SYSTEMATICS AND TAXONOMY OF CADDISFLIES (TRICHOPTERA)

• Sponsoring Institution: State Agricultural Experiment Station
• Project Status: COMPLETE
• Funding Source: STATE
• Reporting Frequency: Annual
• Accession No.: 1027089
• Project Start Date: Jul 1, 2021
• Project End Date: Mar 31, 2023
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108

Performing Department
Entomology

Non Technical Summary
The insect order Trichoptera, or caddisflies, comprises an important component of freshwater ecosystems where species participate in many levels in the aquatic food chain and act as biological indicators of water quality. This project will provide taxonomic and phylogenetic information for the regional and world fauna to assess their evolution and diversity, including the description of new species, amass a collection of specimens for current and future morphological and molecular studies, and provide a publicly accessible database of specimen-level taxonomic and geographic data. In all, the project will aid understanding of the evolution and diversity of the order, its role in aquatic ecosystems, and its practical application in biological assessment of water quality.

Animal Health Component

0%

Research Effort Categories

Basic

100%

Applied

0%

Developmental

0%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
136	0399	1130	100%

Knowledge Area
136 - Conservation of Biological Diversity;

Subject Of Investigation
0399 - Watersheds and river basins, general;

Field Of Science
1130 - Entomology and acarology;

Keywords

taxonomy

caddisflies (insecta: trichoptera)

evolution & phylogeny

specimens & databases

museums

species descriptions

Goals / Objectives
Trichoptera (caddisflies) are an insect order with aquatic larval and pupal stages. These immature stages are ubiquitous in the world's freshwater ecosystems but are especially diverse in rivers and streams. Caddisfly larvae are critical participants in aquatic food webs. Among aquatic macroinvertebrates, they display a wide diversity of trophic adaptations, being surpassed only by aquatic flies in the type of food eaten and the manner in which it is obtained. Caddisfly larvae also exploit a wide variety of aquatic microhabitats. Their ecological diversity has been attributed to the ability of the larva to use silk to construct capture nets, retreats, cases, and pupal shelters (Morse et al. 2019). There is a great diversity of net and case morphology and complex behavior patterns involved in their construction. While the larvae have received much attention, caddisfly adults, which are terrestrial, are less well studied, partly because they are drab, nocturnal, and taxonomically difficult. They resemble small moths, which is not surprising since the Trichoptera and Lepidoptera are very closely related (Thomas et al. 2020). Although collectors and aquatic ecologists often overlook adults, the species taxonomy of the order is based on the adult stage, particularly on structures of the male genitalia. Because of this, immature stages cannot be determined until positive associations have been made with adult males through rearing, the "metamorphotype" method (Morse et al. 2019), or via "DNA barcoding" (Zhou et al, 2016). Progress in larval taxonomy is therefore dependent on advances in adult taxonomy. In Europe and North America, where the fauna is well known in both the adult and larval stages, information about the ecological tolerances of various species of caddisflies has led to their use as water quality indicator organisms. Biological monitoring, the practice of using aquatic organisms for assessing water quality, is currently widely implemented and often even mandated in various public and private enterprises. Various family-, genus-, and species-level measures, including rapid assessment protocols, have been established. There are some 52 families of Trichoptera representing about 15,000 described species. However, estimates of the number of undescribed species place the fauna as high as 50,000 species. If only a 5th of the world fauna is known, there is clearly a great need for taxonomic and descriptive studies of Trichoptera, especially in tropical forests where the greatest undiscovered diversity seems to exist and where the greatest extinction of species is likely to occur. In my own studies in the Neotropics, I have found faunas where 75% or more of the species collected are undescribed.

Project Methods
Established methods for taxonomic study of Trichoptera include clearing male genitalia lactic acid, followed by examination and illustration of structures under a stereomicroscope. Taxonomy is based on male genitalia, but it is also important to examine and illustrate female genitalia and larvae, when available. Digital photography is used to capture images followed by the use of digital illustration and image editing programs (Adobe Illustrator and Photoshop) to enhance and accelerate illustration of specimens. An added advantage of electronic image capture is the ease with which images can be posted on a website. The descriptive taxonomic software DELTA is used to automate the traditionally laborious task of writing taxonomic descriptions and identification keys.Specimen data gathered in conjunction with revisionary and monographic studies will be incorporated into the existing Specify database at the University of Minnesota Insect Collection. This database is designed for recording and analyzing locality or collection-based survey data. Standard methods of DNA barcoding will be used to corroborate or support species hypotheses using an integrative taxonomic approach where needed (Zhou et al. 2016). Genomic analyses will be performed in the labs of collaborators in Utah and Frankfort, Germany.

Progress 07/01/21 to 03/31/23

Outputs
Target Audience:Students and other researchers in Minnesota, the US, and around the world. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Caddisflies, or Trichoptera, are important components of freshwater ecosystems where they participate in many levels in the aquatic food chain and act as biological indicators of water quality. This research project focused on the systematics and taxonomy of caddisflies. Its main objectives were to provide taxonomic revisions and descriptions of the species, to maintain an authoritative research and reference collection of specimens, to produce keys and other guides to identification, and to train graduate students in systematics and taxonomy. The taxonomic research associated with this project resulted in the description and revisions of 100s of new species of caddisflies and led to an understanding of their phylogenetic relationships and their utilization as biological indicators of water quality. 2022 represented the first post-pandemic year of the project. University of Minnesota Insect Collection (UMSP) personnel returned to full-time activities and positive accomplishments were achieved. During pandemic year 2021, no new caddisfly material was formally accessioned into the collection, but with a return to full-time activities, 18,478 specimens were accessioned in 2022. Caddisfly specimens in the collection now total 677,361 individuals including over 200 holotypes and representing 3,451 species. New accessions included material mainly from Ecuador, but also from other regions around the world. The collection maintains its status as one of the most important collections of Trichoptera in the world. All specimens are entered in the collection's Specify database. Holzenthal and Curator Thomson participated in one research trip to Ecuador in March to continue research on caddisfly faunistics of the country with Dr. Blanca Ríos-Touma. Material was collected from 17 separate localities spanning 2 elevational gradients from ca. 3800-300 meters and represents about 2,000 specimens collected. Specimens have all been labelled, identified to species, and entered into the UMSP Specify database. Descriptions of new species from this material is ongoing and planned for 2023. Holzenthal and Dr. Ríos-Touma continued an second research project on the genomics of the fauna with Dr. Paul Frandsen, Brigham Young University, and Dr. Steffen Pauls, Senckenberg Research Institute and Natural History Museum, Germany. A subset of specimens from the March trip were preserved in 95% ethanol and set aside for DNA extraction and sequencing. This research will look at genomic data to study adaptations of Neotropical caddisflies to high Andean environments. Dr. Robin Thomson, curator of the collection, published her work on a world catalog of the microcaddisflies and and continues work on various taxonomic studies with colleagues in Ecuador, Panama, and Pennsylvania. Thomson was awarded a highly prestigious, 5- year NSF CAREER grant in January, 2022 ($962,142). The grant will support research on the caddisfly family Hydroptilidae, the microcaddisflies, using morphological and genomic data as well as support teaching and outreach activities. Project leader Holzenthal will retire in December 2022 and assume emeritus status in the Department of Entomology beginning in January 2023. Publications: Thomson RE (2023). Catalog of the Hydroptilidae (Insecta, Trichoptera). ZooKeys:1140:1-499 Houghton DC, DeWalt RE, Hubbard T, Schmude KL, Dimick JJ, Holzenthal RW, Blahnik RJ, Snitgen JL (2022) Checklist of the caddisflies (Insecta, Trichoptera) of the Upper Midwest region of the United States. In: Pauls SU, Thomson R, Rázuri-Gonzales E (Eds) Special Issue in Honor of Ralph W. Holzenthal for a Lifelong Contribution to Trichoptera Systematics. ZooKeys 1111: 287-300. https://doi.org/10.3897/ zookeys.1111.72345 Thomson RE, Frandsen PB, Holzenthal RW (2022) A preliminary molecular phylogeny of the family Hydroptilidae (Trichoptera): an exploration of combined targeted enrichment data and legacy sequence data. In: Pauls SU, Thomson R, Rázuri-Gonzales E (Eds) Special Issue in Honor of Ralph W. Holzenthal for a Lifelong Contribution to Trichoptera Systematics. ZooKeys 1111: 467-488. https://doi.org/10.3897/ zookeys.1111.85361 Thomson RE, Armitage BJ, Harris SC (2022) The Trichoptera of Panama. XIX. Additions to and a review of the genus Leucotrichia (Trichoptera, Hydroptilidae) in Panama. In: Pauls SU, Thomson R, Rázuri-Gonzales E (Eds) Special Issue in Honor of Ralph W. Holzenthal for a Lifelong Contribution to Trichoptera Systematics. ZooKeys 1111: 425-466. https://doi.org/10.3897/zookeys.1111.77371 Ríos-Touma B, Cuesta F, Rázuri-Gonzales E, Holzenthal R, Tapia A, Calderón-Loor M (2022) Elevational biodiversity gradients in the Neotropics: Perspectives from freshwater caddisflies (Insecta: Trichoptera). PLoS ONE 17(8): e0272229. https:// doi.org/10.1371/journal.pone.0272229 Holzenthal RW, Blahnik RJ, Ríos-Touma B (2022) A new genus and new species of Ecuadorian Philopotamidae (Trichoptera). ZooKeys 1117: 95-122. https://doi.org/ 10.3897/zookeys.1117.86984

Publications

Progress 07/01/21 to 09/30/21

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The project was just recently initiated. No substantive progress to report as of yet.

Publications