Geographic Range
The horned fungus beetle, also known as the forked fungus beetle, can be found in
the northeastern part of United States and eastern part of Canada.
Habitat
These beetles live in dying and dead tree trunks found in forest habitats.
- Habitat Regions
- terrestrial
- Terrestrial Biomes
- forest
Physical Description
The color of horned fungus beetles ranges from black to a dark brown. There is a distinct
sexual dimorphism. While both males and females have antennae, males have two horn-shaped
antennae that extend forward on the head and one forked horn on the middle of the
head. Females have tubercles on the heads and a heavy plate on the back at the abdominal
tip. Adults are about 8 to 12 millimeters long and have wings. They have front wings
that are hardened and hind wings that are membranous.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes shaped differently
Development
There are three stages in the development of
Bolitotherus cornutus
. First, the eggs are deposited in or on fungi. Next, larvae develop feeding on fungal
tissues. About three months later larvae pupate, emerging as adults in late summer
or in early spring after hibernating throughout the winter.
- Development - Life Cycle
- metamorphosis
Reproduction
During courtship a male climbs on the back of a female, twitches its body, and then
it strokes the female’s head with its feet. Males with a bigger horn have a competitive
advantage over other males during courtship. Though it appears that the females have
no control over which male becomes interested in them, they do get to decide which
male can transfer a spermatophore. The heavy plates on the female's back will open
to allow the transfer of spermatophore under the voluntary power of the female only.
The male then guards the female for two to five hours after courtship.
- Mating System
- polyandrous
Females copulate aproximately every nine days, and lay at least one egg per insemination.
Female horned fungus beetles are very particular in selecting where they lay their
eggs. The size of the larval host determines the survival of the larvae as well as
the size of the horn in male offspring.
- Key Reproductive Features
- seasonal breeding
- sexual
- fertilization
- oviparous
Lifespan/Longevity
Behavior
A slow-moving organism, the horned fungus beetle stays within a small area. Males
become aggressive towards one another during courtship, while females lack horns and
do not demonstrate any aggressive behavior. If disturbed, the beetle will feign death
and remain motionless as it blends in with the rotting wood around it. Though the
beetle has wings, it flies only in the rare instance of migration to another area
of fungus. The beetle usually stays in the same fungus covered log from hatching til
death.
- Key Behaviors
- nocturnal
- motile
- hibernation
Food Habits
These beetles and the larvae are saprophagous. They eat fungus off of dying or dead trees.
- Primary Diet
- mycophage
- Other Foods
- fungus
Predation
There are few predators of this beetle.
- Anti-predator Adaptations
- cryptic
Conservation Status
Additional Links
Contributors
Sara Diamond (editor), Animal Diversity Web.
Evelyne Orlander (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- metamorphosis
-
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
- polyandrous
-
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- internal fertilization
-
fertilization takes place within the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- hibernation
-
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
- cryptic
-
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
- mycophage
-
an animal that mainly eats fungus
References
Bartalon, J., L. Brown. 1986. Behavioral Correlates of Male Morphology in a Horned Beetle. American Naturalist , Vol. 127, No. 4.: 565-570.
Conner, J. July, 1988. Field Measurements of Natural and Sexual Selection in the Fungus Beetle, *Bolitotherus cornutus*. Evolution , Vol. 42, No. 4: 736-749.
Evans, A., C. Bellamy. 1996. An Inordinate Fondness for Beetles . New York: Henry Holt and Company.
Kickx, J. 2003. "White Spongy Trunk Rot" (On-line). Accessed October 6, 2001 at http://www.pfc.forestry.ca/diseases/CTD/Group/Heart/heart3_e.html .
Lundrigan, T. 1997. "Movement Rates as an Indicator of Dispersal Potential in the Forked Fungus Beetle, *Bolitotherus cornutus*" (On-line). Accessed October 3, 2001 at http://ace.acadiau.ca/science/biol/honours/biofeedback97/Lundrigan.html .
Milne, L., M. Milne. 1980. The Audubon Society Field Guide to North American Insect and Spiders . New York: University of New Hampshire.
Whitlock, M. May, 1992. Nonequilibrium Population Structure in Forked Fungus Beetles: Extinction, Colonization, and the Genetic Variance Among Populations. American Naturalist , Vol. 139, No. 5: 952-970.