The Spilopyrinae are a small subfamily of the leaf beetles, or Chrysomelidae. They occur in New Guinea, New Caledonia and Chile, they were considered a tribe of the subfamily Eumolpinae. The group was elevated to subfamily rank by C. A. M. Reid in 2000. However, some authors have criticised this placement, preferring to retain them within the Eumolpinae. Allsortsia Reid & Beatson, 2010 Bohumiljania Monrós, 1958 Cheiloxena Baly, 1860 Dorymolpus Elgueta, Daccordi & Zoia, 2014 Hornius Fairmaire, 1885 Macrolema Baly, 1861 Richmondia Jacoby, 1898 Spilopyra Baly, 1860 Stenomela Erichson, 1847 Australian Faunal Directory – Subfamily Spilopyrinae Chapuis, 1874
Biological pest control
Biological control or biocontrol is a method of controlling pests such as insects, mites and plant diseases using other organisms. It relies on predation, herbivory, or other natural mechanisms, but also involves an active human management role, it can be an important component of integrated pest management programs. There are three basic strategies for biological pest control: classical, where a natural enemy of a pest is introduced in the hope of achieving control. Natural enemies of insect pests known as biological control agents, include predators, parasitoids and competitors. Biological control agents of plant diseases are most referred to as antagonists. Biological control agents of weeds include seed predators and plant pathogens. Biological control can have side-effects on biodiversity through attacks on non-target species by any of the same mechanisms when a species is introduced without thorough understanding of the possible consequences; the term "biological control" was first used by Harry Scott Smith at the 1919 meeting of the Pacific Slope Branch of the American Association of Economic Entomologists, in Riverside, California.
It was brought into more widespread use by the entomologist Paul H. DeBach who worked on citrus crop pests throughout his life. However, the practice has been used for centuries; the first report of the use of an insect species to control an insect pest comes from "Nanfang Caomu Zhuang", attributed to Western Jin dynasty botanist Ji Han, in which it is mentioned that "Jiaozhi people sell ants and their nests attached to twigs looking like thin cotton envelopes, the reddish-yellow ant being larger than normal. Without such ants, southern citrus fruits will be insect-damaged"; the ants used are known as huang gan ants. The practice was reported by Ling Biao Lu Yi, in Ji Le Pian by Zhuang Jisu, in the Book of Tree Planting by Yu Zhen Mu, in the book Guangdong Xing Yu, Lingnan by Wu Zhen Fang, in Nanyue Miscellanies by Li Diao Yuan, others. Biological control techniques as we know them today started to emerge in the 1870s. During this decade, in the US, the Missouri State Entomologist C. V. Riley and the Illinois State Entomologist W. LeBaron began within-state redistribution of parasitoids to control crop pests.
The first international shipment of an insect as biological control agent was made by Charles V. Riley in 1873, shipping to France the predatory mites Tyroglyphus phylloxera to help fight the grapevine phylloxera, destroying grapevines in France; the United States Department of Agriculture initiated research in classical biological control following the establishment of the Division of Entomology in 1881, with C. V. Riley as Chief; the first importation of a parasitoidal wasp into the United States was that of the braconid Cotesia glomerata in 1883–1884, imported from Europe to control the invasive cabbage white butterfly, Pieris rapae. In 1888–1889 the vedalia beetle, Rodolia cardinalis, a lady beetle, was introduced from Australia to California to control the cottony cushion scale, Icerya purchasi; this had become a major problem for the newly developed citrus industry in California, but by the end of 1889 the cottony cushion scale population had declined. This great success led to further introductions of beneficial insects into the USA.
In 1905 the USDA initiated its first large-scale biological control program, sending entomologists to Europe and Japan to look for natural enemies of the gypsy moth, Lymantria dispar dispar, brown-tail moth, Euproctis chrysorrhoea, invasive pests of trees and shrubs. As a result, nine parasitoids of gypsy moth, seven of brown-tail moth, two predators of both moths became established in the USA. Although the gypsy moth was not controlled by these natural enemies, the frequency and severity of its outbreaks were reduced and the program was regarded as successful; this program led to the development of many concepts and procedures for the implementation of biological control programs. Prickly pear cacti were introduced into Queensland, Australia as ornamental plants, starting in 1788, they spread to cover over 25 million hectares of Australia by 1920, increasing by 1 million hectares per year. Digging and crushing all proved ineffective. Two control agents were introduced to help control the spread of the plant, the cactus moth Cactoblastis cactorum, the scale insect Dactylopius.
Between 1926 and 1931, tens of millions of cactus moth eggs were distributed around Queensland with great success, by 1932, most areas of prickly pear had been destroyed. The first reported case of a classical biological control attempt in Canada involves the parasitoidal wasp Trichogramma minutum. Individuals were caught in New York State and released in Ontario gardens in 1882 by William Saunders, trained chemist and first Director of the Dominion Experimental Farms, for controlling the invasive currantworm Nematus ribesii. Between 1884 and 1908, the first Dominion Entomologist, James Fletcher, continued introductions of other parasitoids and pathogens for the control of pests in Canada. There are three basic biological pest control strategies: importation and conser
Insect collecting refers to the collection of insects and other arthropods for scientific study or as a hobby. Because most insects are small and the majority cannot be identified without the examination of minute morphological characters, entomologists make and maintain insect collections. Large collections are conserved in natural history museums or universities where they are maintained and studied by specialists. Many college courses require students to form small collections. There are amateur entomologists and collectors who keep collections. Insect collecting has been widespread and was in the Victorian age a popular educational hobby. Insect collecting has left traces in European cultural history and songs; the practice is still widespread in many countries, is common among Japanese youths. Insects are passively caught using funnels, pitfall traps, bottle traps, malaise traps, flight interception traps and other passive types of insect traps, some of which are baited with small bits of sweet foods.
Different designs of ultraviolet light traps such as the Robinson trap are used by entomologists for collecting nocturnal insects during faunistic survey studies. Aspirators or "pooters" suck up insects too delicate to handle with fingers. Several different types of nets are used to collect insects. Aerial insect nets are used to collect flying insects; the bag of a butterfly net is constructed from a lightweight mesh to minimize damage to delicate butterfly wings. A sweep net is used to collect insects from brush, it is similar to a butterfly net, except that the bag is constructed from more rugged material. The sweep net is swept back and forth through vegetation turning the opening from side to side and following a shallow figure eight pattern; the collector walks forward while sweeping, the net is moved through plants and grasses with force. This requires a heavy net fabric such as sailcloth to prevent tearing, although light nets can be used if swept less vigorously. Sweeping continues for some distance and the net is flipped over, with the bag hanging over the rim, trapping the insects until they can be removed with a pooter.
Other types of nets used for collecting insects include beating aquatic nets. Leaf litter sieves are used by coleopterists. Once collected, a killing jar is used to kill required insects before they damage themselves trying to escape. However, killing jars are only used on hard-bodied insects. Soft-bodied insects, such as those in the larval stage, are fixed in a vial containing an ethanol and water solution. Another now historical approach is Caterpillar inflation where the innards were removed and the skin dried; the usual method of display is in a glass-covered box, with the insects mounted on specially made non corrosive insect pins stuck into suitable foam plastic or paper covered cork at the bottom of the box. Common pins are not used. Small insects may be pinned on "minuten" stuck into a block of foam plastic on a standard insect pin. Alternatively they may be glued onto a small piece of card on the pin. There are specific procedures for proper mounting that are used to show off the insects' essential characteristics.
Techniques and equipment may be varied to deal with various requirements. For example, one or both of the wings of a beetle or grasshopper can be pulled open and fanned out to show the wing structure that otherwise would be hidden. At least the date and place of capture should be written or computer printed onto a piece of paper or card transfixed by the pin; this is called a data label. Rare insects, or those from distant parts of the world, may be acquired from dealers or by trading; some noted. Pokémon creator Satoshi Tajiri's childhood hobby of insect collecting is the inspiration behind the popular video game series. Identification key Picture Guide series For college students. Out of date but useful for beginners. Harry Edwin Jaques, 1941 How to know the insects, his Pictured-key nature series Mt. Pleasant, Ia; the author Full text online here Excellent college level guide Hongfu, Zhu, 1949 How to know the immature insects. Pictured key nature series Dubuque, Iowa,W. C. Brown Co. Full text online here Capture methods and techniques Intermediate level Collecting and Preserving Insects and Mites: Tools and Techniques.
Advanced level. How to make an insect collection. Beginner level Curation Of Insect Specimens N P S Beginner level Museum handbook Garthe's Insect Gradebook Butterfly mounting. Coke Smith Insect Collection A. Tereshkin Devices for Ichneumonidae collecting. Advanced Why We Kill Bugs- The Case for Collecting Insects Rationale for insect collecting
One of two types of red paper wasp, Polistes carolina is a species of social wasp in the family Vespidae. They are most found in the eastern US from Texas through Nebraska; the wasp's common name is due to the reddish-brown color of its body. Red paper wasps are known to construct some of the largest nests of any wasp species and prefer to build their nests in protected spaces; the first description of Polistes carolina appears in the first volume of Carl Linnaeus' 12th edition of Systema Naturae published in 1767. In this volume, he referred to the species as Vespa carolina. Ferdinand de Saussure moved it to the genus Polistes in 1855 after Pierre Andre Latreille coined the new genus in 1802. P. Carolina is within the family Vespidae, which includes nearly all of the eusocial wasps and many of the solitary wasps, it is further placed within the subfamily Polistnae, the second-largest of the subfamilies within the Vespidae. The Polistinae contain two main behavioral groups: swarm founding, involving a large numbers of workers and several queens, independent founding, which involve a few workers and foundresses.
P. carolina has been found to be most related to P. metricus. Recent phylogenetic analysis has shown that both P. carolina and P. metricus share a common ancestor with P. aurifer and P. fuscatus. Typical red paper wasps are about 25–32 mm long with black wings of lengths ranging from 15–25 mm. Brown stripes are present on the abdomen. P. carolina is confused with P. perplexus due to its strikingly similar reddish-brown coloring. These two species are the only ones of red wasps in the eastern United States. One distinguishing feature between these two is the greater presence of black markings on the thorax of P. perplexus. Both sexes of the two species can be differentiated by the coarser transverse ridging of the propodeum of P. perplexus when compared with P. carolina. Additionally, female P. carolina specimens have bare malar spaces. Females of Polistes carolina are completely ferruginous with the possibility of black markings forming spots around their eyes, lines on the dorsal surface of the scape, narrow lateral stripes on their scuta, or an incomplete median stripe on their propodea.
Bands on sternum 2 or terga 3 and 4 can be present. Additional restricted yellow markings can be observed on mandibles, inner orbits, terga 1, the outer surfaces of the tibiae, tarsi. Females have more triangular faces with shorter antennae. Males have more developed black or brown markings such as spots on the midfemur and sterna. Yellow markings vary, but have been reported on the face and sterna 1 through 4. Additionally, males have more squarish faces with longer hooked antenna. Like most paper wasps, P. carolina constructs nests by chewing plant and wood fibers with saliva to create a paper-like material. When dried, their nests form an upside-down umbrella or dome shape with exposed honeycomb-like cells, opening at the bottom. P. carolina prefers to nest in protected spaces, such as occurring locations in vegetation or the cavities of trees. They frequently nest in man-made structures, such as the underside of bridges, chimneys and wooden boxes; these nests are some of the largest of any wasp species and contain around 3,000 to 5,000 members.
P. carolina is most found in the eastern United States from Nebraska to Texas and along the Atlantic coast from New York to Florida. It has been recorded as an adventitious species in Ontario and was introduced to Bermuda, it prefers to nest in protected areas such as hollow trees and is observed in woodlands. However, given the opportunity, it will construct nests near humans, such as the undersides of roofs; the Polistes colony cycle involves four separate phases which overlap: the founding phase, the worker phase, the reproductive phase, the intermediate phase. The founding phase begins in the spring and involves young reproductive females building new nests, either alone or in conjunction with other foundresses. In field studies, P. carolina was observed to have a range of one to eight foundresses in surviving colonies. During the founding period, many foundresses move between nests, sometimes settling at another nest and sometimes returning to their own nest. In this way, the foundress continues to reassess her reproductive options.
During these visits, foundresses were observed to lay eggs in other nests. While most nests are initiated by one foundress, they are joined by full sisters which become subordinates during this period. During the worker phase in many Polistes species, adult workers and early males are enclosed. P. carolina, lacks early males during this time and instead only produces worker females. As workers emerge, they begin to assume colony tasks, such as nest maintenance and larval care; the reproductive phase lasts from the emergence of the first reproductives until the colony begins to decline and new reproductives disperse to form their own nests. During this time, each foundress mates with a different male and lays her eggs, with the dominant foundress laying the majority of the eggs; the time between colony decline and the founding of new colonies, the initial colony begins to disperse as new reproductives search for locations to initiate their own nests. The foundresses of the colony disappear during this time, as males accumulate in the nest.
Foundress associations in Polistes species establish clear dominant and subordinate relationships in which the dominant
Oxfordshire is a county in South East England. The ceremonial county borders Warwickshire to the north-west, Northamptonshire to the north-east, Buckinghamshire to the east, Berkshire to the south, Wiltshire to the south-west and Gloucestershire to the west; the county has major education and tourist industries and is noted for the concentration of performance motorsport companies and facilities. Oxford University Press is the largest firm among a concentration of publishing firms; as well as the city of Oxford, other centres of population are Banbury, Bicester and Chipping Norton to the north of Oxford. The areas south of the Thames, the Vale of White Horse and parts of South Oxfordshire, are in the historic county of Berkshire, as is the highest point, the 261 metres White Horse Hill. Oxfordshire's county flower is the snake's-head fritillary. Oxfordshire was recorded as a county in the early years of the 10th century and lies between the River Thames to the south, the Cotswolds to the west, the Chilterns to the east and the Midlands to the north, with spurs running south to Henley-on-Thames and north to Banbury.
Although it had some significance as an area of valuable agricultural land in the centre of the country, it was ignored by the Romans, did not grow in importance until the formation of a settlement at Oxford in the 8th century. Alfred the Great was born across the Thames in Vale of White Horse; the University of Oxford was founded in 1096, though its collegiate structure did not develop until on. The university in the county town of Oxford grew in importance during the Middle Ages and early modern period; the area was part of the Cotswolds wool trade from the 13th century, generating much wealth in the western portions of the county in the Oxfordshire Cotswolds. Morris Motors was founded in Oxford in 1912, bringing heavy industry to an otherwise agricultural county; the importance of agriculture as an employer has declined in the 20th century though. Nonetheless, Oxfordshire remains a agricultural county by land use, with a lower population than neighbouring Berkshire and Buckinghamshire, which are both smaller.
Throughout most of its history the county was divided into fourteen hundreds, namely Bampton, Binfield, Bullingdon, Dorchester, Langtree, Pyrton, Ploughley and Wootton. The Oxfordshire and Buckinghamshire Light Infantry, the main army unit in the area, was based at Cowley Barracks on Bullingdon Green, Cowley; the Vale of White Horse district and parts of the South Oxfordshire administrative district south of the River Thames were part of Berkshire, but in 1974 Abingdon, Faringdon and Wantage were added to the administrative county of Oxfordshire under the Local Government Act 1972. Conversely, the Caversham area of Reading, now administratively in Berkshire, was part of Oxfordshire as was the parish of Stokenchurch, now administratively in Buckinghamshire. Oxfordshire includes parts of three Areas of Outstanding Natural Beauty. In the north-west lie the Cotswolds, to the south and south-east are the open chalk hills of the North Wessex Downs and wooded hills of the Chilterns; the north of the county contains the ironstone of the Cherwell uplands.
Long-distance walks within the county include the Ridgeway National Trail, Macmillan Way, Oxfordshire Way and the D’Arcy Dalton Way. Northernmost point: 52°10′6.58″N 1°19′54.92″W, near Claydon Hay Farm, Claydon Southernmost point: 51°27′34.74″N 0°56′48.3″W, near Thames and Kennet Marina, Playhatch Westernmost point: 51°46′59.73″N 1°43′9.68″W, near Downs Farm, Westwell Easternmost point: 51°30′14.22″N 0°52′13.99″W, River Thames, near Lower Shiplake The central part of Oxfordshire contains the River Thames with its flat floodplains. The Thames Path National Trail parallels the river as it crosses Oxfordshire, continuing towards London. There are many smaller rivers that feed into the Thames such as the Thame, Windrush and Cherwell; some of these rivers have trails running along their valleys. The Oxford Canal follows the Cherwell from Banbury to Kidlington. Oxfordshire contains a green belt area that envelops the city of Oxford, extends for some miles to afford a protection to surrounding towns and villages from inappropriate development and urban growth.
Its border in the east extends to the Buckinghamshire county boundary, while part of its southern border is shared with the North Wessex Downs AONB. It was first drawn up in the 1950s, all the county's districts contain some portion of the belt; this is a chart of trend of regional gross value added of Oxfordshire at current basic prices published by the Office for National Statistics with figures in millions of British pounds sterling. The Oxfordshire County Council, since 2013 under no overall control, is responsible for the most strategic local government functions, including schools, county roads, social services; the county is divided into five local government districts: Oxford, Vale of White Horse, West Oxfordshire and South Oxfordshire, which deal with such matters as town and country planning, waste collection, housing. In the 2016 European Union referendum, Oxfordshire was the only English cou
Pierre André Latreille
Pierre André Latreille was a French zoologist, specialising in arthropods. Having trained as a Roman Catholic priest before the French Revolution, Latreille was imprisoned, only regained his freedom after recognising a rare beetle species he found in the prison, Necrobia ruficollis, he published his first important work in 1796, was employed by the Muséum National d'Histoire Naturelle. His foresighted work on arthropod systematics and taxonomy gained him respect and accolades, including being asked to write the volume on arthropods for George Cuvier's monumental work, Le Règne Animal, the only part not by Cuvier himself. Latreille was considered the foremost entomologist of his time, was described by one of his pupils as "the prince of entomologists". Pierre André Latreille was born on 29 November 1762 in the town of Brive in the province of Limousin, as the illegitimate child of Jean Joseph Sahuguet d'Amarzit, général baron d'Espagnac, who never recognzed him, an unknown mother, who abandoned him at birth.
Latreille orphaned from his earliest age, but had influential protectors – first a physician a merchant from Brive, a baron and his family, who brought him to Paris in 1778. He studied in Brive and in Paris at the Collège du Cardinal-Lemoine attached to the University of Paris to become a priest, he entered the Grand Séminaire of Limoges in 1780, left as a deacon in 1786. Despite being qualified to preach, Latreille wrote that he had never carried out his functions as a minister, although for a few years he signed the letters he wrote "l'Abbé Latreille" or "Latreille, Prêtre". During his studies, Latreille had taken on an interest in natural history, visiting the Jardin du Roi planted by Georges-Louis Leclerc, Comte de Buffon, catching insects around Paris, he received lessons on botany from René Just Haüy, which brought him in contact with Jean-Baptiste Lamarck. After the fall of the Ancien Régime and the start of the French Revolution, the Civil Constitution of the Clergy was declared in 1790, which required priests to swear an oath of allegiance to the state.
Latreille was therefore imprisoned in November 1793 under threat of execution. When the prison's doctor inspected the prisoners, he was surprised to find Latreille scrutinising a beetle on the dungeon floor; when Latreille explained that it was a rare insect, the physician was impressed, sent the insect to a 15-year-old local naturalist, Jean Baptiste Bory de Saint-Vincent. Bory de St.-Vincent knew Latreille's work, managed to obtain the release of Latreille and one of his cell-mates. All the other inmates were dead within one month; the beetle had been described by Johan Christian Fabricius in 1775, but recognising it had saved Latreille's life. Thereafter, Latreille lived as a teacher and corresponded with various entomologists, including Fabricius. In 1796, with Fabricius' encouragement, Latreille published his Précis des caractères génériques des insectes at his own expense, he was placed under house arrest in 1797, his books were confiscated, but the influence of Georges Cuvier, Bernard Germain de Lacépède and Jean-Baptiste Lamarck succeeded in freeing Latreille.
In 1798, Latreille was appointed to the museum, where he worked alongside Lamarck, curating the arthropod collections, published a number of zoological works. Following the death of Guillaume-Antoine Olivier in 1814, Latreille succeeded him as titular member of the Académie des sciences de l'Institut de France. In the following few years, Latreille was productive, producing important papers for the Mémoires du Muséum, all of the volume on arthropods for George Cuvier's Le Règne Animal, hundreds of entries in the Nouveau Dictionnaire d'Histoire Naturelle on entomological subjects; as Lamarck became blind, Latreille took on an increasing proportion of his teaching and research work. In 1821, Latreille was made a knight of the Légion d'honneur. In 1829 he succeeded Lamarck as professor of entomology. From 1824, Latreille's health deteriorated, he handed his lectures over to Jean Victoire Audouin and took on several assistants for his research work, including Amédée Louis Michel Lepeletier, Jean Guillaume Audinet-Serville and Félix Édouard Guérin-Méneville.
He was instrumental in the founding of the Société entomologique de France, served as its honorary president. Latreille's wife died in May of that year, he resigned his position at the museum on 10 April 1832, in order to move to the country and thereby avoid the cholera epidemic. He returned to Paris in November, died of bladder disease on 6 February 1833, he was survived by a niece whom he had adopted. The Société entomologique raised the money to pay for a monument to Latreille; this was erected over Latreille's grave at Père Lachaise Cemetery, comprised a 9-foot obelisk with various inscriptions, including one to the beetle which had saved Latreille's life: "Necrobia ruficollis Latreillii salvator". As testimony to the high esteem in which Latreille was held, many books were dedicated to him, up to 163 species were named in his honour between 1798 and 1850. Taxa commemorating Latreille include: Lumbrineris latreilli Audouin & H. Milne-Edwards, 183
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results