Abstract: Psalmocharias alhageos is an important pest of vine in most parts of Iran, Afghanistan, Pakistan, southern areas of Russia, Turkey and Iraq. This cicada is spread in most provinces in Iran such as Esfahan, Hamedan, Qazvin, Markazi, Lorestan, Qom, Kerman, Tehran and Kordestan. In addition to vine, this insect damages some other fruit trees, such as apple, sour cherry, quince, peach, pomegranate and pear trees and some non-fruit trees, namely white poplar, ash, elm, eglantine, silk and black poplar trees. The nymphs of cicada damage the trees by feeding on root, adult insects on young bud and by oviposition under branch barks. Nourishing root by nymph leads to the weakness of the tree and hinder its growth. The high density oviposition of adult insects inside young barks causes withering of branches. The resulted damage on vine products is 40% which is one of the most important factors in product reduction in vineyard. This research was conducted in Takestan in Qazvin. It was conducted for the first time to study the behaviors of the mates of this vine cicada in order to manage it. Two systems were used to record the sound of male cicada called analog voice-recorder and digital voice recorder. To analyze the recorded sound of the male cicada we used of spectrum analyzer, digital storage oscilloscope and protens 7 computer softwares. We could call the attention of natural enemies an disturb the male insect`s attracting sound by producing natural and artificial sound in the range of 1-6 kHz in two different ripeness status of the fruits and could prevent mating and oviposition of female cicadas.
INTRODUCTION
The initial step in the mating sequence of insects consists of bringing motile males and females in the same place and at the same time (Alexander et al., 1997). During this phase, both sexes usually exchange chemical, acoustical, vibratory and/or visual signals. In many cases, one sex produces a long-range signal encoding specific reproductive information that is perceived and decoded by the other sex (Bradbury and Vehrencamp, 1998). Most male cicadas attract mates with their calling song (Sanborn and Philips, 1995). In male cicadas, sound is generated by a pair of tymbals on the abdomen (Pringle, 1954). The tymbals buckle inwards causing pressure changes in the abdominal cavity, from which sound is radiated through the tympana (Young, 1990). Emitted only by males, the calling song, termed calling tymbalisation (Sueur and Aubin, 2002), informs conspecific reproductively receptive females of the caller`s position (Alexander and Moore, 1958). There are recently many reports on female sounds of cicadas, which apparently use wing-flicking mechanism to respond acoustically to male courtship song since they lack a tymbal apparatus (Cooley and Marshall, 2001). Hence, despite their obvious importance in sexual behavior, there is little information on cicada courtship songs. For example, male courtship songs have only been reported in nine species from the western Palaearctic sub-region. Unlike calling songs, courtship songs are probably not produced by all species (Sueur and Aubin, 2004). In this research we try to examine the behavior and male cicada`s voice of mating, so that disorder in his behavior prevent from mating. We describe the time and frequency features of the calling and courtship songs by digital storage oscilloscope, spectrum analyzer and software. Finally, by analyzing the band width, we got a voice between 1-6 KHz for disorder their behavior.
MATERIALS AND METHODS
Location and climatic condition: The investigative garden which was in the city of Takestan, Qazvin province, is located in 49° and 42` Eastern longitude and 36° and 04` Northern latitude and with an altitude of 1265 m above sea level. Regional climate is under the influence of native inflammations with very cold winter and moderate summer. The annual average of the highest temperature is 22°C and the lowest temperature is 6°C. The average rate of rainfall in this region is 211-250 mm annually.
Male cicadas were tested in the garden from 19 to 30 July 2007, when they are reported to be highly motivated to call. During the experiments the ambient temperature ranged from 18.1-32.2°C and relative humidity ranged from 23.7-49.6%. There is a corn, sunflower and harvested barley garden near vineyard. The weeds around the vineyard include Convulvulus arvensis, Berberis sp., Solanum nigrum, Polygonum avicular, Sonchus sp., Cichorium sp. and Chenepodium album.
Collection of cicadas: We used two methods for collecting cicadas: First, we put a white gauze netting net (2x1x1 m) on the male cicadas that produces sound in the garden, if the place was suitable. Second, if it wasn`t possible to put a net, the cicada was moved by insect net to the suitable place in which a net is set up.
Sound recording instruments: For recording cicada`s sound, we used Digital and Analog tape-recorders. Analog tape-recorder was Panasonic RQ-A320A model that had condenser microphone (frequency response 40-16000 Hz-16 dB) with wide band width, another not to lose any sample sounds. The instrument was Creative mp3 digital voice recorder, with an external microphone. The tape-recorder was used to connect the sound of cicada digitally and to prevent from sound conversion.
After recording the sound of cicada in natural environment, it is transferred to computer and is changed it to WMA format. Finally, these sounds were provided for digital analysis by using software. We put microphone in the net 50 cm far from male cicada.
Signal analysis: The sounds of twelve males were recorded and for analyzing the forfeited sound we use cool edit software. Analog samples are opened with this software. This software draws sound signal curves by using its facilities and shows the changes of sound signal range to frequency and time.
Moreover, for exact study is of the signal, we use digital storage oscilloscope that can produce-send signals directly and show them on the monitor as drawing the frequency and time range. Also by using digital storage oscilloscope software we can show receiving signal as a usable photo or data on the statistical analyzing software on the computer with windows XP (professional, version 2002, service pack 2), as well as obtaining the frequency component.
Emission of male cicada`s natural sound: The recorded sound of the male cicada (which is recorded from the beginning of his singing till the female cicada is attracted by the male) is strengthened by an amplifier and produced in the garden with two 100 W speakers with 10 m distance (from each other).
Emission of synthetic sound: After analyzing the male cicada`s sound according to the band width that was about 6 kHz, a frequency of 1-6 kHz with a high level was produced by using software (proteus 7) and sound card. It is amplified by an amplifier and produced for several days in different hours for cicadas that were in 3 positions with the distance of 30 cm to 5 m from male cicadas. In the first position, the male cicada was singing the garden and in the second, the male cicada was in the laboratory and wasn`t in singing and in the third, the male cicada was in the garden and not singing.
RESULTS
Singing hours: Most sound producing activities of male cicadas was in the warmest hours of the day. When wind blows, the sound of cicadas that were directly against the wind stopped but the cicadas that were among weeds had lower sounds.
Place of sing and mating: Observations show that height percentage of cicadas whose calling songs are produced on weeds. In fact we can result that these cicadas prefer weeds to grapevine for breeding. The minimum distance between two cicadas was about 1 m during calling song. The heads of insects were toward the lower parts of the bush when they song and they were in 30-60 cm above soil level. We didn`t observe any differences in sound producing and their behavior in two ways of collecting male cicadas.
Mating behavior: The female approaches a meter of the males by the male`s calling song. This time, the important thing for the male is whether he can attract female or not and so this is the best time for taking male cicada. The female`s entrance into this territory causes the change of calling song into reply sound and after the acceptance of the male`s sound by the female, the female one sits near the male one (on the same branch). At this time, the male produces a sound like click and the female replies alternately. Then, the male insect approaches the female one which leads to mating. If the male insect is not accepted, the female one tries to recede from the male. Accordingly, the male produces re-reply sound to get the female one back. If the male couldn`t get the female insect back, the re-reply sound would stop. It would start normal calling song again (Fig. 1).
| Fig. 1: | Behavioral algorithm of male cicadas of P. alhageos during mate seeking |
Characteristics of sound of male cicada in attracting female: The male cicada starts his calling song after sitting on a plant and recognizing his environment and feeling no fear. Calling song includes two parts: 1- Start (step of beginning singing), 2-continued sound (Fig. 2).
Start sound (Step of beginning singing): The Start sound is a disordered sound alike the sound of starting car.
Continued sound: This sound (Fig. 3) follows the first step (step of beginning singing) and included Call Duration (CD) and the Silent Inter-Call Duration (SICD) stages. This sound has the highest frequency of 10.2 kHz and a level of 13.7 (Fig. 4, 5). The second harmonic of this signal has the lowest frequency. The second and third components of these sounds are of 30 and 50 kHz, respectively (Fig. 6). The role of this sound is to attract the female cicada of the same species up to 1 m away.
SICD in continued sound is 0.04 m sec. The CD phase is divided into 12 parts which in the first 6 part, reaches from 1.16 to 3.12 sec (the last number is twice of first number) and in the second 6 part, reaches from 1.16 to 4.29 sec (the last number is thrice the first number). These 12 stages will be repeated (Fig. 7). In Fig. 7 if we demodel the signal push from the actual sound, since signal appears that its frequency changes in unite of time. We can say that since signal with lower frequency moduled on base signal (9 kHz). Figure 8 shows a sample of this signal which was taken it by digital storage oscilloscope. As you see the signal shows the longest cycle of this signal and its decaying duration. It should be mentioned that the shape of the signal will repeat every 800 msec.
| Fig. 2: | Audio signal of calling song of P. alhageos calling song of P. alhageos includes two parts: Start (step of beginning singing) and continued sound |
| Fig. 3: | (a) Audio signal of continued sound of P. alhageos, (b) Detailed oscillogram showing continued sound and (c) Detailed oscillogram showing continued sound, CD: Call Duration, SICD: Silent Inter-Call Duration |
| Fig. 4: | Signal of continued sound of P. alhageos |
| Fig. 5: | Frequency spectrum of continued sound of P. alhageos, continued sound has a highest frequency in 10.2 kHz and a level of 13.7 |
| Fig. 6: | Frequency component of continued sound of P. alhageos, F1 = 10.2 kHz, F2 = 30 kHz, F3 = 50 kHz |
| Fig. 7: | CD and SICD sequence: Continued sound of P. alhageos, The CD phase divided in to 12 parts: (a) First 6 part it reaches from 1.16 to 3.12 sec and (b) In the second 6 part it reaches from 1.16 to 4.29 sec, CD: Call Duration, SICD: Silent Inter-Call Duration |
| Fig. 8: | Zoomed signal of continued sound of P. alhageos |
Stimulus and environmental factors which influenced the continued sound process:
| • | Human being: If a male cicada detects a human being near him (0.5-1 m), his sound stops and if a human being comes nearer it leaves the area |
| • | Wind: If the cold wind blows, his sound stops |
| • | The female from another species: The presence of a female cicada from another species doesn`t have any effects on his sound |
| • | The female of the same species: As soon as he feels the presence of a female cicada in the radius of 1 m, his sound changes to reply |
The presence of a female between two singing males causes the continued sounds to change to reply sounds and the sound would be a continued sound as the female one recedes.
Reply sound: As soon as the female came into male`s area, the male cicada produced Reply sounds and male with reply sound attracts the female and this is continued until female go out of the area or they start mating. The base frequency of reply is 8 kHz. This sound like continued includes 2 stages CD and SICD. In this stage the duration of silent sound is lower than continued sound. Here, the point is that, the duration of total SICD are equal and so CD duration. The CD in Continued sound is unsystematic and has upward movement. The range of CD is 0.08±0.05 and SICD is 0.2±0.1 m sec in various individual. This signal with this frequency and alternation continued while female exists in the area of male until mating (Fig. 9).
| Fig. 9: | Audio signal of reply sound of P. alhageos, CD: Call Duration, SICD: Silent Inter-Call Duration |
| Fig. 10: | Audio signal of re-reply sound of P. alhageos, CD: Call Duration, SICD: Silent Inter-Call Duration |
Re-reply sound: If the female cicada is still in the scope of the male cicada, this song will continue until the beginning of copulation. Otherwise if the female cicada leaves from that scope, the tone of male cicada would vary from reply to continued sound but before producing continued sound, the male cicada emits the Reply sound with lower SICD and higher CD (CD>0.08 and SICD<0.2), that we call it Re-reply sound (Fig. 10). This sound is before the continued sound (Fig. 11). If the female insect comes out of the realm completely, the re-reply sound will change to the continued sound.
Emission of synthetic sound: According to the band width of recorded sounds of male cicada, we produced the sound with 1-6 kHz in garden. In 4 kHz frequency signal, the male cicadas produce a disorder sound in all three manners as soon as we stop the sound of the instrument. But, in signal with the highest frequency of 1 kHz, the male cicadas produce disordered sound simultaneously in 3 manners (Fig. 12). The SICD of the male cicada is 0.046 m sec and CD is 0.014 ms (Fig. 13). SICD is the same in both Continued and Response stage, but CD is different in both of them (Table 1).With regard to the emission of the sound and picking up the net, we observed the male cicada didn`t come out of the area and so we can say that this sound isn`t the cause of fear and escape of cicada. During the experiment in successive days and different hours, no female insects were attracted to male ones.
| Table 1: | CD and SICD comparison of Continued, reply, re-reply sounds and response of P. alhageos |
| CD: Call Duration, SICD: Silent Inter-Call Duration | |
| Fig. 11: | (a) Audio signal of re-reply and continued sound of P. alhageos and (b) Detailed oscillogram showing continued voice, CD: Call Duration, SICD: Silent Inter-Call Duration |
| Fig. 12: | Emission of synthetic sound and response of P. alhageos |
Emission of male cicada natural sound: After emission of the natural sound of male cicada some sparrows Passer domesticus (Passeriformes:Ploceidae) that are the natural enemies of cicadas appeared in the garden after 3-5 min. This sound hasn`t caused any disruption in the process of calling songs of the male cicada which was in 4 m away and continued sound to its calling songs procedure. It should be mentioned that female cicada comes into the distance of instrument and the male cicada.
DISCUSSION
Sign hours: Based on our studies, the number of cicadas which were singing and mating reached the maximum around at 3 o`clock p.m. when the weather was very hot. Alexander and Moor (1962) likewise made such a result about Tredecula species.
Place of sign and mating: Psalmocharias alhageos (Kol.) choose weeds for their calling song that are 30-60 cm above from the earth. Sueur (2003) painted that Tibicina species choose trunks or primary stems for their calling song that are low level. He also said that singing cicada has not any movement in this period. This matter completely conforms to present observations. In fact, they prefer to choose weeds than vine, because the accumulation of weed grass is lower than vine.
| Fig. 13: | (a) Audio frequency of Response of P. alhageos, (b) Detailed oscillogram showing response and (c) Detailed oscillogram showing Response, CD: Call Duration, SICD: Silent Inter-Call Duration |
The distance of threshold documented here and the one estimated for Cystosoma saunderii by Doolan (1981) should approximate the radius of the male individual territory defended through acoustic cues. Males of the P. alhageos species appear to be regularly dispersed inside the chorus centers and our view is the same as those of Sueur (2001) in Tibicina species.
The minimum distances, approximately 1 m in P. alhageos, is comparable to those found in the males of T. tomentosa and in T. corsica (0.5 and 0.9 m) by Sueur (2003) and also Cicadetta pellosoma (Uhler, 1861) by Popove (1998) and of Cystosoma saundersii by Doolan and MacNally (1981).
Mating behavior: According to our results, the reply sounds of male cicada conform to Sueur and Aubin (2004) on genus Tibicina, but the re-reply part of the produced sound by the male cicada was not recorded in the studies on cicada and other similar species. As the studies on similar species were done in laboratory, the female insect was in a limited area and didn`t have any other choices; therefore, the male one didn`t need to produce the re-reply sound.
The characteristics of sound of male cicada in attracting female: Sueur and Aubin (2002) NOT PRESENT divided the vocal pattern of Tibicina haematodes into two parts named first part and second part. In our research, we divide calling song into two parts the first part named as start sound (step of beginning singing) and the second part named as continued sound.
Start sound (Step of beginning signing): The first part is a stuttered sound that Seuer and Aubin (2002) called it successive short trains of pulses about T. haemotedes. We called it start sound because it was heard at the beginning of singing period.
Continued sound: Continued sound or calling songs, according to Fitzaptrick and Gray (2001), is used to attract females at long range and constitute the first step in pair formation. Sueur and Aubin (2002) called the continued sound, the Second part and defined it as a sustained train of pulses; however, since the male cicada sing continuously and repeatedly after the start, we call it continued sound.
High-pitched calling songs are about 10.2 kHz in P.alhageos that the research has not been accomplished yet. This is lower than genus Cicadetta in the Palaearctic region (Sueur and Puissant, 2007). Sueur and Puissant (2007) distinguished that acoustic analysis also revealed several sibling species in the Palaearctic genus Cicadetta.
CD and SICD in P. alhageos are 1.6-5.14 and 0.04, respectively (SICD < CD) that this is lower than in T. haematodes (SICD < CD) by Sueur and Aubin (2003).
Reply sound: The beginning of Reply sound is exactly when female cicada enters the 1 m area of male cicada. Sueur and Aubin (2004) and Fitzaptrick and Gray (2001) also pointed to this matter. The female P. alhageous informs the male one that she is in that area by the sound of his wing. The studies of Cooley and Marshall (2001) and Sueur and Aubin (2004) and Sueur (2002) conform to this matter.
Re-reply sound: Re-reply is a sound between reply and continued sound when female comes out of the area, when the male cicada isn`t accepted by female, he changes his sound (Re-reply) to return her. After the female cicada comes out of the area their sounds change to continued sound simultaneously.
The environmental influence factors: Impetus and environmental factors that effect on the duration of continued sound of male cicada include: human being, wind, female from the same species.
Blowing cold wind caused male sound to stop and Babaei (1967) also pointed to this matter. If there is a female cicada from another species, even in the distance of 1 m, it has not any effect on continued sound of male cicada. As soon as male cicada feels that a female cicada from his own species exists in his area (around 1 m), his sound changes from continued sound to reply sound.
Emission of male cicada natural sound: By producing the strengthened sound of male cicada in a farm, we observe that sparrows Passer domesticus (Passeriformes: Ploceidae), the natural enemies of cicadas come near the instrument. This matter increases the possibility of attracting enemies for pest control. Present observations conform to Ooji Ardebili and Nozari (2008) (unpublished or 2007).
Emission of synthetic sound: By emission sound of 1 and 4 kHz frequencies which caused the interruption of calling song, we could perturb the mating process of the insect. Sueur and Aubin (2002) produced a sound (2 kHz) around male cicada (T. haematodes species) that he didn`t reply to it (T. haemothedes frequency band is 2 kHz and P. alhageos frequency band is 6 kHz). With regard to another primary experiment which we performed on the other different species, it seems that this result was different in various species and all the species don`t respond to this kind of emitted sound in the same way.
CONCLUSION
Remembering that at the end of the season, fruits would ripen and the presence of sparrows` natural enemies damages the crops, it is recommended to use the emission of male cicada`s natural sound method in the beginning of the season. The emission of synthetic sound method uses when fruits are ripping in 1-6 kHz band width, so the crops wouldn`t damage.
ACKNOWLEDGMENTS
The costs of this research paid by Science Society of Electronic, Islamic Azad University, Yazd Branch. With thanks of Dr. Mahdi Dehghani, Dean of Plant Protection Department, Islamic Azad University, Yazd Branch and Mr. Mohammad Reza Sedmir responsible of Science Society, Yazd Branch and Dr. Arbab, Education of Deputy, Islamic Azad University, Takestan Branch and grateful to Dr. Pakyari, M.S. Nozari and M.S. Mansori for continual support.