| Western Tent Caterpillar | |
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| Adult | |
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| Species: | M. californicum
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| Binomial name | |
| Malacosoma californicum Packard, 1864
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Malacosoma californicum, the western tent caterpillar, is a moth of the family Lasiocampidae. It is a tent caterpillar.The Western Tent Caterpillar is found in southern Canada, western United States, and parts of northern Mexico.[1]. There are currently six recognized subspecies of M. californicum. Western tent caterpillars are gregarious and live in silken tents during most of their larval stage.[2].
Western tent caterpillars are univoltine, going through a single generation per year[3]. Adults emerge in the late summer to copulate and lay eggs.Adult moths will preferentially lay their eggs on the sunny side of their host trees[4] [5]. Eggs will lay in diapause over the winter and hatch the following spring. Population outbreaks of western tent caterpillar occur in cycles every 6-11 years.[5]. Severe outbreaks can cause defoliation of host trees however, most trees will grow their leaves back quickly [3] [5].
Description
editThe mature Western Tent caterpillar pre-pupae is 4-5 centimeters long. The caterpillars are black, grey, or white with an orange stripe running longitudinally across the body. There are blue-white lines on each segment with dispersed setae extruding from the body. Pupae are 2-2.5 centimeters and reddish-brown to black in colour. Pupae spin a white silken cocoon, powdered in white and yellow. Adults have wingspan between 3.5-5 centimeters. Moths are brown, yellow, tan or grey, with two lighter or darker lines crossing the body [1].
Biology
editWestern tent caterpillars are generalist feeders. However, preference is heavily dependent on their geographical location. Selection for host plant is heavily dependent on where the female deposits the eggs. The most common host plants that caterpilllars feed on are stonefruit trees.[6].
Thermoregulation
editWestern tent caterpillars are ectothermic, therefore they do not produce their own body heat and are heavily influenced by environmental temperatures. Larvae are thought to thermoregulate by basking in the sun and staying in close groups to elevate body temperature[7].
Behaviour
editEarly instar caterpillars are gregarious and remain as a family in silken tents. Aggregations of caterpillars are to discourage predation, increase temperature, and forage for food. During late instars caterpillars get larger and require more food resulting in a solitary behaviour. Caterpillars feed independently, and do not use tents for shelter[8].
reproduction
editMoths will mate in mid-summer. Male-male competition will ensue for females. Females are polyandrous and lay a clutch of eggs sired by multiple males [9]. Eggs are laid as a single band on a branch that is covered by late A single egg band can contain hundreds of eggs. can be sired from multiple males[2]. Females are poly
Nucleopolyhedrovirus
editThe western tent caterpillars are affected by many different parasites. The most prominent parasite affecting larvae is the nuclear polyhedrosis virus(NPV). The body of larvae that die from NPV become thin and liquidy[10]. Increased temperatures has shown to increase the prevalence of NPV [7]. NPV can be transferred from parent to offspring or from individuals that come into contact. Additionally, caterpillars can contract NPV by coming in contact with silk strands from the same species[2]. NPV infections does not always kill the caterpillar and survival is much more likely in late instar caterpillar. NPV infected caterpillars do have reduced fecundity.
Outbreaks
editOutbreaks are caused when population sizes of larvae reach their highest levels. Outbreaks of western tent caterpillar can cause large scale defoliation of trees. The caterpillars are considered by many to be a problem when they reach outbreak population sizes. However, outbreaks of larvae are considered to be more of a nuisance than a problem and does not negatively affect forest health because trees are able to regrow leaves quickly[5]. Human suppresion of western tent caterpillars is most successful when intervening before high population numbers are reached[11]. The exact cause of population outbreaks is not truly understood but,combination of many factors are believed to play a role in population fluctuations such as weather, predators, and virus. However, NPV is believed to play the largest role in the boom-and-bust of population outbreak cycles. Outbreaks of NPV Epizootic disease play significant roles in controlling population sizes of western tent caterpillars As populations of western tent caterpillar increase the prevalence of the disease increases and causes the subsequent crash of a population[10].
Phenological synchrony and climate change
editWestern tent caterpillars have strong ecological interactions with their host plants. The time of caterpillar egg-hatch is closely timed with host plant bud-burst to ensure that early instar larvae are able to feed on leaves. Due to effects of climate change it is predicted that in coming years there will be a phenological asynchrony between host tree and the western tent caterpillar, advancing larval emergence. This doesn't appear to have significant effects on caterpillar larvae fitness because larvae are resistant to starvation[12].
References
edit- ^ a b Ciesla, William; Ragenovich,Iral (May 2008). "Western Tent Caterpillar". Forest Insect & Disease Leaflet. 119: 1–8.
- ^ a b c Franklin, Michelle; Myers, Judith; Cory, Jenny (2014). "Genetic Similarity of Island Populations of Tent Caterpillars During Successive Outbreaks". PLOS ONE. 9: 325–330.
{{cite journal}}: Cite has empty unknown parameter:|1=(help) Cite error: The named reference "Franklin" was defined multiple times with different content (see the help page). - ^ a b Mitchell, Russel (1990). "Seasonal History of the Western Tent Caterpillar (Lepidoptera: Lasiocampidae) on Bitterbrush and Currant in Central Oregon". Journal of Economic Entomology. 83: 1492–1494.
- ^ Moore, Lynn; Myers, Judith; Eng, Rex (1988). "Western Tent Caterpillars Prefer the Sunny Side of the Tree, but Why?". Oikos. 51: 321–326.
- ^ a b c d Myers, Judith (2000). "Population fluctuations of western tent caterpillars in southwestern British Columbia". Population Ecology. 42: 231–241.
{{cite journal}}: Cite has empty unknown parameter:|1=(help) - ^ Barnes, Elizabeth; Gosnell, Sarah; Hallagan, Claudia; Otten, Keelia; Slayter, Lainey; Murphy, Shannon (2016). "Performance of Western Tent Caterpillar (Malacosoma Californicum) on two common host plants, including a new host plant record". Journal of the Lepidopterists Society. 70: 277-282.
- ^ a b Frid, Leonardo; Myers, Judith (2002). "Thermal ecology of western tent caterpilalrs Malacosoma californicum pluviale and infection by nucleopolyhedrovirus". Ecological Entomology. 27: 665–673.
- ^ Safraz, Rana; Cory, Jenny; Myers, Judith (2013). "Life-history consequences and disease resistance of western tent caterpillars in response to localised, herbivore-induced changes in alder leaf quality". Ecological Entomology. 38: 61–67.
- ^ Franklin, Michelle; Ritland, Carol; Myers, Judith; Cory, Jenny (2012). "Multiple mating and family structure of the Western tent caterpillar, Malacosoma Californicum pluviale: Impact on disease resistance". PLOS ONE. 7: 1–9.
- ^ a b Cory, Jenny; Myers, Judith (2009). "Within and between population variation in disease resistance in cyclic populations of western tent caterpillars: a test of the disease defence hypothesis". Journal of Animal Ecology. 78: 646–655.
- ^ Thompson, W.A.; Vertinsky, I.B.; Wellington, W.G. (1981). "INTERVENING IN PEST OUTBREAKS: SIMULATION STUDIES WITH THE WESTERN TENT CATERPILLAR". Researches on Population Ecology. 23: 27–38.
- ^ Kharouba, Heather; Vellend, Marc; Sarfraz, Rana; Myers, Judith (2015). "The effects of experimental warming on the timing of a plant-insect herbivore interaction". Journal of Animal Ecology. 84: 785–796.