Diversity and Ecosystem Services of Trichoptera

Abstract

The holometabolous insect order Trichoptera (caddisflies) includes more known species than all of the other primarily aquatic orders of insects combined. They are distributed unevenly; with the greatest number and density occurring in the Oriental Biogeographic Region and the smallest in the East Palearctic. Ecosystem services provided by Trichoptera are also very diverse and include their essential roles in food webs, in biological monitoring of water quality, as food for fish and other predators (many of which are of human concern), and as engineers that stabilize gravel bed sediment. They are especially important in capturing and using a wide variety of nutrients in many forms, transforming them for use by other organisms in freshwaters and surrounding riparian areas. The general pattern of evolution for trichopteran families is becoming clearer as more genes from more taxa are sequenced and as morphological characters are becoming understood in greater detail. This increasingly credible phylogeny provides a foundation for interpreting and hypothesizing the functional traits of this diverse order of freshwater organisms and for understanding the richness of the ecological services corresponding with those traits. Our research also is gaining insight into the timing of evolutionary diversification in the order. Correlations for the use of angiosperm plant material as food and case construction material by the earliest ancestors of infraorder Plenitentoria-by at least 175 Ma-may provide insight into the timing of the origin of angiosperms.

Keywords: angiosperm; caddisfly; evolution; phylogeny; trait.

Figure 1

Adult of Brachycentrus americanus (Banks, 1899) (Brachycentridae). © J.C. Morse.

Figure 2

Phylogeny of extinct (†) and extant Trichoptera families. Solid lines refer to relationships inferred with molecular data by Kjer et al. [67] with some refinements [69,70]. Dashed lines refer to relationships inferred by other data (mostly morphological) from various sources: †Vitimotauliidae [71,72], Dipseudopsidae [73], †Electralbertidae [74], Kambaitipsychidae [75], Pseudoneureclipsidae [75], Philopotamidae [73], †Necrotauliidae [76,77], Plectrotarsidae [73], †Baissoferidae [72], †Dysoneuridae [78], Kokiriidae [73], †Ningxiapsychidae [79], Rossianidae [73], †Taymyrelectronidae [80], †Yantarocentridae [8], Thremmatidae [81], Uenoidae [73], Atriplectididae [73], †Ogmomyiidae [9], Ceylanopsychidae [82], Antipodoeciidae [82], Beraeidae [82], Chathamiidae [73], Hydrosalpingidae [82], Parasericostomatidae [82], and Heloccabucidae [82]. Lengths of lines are arbitrary and uninformative.

Figure 3

(a): Filter net and gravel retreat of Hydropsyche sp. (Hydropsychidae) between large stones. (b): Larva of Hydropsyche bulgaromanorum Malicky, 1977 (Hydropsychidae). Both images © W. Graf.

Figure 4

Larva of Wormaldia sp. (Philopotamidae) in its filter net. © W. Graf.

Figure 5

Capture nets of Neureclipsis sp. (Polycentropodidae). © W. Graf.

Figure 6

(a): Larva of Plectrocnemia conspersa (Curtis, 1834) (Polycentropodidae). (b): Capture net of P. conspersa. Both figures © W. Graf.

Figure 7

Larvae of Tricholeiochiton fagesii (Guinard, 1879) (Hydroptilidae) in its case. © W. Graf.

Figure 8

(a): Larvae of Glossosomatidae grazing epilithic periphyton from large stones. (b): Larva of Synagapetus sp. (Glossosomatidae) in its case. Both figures © W. Graf.

Figure 9

Larva of Rhyacophila sp. (Rhyacophilidae). © W. Graf.

Figure 10

(a): Larva of Oligostomis reticulata (Linnaeus, 1761) (Plenitentoria: Phryganeidae) in its case composed of pieces of angiosperm leaves; © W. Graf. (b): Larva of Drusus sp. (Plenitentoria: Limnephilidae) in its case composed of gravel; © S. Vitecek.

Figure 11

(a): Larva of Beraeodes minutus (Linnaeus, 1761) (Brevitentoria: Beraeidae) and its case composed of fine sand. (b): Larva of Triaenodes bicolor (Curtis, 1834) (Brevitentoria: Leptoceridae) in its case composed of pieces of angiosperm leaves. The rows of long hairs on the legs are used for swimming. Both figures © W. Graf.

Figure 12

Larvae of Allogamus auricollis (F.J. Pictet, 1834) (Plenitentoria: Limnephilidae) filtering FPOM with their hairy legs. © W. Graf.