Hesperapis rhodocerata : behavioral biology, egg, and larval instars, including behavioral and larval comparisons with H. larreae (Hymenoptera, Melittidae, Dasypodainae). (American Museum novitates, no. 3856)

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American Museum of Natural History.
This paper reports on a large nesting site of the ground-nesting solitary bee Hesperapis (Carinapis) rhodocerata (Cockerell) from southern New Mexico first discovered in the late summer of 2010 and active again in late summer 2015. Because the site was visited annually during intervening years without observation of any specimens, the species is believed to sustain a multiyear diapause that is broken in response to rain. It is judged to be univoltine, and females at the site collect pollen from Heterotheca (Asteraceae). Nests are briefly described as are the nest-digging behavior and pollen-transport system of females. The feeding behavior of larvae involves grazing on the surface of the food sphere, thus reducing its diameter. This is accomplished with the aid of paired ventral tubercles on each of the three thoracic and first eight abdominal segments and a single median ventral tubercle on the ninth abdominal segment. The second and last larval instars are described and illustrated. The first instar is essentially identical to the second instar except for size. Mature larvae are similar to other known Hesperapis larvae. The strongly curved egg of H. rhodocerata is described and illustrated with a diagram and SEM micrographs of the micropyle. Because the last larval instar does not spin a cocoon and freshly constructed brood cells are unlined by females, questions are evoked concerning humidity control and parasite exclusion during the long diapause of mature larvae. This information is compared with and found in some ways different from that uncovered in an earlier study of H. (Amblyapis) larreae Cockerell. It is hypothesized that the clear thin transparent material covering the postdefecating larva of H. rhodocerata may function to inhibit desiccation and furthermore may be the same material that hardens and waterproofs the cell walls of other congeneric species including H. larreae, thereby serving a similar function but in a different way. Because too few mature larvae of H. larreae had been collected at the time of drafting the study of that species, their description is added here as an addendum.
19 pages : illustrations (some color) ; 26 cm. Portion of an unpublished, undated and untitled manuscript on the biology of the bee genus Hesperapis, by Gerry I. Stage and Roy R. Snelling, available in a supplemental file.
Hesperapis rhodocerata., Hesperapis larreae., Hesperapis., Bees., Nests., Larvae., Behavior., New Mexico.