Spodoptera littoralis | |
---|---|
Adult African cotton leafworm | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Lepidoptera |
Superfamily: | Noctuoidea |
Family: | Noctuidae |
Genus: | Spodoptera |
Species: | S. littoralis |
Binomial name | |
Spodoptera littoralis (Boisduval, 1833) | |
Synonyms | |
Spodoptera littoralis, also referred to as the African cotton leafworm or Egyptian cotton leafworm or Mediterranean brocade, is a species of moth in the family Noctuidae. S. littoralis is found widely in Africa, Mediterranean Europe and Middle Eastern countries. It is a highly polyphagous organism that is a pest of many cultivated plants and crops. [1] As a result, this species was assigned the label of A2 quarantine pest by the EPPO and was cautioned as a highly invasive species in the United States. [2] [3] The devastating impacts caused by these pests have led to the development of both biological and chemical control methods. [4] This moth is often confused with Spodoptera litura . [4]
Egyptian cotton leafworm is one of the many species of genus Spodoptera and family Noctuidae. The family Noctuidae was named by a French zoologist, Pierre André Latreille, in 1809 and the genus Spodoptera was named by a French entomologist, Achiwlle Guenée, in 1852. Many of the species of genus Swpodoptera are known to be pest insects. [5] The species was named by Jean Baptiste Boisduval in 1833. Synonyms of S. littoralis include Hadena littoralis and Prodenia littoralis. Due to the similarities between many pest insects, there have been noted incidents of many species that are almost identical to S. littoralis. For example, Spodoptera litura or cotton leafworm is often confused with S. littoralis, since the larvae and adult stages of two species are near identical. However, Viette demonstrated that these are two different species, as S. litura was found to mostly reside in Asia, Australia, and the Pacific Islands. [4] [6]
The adult moth has a body size that ranges from 15 to 20 mm and wingspan that ranges from 30 to 38 mm. The species' forewings are grey-brown colored and has an ocellus that are constructed by white oblique lines. The hind wings are usually much paler and have grey-colored margins. [1] [4]
Spodoptera littoralis is often confused with Spodoptera litura due to similar larvae and adult physical appearances. A bright yellow stripe along the dorsal side of the larvae is characteristic of S. litura. However, due to the variability in markings, the only certain way of distinguishing between the two species is by comparing the genitalia. [4] Specifically, ductus and ostium bursae are known to be the same length in S. littoralis females but different in S. litura females. [7] Similarly, it was reported that Prodenia ornithogalli is an American representative of S. littoralis as forms of the two species are extremely close and related. The main difference between these species is that P. ornithogalli is much darker in color and has sharper markings. [8]
African cotton leafworm is native to Africa and also resides in most regions of Middle Eastern countries such as Israel, Syria and Turkey. Specifically, the species' native habitat is F5 (EUNIS code), which is semi-arid and subtropical habitats in pre-saharan Africa. [9] This species has also been found in Southern and Mediterranean Europe, mainly in Spain, France, Italy and Greece. [1] As the African cotton leafworm is prone to cold weather, the species' natural range is limited in the northern regions of Europe such as the United Kingdom. The optimal temperature for the species' reproductive potential is around 25 °C, so areas with lower winter temperatures or fluctuating temperatures show limited species distribution. [4] [10] Studies have shown that temperatures over 40 °C or below 13 °C showed increased in mortality. [9] Combination of high temperature and low humidity are detrimental to the species survival as temperature over 40 °C or below 13 °C tend to increase mortality rate. [9] As a result, S. littoralis resides in regions where temperature fluctuation is rare to feed on variety of host plants, in which the females lay eggs and the larvae primarily grow. [4]
Species distribution mainly occurs through trade when egg or larvae get on the imported ornamentals or crops. Adult moths are often distributed by wind but are also transported by other species. Adult moths fly as well. [9]
Spodoptera littoralis is reported to be polyphagous, and the range of host plants on which the larvae feed covers over 40 different plant families and at least 87 different plant species. The species is known as a pest of several economically important crops such as Ipomoea batatas (sweet potato), Solanum lycopersicum (tomato), Zea mays (maize), Triticum aestivum (wheat), Capsicum (peppers), Chloris gayana (rhodes grass) and Hibiscus mutabilis (cottonrose). [4] The larvae prefer to feed on young leaves, young shoots, stalks, bolls, buds and fruits. Some of its recorded host plants are known to affect larval growth. For example, larvae that fed on castor oil leaves had shortened larval and pupal duration, whereas these durations were prolonged in larvae that fed on sweet potato leaves. [11]
Oviposition refers to a process in which animals lay eggs. There are three different oviposition sites of S. littoralis females. Of the three, young leaves are particularly preferred by the females as they serve as food sources for the hatching larvae. Eggs are also often deposited on fully expanded leaves or mature leaves but larvae hatching from these leaves move to feed on young leaves. Larvae that fed on young leaves or fully expanded leaves were found to have significantly faster growth rate compared to others that fed on mature leaves. [12]
Female moths lay a batch of eggs that ranges from 20 to 1,000 eggs on the lower side of a host plant's leaves. After the eggs are laid, female coats the eggs with scales from its abdomen. These spherical eggs show white to yellowish color and are 0.6 mm in diameter. These white-yellow color of the eggs turn black just before hatching due to the presence of black larval head near the transparent shell. [1] [4]
Larvae body length ranges from 40 to 45 mm. The larvae is usually hairless and varies in color. It has been noted that new born larvae has grayish or dark-green body color whereas the developed larvae has brownish or yellowish body color. Dark and light longitudinal bands along with two dark semi-circular spots on the back are noted characteristics of the larvae. The newly hatched larvae up to third-instar mainly feed on the lower side of the leaves but the later instar larvae feed on both sides. S. littoralis larvae in general are known to feed in the dark. It also has been observed that larvae up to their third and fourth-instar usually remain in their host plant but fifth and sixth-instar larvae leave the host plant during the day and climb back up at night. [1] [4]
The pupa is around 20 mm long and cylindrical in shape. Initially, the pupa is green colored with reddish abdomen but it turns reddish-brown within few hours. Pupation usually occurs 3–5 cm deep in the solid ground under soil. The duration of pupation is around 5–6 hours. [1] [4]
Adult moth has a greyish-brown body that is around 15–20 millimetres (9⁄16–13⁄16 in) long. The wingspan of the adult moth ranges from 30–38 millimetres (1+3⁄16–1+1⁄2 in). The forewing of the adult moth has brownish color with paler veins whereas the hindwing is more lightly colored (greyish-white). There are also oblique white bands on the forewing. [4] The adult moth appears at night and live about 5–10 days. [13]
Larvae have been found to suffer drastic feeding inhibition from injection with myosuppressin, by Vilaplana et al. 2008. [14]
There are many known predators, pathogens and parasite species that control the growth and distribution of S. littoralis. Of the natural predators of S. littoralis, ladybirds have been noted to prey on young larvae and eggs. Other known generalist predators include Paederus fuscipes (staphylinid rove beetle), Paederus alferii, Labidura riparia, Creontiades pallidus and so on. [4] Spiders are also known predators of this species. Specifically, Cheiracanthium mildei and Ummeliata insecticeps are known dominant predator species of S. littoralis that not only feed on the larvae but also induce dispersion from host plant. [15]
Copulation refers to sexual behaviors observed in animals. Most adult moths mate on the day that they emerge from pupation. Duration of copulation ranges from 20 minutes to two hours. Studies revealed that age difference between the male and female moth is crucial in determining reproductive capacity, adult lifespan and egg quality. [4] The most effective age difference that increased egg fertility was four days difference between the male and female. When a four-day-old male mated with a fresh born female, egg fertility was observed to be high. However, females laid most eggs when it mated with a male who was one day older. [16]
Pheromones refer to chemical factors secreted by an organism that effect the social behavior of other organisms that receive them. The pheromone secreted by females for mate calling is (Z,E)-9,11-tetradecadienyl acetate. As most matings occur at night, females producing largest amount of pheromone was observed 2–3 hours into scotophase, a dark phase of light cycle. The amount of pheromone in these females ranged from 6 to 8 ng. Lowest amount of pheromone was excreted few hours before the dark phase ended. [17] Other than its function to attract mates, female-produced pheromones may also synchronize male circadian rhythm. [18]
Courting is a behavior that displays the attempt of one sex of the species to attract the other sex for copulation. Antennae serves an important function in adult moth courtship. A male answering a female mate-call fully extends its antennae while flying over the female. A sign of rejection in females is noted by rapid wing flicks, whereas lifted wings, curved abdomen and withdrawal of pheromone in females are signs of female's acceptance for copulation. Once male and female are attached during copulation, male move its head downwards. Males without antennae did not answer female mate-call, which resulted in lack of mating. Females without antennae seldom mated but all matings were reported to be abnormal. [19]
Flight in insects refer to a process in which an organism moves from one place to another with the usage of its wings. S. littoralis can fly up to distances of 1.5 km over a four-hour period. Since the species is nocturnal, its peak flight activity is usually between the hours of 20:00 and midnight. [4] The flight activity for the moth can extend up to 10 days while an adult. Research has also shown that wind direction seems to have an effect on the moth's flight activity. [13]
Antenna are paired appendages attached to an arthropod's head that usually has a sensory function. Antenna in S. littoralis has an important function in facilitating mating. Experiments showed that antennal lobe of adult antenna are responsible for detecting different types of sensory inputs that are necessary for the adults to respond to external stimuli. Specifically, antennal lobe are responsible for identifying olfactory and mechanosensory stimulus. [20]
Diapause is defined as a delay in development caused by adverse external environmental factors. Mature larvae dig down the soil where it forms a cocoon to go under pupation. Larvae in its pupal stage can go through diapause but it is vulnerable to continuous frost and cold weather. However, it is generally known that S. littoralis larvae do not go through diapause. [21] [22]
Because of S. littoralis' polyphagous behavior, the species has been damaging to many economically crucial crops such as cotton, tomato, maize and various other vegetables. Most of the damages are a direct result of extensive larvae feeding. Often, larvae will either create large holes in the leaves, only leaving the big veins of the leaves, or bear into the bud for consumption. [23] Most of the plants or vegetables that are attacked by S. littoralis are unsuitable for consumption as the damages are too severe. Of different types of host plants, cotton has been one of the main targets of S. littoralis. The species feed on cotton leaves, flower buds, fruiting points, and bolls, leaving the plant unsuitable for any further usage. Such damage of cotton plant is most prevalent in North Africa, especially in Egypt. [4] As a result, EPPO has assigned S. littoralis as A2 quarantine pest. [2] In the United States, S. littoralis has been listed as an exotic organism with high invasive risk. [3] Since 2004, there have been 65 reported incidents of S. littoralis that were present at various U.S. ports of entry. [24]
Due to S. littoralis' devastating effect on crops, numerous attempts have been made to counteract the species' dispersion and activities. These preventative methods are mainly divided into biological and chemical methods. Biological methods include using parasitoids or predators to control moth reproduction and dispersion. [4] Usage of bacteria such as Bacillus thuringiensis in combination with bacterial endochitinase has also been utilized recently to control many bacteria-resistant strains of S. littoralis larvae. Studies revealed that the synergistic toxic effect of Bacillus thuringiensis and bacterial endochitinase successfully resulted in reduced larval weight. [25] However, direct usage of these biological methods are yet not legal. [4] Similarly, chemical insecticides including organophosphorus, synthetic pyrethroids have been widely used to control S. littoralis. [4] Recent studies also revealed that insect growth regulators such as azadirachtin from neem tree are effective in controlling S. littoralis larvae as azadirachtin-treated larvae had overall higher mortality rate as well as reduced growth rate due to increased deformity and growth disruption. [26]
Helicoverpa zea, commonly known as the corn earworm, is a species in the family Noctuidae. The larva of the moth Helicoverpa zea is a major agricultural pest. Since it is polyphagous during the larval stage, the species has been given many different common names, including the cotton bollworm and the tomato fruitworm. It also consumes a wide variety of other crops.
The Indianmeal moth, also spelled Indian meal moth and Indian-meal moth, is a pyraloid moth of the family Pyralidae. Alternative common names are hanger-downers, weevil moth, pantry moth, flour moth or grain moth. The almond moth and the raisin moth are commonly confused with the Indian-meal moth due to similar food sources and appearance. The species was named for feeding on Indian meal or cornmeal, and does not occur natively in India. It is also not to be confused with the Mediterranean flour moth, another common pest of stored grains.
The cabbage moth is primarily known as a pest that is responsible for severe crop damage of a wide variety of plant species. The common name, cabbage moth, is a misnomer as the species feeds on many fruits, vegetables, and crops in the genus Brassica. Other notable host plants include tobacco, sunflower, and tomato, making this pest species particularly economically damaging.
The cabbage looper is a medium-sized moth in the family Noctuidae, a family commonly referred to as owlet moths. Its common name comes from its preferred host plants and distinctive crawling behavior. Cruciferous vegetables, such as cabbage, bok choy, and broccoli, are its main host plant; hence, the reference to cabbage in its common name. The larva is called a looper because it arches its back into a loop when it crawls.
The African armyworm, also called okalombo, kommandowurm, or nutgrass armyworm, is a species of moth of the family Noctuidae. The larvae often exhibit marching behavior when traveling to feeding sites, leading to the common name "armyworm". The caterpillars exhibit density-dependent polyphenism where larvae raised in isolation are green, while those raised in groups are black. These phases are termed solitaria and gregaria, respectively. Gregaria caterpillars are considered very deleterious pests, capable of destroying entire crops in a matter of weeks. The larvae feed on all types of grasses, early stages of cereal crops, sugarcane, and occasionally on coconut. The solitaria caterpillars are less active and undergo much slower development. The species is commonly found in Africa, but can also be seen in Yemen, some Pacific islands, and parts of Australia. African armyworm outbreaks tend to be devastating for farmland and pasture in these areas, with the highest-density outbreaks occurring during the rainy season after periods of prolonged drought. During the long dry seasons ("off-season"), the population densities are very low and no outbreaks are seen.
The diamondback moth, sometimes called the cabbage moth, is a moth species of the family Plutellidae and genus Plutella. The small, grayish-brown moth sometimes has a cream-colored band that forms a diamond along its back. The species may have originated in Europe, South Africa, or the Mediterranean region, but it has now spread worldwide.
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.
Spodoptera litura, otherwise known as the tobacco cutworm or cotton leafworm, is a nocturnal moth in the family Noctuidae. S. litura is a serious polyphagous pest in Asia, Oceania, and the Indian subcontinent that was first described by Johan Christian Fabricius in 1775. Its common names reference two of the most frequent host plants of the moth. In total, 87 species of host plants that are infested by S. litura are of economic importance. The species parasitize the plants through the larvae vigorous eating patterns, oftentimes leaving the leaves completely destroyed. The moth's effects are quite disastrous, destroying economically important agricultural crops and decreasing yield in some plants completely. Their potential impact on the many different cultivated crops, and subsequently the local agricultural economy, has led to serious efforts to control the pests.
Agrotis ipsilon, the dark sword-grass, ipsilon dart, black cutworm, greasy cutworm or floodplain cutworm, is a small noctuid moth found worldwide. The moth gets its scientific name from black markings on its forewings shaped like the letter "Y" or the Greek letter upsilon. The larvae are known as "cutworms" because they cut plants and other crops. The larvae are serious agricultural pests and feed on nearly all varieties of vegetables and many important grains.
Mythimna unipuncta, the true armyworm moth, white-speck moth, common armyworm, or rice armyworm, is a species of moth in the family Noctuidae. The species was first described by Adrian Hardy Haworth in 1809. Mythimna unipuncta occurs in most of North America south of the Arctic, as well as parts of South America, Europe, Africa, and Asia. Although thought to be Neotropical in origin, it has been introduced elsewhere, and is often regarded as an agricultural pest. They are known as armyworms because the caterpillars move in lines as a massive group, like an army, from field to field, damaging crops.
Peridroma saucia, the pearly underwing or variegated cutworm, is a moth of the family Noctuidae. The species was first described by Jacob Hübner in 1808. It is found in North and South America, Europe, Asia and Africa. The variegated cutworm feeds on many plants, especially common fruits and vegetables. The moth undergoes two to four generations per year. The development of the moth slows in colder temperatures, indicative of its migratory nature. All stages of the life cycle have a developmental threshold for temperature. The moth is known to migrate to the northern regions during warmer months, returning to the southern regions when the climate becomes colder.
Helicoverpa punctigera, the native budworm, Australian bollworm or Chloridea marmada, is a species of moth in the family Noctuidae. This species is native to Australia. H. punctigera are capable of long-distance migration from their inland Australian habitat towards coastal regions and are an occasional migrant to New Zealand.
Utetheisa ornatrix, also called the ornate bella moth, ornate moth, bella moth or rattlebox moth, is a moth of the subfamily Arctiinae. It is aposematically colored ranging from pink, red, orange and yellow to white coloration with black markings arranged in varying patterns on its wings. It has a wingspan of 33–46 mm. Moths reside in temperate midwestern and eastern North America as well as throughout Mexico and other parts of Central America. Unlike most moths, the bella moth is diurnal. Formerly, the bella moth or beautiful utetheisa of temperate eastern North America was separated as Utetheisa bella. Now it is united with the bella moth in Utetheisa ornatrix.
The fall armyworm is a species in the order Lepidoptera and one of the species of the fall armyworm moths distinguished by their larval life stage. The term "armyworm" can refer to several species, often describing the large-scale invasive behavior of the species' larval stage. It is regarded as a pest and can damage and destroy a wide variety of crops, which causes large economic damage. Its scientific name derives from frugiperda, which is Latin for lost fruit, named because of the species' ability to destroy crops. Because of its propensity for destruction, the fall armyworm's habits and possibilities for crop protection have been studied in depth. It is also a notable case for studying sympatric speciation, as it appears to be diverging into two species currently. Another remarkable trait of the larva is that they consistently practice cannibalism, despite its fitness costs.
Chloridea virescens, commonly known as the tobacco budworm, is a moth of the family Noctuidae found throughout the eastern and southwestern United States along with parts of Central America and South America.
Spodoptera eridania is a moth that is known to be a pest. They are one of the most important defoliators in the tropical and subtropical regions of the western hemisphere that feed heavily on plants while they are young, often resulting in skeleton leaves on their food plants. They are also heavy feeders on tomato in Florida. There is a lot of development in producing pesticides against the S. eridania, specifically a neem-based pesticide that can result in smaller and prolonged development. The wingspan is 33–38 mm. Adults are on wing year-round. The larvae feed on various weeds but prefer Amaranthus species and Phytolacca americana.
Helicoverpa assulta, the oriental tobacco budworm, is a moth of the family Noctuidae. H. assulta adults are migratory and are found all over the Old World Tropics including Asia, Africa, and Australia.
The South American potato tuber moth, Andean potato tuber moth or tomato stemborer is a moth of the family Gelechiidae. It is native to South America, but has become a pest worldwide. Records include North America, Australia and New Zealand.
Cadra figulilella, the raisin moth, is a moth of the family Pyralidae. The raisin moth is known most commonly as a pest that feeds on dried fruits, such as the raisin and date. It covers a range that includes much of the world, primarily situating itself in areas of California, Florida, the Eastern Mediterranean region, and some parts of Africa, Australia, and South America. The moth prefers to live in a hot, arid climate with little moisture and plentiful harvest for its larvae to feed on. Study of this species is important due to the vast amount of economic damage it causes yearly and worldwide to agriculture crops.
Ostrinia furnacalis is a species of moth in the family Crambidae, the grass moths. It was described by Achille Guenée in 1854 and is known by the common name Asian corn borer since this species is found in Asia and feeds mainly on corn crop. The moth is found from China to Australia, including in Java, Sulawesi, the Philippines, Borneo, New Guinea, the Solomon Islands, and Micronesia. The Asian corn borer is part of the species complex, Ostrinia, in which members are difficult to distinguish based on appearance. Other Ostrinia such as O. orientalis, O. scapulalis, O. zealis, and O. zaguliaevi can occur with O. furnacalis, and the taxa can be hard to tell apart.
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