Encarsia perplexa
Encyclopedia
Encarsia perplexa is a tiny parasitic wasp, a parasitoid
of the citrus blackfly
, Aleurocanthus woglumi, which is a global pest of citrus
trees. It was originally misidentified as Encarsia opulenta, but was recorded as a new species in 1998. It is a native of Asia but has been introduced to many other parts of the world as a means of controlling
the citrus blackfly.
0.8 millimetre in length. The thorax
is straw coloured, the wings are transparent with a smoky patch in the centre and the legs are whitish. The abdomen
is straw-coloured at the front and dark brown behind with a dark-coloured ovipositor
0.5 millimetres long. The male is smaller, averaging 0.75 millimetres in length and is a uniform dark brown.
in nymphs
of the citrus blackfly. When available, a second instar
nymph is selected and each egg will eventually produce a female adult. At 24°C in the laboratory, it takes 30 to 35 days from egg-laying to adult emergence. Unmated females lay haploid eggs in the fully developed larvae of their own species. These hatch out into males, a process known as adelpho-parasitism. The sex ratio among adults in the field is one male to every seven females. Encarsia perplexa is itself parasitized by Encarsia smithi which was accidentally introduced into Florida in the 1970s.
and Aleurocanthus incertus, another whitefly. This means that introducing the species into a citrus growing area is unlikely to have adverse ecological side effects. Amitus hesperidum
is another citrus blackfly parasitoid that has been used alongside E. perplexa to control the pest. It reproduces rapidly and can produce up to seventy progeny per female and is very successful at controlling heavy infestations. E. perplexa multiplies more slowly but is better at scouting for outlying blackflies and is more effective when populations of potential hosts are lower.
In Hawaii, both species were introduced in 1999 after the citrus blackfly was discovered there for the first time the previous year. They rapidly became established and were soon controlling the pest on the island of Oahu. Later releases on other islands in the group have also been an effective, though not immediate, means of reducing infestations.
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
of the citrus blackfly
Aleurocanthus woglumi
Aleurocanthus woglumi is a species of whitefly in the family Aleyrodidae. It is a pest of citrus crops and is commonly known as the citrus blackfly because of its slate blue colour. It originated in Asia but has spread to other parts of the world...
, Aleurocanthus woglumi, which is a global pest of citrus
Citrus
Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
trees. It was originally misidentified as Encarsia opulenta, but was recorded as a new species in 1998. It is a native of Asia but has been introduced to many other parts of the world as a means of controlling
Biological pest control
Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...
the citrus blackfly.
Distribution
This wasp is a native of India and Vietnam. It has been introduced to and has established itself in Barbados, Cuba, Jamaica, Mexico, Salvador, Venezuela, the USA (Florida, Texas and Hawaii), Kenya and Oman, for the purpose of controlling citrus blackfly.Description
The female is just over one millimetre long with antennaeAntenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
0.8 millimetre in length. The thorax
Thorax (insect anatomy)
The thorax is the mid section of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma in other arthropods....
is straw coloured, the wings are transparent with a smoky patch in the centre and the legs are whitish. The abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
is straw-coloured at the front and dark brown behind with a dark-coloured ovipositor
Ovipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
0.5 millimetres long. The male is smaller, averaging 0.75 millimetres in length and is a uniform dark brown.
Life cycle
After mating, a female lays diploid eggsEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
in nymphs
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
of the citrus blackfly. When available, a second instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
nymph is selected and each egg will eventually produce a female adult. At 24°C in the laboratory, it takes 30 to 35 days from egg-laying to adult emergence. Unmated females lay haploid eggs in the fully developed larvae of their own species. These hatch out into males, a process known as adelpho-parasitism. The sex ratio among adults in the field is one male to every seven females. Encarsia perplexa is itself parasitized by Encarsia smithi which was accidentally introduced into Florida in the 1970s.
Use in biological control
The only hosts that have been identified for Encarsia perplexa are Aleurocanthus woglumiAleurocanthus woglumi
Aleurocanthus woglumi is a species of whitefly in the family Aleyrodidae. It is a pest of citrus crops and is commonly known as the citrus blackfly because of its slate blue colour. It originated in Asia but has spread to other parts of the world...
and Aleurocanthus incertus, another whitefly. This means that introducing the species into a citrus growing area is unlikely to have adverse ecological side effects. Amitus hesperidum
Amitus hesperidum
Amitus hesperidum is a tiny parasitic wasp. It is a parasitoid of the citrus blackfly, Aleurocanthus woglumi, an important pest of citrus trees. It is a native of Asia but has been introduced to many other parts of the world as a means of controlling the citrus blackfly.-Distribution:This wasp is...
is another citrus blackfly parasitoid that has been used alongside E. perplexa to control the pest. It reproduces rapidly and can produce up to seventy progeny per female and is very successful at controlling heavy infestations. E. perplexa multiplies more slowly but is better at scouting for outlying blackflies and is more effective when populations of potential hosts are lower.
In Hawaii, both species were introduced in 1999 after the citrus blackfly was discovered there for the first time the previous year. They rapidly became established and were soon controlling the pest on the island of Oahu. Later releases on other islands in the group have also been an effective, though not immediate, means of reducing infestations.