Macrotera portalis

Macrotera portalis is in the order Hymenoptera, family Andrenidae, genus Macrotera. This species was formerly in Perdita, a very large genus that now contains around 600 species of bees which are located primarily in northern Mexico and the arid southwestern United States. ==Description and identification==

Macrotera portalis is a small (~7 mm), dark bee species. Like most andrenids, it has small depressions between the eyes and the antennal bases called facial foveae. In M. portalis, males are dimorphic, meaning that they have two distinct size classes. Macrotera portalis is closely related to Macrotera texana. Both species are communal, females have provision over one cell each day, and intranest mating is common. Macrotera portalis, however, has more females in each nest, and nests are often re-used for multiple years. Males of M. texana are not dimorphic, and nests are usually not reused for several generations. ==Distribution and habitat==

The species is found in arid grassland and desert regions in northern Mexico, Arizona, and New Mexico. ==Nesting biology==

As is typical for the family Andrenidae, M. portalis is a ground nesting bee. Macrotera portalis are also communal, with many females often sharing the same nest while provisioning their own individual nest cells. ==Seasonal cycle==

There is partial bivoltinism seen in Macrotera portalis, with about 2 broods, perhaps 3, per year; some larvae are second or third generation adults because they develop and emerge in the same year as their mothers. The period of larval development to adulthood takes at least 21 days. Larvae and some prepupae may remain in diapause for more than a year. Bet hedging Bet hedging is characterized through individuals that minimize reproductive success of variance between years. Macrotera portalis practices bet hedging because only a certain portion of bees emerge in any given year, with many remaining in diapause. Although this leads to certain years of lower reproductive success, in years of low resources some offspring will survive and thus the advantages of lower variance may outweigh the disadvantages of reduced average fitness in diverse environments. Since M. portalis lives in a desert environment, in which conditions are extremely unpredictable (between year variation is greater than in any other biome), it is likely that this promotes bet hedging in the species. Overwintering of desert bees have limited adult activity and reproduction during a short period of time after the desert rainy season. Larvae are small, exposed to high temperatures, low humidity, buried in the soil, subject to predation, desiccation, and pathogens. Induced emergence, in other words rainfall-triggered emergence, is observed within M. portalis, which has a synchronous pattern of emergence consistent with the southwestern desert's late summer monsoon rains. There is evidence of slight protandry and small inclination for emergence of large headed males before small headed males. For a comparison of emerging and diapausing pre-pupae, it was found that the pre-pupae that emerged within the year they were produced were much lighter compared to those who remained for an additional year in diapause. The difference was significant between males and females. This further demonstrates that if a pre-pupa contains sufficient mass (i.e., reserves of resources) to overwinter for another year it does so, while the lighter bees emerge the current year. The lighter bees are found deeper in the soil than those in diapause. Thus, emergence is influenced by larval condition as well as triggered by rainfall. ==Demographics==

Nests are usually reused for several generations, so bees within nests may be very closely related to each other. The two morphs are defined by characteristics of male shape and head size: : 1. Small headed morph that is capable of flight. This morph bears a resemblance to males of other closely related species. After emergence, this morph is seen only on flowers and they are aggressive, combating with males of the same species as well as attacking male and female bees of different species. Small headed males regularly mate with foraging females. Resource based engagement sites are usually used by oligolectic bees such as Macrotera portalis. M. portalis has both territorial male behavior in a female emergence site (inside the nests) as well as a resource-based rendezvous site that contains territorial small-headed males, both strategies predicted following the concentration of females in these two specific areas. ==Conservation status==

Currently, there is no information on the conservation status of this bee species. == References ==