Geographic Range
Altica subplicata
, the willow leaf beetle, is found north of Mexico, across the Nearctic region. It
ranges from the southern most point of Texas to southern Canada from British Columbia
to Quebec. The highest concentration of this species is along the Mississippi River
and the Great Lakes, extending west to the Rocky Mountains.
Habitat
Altica subplicata
thrives in sand dune habitats along the Great Lakes and on sand bars in rivers. The
density of beetle populations decreases significantly with increasing distance from
shore on the Great Lakes, and beetles are not found on plants further than 16 meters
from the shore. Willow leaf beetles are more abundant on young dunes than intermediate
or old dunes.
- Habitat Regions
- temperate
- terrestrial
- Terrestrial Biomes
- desert or dune
- Other Habitat Features
- riparian
Physical Description
Altica subplicata
has an oblong, oval body shape. The body is a dark metallic blue color, sometimes
with deep violet reflections. Antennae and legs are the same color as the body. Larvae
of
A. subplicata
are deeply pigmented. Females of this species tend to be larger than males. The elytra
are low and weakly developed. The frontal tubercles are flat, and very finely alataceous
and well defined posteriorly by post ocular sulci. It has a well defined coronal suture
between the eyes, though the eyes are not prominent. The inner pair of setae are distinctly
shorter than others. Willow leaf beetles have a quadrate pronotum with a deep transverse
groove throughout.
A. subplicata
is distinguished from other low costate species as having a dull elytron surface
with a deeper microsculpture.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- poisonous
- Sexual Dimorphism
- female larger
Development
Eggs of
A. subplicata
are laid in the spring. Larvae hatch after about 7 days, and go through 3 larval
instars, during which the larval instars feed. After about 16 days, the larvae move
underground and form pupal cells using mucus secreted by maxillary glands. Larvae
use moist sand as a pupation site. The pupal period lasts 1 week or more depending
on weather conditions. The adults emerge and feed through the rest of the summer.
During the first cold nights of autumn, adults leave the host plant and overwinter
in leaf litter, under stones, logs, and bark. Adults emerge in the spring, find mates,
and then oviposit on host leaves. In total, one generation takes about 34 days to
complete, with the resulting adults living for an extended period of time after emergence.
- Development - Life Cycle
- metamorphosis
- diapause
Reproduction
Adults become sexually mature during winter. After overwintering, the willow leaf
beetles appear on plants in early spring. The preoviposition period lasts 1 to 2 weeks,
starting on the first day that the beetles appear on plants. Adults are very active
during this period, flying around host plants looking for mates. To mate, the male
mounts on the back of the female. Multiple matings are very common.
- Mating System
- polygynandrous (promiscuous)
Adults of
Altica subplicata
emerge from diapause in the spring and enter a prereproductive period of just over
1 week. They then start mating and ovipositing. Females deposit eggs horizontally
in small clusters on the undersurface of young leaves of host plants, along the leaf
veins. Up to 100 eggs can be found in an egg mass and a female can lay more than 400
eggs in a lifetime. The male to female ratio in an egg mass is 1:1. In the southern
part of the United States,
A. subplicata
has 2 or more generations each summer. In northern states and Canada,
A. subplicata
has only one generation during the year.
- Key Reproductive Features
- semelparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- oviparous
There is no parental involvement in development other than provisioning of eggs.
- Parental Investment
-
pre-hatching/birth
-
provisioning
- female
-
provisioning
Lifespan/Longevity
A typical generation from egg to adult takes about 34 days. Adults live for an extended
time after emergence. The final generation of adults enters diapause through the winter
and starts mating and egg-laying again in the spring.
Behavior
Larvae of
Altica subplicata
aggregate in large groups on willow tree hosts to feed, but regularly move from one
plant to another. Adults also aggregate on hosts. They tend to aggregate more frequently
on host plants that occur in high humidity habitats and have taller stems. On dune
habitats in the Great Lakes, they concentrate on the youngest dunes near the shore,
and avoid host plants on older, heavily vegetated dunes. It has been shown in other
willow-feeding
Chrysomelinae
that phenolic glycoside composition can have a major effect on host choice, and this
is likely the case with this species also. Both males and females can fly, though
they do not fly long distances as they keep close to shore. Adults become more active
and airborne when looking for mates.
A. subplicata
is most active during the day.
- Key Behaviors
- arboreal
- flies
- diurnal
- motile
- hibernation
- colonial
Home Range
Adult beetles confine movements almost entirely to local areas of host plants. In
the Great Lakes region these are coastal dunes, where
A. subplicata
stays almost exclusively on the youngest dunes.
Communication and Perception
Altica subplicata
is generally known to find and accept host plants based on phenolic glycoside content.
Many similar species also sequester compounds that are used as defense. This is well
documented in some
Chrysomelinae
, and it is suspected that
A. subplicata
sequesters defense compounds as well. Willow leaf beetles communicate with other
beetles through touch, during mating and aggregation, and can detect each other visually.
They can also sense their environment visually, with smells and chemicals, and through
touch.
- Other Communication Modes
- pheromones
- scent marks
- vibrations
- Perception Channels
- visual
- tactile
- vibrations
- chemical
Food Habits
Altica subplicata
is a specialist herbivore on willows. Along rivers over much of the range, this beetle
feeds primarily on
Salix interior
, the sandbar willow, but it will also feed on
Salix amygdaloides
. On the shores of the Great Lakes it feeds on
Salix cordata
, the sand dune willow. Young larvae eat only on the underside of the leaves, while
later instars and adults eat the entire leaf, leaving only the veins. Larvae are far
more likely to feed on young leaves with a high density of trichomes. Adults will
feed on older leaves, but are also more likely to eat younger leaves.
- Plant Foods
- leaves
Predation
Carabid beetles of the genus
Lebia
are known to prey on
Altica
larvae, and are likely a predator of
A. subplicata
. It is possible that
A. subplicata
sequesters phenolic glycosides and uses these as defense, as is known for some willow-feeding
Chrysomelinae
. The bright, metallic blue coloration (likely aposematic) and aggregation behavior
also suggest this could be true. The aggregation behavior itself also functions as
a defensive mechanism, allowing both the larvae and the adults to appear larger and
more intimidating.
- Anti-predator Adaptations
- aposematic
Ecosystem Roles
Bach (1990) documented that
Altica subplicata
affects plant species composition and potentially succession on sand dunes in the
Great Lakes region. In outbreak years, this species severely defoliates its host plant,
and likely modifies its reproductive capabilities, causing non-host plants to be more
abundant in areas with high beetle density.
A. subplicata
may be a competitor with other willow-feeding beetles, particularly
Disonycha alternata
on
Salix interior
.
Economic Importance for Humans: Positive
There are no known positive effects of Altica subplicata on humans.
Economic Importance for Humans: Negative
There are no known adverse affects of Altica subplicata on humans.
Conservation Status
This species is not a conservation concern, but it is a major herbivore on dunes habitats along the Great Lakes where several other threatened or endangered species occur.
Additional Links
Contributors
Michael Leasia (author), University of Michigan Biological Station, Brian Scholtens (author, editor), University of Michigan Biological Station, Angela Miner (editor), Animal Diversity Web Staff.
- 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.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- desert or dunes
-
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- 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.
- poisonous
-
an animal which has a substance capable of killing, injuring, or impairing other animals through its chemical action (for example, the skin of poison dart frogs).
- 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.
- diapause
-
a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- semelparous
-
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
- 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.
- arboreal
-
Referring to an animal that lives in trees; tree-climbing.
- diurnal
-
- active during the day, 2. lasting for one day.
- 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.
- colonial
-
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- chemical
-
uses smells or other chemicals to communicate
- pheromones
-
chemicals released into air or water that are detected by and responded to by other animals of the same species
- scent marks
-
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- chemical
-
uses smells or other chemicals to communicate
- aposematic
-
having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
References
Bach, C. 1993. Effects of microclimate and plant characteristics on the distribution of a willow flea beetle, Altica subplicata . American Midland Naturalist , 130: 193-208.
Bach, C. 1993. Movement behavior of Altica subplicata ( Coleoptera , Chrysomelidae ) - effects of plant characteristics on patterns of adult movement. Journal of the Kansas Entomological Society , 66: 310-318.
Bach, C. 1993. Movement behavior of Altica subplicata ( Coleoptera , Chrysomelidae ) - larval orientation and movement. Journal of the Kansas Entomological Society , 66: 86-96.
Bach, C., D. Carr. 1990. Aggregation behavior of a willow leaf beetle, Altica subplicata ( Coleoptera , Chrysomelidae ). Great Lakes Entomologist , 23: 65-76.
Bach, C. 1994. Effects of a specialist herbivore ( Altica subplicata ) on Salix cordata and sand dune succession. Ecological Monographs , 64: 423-445.
Bach, C. 1993. Movement behavior of Altica subplicata ( Coleoptera , Chrysomelidae ) - effects of plant characteristics on patterns of adult movement. Journal of the Kansas Entomological Society , 66: 310-318.
Bach, C. 1990. Plant successional stage and insect herbivory: flea beetles on sand-dune willow. Ecology , 71: 598-609.
DeSwarte, D., E. Balsbaugh. 1973. Biologies of Altica subplicata and Disonycha alternata ( Coleoptera : Chrysomelidae ), two flea beetles that feed on sandbar willow. Annals of the Entomological Society of America , 66: 1349-1353.
Gannon, A., C. Bach, G. Walker. 1994. Feeding patterns and attachment ability of Altica subplicata ( Coleoptera , Chrysomelidae ) on sand-dune willow. Great Lakes Entomologist , 27: 87-101.
LeSage, L. 1995. Revision of the costate species of Altica Müller of North America north of Mexico ( Coleoptera , Chrysomelidae ). Canadian Entomologist , 127/3: 295-411.
Milanowski, D., C. Bach. 1994. Between-site variation in suitability of Salix cordata as a host for Altica subplicata ( Coleoptera , Chrysomelidae ). Great Lakes Entomologist , 26: 253-261.
Pettis, G. 2005. "Management of insect pests of crapemyrtle (Lagerstroemia spp) with special reference to the ecology and biology of Altica litigata Fall (Coleoptera: Chrysomelidae)" (On-line pdf). Athenaeum @ UGA. Accessed March 23, 2013 at http://athenaeum.libs.uga.edu/handle/10724/8204 .
Rickelmann, K., C. Bach. 1986. Effects of soil-moisture on the pupation behavior of Altica subplicata ( Coleoptera : Chysomelidae : Cassidinae ). Journal of New York Entomological Society , 94: 98-114.
Rowell-Rahier, M., J. Pasteels. 1986. Economics of chemical defense in Chrysomelinae . Journal of Chemical Ecology , 12: 1189-1203.
Shen, C., C. Bach. 1997. Genetic variation in resistance and tolerance to insect herbivory in Salix cordata . Ecological Entomology , 22: 335-342.
Tahvanainen, J., R. Julkunen-Tiitto, J. Kettunen. 1985. Phenolic glycosides govern the food selection pattern of willow feeding leaf beetles. Oecologia , 67: 52-56.