry et al., 1998). Hypoglycin declines in the aril during ripening from 1000 to <0.1 mg/kg (Brown et al., 1992). Fruit that dehisces naturally has safe levels of hypoglycin. In 1972, US Food and Drug Administration (FDA) banned the import of the canned product unless safety concerns regarding hypoglycin could be met. The ban was lifted in 2000, but importation of canned ackee into the USA is subject to a Hazard Analysis and Critical Point (HACCP) manufacturing system and four Jamaican exporters were authorized by 2002. The nutritional status of the consumer is important to his or her propensity to poisoning, since patients diagnosed with Jamaican Vomiting Sickness (JVS) generally show manifestations of chronic malnutrition and vitamin deficiency. Although JVS has resulted in some fatalities, the increased awareness of the importance of eating only ripe, opened ackees means that such cases are now rare.

Although the foliage and bright-red fruit of ackee are beautiful when planted in home gardens, it is not recommended unless the owners know this tree and the risks involved with the improper handling of its fruit (Janick and Paull, 2008).

Production and Trade

In Jamaica, trees are frequently found in backyards, along fence-rows or in small groves, especially on marginal land. Ackee is usually sold fresh for domestic consumption. A Jamaican canning industry was started in 1956, which involved 18 independent processors in 2000. The Jamaican External Trade Statistics for 2001 show 1.74 million kg canned ackee exported, mainly to Canada, the UK and the USA, with small amounts going to other Caribbean territories, Europe and Japan. Frozen ackee is also exported, but in much smaller quantities (13,140 kg in 2001). Planting on a commercial scale has developed slowly since the early 1990s, encouraged by the lucrative, exported canned product; about 130 ha were under production in small- to medium-sized orchards in 1999. Although Jamaica is the traditional ackee producer, orchards have been established in Costa Rica and Mexico and export has been reported from West Africa (Wright, 2000). Fresh ackee is not generally exported but the arils are canned or frozen. In preparation, the aril is usually first cooked by boiling in salt water and this water discarded. The canned product is exported to ethnic markets worldwide and continues to be enjoyed by both visitors to the island and Jamaicans residing overseas. In 1972, the US Food and Drug Administration banned the import of the canned product unless safety concerns regarding hypoglycin could be met. The ban was lifted in 2000, but importation of canned ackee into the USA is subject to controls to ensure a safe product is imported.

References

AVH, 2019. The Australasian Virtual Herbarium. Council of Heads of Australasia herbaria. https://avh.chah.org.au/

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