Life History of an Ant Parasitoid invicta, and the invasive big-headed ant, Pheidole We do not know exactly how the planidium gets megacephala. Both Solenopsis and Wasmannia are into the nest. Does it always get carried in the considered among the top 100 most invasive infrabuccal pouch? Do the ants pick up the insects. planidia while feeding or grooming? Do they transfer the larvae by trophyllaxis (food What are eucharitid wasps? exchange), or by some other means? The wasp family Eucharitidae are a diverse of insects known to exclusively attack a group of What are extrafloral nectaries? social insects, the ants. This family belongs to a Some eucharitid wasps place their eggs very close larger group of wasps, the Chalcidoidea, which to ExtraFloral Nectaries (EFN). These specialized are an extremely diverse superfamily of mostly plant structures secrete a sugary amino-acid rich insect parasitoids. The chalcidoids are highly liquid that is highly attractive to ants and other diverse, with more than 500,000 species parasitoid adults. EFN nectar is often released as a estimated to exist, although relatively few (23,000 result of damage to the plant. We have a theory species) are known to science. Eucharitidae that the eucharitids may damage the plant to Adult Orasema wasp parasitoid in colony of Pheidole. include about 480 described species, with an increase nectar production, which in turn Photo courtesy of Alex Wild. estimated 300-500 species yet to be described. increases the possibilty of ants interacting with All eucharitids are parasitoids of ant pupae. newly emerged planidia. What do you think? If What is a parasitoid? They mate outside of the ant nest, and deposit you have ideas or observations, let us know. A parasitoid is an insect that takes nourishment their eggs away from their ant host, either in or on from another insect and eventually kills that plant vegetation. Eggs hatch and the minute active insect. True parasitoids are only known in a group first-instar larvae, termed a planidium, about 0.12 of insects with a distinct larval and pupal stage. It mm in size, must find its way into the ant nest. is the larva that kills the other arthropod host. They do this by various means, but always Adults are usually do not kill other insects, and involving a foraging adult ant worker. The instead feed on things very different from the planidia may be associated with fruit, extrafloral larvae. Because they kill other insects, parasitoids nectaries, potential prey of the ants (such as are often considered important for the control of thrips) or may just attach to the wandering ants. other insects, including those insects considered Once on the ant, they appear to make their way to to be human pests. a special cavity in the ant mouthparts called the What are myrmicine ants? infrabuccal pouch. They are able to survive within First-instar larvae (=planidia) of Orasema simulatrix (Eucharitidae) in an EFN of desert willow, Chilopsis Ants belong to the insect family Formicidae. the pouch and are able to be transferred from linearis. Eggs are placed close to the EFN and larvae foraging ants to nurse ants (those that care for the Based on fossils, we know that the first ants emerge and crawl to the nectary. Ants are known to appeared about 100 to 120 million years ago. We ant larvae) to the ant larvae themselves. These feed at the nectaries. Photo courtesy of Judith Herreid. currently recognize 16 higher level groups of ants planidia must be transferred to the ant larvae. (subfamilies) that evolved relatively early in the Once on the larva, the planidium burrows into the What is Biological Control? evolution of ants. Of these, the ant subfamily host and waits for it to pupate. When pupation Biological Control is the natural control of pest Myrmicinae includes the harvester ants, fungus- occurs, the planidium moves to the ventral region insects using their natural enemies. Introduced growing ants and the fire ants. The ant workers of of the ant pupal thorax and begins to feed. After pest species often lack the parasitoids that kept myrmicine ants all have a functional sting that can consuming most, but not all, of the ant, the wasp them in check in their native country of origin. We cause reactions in humans and makes them a finishes develop-ment, pupates and eventually can control these pest by carefully selecting, direct human pest. They can also have an very leaves the nest to finish the cycle. studying and releasing their parasitoids, including negative impact on insect diversity when they are The ants treat the killers very well, and have eucharitids, against these invasive pests. invasive and introduced into a new habitat. Pest been observed to protect the wasps when the ant nest is disturbed or threatened. Semiochemicals Heraty Laboratory, Department of Entomology ants include the Little Fire Ant, Wasmannia University of California, Riverside, CA auropunctata, the Imported Fire Ant, Solenopsis may help disguise the wasps. http://hymenoptera.ucr.edu