Willow sawfly | |
---|---|
Adult | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Hymenoptera |
Suborder: | Symphyta |
Family: | Tenthredinidae |
Subfamily: | Nematinae |
Genus: | Nematus |
Species: | N. oligospilus |
Binomial name | |
Nematus oligospilus Förster, 1854 | |
Synonyms | |
Nematus desantisi |
Nematus oligospilus, commonly known as the willow sawfly, is a species of sawfly in the family Tenthredinidae. Native to central and northern Europe and Asia, it was first recorded in South America in the 1980s and New Zealand in 1997, and has also been introduced to Australia, South Africa and Lesotho. Its larvae feed on the leaves of various species of willow.
An adult is between 8 and 10 mm (0.3 and 0.4 in) long. It is a slender insect with two pairs of membranous wings with black veins, the fore-wings having a yellow leading edge. The head bears a pair of long antennae, a pair of black compound eyes and three ocelli. The sides of the thorax are pale yellowish-brown while the dorsal surface is mid-brown. The abdomen is greenish and the legs are yellowish-brown at the base and darker brown near the clawed tips. The larva resembles a lepidopteran caterpillar; it has a white head with brown markings, a green body, three pairs of true legs near the front and seven pairs of pro-legs behind. [1]
The willow sawfly is widespread in the Holarctic region [2] and has spread to other parts of the world. It was recorded in South America for the first time in the 1980s, in Argentina and Chile where it caused severe defoliation of various species of willow (Salix). In 2017 it was recorded in Colombia on the ornamental willow Salix humboldtiana . [3] It had reached New Zealand by 1997 and was also present around this time in Australia. [1] In both of these countries it spread rapidly, with the larvae feeding on species of willow, which are not native plants in Australia and New Zealand. [2] It has also been found in South Africa and Lesotho. [4]
Eggs are laid on the leaves of the host tree, and the developing larvae feed on the leaf tissue. Larvae have a variable number of instar stages and fall to the ground when fully developed. They make their way underground and overwinter as non-feeding prepupae in the cocoons they form. However, in Colombia it was found that larvae remain on the tree and form their cocoons there; these are green and easily overlooked among the foliage. The prepupae pupate in the spring, the adults emerging when new foliage is available. Adults each lay about thirty eggs soon after emerging. [3]
In South America, all adults are female and reproduction is by parthenogenesis. [3] The same is true in other parts of the Southern Hemisphere where it has been introduced, [5] but in its native range in the Northern Hemisphere, both males and females occur. [6] Shifting from sexual to parthenogenetic reproduction is fairly common in invasive species and offers several advantages. [5] The small number of individuals initially introduced into a new habitat would make it difficult for sexual partners to find each other. Also, a population that is all female can potentially expand at twice the maximum rate of a population with two sexes, allowing an invasive species to establish itself more rapidly. Sexual reproduction with its usual advantage of genetic recombination is not as favored in invasive populations, which lack predators. [5]
Sawflies are wasp-like insects that are in the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay their eggs. The name is associated especially with the Tenthredinoidea, by far the largest superfamily in the suborder, with about 7,000 known species; in the entire suborder, there are 8,000 described species in more than 800 genera. Symphyta is paraphyletic, consisting of several basal groups within the order Hymenoptera, each one rooted inside the previous group, ending with the Apocrita which are not sawflies.
The Pergidae are a moderate-sized family of sawflies occurring in the Western Hemisphere and the Australasian Region. The Pergidae are, with almost 450 described species, the third-largest family of Symphyta after the Tenthredinidae and the Argidae. Morphologically, most pergids are typically sawfly-like, but the form of the antennae varies considerably in number of segments and from simple to serrate and pectinate or even bipectinate. Sexual dimorphism is common and reflected in differences in type of antennae, colour, and size. Included are some of the few known apterous sawflies, those of the genus Cladomacra occurring in Papua New Guinea and Indonesia, and a species with brachypterous females, Clarissa tasbates, in Tasmania.
Tenthredinidae is the largest family of sawflies, with well over 7,500 species worldwide, divided into 430 genera. Larvae are herbivores and typically feed on the foliage of trees and shrubs, with occasional exceptions that are leaf miners, stem borers, or gall makers. The larvae of externally feeding species resemble small caterpillars. As with all hymenopterans, common sawflies undergo complete metamorphosis.
Nematinae is a subfamily of sawflies belonging to the family Tenthredinidae. It contains over 1250 described species in ~40 genera. Members of this subfamily feed on a wide range of plants and employ a wide range of feeding habits, both internally and externally, on their host plants.
Tenthredo colon is a sawfly species belonging to the family Tenthredinidae.
Tomostethus multicinctus, the brownheaded ash sawfly, is a species of sawfly in the family Tenthredinidae that is native to southern Canada and the eastern United States. Adults of this species resemble wasps and the larvae feed on the leaves of ash trees.
Nematus spiraeae is a species of sawfly in the family Tenthredinidae, known as the aruncus sawfly and sometimes the spiraea sawfly. It is native to central and northern Europe and was first recorded in Britain in 1924. Its larvae feed on the leaves of goat's beard.
Hoplocampa testudinea, the apple sawfly or European apple sawfly, is a species of sawfly in the family Tenthredinidae. It is native to Europe but has been accidentally introduced into North America where it became invasive. The larvae feed inside the developing fruits of the apple tree.
Diprion similis is a species of sawfly in the family Diprionidae. It is native to central and northern Europe and Asia but was accidentally introduced into North America where it has become invasive. The larvae feed on the needles of pine trees, especially those of the white pine. In North America it is known as the introduced pine sawfly or the imported pine sawfly. It is also known as the white pine sawfly because of its preference for feeding on the white pine, but this name is confusing because another sawfly, Neodiprion pinetum, whose larvae also feed on this tree, is itself known as the "white pine sawfly".
Neodiprion lecontei is a species of sawfly in the family Diprionidae native to eastern North America, commonly known as the red-headed pine sawfly or Leconte's sawfly. The larvae feed on the foliage of many species of native and imported pines. This species was named after John Lawrence LeConte, an American entomologist of the 19th century.
Dahlbominus fuscipennis, the sawfly parasitic wasp, is a species of chalcid wasp from the family Eulophidae which parasitizes the European pine sawfly Neodiprion sertifer, among other hosts. It is the only species in the genus Dahlbominus.
Euura is a genus of sawflies of the family Tenthredinidae, subfamily Nematinae. Some of the larvae feed externally on plants and some form plant galls on willows (Salix species). In the case of the gall-forming species, when the female lays her eggs she injects a stimulant and the gall starts to form before the eggs hatch. Most sawfly galls are hard and individual larva tend to inhabit the gall, feeding on the tissue and leave the gall to pupate in the soil. Most of the species are monophages although the type species, Euura mucronata, is polyphagous feeding on over thirty species of willow.
Euura atra is a species of sawfly belonging to the family Tenthredinidae. The larvae feed internally on the shoots of willows and do not usually form galls, although it is included in plant gall literature such as British Plant Galls. It was first described by Louis Jurine in 1807. E. atra is one of a number of closely related species known as the Euura atra subgroup.
Eriocampa ovata, known generally as the alder sawfly or woolly alder sawfly, is a species of common sawfly in the family Tenthredinidae. The larvae feed on the leaves of the common alder and the grey alder, sometimes causing defoliation.
Euura dolichura is a species of sawfly belonging to the family Tenthredinidae. It was first described by Carl Gustaf Thomson in 1871. The larvae feed within galls on the leaves of willow. Some of the Euura species of sawfly are closely related and placed in groups of similar species. E. dolichura is a member of the Euura dolichura species group.
Euura nigricantis is a species of sawfly belonging to the family Tenthredinidae. The larvae feed within galls on the leaves of dark-leaved willow. It was described by Jens-Peter Kopelke in 1986.
Euura proxima is a species of sawfly belonging to the family Tenthredinidae. The larvae feed on the leaves of willows, creating galls. It was described by Jean Guillaume Audinet-Serville in 1823. The species was placed in the genus Euura in 2014 and was previously known as Nematus proximus and Pontania proxima.
Euura viminalis is a species of sawfly belonging to the family Tenthredinidae. The larva feed within galls on the leaves of willows. It was first described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae.
Euura collactanea is a species of sawfly belonging to the family Tenthredinidae. The larva feed within galls on the leaves of willows. It was first described by Arnold Förster in 1854.
Profenusa thomsoni, the amber-marked birch leaf miner, is a species of sawfly in the family Tenthredinidae. It is native to the Palearctic realm but has spread to North America. The larvae feed on the foliage of birch trees.