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Length–biomass equations to allow rapid assessment of semi‐aquatic bug biomass in tropical streams

Harianja, Martina F.; Luke, Sarah H.; Barclay, Holly; Chey, Vun K.; Aldridge, David C.; Foster, William A.; Turner, Edgar C.


Martina F. Harianja

Assistant Professor

Holly Barclay

Vun K. Chey

David C. Aldridge

William A. Foster

Edgar C. Turner


1. Length-biomass equations are relatively easy and cost-effective for deriving insect biomass. However, the exact relationship can vary between taxa and geographical regions.
2. Semi-aquatic bugs are abundant and are indicators of freshwater quality, but there are no studies investigating the effect of habitat disturbance on their biomass, although it is useful in assessing ecological processes.
3. We identified the best-fit length-biomass models to predict the biomass of semi-aquatic bugs (Gerromorpha, Hemiptera) collected from streams in Sabah, Malaysia.
4. We used 259 juvenile and adult semi-aquatic bugs to compare a range of plausible length-biomass functions, and to assess whether relationships differed across the following families and body forms: a.Cylindrostethinae, Gerrinae, and Ptilomerinae, which are subfamilies within Gerridae consisting of small to large bugs that have long and slender bodies, b. Halobatinae, a subfamily within Gerridae, consisting of small to medium-sized bugs with wide heads and thoraxes as well as short abdomens, and c. Veliidae, which are small bugs with stout bodies.
5. Estimation used five fitting functions (linear regression; polynomial regression order two, three, and four; and power regression) on the following groupings: three body forms combined; each body form with life stages (juvenile and adult) combined; and each body form with life stages separated.
6. Power regressions were the best fit in predicting the biomass of semi-aquatic bugs across life stages and body forms, and the predictive power of models was higher when the biomass of different body forms was calculated separately (specifically for Halobatinae and Veliidae). Splitting by life stages did not always result in additional improvement.
7. The equations from this study expand the scope of possible future ecological research on semi-aquatic bugs, particularly in Southeast Asia, by allowing more studies to consider biomass-related questions.


Harianja, M. F., Luke, S. H., Barclay, H., Chey, V. K., Aldridge, D. C., Foster, W. A., & Turner, E. C. (2023). Length–biomass equations to allow rapid assessment of semi‐aquatic bug biomass in tropical streams. Entomologia Experimentalis et Applicata, 171(2), 102-115.

Journal Article Type Article
Acceptance Date Jul 21, 2022
Online Publication Date Oct 19, 2022
Publication Date 2023-02
Deposit Date Sep 14, 2022
Publicly Available Date Oct 20, 2023
Journal Entomologia Experimentalis et Applicata
Print ISSN 0013-8703
Electronic ISSN 1570-7458
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 171
Issue 2
Pages 102-115
Keywords Insect Science; Ecology, Evolution, Behavior and Systematics
Public URL
Publisher URL


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