Egg masses of some stream‐dwelling caddisflies (Trichoptera: Hydrobiosidae) from Victoria, Australia

Lancaster, Jill; Glaister, Alena

doi:10.1111/aen.12360

Cited by 13 publications

(25 citation statements)

References 60 publications

(186 reference statements)

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“…However, available measures of body size (see Section 2) suggest no commensurate increase in the size of A. obliquum females to accommodate such a difference in egg numbers. It is possible that a larger range of body sizes (or forewing lengths) is required to detect between‐species patterns in clutch size and body size (Lancaster & Glaister, ).…”

Section: Discussionmentioning

confidence: 99%

“…We surveyed the clutch sizes of three species of caddisfly Ulmerochorema rubiconum , Apsilochorema gisbum , and Apsilochorema obliquum (family: Hydrobiosidae). Egg masses of these species are described by Reich () and Lancaster and Glaister (). All three species oviposit exclusively on emergent rocks (rocks that protrude from the water) making it easy to locate egg masses (Reich, ).…”

Section: Methodsmentioning

confidence: 99%

“…Hydrobiosidae). Egg masses of these species are described by Reich (2004) and Lancaster and Glaister (2018). All three species oviposit exclusively on emergent rocks (rocks that protrude from the water) making it easy to locate egg masses (Reich, 2002).…”

Section: Within Sitesmentioning

confidence: 99%

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Variations in fecundity over catchment scales: Implications for caddisfly populations spanning a thermal gradient

2019

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Population sizes of stream insects depend on the number of eggs that enter the benthos. Densities of oviposited eggs have been linked to densities of oviposition habitat, but variability in fecundity has not been explored. Fecundity may differ between sites where females experience different thermal environments during development, because insects generally grow larger and produce more eggs in cold places (e.g. high elevation and latitude). We predicted that because the fecundity of emerging females should increase with elevation then the numbers of eggs in oviposited egg masses (clutch sizes) should also increase with elevation. Alternatively, individuals may routinely disperse along channels or between rivers, mixing individuals that have grown and developed in different thermal environments, in which case clutch sizes may not vary with elevation but could vary greatly within sites. We tested these hypotheses across an elevation gradient of 250–1,080 m above sea level, in seven streams in southeast Australia. We surveyed the fecundity of three species of caddisflies (Trichoptera: Hydrobiosidae) in 2009 (eight sites) and 2010 (17 sites). Female hydrobiosids attach their entire clutch of eggs to an emergent stream boulder, in a single egg mass. At each site we censused the number of egg masses in two random 50 m stretches and photographed a sample of egg masses. Clutch sizes were quantified by counting eggs from the photographs. From numbers of egg masses and mean clutch size per site, we estimated the number of individual eggs per site, to determine whether spatial differences in clutch size affect patterns of egg supply. Potential trade‐offs between egg number and size were also examined. Strong thermal gradients were observed in both years. Sites at lowest elevations were 4.8°C (2009) and 3.6°C (2010) warmer than sites at highest elevations, and accumulated 392 (2009) and 361 (2010) more degree‐days (>0°C) over a period of 88 days. Clutch sizes of each species varied markedly within and between species but did not differ along the thermal gradient. Within species, 83.7–93.7% of variation in clutch size was expressed within sites. Relatively little variation occurred between sites or rivers. Within species, counts of egg masses adequately described relative egg supply to each site, because clutch sizes were similar between sites and rivers. Comparing egg supply between species, however, required including clutch sizes to estimate supply. Egg size differed within but not between species. Significant but small variations in egg size were trivial compared to much larger variations in clutch size. Our results suggest that any spatial differences in fecundity caused by temperature may be erased by dispersal, such that females from multiple locations mix between sites prior to oviposition. A warming global climate may reduce the fecundity of ectotherms such as aquatic insects but consequences for populations are difficult to predict. Moreover, climate‐related effects on fecundity may not be apparent when d...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Variations in fecundity over catchment scales: Implications for caddisfly populations spanning a thermal gradient

2019

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“…There are at least three distinctly different oviposition habits within this set of nine species. The five hydrobiosids and one hydropsychid, Cheumatopsyche AV3, lay their eggs as plaque‐shaped masses attached to the underside of emergent rocks in riffles (Lancaster & Glaister, ; Reich, ; Reich & Downes, ). The second hydropsychid, Asmicridea edwardsi , also oviposit plaque‐shaped masses attached to rocks in riffles, but on both submerged and emergent rocks (Reich, ).…”

Section: Methodsmentioning

confidence: 99%

“…For example, some species lay eggs on submerged rocks in pools (Deutsch, ; Lancaster, Downes, & Arnold, ), whereas others oviposit in riffles and primarily on rocks that protrude above the water surface, i.e. emergent rocks (Hoffmann & Resh, ; Lancaster et al, ; Lancaster & Glaister, ; Reich & Downes, ). However, numbers of such emergent rocks vary between riffles and there is often a correlation of oviposition site densities with egg mass densities, and sometime with larval densities also (Lancaster & Downes, , ).…”

Section: Introductionmentioning

confidence: 99%

Terrestrial–aquatic transitions: Local abundances and movements of mature female caddisflies are related to oviposition habits but not flight capability

2020

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Movement behaviours of adult aquatic insects can produce distinct spatial distribution patterns. Studies of adult abundance with distance away from water bodies are common and may invoke flight capability to explain species differences. In contrast, distribution patterns along river channels are poorly described, but are no less important for understanding population dynamics. Longitudinal patterns in adult abundance along short river lengths may differ between sexes and at different life stage transitions between aquatic and terrestrial environments, i.e. at emergence and oviposition. Flight capability is unlikely to influence longitudinal patterns created at emergence, but may influence local abundances of mature females seeking to lay eggs. We tested hypotheses about how local abundances of mature females might differ according to oviposition habits and flight capability. We surveyed abundances of mature female caddisflies at adjacent riffle–pool pairs along short river lengths with homogeneous riparian cover. Our survey included nine species in three families (Hydrobiosidae, Leptoceridae, Hydropsychidae), which encompassed multiple different oviposition habits and a range of wing sizes and shapes. Several of the species oviposit preferentially in riffles. Accordingly, we tested for differences in female abundance between channel units (adjacent riffle–pool pairs). We also tested whether females attained higher abundances in some places along channels than others (i.e. over larger spatial scales and regardless of channel unit) which imply movements along the channel and aggregation in some locations. Wing morphology was used as a proxy measure of flight capability and included measures of wing span, area, aspect ratio and the second moment of wing area. Three distinctly different distribution patterns of mature female caddisflies were identified. The abundance of three species varied over larger scales only (multiple channel units). Six species that oviposit preferentially in riffles had higher female abundances at riffles than pools, but for only one did abundances also vary over larger scales. There was no association between these different patterns and measures of wing morphology, after removing metrics that were correlated and that differed systematically between taxonomic families. However, we could not reject the hypothesis that some aspect of flight behaviour may have contributed to observed patterns. The diverse but distinct distributions of mature female caddisflies we observed along short channel lengths are novel and suggest that species differ in their propensity for movement along streams, which could have consequences for local densities of eggs and juveniles in the aquatic environment. The degree to which population sizes are coupled across the terrestrial‐to‐aquatic transition is rarely investigated in aquatic insects and may provide fresh insight into sources of spatial variation within populations. Similarly, a more nuanced approach to research on the flight of aquatic insects, in...

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Avoidance and aggregation create consistent egg distribution patterns of congeneric caddisflies across spatially variable oviposition landscapes

et al. 2020

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Egg masses of some stream‐dwelling caddisflies (Trichoptera: Hydrobiosidae) from Victoria, Australia

Cited by 13 publications

References 60 publications

Variations in fecundity over catchment scales: Implications for caddisfly populations spanning a thermal gradient

Variations in fecundity over catchment scales: Implications for caddisfly populations spanning a thermal gradient

Terrestrial–aquatic transitions: Local abundances and movements of mature female caddisflies are related to oviposition habits but not flight capability

Avoidance and aggregation create consistent egg distribution patterns of congeneric caddisflies across spatially variable oviposition landscapes

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