Behavioural Ecology: The objectives of the study was to check if there is a relationship between size and copulation and mounting time, (2) to test if there is correlation between antennating and copulation/mounting frequency or time, and (3) compare the general behaviour performance of each male when they are alone with the female (experiment one) vs. when the other male is present (experiment two).

1. Mating behaviour of the small hive beetle,
Aethina tumida.
ZEN 363 Practical 2
Pitswane M.L
10294547
Department of Zoology & Entomology, University of Pretoria, Pretoria, 0002

2. Abstract
In many insect species females commonly mate with more than one male. In such events, one
must consider if there is a selection advantage to first male mating, second male mating, or to
either. The objective of the current study was to analyse the mating behaviour in Aethina
tumida, small hive beetles under laboratory conditions. We found that males and females of
the small hive beetles did not differ in their body size (head, length, and width). It was also
found that there was a negative correlation between size and mounting-copulation (P<0.05);
however a positive correlation was observed between size and mounting duration (P>0.05).
No relationship was observed between mounting and copulation frequency with antennating
time (R=0.02). It was found that experiment one and two differed significantly in terms of
mounting duration with relation to length, width and size. In addition, there was a significant
difference in terms of mounting frequency for length and width. There is too much
consistency in the data collected from this experiment, and we therefore suggest that more
experiments should be conducted and we advise future researchers to pay attention to detail.
Introduction
Sexual selection is defined as natural selection arising through preference by one sex
for certain characteristics in individuals of the other sex. Mate choice, a component of sexual
selection, is an evolutionary process in which selection of a mate depends on the
attractiveness of his or her traits. Sexual selection may be influenced by length, and body size
may have a large influence on male-male competition (Forslund 2000). It can be found that
male-male competition may determine which males are able to access females, and further,
female choice among available males (Forslund 2000).
Previous studies have found that in many species females commonly mate with more
than one male. In such events, one must consider if there is a selection advantage to first male
mating, second male mating, or to neither (Ginsberg and Huck 1989). If a single female had
to mate with sat male one (P1) and later male two (P2), the probability of success of sperm
from P2 can be low (first male precedence as seen in spiders, Austad 1984), or it can be high
(as seen in many insects, Parker and Simmons 1991).
In this experiment we look at the mating behaviour of small hive beetles, Aethina
tumida Murray (Coleoptera: Nitidulidae). These species are native to sub-Saharan Africa, and
are considered serious pests of honeybees in countries such as Canada and Australia (Hood
2004). Honeybees are economically valuable to man- in US alone the European honeybee,
Apis mellifera Lepeletier (Hymenoptera: Apidae) pollinates about US$215 billion worth of

3. crops (Gallai et.al 2009). The knowledge obtained from this paper can be used in Integrated
Pest Management to work against small hive beetles and ensure less damage to honeybees.
The current study looked at the beetle behaviour of males under no competition vs.
competition. The objectives of the study was to check if there is a relationship between size
and copulation and mounting time, (2) to test if there is correlation between antennating and
copulation/mounting frequency or time, and (3) compare the general behaviour performance
of each male when they are alone with the female (experiment one) vs. when the other male
is present (experiment two). Our null hypothesis is that there will be significant difference in
male behaviour between experiment one and experiment two.
Methods and Materials
Experiment
Male and female beetles were collected from the Department of Zoology & Entomology,
University of Pretoria. The insects were maintained in the fridge prior to experiment. The
females were marked using paint-like marker on their head. One male (P1) was placed inside
a petri-dish with the female and their behavioural pattern was observed for 10 minutes. After
10 minutes the first male was replaced with the second male (P2), and the same observations
were made. In the second part of the experiment, all beetles, male one, male two and the
female were all in one petri-dish together for 10 minutes, and their behavioural pattern was
observed.
In each case, the following behaviours were noted: mounting, antennating, standing, walking,
and walk-over, grooming, and copulation. We assumed that mounting is a proxy for mating
in addition to copulation.
Data analysis
All analysis was conducted in Microsoft Excel (Microsoft 2010) and IBM SPSS (Statistics
22). A correlation under case-wise deletion was used to analyse relationship between size and
copulation and mounting time as well as frequency. To determine if there was correlation
between antennating, mounting and copulation, a correlation case-wise deletion analysis was
conducted and a simple scatter plot graph was done. To compare the behavioural patterns
(copulation time, mounting duration, and mounting frequency) of each male between the two
experiments in relation to their size (length, width and head), a Wilcoxon matched pair’s test

4. was conducted. The Wilcoxon test is a non-parametric hypothesis test used for comparing
related samples, and it serves as an alternative for data that is not normally distributed.
In total 49 beetles, 22 of which were males and 18 of which were females.
Results
Body size in males and females
It was found that on average the body length, body width and head size of male and female
subjects did not differ (Table 1).
Table 1: The average sizes of the length, width and head of the female and male Aethina tumida, small hive
beetles.
Beetles Length Width Head
Females 6.3 3.8 1.3
Males 6.7 3.8 1.7
In the first correlation test analysing the relation between size and mounting-copulation, we
found that there was a significant correlation for size and mounting duration (P<0.05),
however the opposite was observed for mounting frequency (P>0.05) (Figure 1 and Figure 2).
Mount duration (sec)
Small Size category Big
Figure 1: Correlation between mounting duration and size category of male Aethina tumida species.
The males were classified as either small or big based on their size, and therefore the data was not
continuous. Data was obtained from both experiments where (1) each male was given ten minutes
with the female alone, and (2) both males and the females were together in one petri-dish. N=16

5. Small Size category Big
Mount frequency
Figure 2: Correlation between mounting frequency and size category of male Aethina tumida species. The
males were classified as either small or big based on their size, and therefore the data was not continuous.
Data was obtained from both experiments where (1) each male was given ten minutes with the female
alone, and (2) both males and the females were together in one petri-dish. N=16
Correlation between antennating and mounting/copulation frequency and duration
Analysis of mounting and copulation frequency combined against antennating time revealed
that there was no relationship between the two parameters (R²=0.02) (Fig.1).
y = -0.1538x + 95.747
R² = 0.0131
600
500
400
300
200
100
0
0 100 200 300 400 500
Mounting/Copulation time (sec)
Antennating time (sec)
Figure 3: A scatter plot showing the relationship between antennating time and mounting/copulation time
of Aethina tumida male species. Data was collected from 22 males that were singularly exposed to one
female (different for each male) for ten minutes each.

6. Comparison of male behaviour between experiment one (single male and female) and
experiment two (two males and one female)
It was found that experiment one and two differed significantly in terms of mounting duration
with relation to length, width and size (Table 2). In addition, there was a significant
difference in terms of mounting frequency for length and width. Data for experiment two for
copulation time was missing.
Table 2: Comparison of mating behaviour patterns of Aethina tumida males when
exposed to one female (exp 1) and when exposed to one female in presence of another
male (exp 2). Those behaviours that showed a significant difference between the two
experiments are highlighted (dark writing). (-) indicates no data.
Mount duration Mount frequency Copulation time
Exp 1 Exp 2 Exp 1 Exp 2 Exp 1 Exp 2
Length 0.313464 0.025094 0.000276 0.000112 0.575487 -
Width 0.287338 0.021679 0.006947 0.001507 0.575487 -
Head 0.145401 0.005685 0.663197 0.687409 0.575487 -
Discussion
P-values
In this species, we found that males and females do not differ very much in terms of their
body size (head, length, and width). Given these results, we cannot expect size to have a
significant difference on mating behaviours; however care must be taken that this lack of
difference is observed between the sexes, there might be a large variation within the same
sex. Mounting duration showed a negative correlation with size, and surprisingly, mounting
frequency showed a positive correlation. In this study there were a lot of inconsistencies with
regards to the data and this proved a difficulty in data analysis. For example, measurements
were not consistent, in experiment two we failed to record copulation duration.
In comparing the two experiments to find out if presence of second male played a role
in the mating behaviour, we found that there was no difference. Whether the male was alone
with the female or with yet other male, mating behaviours were similar, in other words, we
could say that there was no competition. However, in some individuals we observed some
dominance during the second experiment, of which varied from the larger male to the smaller
male within the enclosure.

7. In certain individuals we observed that other males would mount on the other male
instead of the female. Switzer et.al (2014) suggests that the reasons behind this observation
may lie in understanding the selection pressures resulting from the mating systems of the
species. In addition, we did not observe any aggressive competition between the beetles.
However, the males did sometimes attempt to take over ecen after the first male had
mounted/copulated with the female. Kruse and Switzer (2007) contest that even though such
events may last longer, the chances of successfulness is minimal. Thus, a male’s best option
may be to be the first male and find an available female (Switzer et.al 2014)

8. References
Bonduriansky, R. 2001. The evolution of male mate choice in insects: a synthesis of ideas
and evidence. Biology Review 76: 305-339
Fisher, R. A. 1930. The Genetical Theory of Natural Selection. Oxford, Clarendon Press
Forslund P. 2000. Male-male competition and large size mating advantage in European
earwigs, Forficula auricularia. Animal Behaviour 59:753-762.
Gallai N., Salles J.M, Settele J., Vaissiere B.E. 2009. Economic valuation of the vulnerability
of world agriculture confronted with pollinator decline. Ecological Economics 68(3):810–821
Ginsberg, J.R., Huck, U.W. 1989.Sperm competition in mammals. Trends Ecological
Evolution 4: 74-79
Kruse, K.C., Switzer, P.V. 2007. Physical contests for females in the Japanese beetle,
Popillia japonica. Journal of Insect Sciences 7:34
Switzer, P.V., Forsythe, P.S., Krusel, K.C. 2014. Male-male mounting and the unreliability of
body size as a character for mate choice in male Japanese beetles (Popillia japonica
Newman). Zoological Studies 53:53
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