Oxyops vitiosa
Encyclopedia
Oxyops vitiosa is a species of weevil
in the Curculionidae
family. Common names include the melaleuca leaf weevil and the melaleuca snout beetle. It feeds on the leaves and shoots of the broad-leaved paper bark
tree, Melaleuca quinquenervia, which is endemic to Australia where it grows on seasonally inundated plains and swampland. It was introduced into Florida in order to help drain flooded portions of the Everglades.
After mating, the females lays eggs
singly or in small groups on the tips of young leaves or sometimes on more mature leaves and new plant growth. The eggs are yellow and one millimetre long when laid but the female usually covers them in a protective secretion which dries to form a hard, dark coloured casing. Female weevils can live for up to ten months, during which time they may produce from 500 to 1000 eggs at the rate of up to nine eggs per day.
The eggs hatch in about a week and the larvae
moult four times, eventually reaching about 1.4 millimetres long. They are yellow when newly hatched but later instar
s are gray and slug
-like. As they develop they become covered with a translucent yellowish oily secretion which turns black as faecal
material adheres to it. This coating may provide protection from fire ant
s and other predator
s. The larvae often trail a black faecal string behind them. When feeding, they eat through all the layers of the leaf except for the cuticle on the far side, leaving paper-thin trails across the leaf surface as wide as their bodies. They take about seven weeks to develop and migrate downwards as they mature.
The fourth instar is the puparium
. The larva ceases to feed and crawls or falls to the ground and finds a suitable underground site in which to pupate. It develops a capsule about ten millimetres in diameter which becomes coated with soil that adheres to the oily surface coating. This stage lasts from two to six weeks but usually about four weeks. Various soil types support pupation but success rates may be higher where soils are sandy and well drained. Sites with saturated soils or permanently flooded areas did not support colonisation when the species was introduced in Florida in 1997.
family native to Australia. Tests were conducted in Australia to see whether any other plants acted as hosts to the weevil. Fewer than seven individuals were found on non-host species compared with more than a thousand on melaleuca. In laboratory tests, melaleuca was the only plant on which it proved possible to raise adults. Before it was introduced into Florida the weevil was tested in quarantine on over one hundred species of plant growing locally including all the members of the Myrtaceae native to Florida. It was found that adults might sporadically feed on other plants but that the weevil did not reproduce on any other of the species tested.
as an ornamental and began to naturalize in about 1906. It was later planted extensively in order to help drain flooded portions of the Everglades
. Here it flourished and is now considered to be an invasive species
and a serious threat to the ecosystem
. In Florida it has no host-specific natural enemies and the introduction of certain insect species from Australia to help control it is being investigated. USDA
scientists imported four insect species into quarantine for evaluation. Of these, the melaleuca leaf weevil seems the most promising. Both adults and larvae were found to disrupt the plant's normal growth processes which may make the plants more susceptible to other control measures. At certain test sites where the weevil has been introduced experimentally, flowering of the melaleuca tree has been reduced by up to 90%. This scale of damage may help to minimise the numbers of seeds produced and thus the spread of this invasive tree.
Weevil
A weevil is any beetle from the Curculionoidea superfamily. They are usually small, less than , and herbivorous. There are over 60,000 species in several families, mostly in the family Curculionidae...
in the Curculionidae
Curculionidae
Curculionidae is the family of the "true" weevils . It was formerly recognized in 1998 as the largest of any animal family, with over 40,000 species described worldwide at that time...
family. Common names include the melaleuca leaf weevil and the melaleuca snout beetle. It feeds on the leaves and shoots of the broad-leaved paper bark
Melaleuca quinquenervia
Melaleuca quinquenervia, commonly known as Niaouli or Broad-leaved paperbark or the Paper Bark Tea Tree, is a small- to medium-sized tree of the allspice family, Myrtaceae. The plant is native to New Caledonia, Papua New Guinea and coastal Eastern Australia, from Botany Bay in New South Wales...
tree, Melaleuca quinquenervia, which is endemic to Australia where it grows on seasonally inundated plains and swampland. It was introduced into Florida in order to help drain flooded portions of the Everglades.
Life cycle
Adult weevils are gray and six to nine millimetres long, the males being slightly smaller than the females. They are usually found on the leaves and twigs of saplings or the new growth of larger melaleuca trees but are inconspicuous and their presence is most noticeable from the holes they chew in the buds, leaves and stems.After mating, the females lays eggs
Egg (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...
singly or in small groups on the tips of young leaves or sometimes on more mature leaves and new plant growth. The eggs are yellow and one millimetre long when laid but the female usually covers them in a protective secretion which dries to form a hard, dark coloured casing. Female weevils can live for up to ten months, during which time they may produce from 500 to 1000 eggs at the rate of up to nine eggs per day.
The eggs hatch in about a week and the larvae
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
moult four times, eventually reaching about 1.4 millimetres long. They are yellow when newly hatched but later 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...
s are gray and slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
-like. As they develop they become covered with a translucent yellowish oily secretion which turns black as faecal
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
material adheres to it. This coating may provide protection from fire ant
Fire ant
Fire ants are a variety of stinging ants with over 285 species worldwide. They have several common names, including ginger ants, tropical fire ants and red ants.- Appearance :...
s and other predator
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
s. The larvae often trail a black faecal string behind them. When feeding, they eat through all the layers of the leaf except for the cuticle on the far side, leaving paper-thin trails across the leaf surface as wide as their bodies. They take about seven weeks to develop and migrate downwards as they mature.
The fourth instar is the puparium
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
. The larva ceases to feed and crawls or falls to the ground and finds a suitable underground site in which to pupate. It develops a capsule about ten millimetres in diameter which becomes coated with soil that adheres to the oily surface coating. This stage lasts from two to six weeks but usually about four weeks. Various soil types support pupation but success rates may be higher where soils are sandy and well drained. Sites with saturated soils or permanently flooded areas did not support colonisation when the species was introduced in Florida in 1997.
Host range
This weevil feeds on Melaleuca quinquenervia, a tree in the myrtleMyrtaceae
The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...
family native to Australia. Tests were conducted in Australia to see whether any other plants acted as hosts to the weevil. Fewer than seven individuals were found on non-host species compared with more than a thousand on melaleuca. In laboratory tests, melaleuca was the only plant on which it proved possible to raise adults. Before it was introduced into Florida the weevil was tested in quarantine on over one hundred species of plant growing locally including all the members of the Myrtaceae native to Florida. It was found that adults might sporadically feed on other plants but that the weevil did not reproduce on any other of the species tested.
Use in biological control
The melaleuca tree, Melaleuca quinquenervia, was introduced into FloridaFlorida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
as an ornamental and began to naturalize in about 1906. It was later planted extensively in order to help drain flooded portions of the Everglades
Everglades
The Everglades are subtropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large watershed. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee...
. Here it flourished and is now considered to be an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
and a serious threat to the ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
. In Florida it has no host-specific natural enemies and the introduction of certain insect species from Australia to help control it is being investigated. USDA
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
scientists imported four insect species into quarantine for evaluation. Of these, the melaleuca leaf weevil seems the most promising. Both adults and larvae were found to disrupt the plant's normal growth processes which may make the plants more susceptible to other control measures. At certain test sites where the weevil has been introduced experimentally, flowering of the melaleuca tree has been reduced by up to 90%. This scale of damage may help to minimise the numbers of seeds produced and thus the spread of this invasive tree.