Journal of Threatened Taxa | www.threatenedtaxa.org | 26 June 2021 | 13(7): 18949–18952

 

ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) 

https://doi.org/10.11609/jott.7198.13.7.18949-18952

#7198 | Received 07 December 2020 | Final received 03 April 2021 | Finally accepted 09 June 2021

 

 

Do predatory adult odonates estimate their adult prey odonates’ body size and dispersal ability to proceed with a successful attack?

 

Tharaka Sudesh Priyadarshana

 

Asian School of the Environment, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore.

tharakas001@e.ntu.edu.sg, tharakas.priyadarshana@gmail.com

 

 

Editor: Anonymity requested.   Date of publication: 26 June 2021 (online & print)

 

Citation: Priyadarshana, T.S. (2021). Do predatory adult odonates estimate their adult prey odonates’ body size and dispersal ability to proceed with a successful attack? Journal of Threatened Taxa 13(7): 18949–18952. https://doi.org/10.11609/jott.7198.13.7.18949-18952

 

Copyright: © Priyadarshana 2021. Creative Commons Attribution 4.0 International License.  JoTT allows unrestricted use, reproduction, and distribution of this article in any medium by providing adequate credit to the author(s) and the source of publication.

 

Funding: Self-funded.

 

Competing interests: The author declares no competing interests.

 

Acknowledgements: I thank all those who shared their records and identified predatory and prey odonate species through cyberspace, Christos Mammides for his comments on the first draft, and Subramaniam Gopalakrishnan for the Image 2.

 

 

The average body size and dispersal ability of a species significantly depends on its taxonomic order (Siemann et al. 1999). Indeed, there are significant body size and dispersal ability differences between predatory odonates and their typical prey items such as gnats, mayflies, flies, mosquitoes, and other small-sized flying insects. During one of my field visits in Sri Lanka in 2015, I observed an adult dragonfly (Orthetrum sabina) eating another species of dragonfly (O. luzonicum) (Image-- 1), and their average body sizes and dispersal abilities were similar. Similar observations were being circulated on Odonate-specialists’ Facebook (FB) groups, suggesting that adult odonates feed on other species of odonates or even the same species (see Image 2). When predators prey upon members of the same taxonomic group, it is difficult to predict whether the predators still estimate the size and dispersal ability of their potential prey items to proceed with a successful attack (Woodward & Hildrew 2002). This, however, can be measured by using a robust statistical analysis and a precise dataset.

Even though adult odonates feed upon adult odonates, such records are uncommon. To build the dataset, I surveyed two private FB specialists’ groups for such potential records. I manually checked every single post of the “DragonflySouthAsia” (https://www.facebook.com/groups/dragonflyindia) FB group between 2020 to 2016 and posts of the “Dragonfly Interest Group of Sri Lanka” (https://www.facebook.com/groups/256874097746055) FB group between 2020 to 2012. I also searched the “Odonata of India” (https://www.indianodonata.org/) website for more potential records. For most of those records, predator and prey species had been identified by experts within those groups. Prey odonates that could not be identified to species level due to predation were excluded from the final dataset. The records of mature predators preying upon juveniles were also excluded because that might result in some biases in the dataset as those individuals are immature. The final dataset included 67 records of adult predatory and prey odonate encounters from Sri Lanka (24) and India (43) — nine species of predators and 27 species of prey (see Table 1).

Morphometric trait measurement data related to body size and dispersal ability for each predator and prey odonate was extracted from the “Odonate Phenotypic Database” (OPD) at http://www.odonatephenotypicdatabase.org/ (Waller et al. 2019). When the data was not available in the OPD (only for eight species), the data was extracted from other published literature (see the Supplementary data for references). The average body length of each predator and prey species considered as the body size and potential dispersal ability was measured with the hind-wing length (only males in mm) for each species (Moretti et al. 2017). To measure whether there is a significant difference in body size and dispersal ability between predatory and prey odonates, I performed a Bayesian t-test using the “BEST” package with flat priors (Kruschke & Meredith 2020). Due to available replicates and data distribution, the Bayesian t-test approach provides a more robust way of estimating posterior probabilities of group differences (Kruschke 2013; Kruschke & Meredith 2020). All the statistical analyses were performed in R version 4.0.3 (www.r-project.org/).

The final dataset showed three types of predation behaviors between the two suborders of Odonata, i.e., (i) Anisoptera (dragonflies) prey upon Anisoptera (60 %, n= 40), (ii) Anisoptera prey upon Zygoptera (damselflies) (24 % of n= 16), and (iii) Zygoptera prey upon Zygoptera (16 %, n= 11), but there was no record of Zygoptera preying upon Anisoptera. Therefore, three separate analyses were performed for each type of predation to estimate the body size and dispersal ability differences between adult predatory and prey odonates. Since each suborder was separately analyzed, the hind-wing length measurements were not scaled relative to body length.

The results of the analysis showed strong evidence that the predatory odonates performing the attack had larger body size and greater hind-wing length than their prey odonates across all three predation types (see Table 2–4). This indicates that predatory adult odonates may estimate the body size and dispersal ability of the adult prey odonates to execute a successful attack even when both groups belong to the same taxonomic group. Orthetrum sabina had the highest percentage with 70 % (n= 47) of attacks on both Anisoptera and Zygoptera species, including O. sabina-O. sabina attacks (Image 2). It is also important to note that the attacks of the predatory odonates were mostly on the head or thorax of their prey odonates.

Data accessibility: Supplementary data for this study is available at, https://github.com/Tharaka18/Predatory-adult-odonates-and-their-adult-prey-odonates

 

 

Table 1. Records of adult predator and prey odonate encounters from Sri Lanka (24) and India (43) from 2012 to 2020. Please see the supplementary data for additional information and references.

Record number

Country

Predator odonate species

Prey odonate species

Records of Anisoptera (dragonflies) preying upon Anisoptera (n= 40)

1

Sri Lanka

Orthetrum sabina

Neurothemis tullia

2

Sri Lanka

Orthetrum sabina

Neurothemis tullia

3

Sri Lanka

Orthetrum sabina

Diplacodes trivialis

4

Sri Lanka

Orthetrum sabina

Orthetrum pruinosum

5

Sri Lanka

Ictinogomphus rapax

Brachythemis contaminata

6

Sri Lanka

Orthetrum sabina

Brachythemis contaminata

7

Sri Lanka

Orthetrum sabina

Orthetrum luzonicum

8

Sri Lanka

Orthetrum sabina

Neurothemis tullia

9

Sri Lanka

Orthetrum sabina

Orthetrum luzonicum

10

Sri Lanka

Orthetrum sabina

Brachythemis contaminata

11

Sri Lanka

Orthetrum sabina

Orthetrum luzonicum

12

Sri Lanka

Orthetrum sabina

Orthetrum pruinosum

13

India

Orthetrum sabina

Neurothemis fulvia

14

India

Orthetrum sabina

Tetrathemis platyptera

15

India

Orthetrum sabina

Diplacodes trivialis

16

India

Orthetrum sabina

Potamarcha congener

17

India

Orthetrum sabina

Diplacodes trivialis

18

India

Orthetrum sabina

Orthetrum sabina

19

India

Orthetrum sabina

Diplacodes trivialis

20

India

Orthetrum sabina

Diplacodes trivialis

21

India

Orthetrum sabina

Orthetrum sabina

22

India

Orthetrum sabina

Orthetrum pruinosum

23

India

Rhodothemis rufa

Neurothemis tullia

24

India

Orthetrum sabina

Rhyothemis variegata

25

India

Orthetrum sabina

Orthetrum pruinosum

26

India

Orthetrum sabina

Potamarcha congener

27

India

Orthetrum sabina

Diplacodes trivialis

28

India

Orthetrum sabina

Orthetrum sabina

29

India

Orthetrum sabina

Orthetrum sabina

30

India

Orthetrum sabina

Crocothemis servilia

31

India

Orthetrum sabina

Trithemis aurora

32

India

Orthetrum sabina

Pantala flavescenes

33

India

Orthetrum sabina

Potamarcha congener

34

India

Orthetrum sabina

Diplacodes trivialis

35

India

Orthetrum sabina

Pantala flavescenes

36

India

Orthetrum sabina

Trithemis aurora

37

India

Orthetrum sabina

Tholymis tillarga

38

India

Acisoma panorpoides

Acisoma panorpoides

39

India

Orthetrum sabina

Orthetrum sabina

40

India

Orthetrum sabina

Paragomphus lineatus

Records of Anisoptera (dragonflies) preying upon Zygoptera (damselflies) (n= 16)

41

Sri Lanka

Orthetrum sabina

Pseudagrion microcephalum

42

Sri Lanka

Acisoma panorpoides

Ceriagrion coromandelianum

43

Sri Lanka

Orthetrum sabina

Pseudagrion rubriceps

44

Sri Lanka

Orthetrum sabina

Pseudagrion microcephalum

45

Sri Lanka

Orthetrum sabina

Ceriagrion coromandelianum

46

Sri Lanka

Brachythemis contaminata

Pseudagrion rubriceps

47

India

Orthetrum sabina

Onychargia atrocyana

48

India

Orthetrum sabina

Lestes viridulus

49

India

Orthetrum sabina

Ischnura rubilio

50

India

Orthetrum sabina

Ischnura rubilio

51

India

Acisoma panorpoides

Ceriagrion coromandelianum

52

India

Acisoma panorpoides

Agriocnemis splendidissima

53

India

Brachythemis contaminata

Ischnura senegalensis

54

India

Brachythemis contaminata

Ischnura senegalensis

55

India

Orthetrum sabina

Ischnura senegalensis

56

India

Orthetrum sabina

Agriocnemis pygmaea

Records of Zygoptera (damselflies) preying upon Zygoptera (n= 11)

57

Sri Lanka

Ceriagrion cerinorubellum

Ceriagrion coromandelianum

58

Sri Lanka

Ceriagrion coromandelianum

Agriocnemis pygmaea

59

Sri Lanka

Ceriagrion coromandelianum

Onychargia atrocyana

60

Sri Lanka

Ischnura senegalensis

Agriocnemis pygmaea

61

Sri Lanka

Ceriagrion coromandelianum

Pseudagrion microcephalum

62

Sri Lanka

Ischnura senegalensis

Agriocnemis pygmaea

63

India

Ceriagrion coromandelianum

Ceriagrion cerinorubellum

64

India

Ceriagrion coromandelianum

Ceriagrion cerinorubellum

65

India

Ischnura senegalensis

Agriocnemis pygmaea

66

India

Ceriagrion coromandelanium

Ischnura senegalensis

67

India

Ceriagrion coromandelanium

Agriocnemis pygmaea

 

 

Table 2. Differences in body size (average body length in mm) and dispersal ability (hind-wing length in mm) between predator and prey odonates when both groups belong to Anisoptera (dragonflies) suborder (n= 40). SD indicates standard deviations, and L-95% and U-95% indicate 95% credible interval (lower and upper, respectively).

 

Mean

SD

L-95%

U-95%

Body size of predator odonates

46.500

0.001

46.498

46.502

Body size of prey odonates

39.992

2.415

35.208

44.530

Body size differences between predator and prey odonates

6.507

2.415

6.492

6.522

Dispersal ability of predator odonates

30.500

0.0006

30.498

30.501

Dispersal ability of prey odonates

28.251

1.482

25.287

31.027

Dispersal ability differences between predator and prey odonates

2.248

1.482

2.239

2.257

 

 

Table 3. Differences in body size (average body length in mm) and dispersal ability (hind-wing length in mm) between predator and prey odonates when predators belong to Anisoptera (dragonflies) and prey belong to Zygoptera (damselflies) suborder (n= 16). SD indicates standard deviations, and L-95% and U-95% indicate 95% credible interval (lower and upper, respectively).

 

 

Mean

SD

L-95%

U-95%

Body size of predator odonates

45.749

2.037

40.313

46.533

Body size of prey odonates

32.808

1.235

30.371

35.155

Body size differences between predator and prey odonates

12.941

2.252

12.926

12.955

Dispersal ability of predator odonates

30.499

0.003

30.494

30.505

Dispersal ability of prey odonates

18.624

0.871

16.797

20.221

Dispersal ability differences between predator and prey odonates

11.875

0.871

11.869

11.881

 

 

Table 4. Differences in body size (average body length in mm) and dispersal ability (hind-wing length in mm) between predator and prey odonates when both groups belong to Zygoptera (damselflies) suborder (n= 11). SD indicates standard deviations, and L-95% and U-95% indicate 95% credible interval (lower and upper, respectively).

              

Mean

SD

L-95%

U-95%

Body size of predator odonates

32.984

0.938

31.117

34.820

Body size of prey odonates

28.387

2.477

23.564

33.450

Body size differences between predator and prey odonates

4.597

2.658

4.581

4.614

Dispersal ability of predator odonates

18.600

1.010

16.606

20.324

Dispersal ability of prey odonates

14.359

1.718

10.919

17.829

Dispersal ability differences between predator and prey odonates

4.241

2.009

4.228

4.253

 

 

For images - - click here

 

 

References

 

Kruschke, J.K. (2013). Bayesian estimation supersedes the t test. Journal of Experimental Psychology: General 142(2): 573–603. https://doi.org/10.1037/a0029146

Kruschke, J.K. & M. Meredith (2020). BEST: Bayesian estimation supersedes the t test. R package version 0.5.1

Moretti, M., A.T.C. Dias, F. de Bello, F. Altermatt, S.L. Chown, F.M. Azcárate, J.R. Bell, B. Fournier, M. Hedde, J. Hortal, S. Ibanez, E. Öckinger, J.P. Sousa, J. Ellers & M.P. Berg (2017). Handbook of protocols for standardized measurement of terrestrial invertebrate functional traits. Functional Ecology 31(3): 558–567. https://doi.org/10.1111/1365-2435.12776

Siemann, E., D. Tilman & J. Haarstad (1999). Abundance, diversity and body size: patterns from a grassland arthropod community. Journal of Animal Ecology 68(4): 824–835. https://doi.org/10.1046/j.1365-2656.1999.00326.x

Waller, J.T., B. Willink, M. Tschol & E.I. Svensson (2019). The odonate phenotypic database, a new open data resource for comparative studies of an old insect order. Scientific Data 6(1): 316. https://doi.org/10.1038/s41597-019-0318-9

Woodward, G. & A.G. Hildrew (2002). Body-size determinants of niche overlap and intraguild predation within a complex food web. Journal of Animal Ecology 71(6): 1063–1074. https://doi.org/10.1046/j.1365-2656.2002.00669.x

Zhang, H. (2019). Dragonflies and damselflies of China. Chongqing University Press, Chongqing, China, xiv+1460pp.