Brachygastra lecheguana

Common names include marimbondo-do-campo, marimbondo-do-pasto,[4] marimbondo-exu, marimbondo-de-pote, marimbondo-de-purrão, and avispa-de-pote,[5] among others depending on the location.

It is called tu in the Kwaza language of Rondônia, Brazil.[6]

B. lecheguana belongs to the Epiponini tribe of Polistinae wasps,[7] sometimes referred to as Polybiinae wasps.[2][7] It is a Neotropical social wasp species that falls under the genus Brachygastra.[7]

Brachygastra wasps are identified, as noted in Andena and Carpenter (2012), by an anatomical projection over their posterior. The scutellum, metanotum, and propodeum, three of the hymenopteran back structures, combined form a flat, vertical surface in the middle of the body (mesosoma).[8]

B. lecheguana is very closely related to B. mellifica and B. borellii,[8] and indeed some authors suggest that B. lecheguana and B. mellifica can only be differentiated based on where they are found with respect to their reported distribution throughout the Americas.[2] However, there are morphological and genetic differences between these species.[8][9][10]

Brachygastra lecheguana was first described by Pierre André Latreille in 1824.[2] It was originally named Nectarina lecheguana,[2] and the switch from Nectarina to Brachygastra as a name for this genus was not standard in the scientific literature until the 1940s.[8] Between 1824 and 1943, this species was documented as a member of the following genera: Polistes, Vespa, Nectarinia (a misspelling of Nectarina, and a misuse of this genus of birds), Brachygaster (another misspelling, and a misuse of this genus of parasitic wasp), Melissaia, and Caba.[2][8]

In 1923, Bequeart performed a survey of the literature on this species, compiling accounts and descriptions by entomologists de Saussure, von Ihering, and du Buysson among numerous others, creating a source of descriptive information on this species.[2] One study has focused on the morphological caste differentiation of B. lecheguana[11] and another directly studied its foraging behavior.[3] While not the focus, B. lecheguana has been included in studies of groups of wasps known to be natural enemies of agricultural pests,[12][13][14] and has been documented in a number of papers cataloging flower visitation by insects and birds.[15][16]

Bequaert provides a detailed description of the anatomy and features of B. lecheguana.[2] This species is black, with an abdomen colored with yellow stripes, having patches on the thorax and head colored yellow as well.[4] The abdomen is wide and truncate,[8] and nests are globular,[4] gray, and close to the ground.[2] Queens and workers were recorded to be ~7.5–9 mm long and males ranged from ~7.5–8 mm in length.[2] B. lecheguana can be differentiated from B. mellifica based on the male reproductive anatomy; in B. lecheguana the males have an apically wide digitus while that of B. mellifica males is relatively narrow.[8]

B. lecheguana is found across Central and South America, ranging from Mexico to Argentina. This species has been observed a couple times as far north as Texas and Arizona, but tends to be rare north of Mexico.[2]

Nests are oval, about the size of a human head, made of gray paper-like material, and close to the ground.[2] Bequeart includes a lengthy description of the construction process for one of these nests in his 1932 publication on Polybiinae wasps.[2] Nests are located in undergrowth,[4] and it appears that these wasps prefer more temperate locations characterized by open, less humid, grassland environments.[15][17][18]

As a member of the polistine wasp tribe Epiponini, B. lecheguana is a swarm-founding species.[7] Their nests are polygynous,[7] with reproductively active females numbering anywhere from 1% [11] to possibly even 17% of a colony.[19] Reports of the total number of individuals in a given colony have been recorded by a couple different sources ranging from 13800 [11] to 15000,[2] although it appears that a limited number of colony counts are documented in the scientific literature. The male to female ratio was reported as 0 in a colony collected in May,[11] 1:15 in a colony collected in January, and 1:1 in a colony observed in the fall.[2]

Nests are recorded to be perennial, often lasting several years.[2] New colonies are formed in the spring when several fertile queens, accompanied by a few worker wasps in a swarm, establish new nest sites.[2]

In a study that characterized the morphological difference between different castes in B. lecheguana, researchers used ovary development to classify individuals as workers, queens, or "intermediates". Workers had either undeveloped or slightly developed ovaries, and constituted around 39% of the study's pool of individuals, while queens, with well developed ovaries containing 6-12 oocytes, accounted for around 0.7% of the individuals. A third group, with moderately developed ovaries containing 1-5 oocytes, was identified as an intermediate caste and accounted for around 60.3% of the colony. While the ovaries belonging to queen individuals had evidence of insemination, there was no detectable sperm in the reproductive organs of the intermediate individuals.[11]

Anecdotal accounts of B. lecheguana nests suggest that queens are larger than workers.[2] However it appears that a more careful statistical analysis indicates that there is no overall size difference between queens, workers, or intermediates.[11] There is no difference in overall size, but the queens have a set of anatomical proportions distinct from the intermediates and workers, smaller in some structures and larger in others.[11]

While it appears that caste might be discernible through ovary development,[11] the absence of morphological differences between individuals in B. lecheguana suggests that there is no meaningful morphological caste.[7] However it is clear that individuals can be designated reproductives and nonreproductives.[7]

Bequaert describes the extensive color and shape similarities between B. lecheguana and a number of other species with the word "homeochromic" instead of "mimic". He lists a number of vespid wasps and potter wasps belonging to the genera Pachodynerus, Odynerus, and Ancistrocerus, and several crabronid wasps of the genera Gorytes and Cerceris. Along with wasps, there are several bee species that are homeochromic, including mason bees of the genera Megachile, Anthidiellum, Hypanthidium, Dianthidium, and the species Stelis costaricensis, cuckoo bees belonging to the genus Epeolus, stingless Trigona bees, and sweat bees from the genus Halictus. He also lists a soldier fly of the genus Stratiomys as a homeochromic species.[2]

While B. lecheguana, Bequaert suggests, is the most abundant in this group of homeochromic species, he does not make the claim that these similarities arose from mimicry in the classic sense, but he suggests that further research would be helpful.[2]