Pardosa agrestis | |
---|---|
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Chelicerata |
Class: | Arachnida |
Order: | Araneae |
Infraorder: | Araneomorphae |
Family: | Lycosidae |
Genus: | Pardosa |
Species: | P. agrestis |
Binomial name | |
Pardosa agrestis Westring, 1861 | |
Pardosa agrestis is a non-web-building spider in the family Lycosidae, commonly known as wolf spiders.
Pardosa agrestis have brown bodies with longitudinal bands. Females are slightly larger ranging from 6–9 mm, while males range from 4.5 to 7 mm. They are hard to distinguish from their related taxonomic species. P. agrestis is the most abundant spider in central European agricultural habitats, preferring to inhabit open spaces. Its lifespan is around 1–2 years and its diet consists mainly of other arthropods, exhibiting non-sexually cannibalistic behavior at times. It has a long copulation duration that averages around two hours. The two mating seasons are June and August, producing 40-60 spiderlings per cocoon. Pardosa agrestis do not spin webs and are not venomous. They will chase after their pray and deliver bites using their chelicerae. [1]
Pardosa agrestis has a dark brown body with longitudinal bands. It is hard to distinguish from its related species. Pardosa agrestis is characterized by the arrangement of its eyes. Its eight eyes are arranged so that there are four eyes in the front row and two eyes in each back row. There are minimal differences in size between sexes, females being slightly larger. Females range from 6–9 mm, while males range from 4.5 to 7 mm. [2] The average female body size is representative of the abundance of resources in its habitat and also is positively correlated with fecundity. [3]
Pardosa agrestis prefers open habitats, specifically arable crop fields. Since Pardosa agrestis populates crop fields in high densities, it potentially plays a significant role as a control agent against insects and pests. [4]
Because Pardosa agrestis inhabit agricultural areas, they frequently face decimation, subsequently rebuilding and recolonizing. Following decimation or disturbances, spiders of this species will recolonize in non-arable areas surrounding their original habitat. Therefore, the availability and quality of non-arable land around the spiders’ natural habitat plays a major role in the abundance of Pardosa agrestis in an arable field. Its population density is highest in farming fields that are a short distance away from long, wide, and grassy road-side strips. [3]
Certain slow-maturing members of Pardosa agrestis are vulnerable during the winter months as they have not yet developed techniques and structures necessary to survive the winter. Presence of woody areas around the spiders’ main habitats provide shelter to overwintering spiders, increasing the likelihood of surviving through the winter by providing them with refuge and sufficient prey. Woody areas also provide shelter to females carrying egg sacs, resulting in enhanced offspring survival. [3]
Pardosa agrestis is the dominant surface-dwelling spider species in farming grounds in Central Europe and certain areas in North America and Asia. [1]
The diet of Pardosa agrestis consists exclusively of small arthropods such as diptera and aphids. The prey targeted is almost always smaller than the size of the spider itself. Pardosa agrestis is a generalist predator. It is not specific in the way it selects prey among the arthropods it predates. Its choice of prey heavily depends on the prey's size, frequency of collision, and encounter. This holds for small and medium-sized spiders. However, large spiders can also feed on larger hard-bodied insects. In the earliest stages of their lifecycle, the spiderlings will be protected by reproductive females; however, adult males and virgin females consume spiderlings as a part of their diet from time to time. [1]
Females without egg sacs have been observed to capture prey more than the males. This is attributed to their larger average size and the need to supply sufficient energy. However, egg-carrying females have significantly less prey capturing behavior. [4]
Pardosa agrestis regularly faces conditions of insufficient food and starvation. To combat this, it has evolved to be resistant to hunger and will masticate its food to compensate for the lack of prey captured, especially in the winter. It also compensates for its lack of food with its ability to capture multiple prey in one attempt. 40-50% of Pardosa agrestis’ diet is strongly masticated and thus are not readily identifiable. Because they are regularly in a scenario where there is insufficient food, these spiders need to extract as much energy from their food as possible. The spider chews down the hunted prey to a meat ball using their chelicerae, lengthening the digestion process and abstracting as many nutrients as possible. [4]
Pardosa agrestis has a widely distributed copulation duration ranging from a couple of seconds to several hours. For Pardosa agrestis, copulation often lasts more than two hours. Reproduction occurs most intensively during May and July to early August. They have multiple reproductive periods that result in coexisting offspring that have a wide size distribution. A typical female will have 40-60 spiderlings per cocoon and can produce multiple cocoons. [1]
Although Pardosa agrestis copulates for an extended period of time, ten minutes of copulation is sufficient for fertilization in half of the cases. Forty minutes of copulation is needed for near-certain fertilization. Even when the extended copulation period was interrupted at ten minutes, the number and size of offspring, and the time the female took to produce an egg did not change. The egg sacs are visible 2–3 weeks after copulation occurs, regardless of the copulation duration. [5]
The long copulation duration exhibited by Pardosa agrestis is costly for the spider. The spider spends a considerable amount of energy during copulation, misses opportunities to mate with others, and foregoes foraging resources. Long copulation in Pardosa agrestis occurs without hiding in a safe area, thus increasing the spider's vulnerability to predation. Aside from this, long copulation increases the probability of parasite infections. The exact reasoning for long copulation in Pardosa agrestis is unknown. However, it is hypothesized that long copulation could serve a role in overpowering other males’ sperm by releasing sperm for an extended period of time. Another hypothesis is that long copulation prevents other males from copulating with the female immediately after fertilization. [5]
The lifespan of Pardosa agrestis is around one year in Western and Central Europe but was recorded to go up to two years in more Northern regions. The life cycle can be divided into four stages: spiderlings (instar that leaves the cocoon), juveniles (in between spiderling and subadult), subadults (instar pre-adult stage), and adults. The population dynamics and numbers among these stages vary throughout the span of a year. [6]
After winter, the population of juveniles increases significantly, along with a minor increase in subadult population. The population of subadults reaches its highest number in April. Adult females and males start appearing more in late April and peak in June, which is the first mating season for Pardosa agrestis. In late July, subadults peak again, leading to a peak of adults in August, explaining the second mating season. As a result, the number of spiderlings peak once again in September, and subadults peak in late Autumn. These population dynamics suggest a bimodal life pattern for Pardosa agrestis. [6]
Some of the spiderlings born early in the summer will not mature until next spring (overwintering), whereas some will mature and reproduce within three months. This results in different cohorts within a population with different paces of life. [7]
Pardosa agrestis engage in intricate display behavior and will have ritualized combative confrontations. Generally, neither of the interacting spiders are harmed, except for the case of cannibalistic behavior. They typically do not engage in territorial behavior and they tend to live in overlapping areas. [1]
Some spiderlings take close to a year to mature and reproduce, whereas others can take around 3 months. This creates two main groups of slow and rapidly developing spiders. Rapidly developing spiders tend to have a shorter life span. Spiders that have a slower development are seen to be less active when put in novel environments. Slow-developing spiders are also less likely to attack and capture a potential prey than rapidly developing individuals. Slowly developing spiders are also slower at emerging from safe spaces. Spiders that were rapidly developing are more active, have more hunting motivation and are bolder than those who develop slowly. [7]
An advantage of developing rapidly is avoiding the high mortality rate of overwintering. A slowly developing spider will need to face the high mortality rate of surviving the winter as a non-adult. Another advantage is that rapidly developing spiders tend to have a larger adult size. On the other hand, rapidly developing spiders are disadvantaged because they have lower fecundity and will have less offspring. [7]
Male Pardosa agrestis find females through the use of sexual chemical signals. It was found that certain pesticides found in today's agroecosystems can disturb their methods of chemical communication. Investigating their sexual communication methods, researchers used the glyphosate-based herbicide Roundup and the pyrethroid-based insecticide Nurelle D. They found that the male spiders' ability to find the females was based on following the female's dragline silk cues, not through airborne cues, and that using both of these treatments for 3 hours significantly disturbed the males' abilities to find the female dragline silk cues. [8]
As the Pardosa agrestis inhabit arable fields, they will have to relocate following a disruption of their habitat. Juvenile Pardosa agrestis spiders play the main role in recolonizing following a disruption of their habitat, as they have a greater range of movement when compared to adults, thanks to their ballooning ability. Larger instars and adults can only use cursorial movement, restricting their range. The juveniles will travel to a safe, non-arable area to regroup and recolonize. [3]
Pardosa agrestis exhibits non-sexual cannibalism. This process serves to strengthen the fitness of larger spiders when other nutrients are not in reach, and plays a role in population regulation. The factors that influence the possibility of cannibalistic activity is the size difference between predator and prey, and the hunger level of the predator. In instances where cannibalism occurs, the larger spider is almost always the cannibal. Cannibalism is most likely to occur between spiders in different life stages and sexes. In deciding whether to engage in cannibalistic behavior, handling time is an important determining factor. Handling time takes into account the size difference between the predator and prey, aiming to minimize retaliation risk and profitability of the interaction. Another important factor that contributes to the occurrence of cannibalistic behavior in Pardosa agrestis is encounter frequency. This variable depends on how densely populated an area is and movement behaviors of individual spiders. [1]
Young spiders do not possess the reserves necessary to survive food shortages. Therefore, young spiders are more willing to take risks and engage in cannibalistic activities among each other more frequently. [1]
On the other hand, cannibalism has its costs on the species. The killing of a conspecific spider leads to a reduction of the inclusive fitness of the cannibalistic individual. This behavior also adds to the risk of pathogen or parasite transmission among spiders from the same species. During the act of cannibalism, the spider will have to face a prey that contains similar predatory mechanisms, which increases the chance of retribution. Also, if a hungry spider has limited access to resources, it will be more prone to cannibalize, resulting in it attacking larger prey and increasing its chances of getting injured or killed. [1]
Pardosa agrestis do not weave webs, but instead will chase their prey in order to capture them. [1]
Pardosa agrestis is venomous but will not bite or attack humans unless threatened or has egg sacs around. Its bite might cause an allergic reaction or minor pain. [2]
Wolf spiders are members of the family Lycosidae. They are robust and agile hunters with excellent eyesight. They live mostly in solitude, hunt alone, and do not spin webs. Some are opportunistic hunters, pouncing upon prey as they find it or chasing it over short distances; others wait for passing prey in or near the mouth of a burrow.
The raft spider, scientific name Dolomedes fimbriatus, is a large semi-aquatic spider of the family Pisauridae found throughout north-western and central Europe. It is one of only two species of the genus Dolomedes found in Europe, the other being the slightly larger Dolomedesplantarius which is endangered in the UK.
Misumena vatia is a species of crab spider with a holarctic distribution. In North America, it is called the goldenrod crab spider or flower (crab) spider, as it is commonly found hunting in goldenrod sprays and milkweed plants. They are called crab spiders because of their unique ability to walk sideways as well as forwards and backwards. Both males and females of this species progress through several molts before reaching their adult sizes, though females must molt more to reach their larger size. Females can grow up to 10 mm (0.39 in) while males are quite small, reaching 5 mm (0.20 in) at most. Misumena vatia are usually yellow or white or a pattern of these two colors. They may also present with pale green or pink instead of yellow, again, in a pattern with white. They have the ability to change between these colors based on their surroundings through the molting process. They have a complex visual system, with eight eyes, that they rely on for prey capture and for their color-changing abilities. Sometimes, if Misumena vatia consumes colored prey, the spider itself will take on that color.
Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, both in ancient and in recent times.
Sexual cannibalism is when an animal, usually the female, cannibalizes its mate prior to, during, or after copulation. It is a trait observed in many arachnid orders and several insect orders. Several hypotheses to explain this seemingly paradoxical behavior have been proposed. The adaptive foraging hypothesis, aggressive spillover hypothesis and mistaken identity hypothesis are among the proposed hypotheses to explain how sexual cannibalism evolved. This behavior is believed to have evolved as a manifestation of sexual conflict, occurring when the reproductive interests of males and females differ. In many species that exhibit sexual cannibalism, the female consumes the male upon detection. Females of cannibalistic species are generally hostile and unwilling to mate; thus many males of these species have developed adaptive behaviors to counteract female aggression.
Dolomedes minor is a spider in the family Pisauridae that is endemic to New Zealand, where it is known as the nursery web spider.
Trichonephila plumipes is a species of spider found in Australia, Indonesia and some Pacific Islands, which exhibits extreme sexual dimorphism through its sexual cannibalism behavior. It is sometimes called the tiger spider due to its markings which look similar to a tiger. This species was formerly called Nephila plumipes. As with other spiders from the genus Nephila, these spiders have a distinct golden web.
The six-spotted fishing spider is an arachnid from the nursery web spider family Pisauridae. This species is from the genus Dolomedes, or the fishing spiders. Found in wetland habitats throughout North America, these spiders are usually seen scampering along the surface of ponds and other bodies of water. They are also referred to as dock spiders because they can sometimes be witnessed quickly vanishing through the cracks of boat docks. D. triton gets its scientific name from the Greek mythological god Triton, who is the messenger of the big sea and the son of Poseidon.
Allocosa brasiliensis is a burrowing wolf spider species from southern South America. Long known to science, it remained almost unstudied until its unusual sexual behavior was described in the early 21st century.
→Hogna carolinensis, commonly known as the Carolina wolf spider, is found across North America. It is the largest of the wolf spiders in North America, typically measuring at 18–20 mm for males and 22–35 mm for females.
Pisaurina mira, also known as the American nursery web spiders, is a species of spider in the family Pisauridae. They are often mistaken for wolf spiders (Lycosidae) due to their physical resemblance. P. mira is distinguished by its unique eye arrangement of two rows.
Pardosa amentata, otherwise known as the wolf spider or spotted wolf spider is a species of spider in the genus Pardosa belonging to the family of wolf spiders, Lycosidae. The species has a widespread distribution in central Europe and northwestern Europe and are commonly found on the British Isles. The species hunts its prey on the ground rather than weaving a web.
Anelosimus jabaquara is a species of spider found in subtropical, humid, lowland forests in Brazil. Anelosimus jabaquara was first described by Herbert W. Levi in 1956. These spiders cooperate to spin and repair the colonial web, capture prey, and care for the brood. Colony size is small, and the sex ratio is biased towards females.
Tigrosa helluo is a species of spider belonging to the family Lycosidae, also known as wolf spiders. T. helluo was formerly known as Hogna helluo before differences between dorsal color patterns, habitat preferences, body structures, etc. were discovered. The species is native to the United States, Canada, and Mexico. It can be found across the eastern half of the United States, primarily in the Northeast and New England, and as far west as Nebraska and Kansas. T. helluo can be found in diverse habitats including woods, marshes, fields, and riparian areas. Typically, members of this species prefer to live in wetter areas as opposed to dry environments. Males tend to live for around a year and females will live for close to two years.
Pardosa monticola, or pin-stripe wolf spider, is a species of wolf spider found mainly in Europe. It is found in both dry and humid habitats, and up to an altitude of 2000m.
Agelenopsis pennsylvanica, commonly known as the Pennsylvania funnel-web spider or the Pennsylvania grass spider, is a species of spider in the family Agelenidae. The common name comes from the place that it was described, Pennsylvania, and the funnel shape of its web. Its closest relative is Agelenopsis potteri.
Pardosa milvina, the shore spider, is a species in the wolf spider family. They are mainly found near rivers and in agricultural areas in eastern North America. P. milvina feed on a large variety of small insects and spiders. Ground beetles such as Scarites quadriceps and large wolf spiders such as Tigrosa helluo are predators of P. milvina. P. milvina are smaller spiders with thin, long legs. This species captures prey such as arthropods with their legs and then kills them with their venom. Their predators are larger wolf spiders and beetles. P. milvina are able to detect these predators from chemotactile and vibratory cues. These spiders lose limbs when escaping from predators and they can change their preferred location in order to avoid predators. P. milvina also use chemical cues in order to mate. During their mating ritual, the male raises his legs and shakes his body. Both males and females can use silk, a chemotactile cue, for sexual communication. Additionally, female shore spiders heavily invest in their offspring, keeping them in egg sacs and carrying them for a few weeks after they are born.
Leucauge mariana is a long-jawed orb weaver spider, native to Central America and South America. Its web building and sexual behavior have been studied extensively. Males perform several kinds of courtship behavior to induce females to copulate and to use their sperm.
Schizocosa stridulans is a sibling species of S. ocreata and S. rovneri and is part of the wolf spider family. The name of the genus comes from the epigynum structure being lycosid and having a split T excavation. This spider is well-known for its specific leg ornamentation and courtship rituals and that is how it has been differentiated from its related species. The S. stridulans take systematic steps during its courtship ritual, which involves two independent signals. More specifically, female spiders will leave silk and pheromones to communicate that they are ready to mate.
Pardosa pseudoannulata, a member of a group of species referred to as wolf-spiders, is a non-web-building spider belonging to the family Lycosidae. P. pseudoannulata are wandering spiders that track and ambush prey and display sexual cannibalism. They are commonly encountered in farmlands across China and other East Asian countries. Their venom has properties that helps it function as an effective insecticide, and it is, therefore, a crucial pesticide control agent.