Alydus eurinus

Geographic Range

Members of Alydus eurinus are broad-headed bugs (the common name for the entire family) native to North America. They have been found in 43 of the 50 states in the United States. These bugs are found across the entire continental United States from coast to coast and have been found as far south as Texas and Florida. Their range extends northward into Alaska and all 10 provinces of Canada. These insects also inhabit the Yukon Territory of Canada.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Alydus eurinus is found in many legume fields. Both adults and nymphs can be found on soybeans ( Glycine max ). They can also be found on wild legumes such as patches of crimson clover ( Trifolium incarnatum ) in fallow grasslands. These true bugs do not move far beyond these fields.

• Habitat Regions
• temperate temperate

• Terrestrial Biomes
• savanna or grassland savanna or grassland

• Other Habitat Features
• agricultural agricultural

Physical Description

Broad-headed bugs ( Alydus eurinus ) can exist as an egg, a nymph and an adult. The eggs are less than 1mm in width and about 1mm in length. In their nymph stage, these true bugs are ant mimics. These bug possess has three major sections: the head, thorax and abdomen, with their six legs are attached to the thorax. The legs are very thin compared to the rest of the body. The legs articulate in two places, dividing them up into three sections. Their abdomen is shaped like an oval.

The nymph stage is divided up into 5 instars of growth. In the first instar they are 2.25-2.75mm in length. By the fifth instar, these bugs are ca. 7-11mm long. As adults, they mimic spider wasps (members of the family Pompilidae) with black bodies and orange under the wings. They have two sets of wings and when they are not flying the wings are closed on the back. Their adult legs are slightly thicker than their nymph legs in the first section. These larger sections have small spines that stick backwards from the leg.

The adults are about 10-14mm long. Adults have broad heads as their name would suggest, about the width of their thorax. Their compound eyes also stick out to the side of their head. Members of Alydus eurinus are true bugs, which means they possess piercing sucking mouthparts to feed. Adults are usually black but they can be lighter or almost brown in color.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Development

Members of Alydus eurinus have 5 stages as a nymph called instars. Each instar lasts for 2.78 days on average. Between each instar, individuals molts their exoskeleton to allow for more growth. Females and males reach sexual maturity at 13.9 days after hatching on average. Eggs under short day conditions eggs have been observed to enter diapause until conditions are more favorable. Members of Alydus eurinus overwinter as eggs.

• Development - Life Cycle
• diapause diapause

Reproduction

Females of Alydus euriunus use a pheromone containing 2-methylbutyl butyrate and (E)-2-methyl-2-butenyl butyrate to attract males. Both sexes have striations on their hind femur that allows for the production of sound. This sound can only be heard from a few centimeters away but allows for individual pairs to separate from other individuals within the species. Females and males are polygynandrous, meaning they have multiple mates. They use internal fertilization for reproduction.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

The breeding for broad-headed bugs occurs between the months of April and August. Females can lay up to ten eggs five times per breeding season. The average number of eggs produced per season is 27. Eggs take 2.4 to 2.9 days to incubate. Time to independence is zero days, as parents provide no care post egg-laying or mating. Individuals of Alydus eurinus have 5 stages as a nymph called instars. Each instar lasts for 2.78 days, on average. Females and males reach sexual maturity ca. 13.9 days after hatching, on average. Females live for up to 180 days, though the average of 66.8 days is significantly shorter. Males live up to 176 days with the average being 76.1 days. These lifespans suggest they are semelparous - breeding for one season or effort and then dying.

• Key Reproductive Features
• semelparous semelparous
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

After laying eggs, females have no involvement with their young after ovipositing. Males exhibit no parental investment beyond the act of mating.

• Parental Investment
• no parental involvement

Lifespan/Longevity

Members of Alydus eurinus have been observed in captivity to have female lifespans averaging 66.8 days (range 28 to 180 days) and male lifespans averaging 76.1 days (range 38 to 175 days). Members of Alydus eurinus have not be observed for longevity in the wild.

Behavior

Individuals of Alydus eurinus spends most of their time in solitude. They aggregate to feed and mate. Breeding and egg-laying occurs on the stems and pods of legumes. Nymphs and adults move from on legumes into leaf litter to hide from predators. Adults have wings to allow them to move around to feed or find mates

• Key Behaviors
• flies
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

Not reported

Communication and Perception

Broad headed bugs ( Alydus eurinus ) use pheromones to attract mates. These pheromones are produced by females and attract males, and sometimes other females. They excrete these pheromones from a metathoracic scent gland. These true bugs attract mates by stridulation (producing sound by rubbing body parts together). The sound produced in this way can only be observed from a few centimeters away, indicating it is not effective over long distances. Individuals of Alydus eurinus have large compound eyes to see. They have antennae that help them feel their surroundings, detect pheromones and changes in temperature.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones
• vibrations vibrations

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Members of Alydus eurinus feed primarily on legumes. These broad-headed bugs are commonly found on commercially-grown legumes including soybeans ( Glycine max ) and crimson clover ( Trifolium incarnatum ). They use their piercing sucking mouthparts to suck out the fluid in a seed or leaf. In this way, these bugs are folivores and granivores. Individuals of Alydus eurinus aggregate together when it feeds. It has also been found on carrion and feces but it is not a significant portion of its diet.

• Primary Diet
• carnivore carnivore
  • scavenger scavenger
• herbivore herbivore
  • folivore folivore
  • granivore granivore
• coprophage coprophage

• Animal Foods
• carrion carrion

• Plant Foods
• leaves
• seeds, grains, and nuts

• Other Foods
• dung

Predation

Instars of Alydus eurinus mimic ants (members of the family Formicidae ), while adults mimics spider wasps (members of the family Pompilidae ). Birds who frequent their habitats will opportunistically prey on these insects in its habitat. Spiders ( Araneae ) and other insects ( Insecta ) will eat them. Nymphs and adults move from on legumes into leaf litter to hide from predators.

• Anti-predator Adaptations
• mimic

Ecosystem Roles

Individuals of Alydus eurinus consume nutrient rich fluids from the seeds and leaves of the plants in the family Fabaceae . This feeding does not directly kill the plant but does reduce productivity and yield in a commercial setting. Birds, spiders, and predatory insects prey on Alydus eurinus . Immature parasitic nematodes in the genus Hexamermis have been found on females of this species.

Economic Importance for Humans: Positive

There are no known positive economic effects of Alydus eurinus on humans.

Economic Importance for Humans: Negative

Members of Alydus eurinus cause significant damage to commercial legume crops such as soybeans ( Glycine max ). They damage the pods and leaves reducing yield and marketability.

• Negative Impacts
• crop pest

Conservation Status

Members of Alydus eurinus have not been evaluated for the IUCN Red List. They have no special status on the CITES appendices, the United States endangered species list or the State of Michigan List.

Two threats to the species would be human use of insecticides to remove them from fields and predation.

Conservation efforts are not in place for this pest species. However, anti-conservation efforts are in place in areas where they damage legume crops. Insecticides are used such as pyrethroids to control them.

Additional Links

Encyclopedia of Life

Contributors

Brian Currin (author), Radford University, Logan Platt (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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