Mexican Paper Wasp

Appearance

The genus "Mischocyttarus" is recognized by having asymmetrical internal and external lobes of the tarsal segments in adults and by appendix-like projections extending forward from the abdominal sternum of mature larvae. "M. mexicanus" belongs to a group of species within the genus that all share certain similarities, which includes "Mischocyttarus flavitarsis" and "Mischocyttarus angulatus". This group of species is known for having a sharp secondary margin on their pronotum, which is the dorsal surface of the prothorax. In addition, males have very short, thick antennae. Females also have a clypeus, or head plate, with a flattened apex. "M mexicanus" typically has an orange-yellow color.

Distribution

"M. mexicanus" is a New World wasp species found anywhere from the southern United States to Costa Rica. Subspecies "M. m. mexicanus "is predominantly present anywhere between Mexico and Costa Rica, though it has been sighted in Texas. On the other hand, the subspecies "M. m. cubicola" has been observed in the southeastern U.S., the Bahamas, Cuba, Puerto Rico, Texas, and Missouri. "M. m. cubicola" has been seen in almost every county of Florida except for the most northwestern counties of the state. It has been proposed that there is a distribution barrier that runs through northwestern Florida preventing the spread of "M. m cubicola" west of Alabama. However, this subspecies was observed in Texas and Missouri in 2009 nesting in a number of palm species, other trees, and human constructions.

Behavior

"M. mexicanus" females in a colony are at various levels of ovary development, and though there is typically one or more queen per colony, a relatively large proportion of females are reproductively viable. Females within a nest have been found to be highly variable, in that after a nest is initiated, one female may become the primary reproductive female, and the others may become subordinates. However, nest switching is frequent, and if a queen is removed, then a nestmate may replace her within the span of a week. Interestingly, the females in any given nest have a surprisingly low level of relatedness. Some reasons why "M. mexicanus" nests would be pleotropic in spite of this low relatedness include reduced mortality rates of multiple-foundress nests, reduced development times, and larger colony sizes.Biting has been found to be a frequent occurrence between nestmates. The individuals that do the most foraging in a multi-foundress colony were found to be the least aggressive individuals of the group. It was also found that the individuals with the least developed ovaries were the individuals that did the most foraging of the group. Additionally, there has been speculation that "M. mexicanus" individuals accumulate a particular odor as they age, which is consistent with the observation that older females are more often rejected by foreign nests. Males were found to have exocrine gland cells in their gastral sternites, though they have very few ducted exocrine gland cells when compared to other species of "Mischocyttarus". However, these observations are consistent with the idea that "M. mexicanus", like other wasps, use chemicals to communicate through nestmate recognition, pheromone signaling, etc.

Habitat

"M. mexicanus" is a New World wasp species found anywhere from the southern United States to Costa Rica. Subspecies "M. m. mexicanus "is predominantly present anywhere between Mexico and Costa Rica, though it has been sighted in Texas. On the other hand, the subspecies "M. m. cubicola" has been observed in the southeastern U.S., the Bahamas, Cuba, Puerto Rico, Texas, and Missouri. "M. m. cubicola" has been seen in almost every county of Florida except for the most northwestern counties of the state. It has been proposed that there is a distribution barrier that runs through northwestern Florida preventing the spread of "M. m cubicola" west of Alabama. However, this subspecies was observed in Texas and Missouri in 2009 nesting in a number of palm species, other trees, and human constructions.

Food

"M. mexicanus" was found to forage both arthropod and nectar-based foods. It is suspected that they prey on arthropod larvae. Additionally, females have been observed foraging on palmetto and "Lyonia" flowers. Males are also commonly found on flowers, and they often pounce on other "M. mexicanus" individuals that are foraging on those flowers, which is presumably related to the mating habits of this species.

Predators

Birds are a major source of predation on "M. mexicanus". Carolina wrens, scrub jays, blue jays, common yellowthroats, cardinals, thrashers, mockingbirds, woodpeckers, and robins are suspected to be predators of this species and are thought to destroy nests. Additionally, spiders such as orb weavers "Argiope aurantia" and "Nephila clavipes" are thought to be predators of "M. mexicanus".

Ants are commonly found raiding nests of this species, though it is rare that ants will raid a nest that hasn’t already been abandoned. Species including "Campanotus floridanus", "Crematogaster ashmeadi", and "Pheidole floridana" are known to raid live nests and eat the brood of the wasp colony. However, it was found that most commonly, a single ant will encounter a nest and be successfully deterred.

Defense

"M. mexicanus" has been found to have two stable nesting strategies: haplometrosis and pleometrosis. Haplometrosis refers to the single-foundress nesting strategy, while pleometrosis refers to a strategy involving multiple cofoundresses. It is interesting that both of these tactics are stable in "M. mexicanus" and it has been found that this is because each of these strategies is favorable in certain conditions, so this is an example of a context-dependent trait. Haplometric nests are more susceptible to greater mortality, and indeed up to 80% of haplometrotic nests fail within 20 days. However, haplometrosis has been found to be more frequent in the winter and spring, while pleometrosis is more frequent during the fall. It has been proposed that larger females are more likely to be solitary foundresses in the spring, and group foundresses in the summer, which a preference not found in smaller females. Additionally, when the number of potential habitats is experimentally decreased in an area, then nests are more likely to be founded by multiple females, and the converse has been found to hold true as well, indicating that these nesting tactics are context-dependent. Additionally, a female can switch between nesting tactics as an adult, suggesting that this trait is plastic.