Fall webworm | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Lepidoptera |
Superfamily: | Noctuoidea |
Family: | Erebidae |
Subfamily: | Arctiinae |
Genus: | Hyphantria |
Species: | H. cunea |
Binomial name | |
Hyphantria cunea (Drury, 1773) | |
Synonyms | |
|
The fall webworm (Hyphantria cunea) is a moth in the family Erebidae known principally for its larval stage, which creates the characteristic webbed nests on the tree limbs of a wide variety of hardwoods in the late summer and fall. It is considered a pest but does not harm otherwise healthy trees. It is well known to commercial tree services and arboriculturists. Fall webworms are an invasive species in East Asia. [1]
The adult fall webworm has a wingspan of approximately 30 mm and is generally white-colored, although some individuals may have dark-colored marks. [2]
The moth is native to North America, ranging from Canada to Mexico and has been introduced into other continents. [3] Introduced to what was formerly Yugoslavia in the 1940s (firstly recorded in 1949 [4] ), it now has occupied probably its entire range in Europe from France to the Caspian Sea in the east as well as penetrated into Central Asia: Turkmenistan (from 1990 to 1993), Uzbekistan (Fergana valley from 1996 to 1997), Kyrgyzstan, and southeastern Kazakhstan. It was also introduced into Japan in 1945 and has adjusted its number of generations per year since its arrival. [5] It spread into China, southern Mongolia, Korea and southern Primorsky Krai of Russia so that now it is considered holarctic in distribution. [1]
One generation per year emerges in the northern part of North America, with larvae appearing in late summer through early fall. South of an approximate latitude of 40°N there are two or more generations annually, with webs appearing progressively earlier further south. [6]
The adult moth lays her eggs on the underside of leaves in 'hair'-covered clusters of a few hundred. [7] Eggs hatch in about a week. [8]
The caterpillars are highly variable in coloration, ranging from a pale yellow to dark grey, with yellow spots and long and short bristles. [6] There are two cream stripes along the sides. The two races—one more common in the north, the other in the south—differ in head capsule coloration. [8] The maximum length of larvae is 35 mm. Webs are progressively enlarged and much messier looking than those of tent caterpillars (which occur only in spring and have shorter hairs and very little yellow on their bodies); also, webs from the fall webworm are concentrated to the tips of the branches, whereas the tent caterpillar webs are largely found in the unions. Larvae feed inside the tents until the late instars. Very young larvae feed only on the upper surfaces of leaves; later, they consume whole leaves. The larval stage lasts about four to six weeks. [8] Larvae are known to wiggle vigorously at periodic intervals in synchrony. How they synchronize these movements especially when distributed over a wide area has not been established. [9]
The pupa stage overwinters in the bark and leaf litter at the base of the trees. It is dark brown and about 10 mm long. The thin brown cocoon is made of silk with bits of detritus interwoven. [8]
The adult is mostly white in the North America regions, but in the south it may be marked with black or brown spots on the forewings. [7] [8] It is quite 'hairy' and the front legs have bright yellow or orange patches. The underwings will have less marking than the forewings, and the abdomen often has a sprinkling of brown hairs. It has a wingspan with a range of 35–42 mm.
The fall webworm feeds on just about any type of deciduous tree, where leaves are chewed; branches or the entire tree may become defoliated. Worldwide, it has been recorded from 636 species, [10] and it is considered to be among the most polyphagous of insects. In the eastern U.S., pecan trees (Carya illinoinensis), black walnut, American elm ( Ulmus americana L.), hickory, fruit trees, and some maples are preferred hosts; in some areas persimmon and sweetgum are also readily eaten. In the west, alder, willow (Salix spp.), cottonwood and fruit trees are commonly used. Additional host plant examples include madrone ( Arbutus menziesii Pursh), mulberry, ailanthus, American sycamore ( Platanus occidentalis L.), and Asian white birch ( Betula platyphylla ). [2] [7] [11] [12]
Host plant selection is dependent on factors like the plant's degree of sun exposure, age, environmental stress undergone, toughness, and nutritional quality. [2] [11] For example, for an insect that needs energy for processes like dispersal or diapause, consuming plants that provide a lot of carbohydrates could be beneficial; for a female insect that is producing eggs, consuming plants that provide a lot of protein could be beneficial. [11]
The fall webworm is a gregarious insect. [13] Groups of larvae live in self-created large webs that are found on tree branches. [13] [14] These webs allow for the finding of mates, temperature regulation, increased growth rate, and protection from predators, but also result in higher rates of infections and predation. [13] [14]
The caterpillars of the fall webworm have several strategies to defend against threats. Some examples of protective behavior or defense are shaking and jerking together, repellant scent, and irritants on hairs or spines. [2] [14]
The fall webworm exhibits a form of parental care, where the female will try to protect the eggs after oviposition by covering her newly laid eggs with her abdomen hairs. [2]
Male fall webworms are typically only available for mating for about 30–60 minutes per day. [2]
The sex pheromone consists of the components (9Z,12Z)- 9,12-octadecadienal (I), (9Z,12Z,15Z)-9,12,15-octadecatrienal (II), cis-9,10-epoxy-(3Z,6Z)-3,6-henicosa- diene (III), and cis-9,10-epoxy-(3Z,6Z)-1,3,6-henicosatriene (IV). [15]
Fall webworms experience behavioral thermoregulation. [2] [16] The fall webworms' self-created web (which is where the fall webworms live) is able to trap heat. [2] [16] Due to this, the fall webworm (which is an ectotherm) is able to maintain a warm temperature of about 40-50 °C, which allows the larvae to grow and develop faster. [2] [16] Inside the web, there is a temperature difference because the central part tends to have a higher temperature, while the back part tends to have a lower temperature. [16] However, a web's heat trapping process is not always stable; wind can disturb the heat trapping. [16]
There are several components to the fall webworm gut, such as the foregut and the midgut. The foregut and midgut of the fall webworm are alkaline, and Johnson and Felon found that the midgut pH ranged from 8.7 to 11.4. [17] [18]
There are many predators of the fall webworm, such as Monomorium minimum , Vespula spp., Coleomegilla maculata , and Rogas hyphantriae . [2] [3]
The fall webworm is parasitized by around 50 species, such as the flies Musca domestica and Muscina stabulans , and parasitic wasps such as Chouioia cunea and Therion morio . [2] [3] [19] [20] [1] There are also several species of microsporida that can be harmful, such as Nosema necatrix Kramer (N. necatrix), Pleistophora schubergi hyphantriae Weiser (P.s. hyphantriae), Nosema sp., and Nosema bombycis (N. bombycis ). [21] Nosema bombycis can affect many body tissues, such as the midgut, fat body, gonads, nervous tissue, and Malpighian tubules, and the length of its polar filament is 100 μm. [21] Spores from Nosema of fall webworms are typically egg-shaped and can sometimes be attached to each other, and the length of its polar filament is 57.5 μm ± 8.7 μm. [21]
Several types of pathogens can infect this species, such as granulovirus (which causes granulosis disease) and nucleopolyhedrosis virus. [2] [3] [22] Granulovirus has a rod-like shape. [23] Also, an individual will be more likely to be infected at a younger age. [22]
The fall webworm’s interaction with humans is important because of how adaptable this species is, which is one of the main reasons that it spread so widely across the world. [24] [3] Fall webworms are able to forage on large amounts of leaves inside their web, they are able to create webs on many different types of host plants, they are able to create webs at many different elevations and of many different shapes, and they spread very quickly. [2] [24] [16] [25] [3] In addition, the fall webworm tends to create many webs or defoliate plants in places that humans spend time, such as recreational areas and parks; fall webworms tend to create their webs on branches and therefore defoliate parts of the tree that are very visible and draw attention. [2] [3] [16] [24] There have been methods with trying to control this organism, such as physical removal or chemical methods; however, there are some issues with these options because physical removal can be challenging with certain types of trees (based on factors like how tall the tree is, what its function is, where it is located), and the side effects of chemicals (such as important pollinators dying and therefore not being able to perform their functions). [2] [3] New, effective methods are needed to control this organism; Wang et al. (2016) showed the effectiveness of a community-based system to monitor webworms, which involved using mobile devices. [24]
A tree, when covered by the web of the fall webworm is, in the Southern States, sometimes called a "fuzzy tree" because of its fuzzy appearance.
Caterpillars are the larval stage of members of the order Lepidoptera.
An ectotherm, more commonly referred to as a "cold-bloodedanimal", is an animal in which internal physiological sources of heat are of relatively small or of quite negligible importance in controlling body temperature. Such organisms rely on environmental heat sources, which permit them to operate at very economical metabolic rates.
The Arctiinae are a large and diverse subfamily of moths with around 11,000 species found all over the world, including 6,000 neotropical species. This subfamily includes the groups commonly known as tiger moths, which usually have bright colours, footmen, which are usually much drabber, lichen moths, and wasp moths. Many species have "hairy" caterpillars that are popularly known as woolly bears or woolly worms. The scientific name Arctiinae refers to this hairiness. Some species within the Arctiinae have the word "tussock"' in their common names because they have been misidentified as members of the Lymantriinae subfamily based on the characteristics of the larvae.
Prunus serotina Ehrh., commonly called black cherry, wild black cherry, rum cherry, or mountain black cherry, is a deciduous tree or shrub in the rose family Rosaceae. Despite being called black cherry, it is not very closely related to the commonly cultivated cherries such as sweet cherry, sour cherry and Japanese flowering cherries which belong to Prunus subg. Cerasus. Instead, P. serotina belongs to Prunus subg. Padus, a subgenus also including Eurasian bird cherry and chokecherry. The species is widespread and common in North America and South America.
The brown-tail moth is a moth of the family Erebidae. It is native to Europe, neighboring countries in Asia, and the north coast of Africa. Descriptions of outbreaks, i.e., large population increases of several years duration, have been reported as far back as the 1500s. The life cycle of the moth is atypical, in that it spends approximately nine months as larvae (caterpillars), leaving about one month each for pupae, imagos and eggs. Larvae (caterpillars) are covered in hairs. Two red spots on the back, toward the tail, distinguish these species from other similarly hairy moth larvae. The winged adults have white wings and a hairy white body with a tuft of brown hair at the tip of the abdomen. Females lay one egg cluster, usually on the underside of a leaf of a host plant. The species is polyphagous, meaning that it feeds on many different species of trees, including pear, apple, maple and oak.
Baculoviridae is a family of viruses. Arthropods, among the most studied being Lepidoptera, Hymenoptera and Diptera, serve as natural hosts. Currently, 85 species are placed in this family, assigned to four genera.
The codling moth is a member of the Lepidopteran family Tortricidae. They are major pests to agricultural crops, mainly fruits such as apples and pears, and a codling moth larva is often called an "apple worm". Because the larvae are not able to feed on leaves, they are highly dependent on fruits as a food source and thus have a significant impact on crops. The caterpillars bore into fruit and stop it from growing, which leads to premature ripening. Various means of control, including chemical, biological, and preventive, have been implemented. This moth has a widespread distribution, being found on six continents. Adaptive behavior such as diapause and multiple generations per breeding season have allowed this moth to persist even during years of bad climatic conditions.
Tent caterpillars are moderately sized caterpillars, or moth larvae, belonging to the genus Malacosoma in the family Lasiocampidae. Twenty-six species have been described, six of which occur in North America and the rest in Eurasia. Some species are considered to have subspecies as well. They are often considered pests for their habit of defoliating trees. They are among the most social of all caterpillars and exhibit many noteworthy behaviors.
The collective behaviors of social caterpillars falls into five general categories: collective and cooperative foraging, group defense against predators and parasitoids, shelter building, thermoregulation and substrate silking to enhance steadfastness.
The European corn borer, also known as the European corn worm or European high-flyer, is a moth of the family Crambidae. It is a pest of grain, particularly maize. The insect is native to Europe, originally infesting varieties of millet, including broom corn. The European corn borer was first reported in North America in 1917 in Massachusetts, but was probably introduced from Europe several years earlier. Since its initial discovery in the Americas, the insect has spread into Canada and westwards across the United States to the Rocky Mountains.
Choristoneura fumiferana, the eastern spruce budworm, is a species of moth of the family Tortricidae native to the eastern United States and Canada. The caterpillars feed on the needles of spruce and fir trees. Eastern spruce budworm populations can experience significant oscillations, with large outbreaks sometimes resulting in wide scale tree mortality. The first recorded outbreaks of the spruce budworm in the United States occurred in about 1807, and since 1909 there have been waves of budworm outbreaks throughout the eastern United States and Canada. In Canada, the major outbreaks occurred in periods circa 1910–20, c. 1940–50, and c. 1970–80, each of which impacted millions of hectares of forest. Longer-term tree-ring studies suggest that spruce budworm outbreaks have been recurring approximately every three decades since the 16th century, and paleoecological studies suggest the spruce budworm has been breaking out in eastern North America for thousands of years.
Hyblaea puera, the teak defoliator, is a moth and cryptic species complex native to South Asia and South-east Asia. It was first described by Pieter Cramer in 1777. The species has also been recently reported to be present in Central America and Africa. The caterpillar feeds on teak and other trees. It is considered to be one of the major teak pests around the world.
The little black ant is a species of ant native to North America. It is a shiny black color, the workers about 1 to 2 mm long and the queens 4 to 5 mm long. It is a monomorphic species, with only one caste of worker, and polygyne, meaning a nest may have more than one queen. A colony is usually moderately sized with only a few thousand workers.
Chouioia is a genus of endoparasitic wasp of the family Eulophidae. Chouioia cunea is considered an important parasite of the fall webworm in China, where the moth is an invasive species.
Coleomegilla maculata, commonly known as the spotted lady beetle, pink spotted lady beetle or twelve-spotted lady beetle, is a large coccinellid beetle native to North America. The adults and larvae feed primarily on aphids and the species has been used as a biological control agent. Based on name connotation and to avoid confusion with other species also called "spotted ladybeetle", spotted pink ladybeetle is probably the most appropriate common name for this species.
John Douglas Tothill DSc, CMG, was an English-born entomologist, agriculturalist and civil servant, whose career took him to Canada, Fiji, Uganda and the Sudan. He was the son of Walter Tothill and Frances L. Williams.
Therion morio is a species of parasitic ichneumon wasp in the family Ichneumonidae. It is a parasite of the webworm caterpillar in North America.
Heteropelma is a genus of parasitoid wasps belonging to the family Ichneumonidae. Species in this genus are around 25 mm in length.
Habronyx is a genus of parasitoid wasps belonging to the family Ichneumonidae. The species of this genus are found in Europe, Australia, and North and South America.
Habronyx fulvipes is a species of parasitic ichneumon wasp. It was renamed by Townes, Momoi and Townes in 1965 ; prior to that the species had been named Habronyx chinensis, chinensis meaning "China", in 1955 by Japanese entomologist Toichi Uchida. The holotype and allotype were collected by R. Mell. The species was first named Exochilum Chinense by Morley in 1913.