Source: UNIVERSITY OF ARIZONA submitted to
COLORADO RIVER CADDISFLY BIONOMICS AND ABATEMENT
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0189210
Grant No.
(N/A)
Project No.
ARZT-136329-H-31-135
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jul 1, 2001
Project End Date
Sep 30, 2005
Grant Year
(N/A)
Project Director
Smith, R. L.
Recipient Organization
UNIVERSITY OF ARIZONA
888 N EUCLID AVE
TUCSON,AZ 85719-4824
Performing Department
ENTOMOLOGY
Non Technical Summary
Caddis fly adults emerge in mass on the Colorado River near Parker Dam. These insects annoy residents, dissuade tourists, and cause health problems. We will study the biology of caddis flies near Parker dam and attempt to develop a bio-rational integrated management protocol for this problem.
Animal Health Component
(N/A)
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
13403101130100%
Knowledge Area
134 - Outdoor Recreation;

Subject Of Investigation
0310 - River basins;

Field Of Science
1130 - Entomology and acarology;
Goals / Objectives
1)Define the caddisfly problem on the Colorado River below Parker Dam in terms of human tolerances and the problem history. 2)Inventory the species of caddisflies produced by the Colorado River below Parker Dam and determine which species most contribute to the adult caddisfly biomass in the impacted area. 3)Assess the distribution and abundance of adult caddisflies in the impacted areas from Parker Dam down stream to 4)Investigate important life history parameters for the problematic species, including the periods of reproduction, number of larval instars, number of generations/year, larval developmental times and longevity of adults. 5)Characterize the reproductive behavior, especially swarming, of adults of the important species. 6)Study larval biology of the most important species including substrate requirements, flow tolerances, temperature tolerances, individual spacing, agonistic interactions, and food requirements. 7)Determine how discharge management practices at Parker Dam and Head Gate Dam have created conditions conducive to the production of the astronomical numbers and enormous biomasses of adult caddisflies downstream of Parker Dam. 8)Evaluate Bt and Bt I as larvicides against the problematical caddisfly larvae. 9)Provide prioritized management recommendations. 10)Evaluate management strategies in the field.
Project Methods
1)Long term residents in the impacted area will be interviewed about the caddisfly problem. The interviews will be designed to reveal consensus views of when the problem started, when the problem is most acute. 2)Light traps placed at regular intervals along the impacted parts of the river will be used throughout the study. Contents of the light traps will be weighed and frozen daily. 3)Samples of the catch will be preserved, identified, sexed and counted. Species catches will be recorded as percentage of total sample and percentages will be multiplied by the weight of the total catch. 4)Stratified samples of benthic substrate and macrophytes will be taken provide caddisfly larval counts. These larval samples will be examined microscopically and measured. Measurement data will provide the basis for determining the number of stadia in the life history of the important species. In addition the abundance of different stadia larval population taken monthly throughout the season will provide measures of the number of annual cohorts of the important species produced each year. Adults captured on the evening of their emergence will be set aside in cages provisioned with sugar water and observed hourly until 50 percent die. 5)Swarms will be observed directly and videotaped. Aerial sweep samples will be taken through various parts of the swarm. Individuals contained in the sweep samples will be counted and sexed. Individuals will be dusted with several different colored fluorescent powders on their resting substrate and in swarms. Following these dustings, resting or swarming populations will be sampled to determine patterns of pre-swarm aggregation behavior and post-swarm dispersal behavior. 6)At each larval sampling site, a variety of abiotic and biotic factors will be measured to characterize larval habitat. These will include water depth, temperature, substrate type, dissolved oxygen, plankton and suspended detritus, presence and abundance of rooted macrophytes. In cooperation with Parker and Head Gate dam managers study discharge practices and records over a 10 year period. We will attempt to correlate consensus views of residents (see procedure 1) with dramatic changes in regulation of flow regimes at Parker Dam. 7)Bt products with demonstrated activity for Lepidoptera in crops and Bt I products used for aquatic fly larva control will be screened against the important species of Colorado river caddisfly larvae in the laboratory. Plastic flow chambers will be calibrated to field measured flow regimes. Initially, aliquots of known concentrations of product will be circulated in the chambers and the contained larvae will be observed over a 72 hour period. If and when mortality is detected, experimental A.I. concentrations will be adjusted to produce L.D.50 data on one cycle to approximate "slug" exposure under field conditions. 8)An annotated list of management strategies with supporting biological rationale will be submitted to the community. 9)Management strategies will be implemented in the field and evaluated using light trap catches as the method for measuring the efficacy of each experimental management approach.

Progress 07/01/01 to 09/30/05

Outputs
The Insects Species Composition Light trap samples were comprised almost entirely of the net-spinning caddisfly Smicridea fasciatella (MacLachlan). Members of the Leptoceridae, Hydroptilidae, and Lepidoptera comprising the remainder of the sample weights. Abundance, Distribution and Emergence Patterns Because sampling began mid-season in 1999, it was necessary to construct the flight season of S. fasciatella over the course of two field seasons. Flight recordings of S. fasciatella continued from July 1999 through the first half of November 2000 when larval development slowed. Remaining larvae over-wintered in that life stage. Adult emergence did not resume until the first week of April 2000. S. fasciatella was only absent from light trap samples during the winter period. Peaks in emergence occurred in late June and early July, late September and early October, and again in April. Individual light trap samples ranged from 2 g (ca. 1200 individuals) during intergenerational periods to a climax of 5800g (ca. 3.5 million individuals) on July 16th 1999. Samples from peak emergence periods maintained daily weights of 350 g (200,000 individuals) for episodes lasting up to 3 wk. Data from the four light traps showed S. fasciatella to be most abundant about 4 km below Parker Dam with sample weights decreasing dramatically downstream (F = 28.18, df = 29, P < 0.0001). Adult Caddisfly Behavior Swarming began about 20-30 min prior to sunset and continued for up to three hours during times of peak emergence. During daylight hours, adults were commonly found resting in grass, under docks, and in other shady areas. Swarms of flying males and females often resembled adult roosting sites in that their size and location appeared to be dependent on that of the roost. The largest of these swarms were associated with dense riparian vegetation about 4 km below Parker Dam and measured approximately 15,000 m-3 (10m X 20m X 75m). Emergence Data Emergence trap data corroborated our light trap samples (Fig 1). Light traps having the highest abundance of adults coincided with locations having the highest emergence rates. Peaks in emergence occurred approximately 4 km below Parker dam and rapidly decreased downstream from that point (F = 4.11, df = 47, P < 0.04). The largest numbers of emerging adults were sampled over shallow riffle areas with substrates consisting of cobble to boulder sized rocks. Larvae and emerging adults also were associated with submerged macrophytes. Survey Data Of the 300 surveys distributed, 77 were returned. Of those surveyed, 87% termed the caddisfly problem at Parker as either intolerable and 29% reported having asthma-like symptoms or other breathing related difficulties due to swarming caddisflies. Less than 12% of respondents indicated tolerance for the problem and no respondent was unaware of the caddisfly situation at Parker. Several questions were phrased to address respondent's knowledge of the history of the caddisfly problem. The most common complaint (73%) listed by those surveyed involved alighting and crawling of adult caddisflies on exposed skin of people, entering homes, and creating the task of sweeping up expired adults.

Impacts
We defined the problem objectively, identified the speices involved, learned why populations were elevated in the Parker area, characterized the biology of the primary species, including seasonal and diel behavioral patterns. Finally, we communicated the results of this study to the residents of the impacted area. Master's Thesis produced

Publications

  • Grundy, N. and R.L.Smith 2008. Nuisance Caddisflies on the Lower Colorado River: A Field Assessment of the Problem and Results of a Residential Survey. Manuscript for publication in Journal of Economic Entomology.