SUMMARY. 1. Life cycles, food habits, mouthpart morphologies, prey preferences, and predator-prey size relationships were investigated for the three most common stoneflies in leaf packs in the Little Missouri River, Arkansas: Clioperla clio (Newman), Isoperla namata Prison, and Perlesta spp. Each species was univoltine and had a fast seasonal cycle, with extended egg or nymphal diapause, rapid nymphal growth and emergence in spring to early summer.



2. Foregut analysis showed predictable dietary shifts by C. clio and Perlesta spp., from detritus and diatoms in early instars to invertebrate prey in later instars. Isoperla namata fed facultatively on insects, detritus and diatoms, with no conspicuous ontogenetic shifts. The mouthparts of all three species strongly reflected their diet.



3. Electivity analysis indicated opportunistic feeding by the three species, with feeding rarely differing significantly from random.



4. Sizes of stonefly predators and their ingested prey were highly correlated (P<0.01). However, rather than shifting toward larger prey sizes, growing predators expanded their size thresholds and continued to include numerous small prey items in their diet. Prey choice was governed most directly by prey availability, because stoneflies selected the most abundant groups, irrespective of size or taxon.



5. The likelihood of competition among the three stoneflies for prey was minimized by timing of their life cycles, differential food use and probably the temporary nature of leaf pack habitats.

Diet and predation by three leaf‐associated stoneflies (Plecoptera) in an Arkansas mountain stream

The seasonal change in gut contents of nymphs of Isoperla grammatica and I. difformis from six streams in southern Sweden was analysed. Both species had ingested a variety of benthic prey and vegetable matter, predominantly diatoms. Some seasonality was evident with high percentages of diatoms in spring in I. grammatica, and in autumn in I. difformis. The scope of food was larger in the latter species which contained about equal proportions of vegetable matter, chironomids, mayfly, stonefly, and black fly larvae. In I. grammatica plant matter and chironomids dominated strongly, comprising > 50% of the gut contents on an annual basis, > 90 % in spring. While small nymphs of I. difformis contained a low proportion of animal matter, only gradually increasing with size, the nymphs of I. grammatica were carnivorous from very early instars. Both species switched to a temporarily strong utilization of algae in spring. This differed among sites, and appeared to reflect differences in insolation and thus the availability of algae. There was a significant negative relationship between the mean densities of Isoperla nymphs and the proportion of animal material found in the guts of I. grammatica (R
2 = 0.86). Considering the density of I. grammatica alone, the relationship was weaker (R
2 = 0.56). A positive correlation between predator and prey size was observed. With chironomid prey the size range increased with predator size. With simuliid prey, however, prey size increased with predator size in such a way that it suggests selection rather than just an expanding prey size range. Correlations were stronger and regression coefficients significantly higher for I. grammatica than for I. difformis. We suggest that I. grammatica, which ingests a much wider size range of prey might choose prey of optimal sizes more readily than the more synchronously developing I. difformis. Although the life cycles of the two species are staggered, overlap in size distribution indicates that competition for food could be important in spring. However, observed differences in diet should facilitate coexistence. Gut content differences might in turn be accomplished through microhabitat segregation.

The diet of two species of Isoperla (Plecoptera: Perlodidae) in relation to season, site, and sympatry

Two Perlidae species, Dinocras cephalotes and Perla bipunctata, were studied in a river in Spain with the objectives of: a) describing their diets; b) detecting differences between size classes; c) analyzing niche breadth; and d) assessing the degree of niche overlap between both species and size classes. Dinocras cephalotes and Perla bipunctata nymphs fed mainly on Baetidae and immature Chironomidae. We did not detect significant differences in the quantity of ingested detritus, algae, and leaf pieces. Niche breadth was very low, although both species presented a high niche overlap. P. bipunctata seems to select some prey items throughout its nymphal development, whereas D. cephalotes augments its diet with other prey items as it grows. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Trophic Behavior of Two Perlidae Species (Insecta, Plecoptera) in a River in Southern Spain

We here review the current knowledge on the trophic ecology of stoneflies, an aquatic insect group of substantial ecological importance in lotic systems. We provide information on the feeding habit...

https://tandfonline.com/doi/pdf/10.1080/24750263.2019.1592251

Trophic ecology of Plecoptera (Insecta): a review

The life history of Dinocras cephalotes was investigated in a quantitative one‐year‐study in a river in the Swiss lower Alps and by growth studies in the laboratory. The relative growth between the instars is smaller for the males than for the females and decreases with increasing body size. By means of a growth model it is shown that there are 17 larval instars for the males and 18 for the females (95% confidence limits 15–20 and 17–21 resp.). Measurements of the wing pad size indicate that the males pass through fewer instars than the females. The life cycle of D. cephalotes lasts three years, of which almost one year is spent in embryogenesis. A survival rate of 85–90% was found per instar. The growth of this stonefly reaches a maximum in summer and drops to practically zero in winter.

Investigations on the life‐history of the stonefly Dinocras cephalotes Curt. (Plecoptera: Perlidae)

La part prise par les aliments vegetaux decroit dans la serie Arcynopteryx -Isoperla - Periodes - Perla et Dinocras Des differences morphologiques sont liees a cette evolution Les regimes alimentaires des Isoperla, Perla et Dinocras varient au cours de la vie larvaire Les relations entre la taille du predateur et celle des proies sont plus nettes pour les Baetis que pour les Chironomides Pour les Chironomides, elles sont de plus en plus marquees dans la serie Arcynopteryx - Isoperla - Perlidae

/pdf/regimes-alimentaires-et-pieces-buccales-de-quelques-5cyvwl4ido.pdf

M. Lahoud

Papers

Régimes alimentaires et pièces buccales de quelques Perlodidae et Perlidae des Pyrénées [Plecoptera]