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 |
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.