Search

The fungal genus Massospora (Zoopagomycota: Entomophthorales) includes more than a dozen obligate, sexually transmissible pathogenic species that infect cicadas (Hemiptera) worldwide. At least two species are known to produce psychoactive compounds during infection, which has garnered considerable interest for this enigmatic genus. As with many Entomophthorales, the evolutionary relationships and host associations of Massospora spp. are not well understood. The acquisition of M. diceroproctae from Arizona, M. tettigatis from Chile, and M. platypediae from California and Colorado provided an opportunity to conduct molecular phylogenetic analyses and morphological studies to investigate whether these fungi represent a monophyletic group and delimit species boundaries. In a three-locus phylogenetic analysis including the D1-D2 domains of the nuclear 28S rRNA gene (28S), elongation factor 1 alpha-like (EFL), and beta-tubulin (BTUB), Massospora was resolved in a strongly supported monophyletic group containing four well-supported genealogically exclusive lineages, based on two of three methods of phylogenetic inference. There was incongruence among the single-gene trees: two methods of phylogenetic inference recovered trees with either the same topology as the three-gene concatenated tree (EFL) or a basal polytomy (28S, BTUB). Massospora levispora and M. platypediae isolates formed a single lineage in all analyses and are synonymized here as M. levispora. Massospora diceroproctae was sister to M. cicadina in all three single-gene trees and on an extremely long branch relative to the other Massospora, and even the outgroup taxa, which may reflect an accelerated rate of molecular evolution and/or incomplete taxon sampling. The results of the morphological study presented here indicate that spore measurements may not be phylogenetically or diagnostically informative. Despite recent advances in understanding the ecology of Massospora, much about its host range and diversity remains unexplored. The emerging phylogenetic framework can provide a foundation for exploring coevolutionary relationships with cicada hosts and the evolution of behavior-altering compounds.

Periodical cicadas, known for strict life-cycle lengths of 13 or 17 yr, actually exhibit developmental plasticity in cycle length. This variation tends to occur in 1- and 4-yr increments for both life-cycle types, with the largest events involving 4-yr accelerations of the 17-yr species. The pattern has stimulated hypotheses to explain brood formation and life-cycle evolution, but most of the evidence is anecdotal. We present the first quantitative evidence confirming that a site with a 4-yr acceleration does not necessarily experience comparable emergence in the following year, and we provide the first density estimate for a 4-yr early emergence of 17-yr cicadas (1.28/m2, within the range of published estimates for on-schedule emergences). We also document a 4-yr early 13-yr emergence--cicadas apparently emerging in 9 yr. Multimodal life-cycle patterns spanning -4 to +4 yr are evident in both 13- and 17-yr cicadas. [ABSTRACT FROM AUTHOR]

Periodical cicadas, known for strict life-cycle lengths of 13 or 17 yr, actually exhibit developmental plasticity in cycle length. This variation tends to occur in 1- and 4-yr increments for both life-cycle types, with the largest events involving 4-yr accelerations of the 17-yr species. The pattern has stimulated hypotheses to explain brood formation and life-cycle evolution, but most of the evidence is anecdotal. We present the first quantitative evidence confirming that a site with a 4-yr acceleration does not necessarily experience comparable emergence in the following year, and we provide the first density estimate for a 4-yr early emergence of 17-yr cicadas (1.28/m2, within the range of published estimates for on-schedule emergences). We also document a 4-yr early 13-yr emergence-cicadas apparently emerging in 9 yr. Multimodal life-cycle patterns spanning −4 to +4 yr are evident in both 13- and 17-yr cicadas. [ABSTRACT FROM AUTHOR]

Abstract: Anatomical and histological study of the Malpighian tubules in the cicada genera Tibicen and Magicicada (Cicadoidea) demonstrated that, at the nymphal stage, these organs display a glandular modification, similar to one involved in the production of the “froth” in spittlebug nymphs (Cercopoidea). Proximal parts of the tubules contain a short smooth inflated segment, which produces granules of an acid mucopolysaccharide. A more distal long nodulose segment comprises cells which display extensive rough endoplasmic reticulum and numerous secretory vacuoles, indicating the manufacture of a proteinaceous product. These cells are strongly PAS-positive, suggesting the secretory product also contains carbohydrates. The production of secretory products in the tubules ceases at the adult stage. Available observations of the behaviors of cicada nymphs suggest that the tubule secretory products mix with copious watery excretion of the gut to form the anal liquid, which is used by the nymphs to cement the walls of the burrows and clean the body. The Malpighian tubule products apparently account for the adhesive properties of the anal liquid. The regional differentiation of the tubules, details of the cell ultrastructure in each of the segments, and the major secretory products are similar to those of spittlebug nymphs, which live immersed in their excretion which is conditioned with the Malpighian tubule secretory products. The results suggest that the distinctive adaptations of juvenile Cicadoidea and Cercopoidea have a common origin. [Copyright &y& Elsevier]