Journal of Threatened Taxa | www.threatenedtaxa.org | 26 July
2019 | 11(9): 14137–14143
Observations on nesting
activity, life cycle, and brood ball morphometry of the Bordered Dung Beetle Oniticellus cinctus
(Fabricius, 1775) (Coleoptera:
Scarabaeidae) under laboratory conditions
Amar Paul Singh 1, Kritish De
2, Shagun Mahajan 3, Ritwik Mondal 4 & Virendra Prasad Uniyal 5
1,2,5 Department
of Landscape Level Planning & Management, Wildlife Institute of India, Chandrabani, Dehradun, Uttarakhand 248001, India.
1,4 Department
of Zoology, University of North Bengal, Darjeeling, West Bengal 734013, India.
3 Department of
Zoology, Alpine Institute of Management and Technology, Dehradun, Uttarakhand
248007, India.
1 amarpaulsingh4@gmail.com,
2 kritish.de@gmail.com, 3 shagunmahajan2017@gmail.com,
4 ritwik.uk12@gmail.com
(corresponding author), 5 uniyalvp@wii.gov.in
doi: https://doi.org/10.11609/jott.4023.11.9.14137-14143
Editor: Hemant V. Ghate, Modern College of Arts Science and Commerce, Pune,
India. Date
of publication: 26 July 2019 (online & print)
Manuscript details: #4023 | Received 23 January 2018 | Final received 23
June 2019 | Finally accepted 02 July 2019
Citation: Singh, A.P., K. De, S. Mahajan, R. Mondal & V.P. Uniyal (2019). Observations on nesting activity, life cycle, and
brood ball morphometry of the Bordered Dung Beetle Oniticellus
cinctus (Fabricius,
1775) (Coleoptera: Scarabaeidae)
under laboratory conditions. Journal of
Threatened Taxa 11(9): 14137–14143. https://doi.org/10.11609/jott.4023.11.9.14137-14143
Copyright: © Singh et al.
2019. Creative Commons Attribution 4.0
International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by adequate credit to the author(s)
and the source of publication.
Funding: No funding was
received for this study.
Competing interests: The authors
declare no competing interests.
Author
details: Amar Paul
Singh was a postgraduate (zoology)
student and he is presently working as a researcher. His research interests
include diversity, taxonomy, ecology and behaviour of
insects particularly in beetles. Kritish De
is presently working as a researcher and his research interests include
diversity and ecology of insects. Shagun Mahajan
was a postgraduate (zoology) student and she is interested in the field of
biodiversity and ecology. Ritwik Mondal is working as an assistant
professor. He has previous research experience in the field of mosquito
ecology, vector biology and fish toxicology. His current research interest is
in the field of molecular taxonomy of arthropods and fish as well as in the
physiological and genotoxic effects of insecticides and pesticides on fish. Virendra
Prasad Uniyal
is working as Senior Professor and Scientist G. He is a Fellow of The Royal
Entomological Society, London. His research interests include ecology and
systematic of insects, bioindicators, biodiversity surveys and ecological
monitoring in western Himalayan protected areas.
Author
contribution: APS—collection of samples,
laboratory work, and preparation of the manuscript; KD—laboratory work, data
analysis, and preparation of the manuscript; SM—collection of samples and
laboratory work; RM—designing the study, directing and supervising laboratory
work and data analysis, and preparation of the manuscript; VPU—designing the
study, directing and supervising laboratory work and data analysis, and
preparation of the manuscript.
Acknowledgements:
Authors are thankful to the
Director and the Dean, Wildlife Institute of India, Dehradun and Dr V.P.
Sharma, Principal, Alpine Institute of Management and Technology, Dehradun for
their support and for providing necessary facilities for the study.
Abstract: The nesting activity, life cycle, and brood ball
morphometry of the dung beetle Oniticellus cinctus (Fabricius, 1775) (Coleoptera: Scarabaeidae) were
studied under laboratory conditions for the first time in India. The females made a brood chamber within the
dung mass provided, wherein they made brood balls to lay eggs. The life cycle includes egg, larva (three
instars), pupa, and adult stages. The
total duration for the development was about one month. The study found that there was a significant
difference present in the brood ball diameter (except in the first and second instars) and brood ball weight (except in the second instar
and pupa) of the six life cycle stages.
It was also found that brood ball weight and diameter have a significant
positive correlation as well as a linear relationship.
Keywords: Morphometry, nidification,
scarabaeid beetle, Scarabaeinae,
weight-diameter relationship.
INTRODUCTION
The coleopteran insects (beetles) belonging to the
subfamilies Aphodiinae and Scarabaeinae
under the family Scarabaeidae are commonly called
dung beetles as they feed primarily on mammalian dung and also use it for
providing nesting and food for their larvae.
The beetles of the subfamily Scarabaeinae are
well-represented insects in the tropical regions (Filgueiras
et al. 2009). Both sexes of the adults
were identified with the help of published taxonomic keys (Chandra & Gupta
2013).
Globally, some studies have been done to understand nidification of dung beetles. Klemperer (1982a,b,c, 1983a,b,c, 1984)
studied the nesting behaviour of several species of dung beetles. Biscoe (1983) studied the effects of ovarian
condition on the nesting behaviour of Copris
diversus Waterhouse, 1891. Sato & Imamori
(1987) studied the nesting behaviour of the African Ball-roller Kheper platynotus
(Bates, 1888). Edwards & Aschenborn (1987) studied patterns of nesting and dung
burial in Onitis dung beetles. Davis (1989) studied nesting of the
Afrotropical Oniticellus and its evolutionary
trend from soil to dung.
So far, there are no studies to understand the
morphometry of brood balls (the round-shaped ball made up of dung constructed
by the female to lay eggs within it) as well as the weight-diameter
relationship of different life cycle stages of Oniticellus
cinctus from India.
MATERIAL AND METHODS
The study was carried out from the first week of May
to the end of the second week of June 2017 for a period of about six
weeks. The adults (both males and
females) of Oniticellus cinctus
were collected from dung that was 2–3 days old using hand-sorting method and
were transported to the laboratory of the zoology department, Alpine Institute
of Management and Technology, Dehradun.
Five pairs of beetles (one male and one female in each
pair) were chosen for the study. Five
rearing trays, each of 40cm (L) × 30cm (W) × 15cm (H) size were set up and
filled up to two-thirds with a mixture of soil and sand. The mixture was moistened with the requisite
amount of water. For the maintenance of
adequate temperature, humidity, and darkness, each rearing tray was covered
with inverted earthen pots. One pair of
adults (one male and one female) was released in each tray. Fresh cow dung was provided and the old dung
replaced daily.
After about six days from the release of the adults in
the rearing trays, the nest construction occurred. A total of 50 brood balls (10 from each pair
in each tray) were selected for our study; the rest of the brood balls were
removed from the tray. Regular
observations were conducted once a day (at 08.00h) by opening the brood balls
to observe the development of the individual from egg to adult stage. The opening in the brood balls was
immediately sealed after observation with the help of fresh dung. The weight and diameter of the brood balls
were taken on the final day of each developmental stage by Kerro
laboratory analytical balance (accuracy 0.01gm) and Mitutoyo digital vernier calliper.
One-way ANOVA followed by post hoc Dunn’s test was
performed to find out the presence of a significant difference (if any) in the
diameter and weight of brood balls between lifecycle stages. Pearson’s product-moment correlation
coefficient (r) was calculated to explore the strength of association between
the diameter and weight of brood balls between lifecycle stages. Linear regression model between diameter and
weight of brood balls in different life cycle stages was calculated. All the statistical analysis was performed
using R version 3.3.1 (R Core Team 2016).
RESULTS
The life cycle of Oniticellus
cinctus includes egg, three larval (first,
second, and third instar) stages, pupal stage, and adult.
The body of the adult (Image 1A) is dorsoventrally
compressed and oblong and the colour is shiny black. The head is shining, smooth, and without any
carina (elevation or ridge of the cuticle).
The antennae are 8-segmented. The
scutellum is visible. The pronotum is
smooth and a deeply impressed median longitudinal line is present upon its
posterior half. The elytra (external and
sclerotized forewings) are deeply striated and each elytron has a pale yellow
external border. Fore tibia of the male
have small inner teeth with inner spur while that of the female have broad
inner teeth and no spur.
The female mangled the dung gradually to prepare a
lopsided (one side lower or smaller than the other) chamber initially. Finally, a hollow chamber (called brood
chamber) of around 6–10 cm in width, 4–8 cm in height, and 5–7 cm in depth was
constructed to store brood balls within the provided dung mass (Image 2). The females used prothoracic legs (Image 1B)
for the construction of the brood chamber or nest. Approximately 12–20 brood balls were
constructed by each female and one egg was laid within each brood ball. The female beetle was present in the chamber
during the entire period of the brood development. It also applied fresh dung on the brood ball
during the entire period of the brood development and made the next nest after
the development was completed.
Eggs were cylindrical and white or creamy and only one
egg was present in each brood ball (Image 3).
Egg development was completed and the larva hatched within 3–5 days
(mean = 4.2 days, SD = 0.75; Fig. 1).
Three larval stages, namely first instar larva (Image
4), second instar larva (Image 5), and third instar larva (Image 6), were
observed. The developmental time for the
first, second, and third instars was 1–3 days (mean = 2.32 days, SD = 0.68),
1–3 days (mean = 2.24 days, SD = 0.74), and 10–16 days (mean = 13.52 days, SD =
1.52), respectively (Fig. 1). Larvae
were C-shaped with a projecting hump, light grey; the head was somewhat light
orange. Four segmented antennae and two
segmented legs were present. Maxilla
with galea and lacinia were distinctly separated in the larva.
The pupa (Image 7) was whitish and appeared pointed
from the posterior portion. A large and
blunt pronotal projection extended over a posterior
portion of the head. Pupa development
was completed within 4–8 days (mean = 5.58 days, SD = 1.2; Fig. 1).
The adult remained in the brood ball for 1–3 days
(mean = 2.24 days, SD = 0.72; Fig. 1), after which it emerged. The total duration of the development was
about one month (mean = 30.08 days, SD = 5.35).
Mean weight and diameter of the brood balls on the
final day of egg development (freshly-hatched larva) were 0.27g (SD = 0.11;
Fig. 2) and 6.25mm (SD = 1.24; Fig. 3), respectively. Mean weight and diameter of the brood balls
on the final day of the first instar larval development was 0.50g (SD = 0.15;
Fig. 2) and 9.55mm (SD = 1.48; Fig. 3), respectively. Mean weight and diameter of the brood balls
on the final day of second instar larva development was 1.14g (SD = 0.30; Fig.
2) and 10.046mm (SD = 1.02; Fig. 3), respectively. Mean weight and diameter of the brood balls
on the final day of third instar larval development was 1.83g (SD = 0.31; Fig.
2) and 12.012mm (SD = 1.47; Fig. 3), respectively. Mean weight and diameter of the brood ball on
the final day of pupa development was 1.11g (SD = 0.23; Fig. 2) and 15.018mm (SD = 0.66; Fig. 3),
respectively. Mean weight and diameter
of the brood balls where freshly developed adults rested was 0.66g (SD = 0.26;
Fig. 2) and 15.294mm (SD = 0.71; Fig. 3), respectively.
The result of one-way ANOVA showed that there was a
significant difference present in the brood ball weight of the six life cycle
stages (F = 279.24, df = 5,294; p < 0.05). The result of post-hoc Dunn’s test suggested
that there was no significant difference (at α = 0.05) present in the brood
ball weight of the second instar and pupa (z score = -0.066, p = 0.474; Fig.
2).
The result of one-way ANOVA showed that there was a
significant difference present in the brood ball diameter of the six life cycle
stages (F = 458.84, df = 5,294; p < 0.05). Result of post-hoc Dunn’s test suggested that
there was no significant difference (at α = 0.05) present in the brood ball
diameter of first instar and second instar (z score = -0.843, p = 0.1995) and
of pupa and adult (z score = -0.594, p = 0.276; Fig. 3).
Pearson product-moment correlation between diameter
and weight of brood balls in different life cycle stages was found to be
significant (p < 0.05) and positive (Fig. 4). It was found that the weight of the brood
balls of different life cycle stages had a
simple linear relationship with the diameter of the brood balls (Fig.
4).
DISCUSSION
Three groups of dung beetles are
distinguished based on their behaviour in creating a brood mass, namely teleocoprids, paracoprids, and endocoprids (Ridsdill-Smith
2003). Teleocoprid
dung beetles make balls of dung and roll the dung ball away from the dung pat
and bury it in soil. Paracoprid
dung beetles dig a tunnel in the soil under the dung pat, carry small piece of
dung down that tunnel, and pack in to the end as a compacted brood mass. Endocoprid dung
beetles construct brood balls in cavities within the dung pat (Ridsdill-Smith 2003).
Oniticellus cinctus,
which was chosen for the study, is an endocoprid dung
beetle. This genus belongs to the
variation 1 of Group 1 nidification category (Halffter & Matthews 1966) because the female prepares a
small dung mass and lays one egg in each under the food source, i.e., the dung.
The present study found that the
life cycle of Oniticellus cinctus is completed within six weeks with egg, three
larval stages (first, second, and third instar), pupa and adult stages, of
which duration of third instar larva is maximum.
By performing one-way ANOVA, it
was found that the mean weight and mean diameter of the brood balls of
different life cycle stages had significant differences; however, as it is an
omnibus test, it did not specify which stage of the life cycle had different
mean weight and mean diameter of the brood balls. Post hoc Dunn’s test was performed to
overcome this issue. It was found that
there was no significant difference in brood ball diameter of first instar and
second instar and of pupa and adult and there was no significant difference in
brood ball weight of second instar and pupa and of first instar and adult. As correlation and simple linear regression
models are two ways of exploring a potential linear relationship between the
values of the two traits (Puth et al. 2014), these
methods were applied to find the relationship between diameter of the brood
balls of different life cycle stages of Oniticellus
cinctus; it was found that weight and
diameter of brood balls had significant (p < 0.05) positive correlation and
they fit the simple linear model.
Previously only Klemperer
(1983b) had studied the effect of the brood on parental care and oviposition of
this dung beetle species. The present
study had similarities with the study by Klemperer (1983b) in terms of
morphometry of brood balls and developmental times for different life cycle
stages. The present study reported the
use of prothoracic legs by female to built brood
chamber or nest. Klemperer (1983b) found that often a male adult was present in
the nest when several beetles were present in the experimental setup. But the present study did not observe such
thing, most probably because of only one pair of adult beetles (one male and
one female) was released in each rearing tray for the study.
It is necessary to study the nidification of dung beetles of all three behavioural
categories (teleocoprids, paracoprids,
and endocoprids) in both laboratory and field
conditions, especially the field-level nidification
and brood ball morphometry studies in different seasons and habitats.
For figures
& images – click here
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