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Do Crickets Use Vibrations to Detect Potential Predators?

ABSTRACT

Predator detection in any environment is necessary for survival. The aim of the paper is to find out whether crickets use vibrations to detect potential predators. The experimental design involved 10 males and 5 females. Music was used as the source of predation at varying music volumes. In the control experiment, the crickets were not exposed to any music, but in two successive tests, the crickets were exposed to slow and high music. The number of chirping per test was recorded and the numbers of chirps were counted for each test. The experiment was repeated three times. The results showed that the number of chirps decreased as the music volume increased. But the decrease was tremendous when the crickets were exposed to high volume music. Chirping in crickets is used to communicate but when they sense that predators are eavesdropping, they immediately stop chirping or reduce the number of chirps. The study showed that crickets definitely use vibration to sense the presence of predators. When the music volume increased, the numbers of chirps reduce completely.

INTRODUCTION

Predator detection is an important aspect of survival in any given environment. Crickets are defenseless insects compared to other animals that can rapidly fly or use venomous stingers (Yager, 2012). Therefore it is appropriate for them to detect predators as early as possible to be able to hide or fly away. Without predator detection techniques, then predators can easily locate them given their courtship communication by chirping at night. Communication through vibration detection is not uncommon in crickets. It is essential that crickets communicate and locate potential mates to sustain their population but also evade predators at the same time. A study done by researchers at Indian Institute of Science, Bangalore and Hyderabad Central University, found out that a particular species of bushcricket use disguised vibrations to seek the male (Vaidya, 2015). In usual circumstances, the female would come looking for the calling male to mate. But the bushcricket females camouflage themselves by hiding under jackfruit leaves and silent. The female send the vibration through the tree to guide the male where she is. The researchers found out that the bushcricket has evolved some unusual low frequency call that cannot be detected by predators.

Crickets commonly use acoustical communication to relay messages to one another especially during courtship (Yager, 2012) Crickets produce air-borne sounds which can be heard by humans. Therefore, this kind of communication has been extensively studied for a long time meaning that there is possibility of communication through vibrations. However, vibrational communication has been known to exist for many years but it was thought to be of less importance. In the recent years substrate-borne vibrations have become clear that it is important and widespread. Therefore the purpose of the study is to find out whether crickets use vibrations to detect potential predators. The hypotheses of the study are: 1) there will be cricket chirping when there is no music, 2) there will be low or no cricket chirping with soft music and 3) there will be no cricket chirping with high music.

MATERIALS & METHODS

The crickets were collected at night using an insect trap. From the sample, 10 males and 5 females were taken randomly. The crickets were placed in the same room. Music from a phone was used as the source of predator. High and soft music NOTE: How do you define high and soft music?? represented the predator presence and no music represented absence of predator and acted as the control experiment. The number of cricket chirping was recorded How was this recorded? By using Click Counter application on the iPhone then later counted with no music, with soft music and finally with loud music. The experiment was repeated three times for accuracy purposes. When was it repeated? We repeated it immediately at the same time.

RESULTS

The outcome of the experiment showed that the number of cricket chirping decreased as the volume of music increased Volume or type of music? This is under tone. The number of chirping is shown in the table below.

Table 1: Showing number of cricket chirping in the absence and presence of music

Figure 1.

Figure 1 showing that the number of cricket chirping decreased as the volume of music increased.

Table 2: Calculations for the chi square test of independence

Chi Square (X2) = the sum of all the (fo- fe)2/fe

Where by fo is the frequency of the observed (O) data while fe is the frequency of the expected (E)data.

Therefore Chi Square Total is 6.4314 and the Degree of Freedom (df) is number of columns (c)minus one, multiply by number of rows (r) minus one: (c-1)(r-1)= 4

Predetermined alpha level of significance is: 0.05. From the Chi Square Distribution table, the p-value is 9.488. Thus, the Ho (null hypothesis) will not be rejected because the p-value (6.4314) is greater than the significance level (0.05), p>0.05.

Figure 2.

figure 2 shows plots of chi square values at various degrees of freedom.

DISCUSSION

Crickets can detect vibrations produced by sounds within their environments. Crickets can easily detect vibrations produced by their predator. The music in the experiment represented sound produced by a predator Who do you know this?. The results showed that as the volume of music increased, the number of chirping decreased. This means when crickets detect danger, they decrease the rate of chirping or stop completely to prevent predators from locating them. The control experiment was done with no music and the number of chirping was the highest. But the number of chirping decreased as the experiment was repeated. When the music volume was slow, the number of chirping decreased but within the range of four hundred and above chirps. However, when the volume was changed to high, the number of chirping decreased tremendously. Need to fix this section

The experiment supported our hypotheses formulated were right. The first hypothesis predicted that there will be cricket chirping with no music. According to the results in table 1, the number of chirping was recorded the highest for all the three experiments. But the second hypothesis predicted that there will be low or no chirping with slow music. The results however showed that there were chirping but not as many as when there is no music. For the third hypothesis, it predicted that there will be no chirping, which is not true because there was chirping but very minimal. Therefore, this study has shown that crickets use vibrations to detect potential predators (Kortet, & Hedrick, 2004). According to a study done by Benz, et al. (2014) crickets distinguish the cues for different predators which include vibrations What types do vibrations?. The vibrations that are released by approaching predators are unique and crickets can easily identify and respond accordingly (Bucher et al, 2014). This adds to the little existing knowledge about crickets’ use of vibration to detect predators. Research has shown that crickets use filiform hairs found on their cerci to sense the faintest air movements produced by approaching predators (Magal et al, 2006).But further studies need to be done to determine how they detect the vibration from predators.

Work Cited

Binz, H., Bucher, R., Entling, M. H., &Menzel, F. (2014).Knowing the risk: crickets distinguish between spider predators of different size and commonness.Ethology, 120(1), 99-110.

Bucher, R., Binz, H., Menzel, F., &Entling, M. H. (2014). Spider cues stimulate feeding, weight gain and survival of crickets. Ecological Entomology, 39(6), 667-673.

Magal, C., Dangles, O., Caparroy, P., & Casas, J. (2006). Hair canopy of cricket sensory system tuned to predator signals. Journal of theoretical biology, 241(3), 459-466.

Kortet, R., & Hedrick, A. (2004). Detection of the spider predator, Hololenanedra by naive juvenile field crickets (Gryllus integer) using indirect cues. Behaviour, 141(9), 1189-1196.

Vaidya, A. (2015). Bushcricket duets combine discreet vibrations with sound to elude predators. IndiaBioscience. Retrieved 22 February 2016, from https://indiabioscience.org/news/2015/bushcricket-duets-combine-discreet-vibrations-with-sound-to-elude-predators

Yager, D. D. (2012).Predator detection and evasion by flying insects.Current opinion in neurobiology, 22(2), 201-207.

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N Mean Std Dev S.E.

0

100

200

300

400

500

600

No Music

Soft Music

Hard Music