Contribution of fungal biomass to the growth of the shredder, Pycnopsyche gentilis (Trichoptera: Limnephilidae)

1.  1. It has been accepted that aquatic hyphomycetes colonising submerged leaves increase the nutritional value of leaf detritus and suggested that fungal biomass plays a greater role in the growth of shredders than leaf tissue itself. However, it is not clear what proportion of the nutritional needs of shredders is met by fungal biomass.
2.  We fed Pycnopsyche gentilis larvae with tulip poplar ( Liriodendron tulipifera ) leaf discs colonised by the aquatic hyphomycete, Anguillospora filiformis , which had been radiolabelled to quantify the contribution of fungal carbon to the growth of the shredder at different larval developmental stages. Instantaneous growth rates of larvae on this diet were also estimated.
3.  When provided with fungal-colonised leaves (14–16% fungal biomass), the third and the fifth instar larvae of P. gentilis grew at the rates of 0.061 and 0.034 day⁻¹, respectively, but on a diet of sterile leaves, both larval instars lost weight. The incorporation rates of fungal carbon were 31.6 μg C mg⁻¹ AFDM day⁻¹, accounting for 100% of the daily growth rate of the third instar larvae and 8.6 μg C mg⁻¹ AFDM day⁻¹, accounting for 50% of the daily growth rate of the fifth instar larvae.
4.  These results suggest that leaf material colonised by A. filiformis is a high quality food resource for P. gentilis larvae, and that fungal biomass can contribute significantly to the growth of these larvae. Differences in feeding behaviour and digestive physiology may explain the significantly greater assimilation of fungal biomass by the earlier instar than the final instar. To satisfy their nutritional needs the fifth instar larvae would have to assimilate detrital mass that may have been modified by fungal exoenzymes.     

Systematics of Crumomyia Macquart and Alloborborus Duda (Diptera: Sphaeroceridae)

ABSTRACT. The phylogenetic relationships of two sphaerocerid genera, Alloborborus Duda (1923) and Crumomyia Macquart (1835), are analysed, and their taxonomic status within the tribe Copromyzini (= Copromyza Fallén s.lat.) is clarified. Accepted here are a monotypic Alloborborus , which includes A.pallifrons (FalléAn) from northern and central Europe, and twenty-six species of the Holarctic Crumomyia. Within Crumomyia , five species-groups are recognized: pedestris group: pedestris (Meigen); annulus group: immensa (Spuler), maculipennis (Spuler), annulus (Walker), nipponica (Richards), pruinosa (Richards); notabilis group: glabifrons (Meigen), glacialis (Meigen), absoloni (Bezzi), notabilis (Collin), rohaceki sp.n., zuskai (Roháček); nitida group: nitida (Meigen); setitibialis group: setitibialis (Spuler), pilosa sp.n., nigra (Meigen), parentela (Séguy), deemingi (Hackman), pollinodorsata (Papp), subaptera (Malloch), gelida (Hackman), fimetaria (Meigen), roserii (Rondani); unplaced species: hentscheli (Duda), hungarica (Duda), promethei (Nartshuk). Apterina Macquart, Fungobia Lioy and Speomyia Bezzi are synonymized with Crumomyia , and the following nominal species are synonymized: tuxeni Collin with nigra, freyi Hackman with setitibialis , and annulipes Duda with annulus. C. pruinosa is considered distinct from annulus, and Copromyza subaptera is placed in Crumomyia. The identity of C.glacialis , the type species of Crumomyia , is clarified, and lectotypes are designated for five nominal species: rufoannulata Duda, annulipes, annulus, flavipennis Haliday and pallifrons. The cladistic relationships of the species of Crumomyia and Alloborborus are established and their phylogeny and biogeography are discussed. Keys to the species of Crumomyia and to the Holarctic genera of the Copromyzinae are provided.     

A Comparative Study of the Effects of Egg Rotation (Gravity Orientation) and UV Irradiation on Anuran vs. Urodele Amphibian Eggs

The response of various anuran and urodele eggs to a brief rotation prior to first cleavage were observed. In all instances, the dorsal lip formed on the side of the egg which opposed gravity during the rotation. The ability of egg rotation to prevent the series of developmental abnormalities associated with UV irradiation of the uncleaved egg was also examined. Anuran and urodele eggs responded to those manipulations in a similar fashion. These results should facilitate future studies on the mechanisms involved in the establishment of the dorsal/ventral polarity of the amphibian egg.