EFFECT OF TEMPERATURE ON DEVELOPMENT AND REPRODUCTION OF PEACH FRUIT FLY, BACTROCERA ZONATA (SAUND.)(DIPTERA: TEPHRITIDAE)

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1 Egypt. J. Exp. Biol. (Zool.), 6(2): (2010) The Egyptian Society of Experimental Biology RESEARCH ARTICLE Mohamed WF. Younes Faten A. Akel EFFECT OF TEMPERATURE ON DEVELOPMENT AND REPRODUCTION OF PEACH FRUIT FLY, BACTROCERA ZONATA (SAUND.)(DIPTERA: TEPHRITIDAE) ABSTRACT: The objective of this study was to assess the effect of different constant temperatures (20, 25, 30, and 35 C) at a constant relative humidity (70 5% R.H.) on some biological aspects of the peach fruit fly Bactrocera zonata (Saund.). Results clearly revealed that the embryonic development of B. zonata declined gradually as the temperature increased from 20 to 35 C. The highest percentage of egg hatch was at 30 C and the lowest rate was 71.18% at 35 C. s of 25 and 30 C were considered the favorable zone for egg hatching. The developmental rate of larvae gradually increased with the increase of temperature.the same trend was also observed for pupation rate. The pupal duration declined as temperature increased. The highest rate of adult emergence was 97.42% at 30 C and the lowest rate was 83.54% at 20 C. The sex ratio of emerged adults was female biased at all temperatures except at 30 C. The average pre-oviposition periods were 29.4, 22.8, 20.4, and days at 20, 25, 30, and 35 C, respectively. On the other hand, an inverse effect was observed in oviposition periods. The optimum and favorable temperatures for female fertility ranged between 25 and 30 C, where the average of egg hatching was 186 and 174.8, respectively. No significant differences were observed between the averages of preoviposition period relative to types. On the other hand, the oviposition period was affected by the type of. Repeated induced the female to deposit remarkably higher number of eggs than the other two types (delayed and copulated once). The average of egg hatching of the deposited eggs in the three different types of, i.e., repeated, delayed and copulated once was 73.90, 60.33, and 63.02, respectively. Key words: Bactrocera zonata threshold temperaturethermal units (degree-days)-biological aspectsmating types. CORRESPONDANCE: Mohamed WF. Younes Zoology Department Faculty of Science Menoufia University Egypt. m_wagdyyounes@yahoo.com Zoology Department,Faculty of Science, Menoufia University, Egypt. ARTICLE CODE: INTRODUCTION: The peach fruit fly, Bactrocera zonata (Saund.) is one of the most harmful species of Tephritidae (Diptera). It is a major threat to different kinds of fruits and vegetables (e.g. mango, fig, guava, peach, apple, citrus, tomato, potato etc). The larvae feed on the pulp of ripe fruits inflecting a serious damage, making the fruits unfavorable for marketing and exportation, (White and Elson-Harris, 1994; Aluja et al., 1996). During the 90's of the last century, the Egyptian ecosystem was attacked by this pest, to be a new record in the north of Africa. However, the peach fruit fly was first recorded in Egypt in 1924 (Efflatoun, 1924), but it was not distributed throughout Egypt before the 90's of 20 th century. B. zonata is now widely distributed in Egypt and infest mango, apple, peach, guava and citrus in Egypt, and its population increased gradually with fruiting and ripening (Hashem et al., 2001). is considered one of the most important ecological factor affecting clearly survival and development rate of insects. Therefore, the study of this environmental factor is very important particularly for insects of economic importance. Moore (1960) gave ample guide to the effect of temperature on the development of the olive fruit fly, Dacus oleae. Accumulated thermal units have been used to predict the seasonal development and emergence of various insects (Eckenrode et

2 256 al., 1975; Sevacherian et al., 1977). The effect of constant temperature on some biological aspects of guava fruit fly, Dacus zonatus was studied by Rana et al. (1992). As little is known regarding the effect of this ecological factor on B. zonata, the objective of the present study was to: 1) Determine the developmental threshold and thermal requirements for various stages of B. zonata. 2) Assess the effect of four selected temperatures on B. zonata embryonic development, egg hatch rate, larval and pupal duration, pupation and adult emergence rates. 3) Determine the effect of mating type (repeated, delayed and once) on pre- and ovipositional periods, fecundity and fertility of the oviposited eggs. MATERIAL AND METHODS: A stock culture of the peach fruit fly, Bactrocera zonata, was initiated from a permanent stock laboratory strain kept at Entomological Research Unit, Biology Department, National Research Center, Dokki, Cairo, Egypt. A laboratory strain of the peach fruit fly B. zonata was reared under constant temperature of 30 1 C and 70 5% R.H. Adults were maintained in wooden cages covered on one side with a removable muslin screened frame and the top side was made of wire mesh. The adults were provided with food consisting of sugar and protein hydrolysate and each cage hold about adult flies. Female flies were allowed to oviposit in an artificial egg laying device. The device consists of perforated plastic mandarin provided with water at the lower 1/3 non perforated portion, to prevent eggs from desiccation. Eggs were collected daily from the plastic mandarin models and then carefully scattered on the surface of artificial medium which consisted of wheat bran, dried brewer's yeast, sucrose, sodium benzoate, HCl (0.1 N) and tap water. After 7 days, mature larvae jumped out from the diet pupated in a layer of fine sand. Pupae (jumped during 48 hours) were collected and transferred to the rearing cages. The present study was carried out under controlled conditions of temperature and relative humidity. An incubator was used to provide constant temperatures of 20, 25, 30, and 35 C and 70 5% R.H. To study the effect of temperatures and relative humidity on the incubation period, as well as the percentage of egg hatching, five replicates of 150 eggs/each temperature were used. To evaluate the larval development of the pest, the newly hatched larvae were Egypt. J. Exp. Biol. (Zool.), 6(2): (2010) placed in glass Petri dishes provided with artificial diet. The larvae were kept in an incubator at different temperatures and constant relative humidity until pupation. The newly formed pupae were collected at the same day of pupation and then put in rearing cages until adult emergence. The newly emerged flies were allowed to mate in the rearing cages and hold on the same temperature and relative humidity. The newly emerged flies were provided with adult food consisting of sugar mixed with protein hydrolyzate and wet cotton as a source of water. The cages were provided with plastic mandarin shaped scratched and full of water for the oviposition. Daily observation were made to record the adult survival and number of deposited eggs as well as the number of hatched eggs. The incubation period (the rate of embryonic development) as well as the percentage of egg hatching, larval and pupal durations, percentage pupation, percentage adult emergence, sex ratio, pre- and oviposition periods, fecundity and fertility were recorded for each treatment. The obtained results were statistically analyzed according to F-test and analysis of variance (ANOVA). The theoretical developmental threshold was determined according to the following: 1- Plotting the time (Y) in days against temperature (T) in degrees centigrade. So that the distribution of these points indicates the course of temperature time-curve. The relationship in hyberbolic as commonly observed in many insect species (Miyashita, 1971 and Nasr et al., 1980). 2- Plotting reciprocal for time (1/y) in days against temperature (T) in degrees centigrade; each of reciprocals multiplied by 100. Values on the ordinate (100/y) represent the average percentage development made by the stage per day at the given temperature. Therefore, the distribution of the points indicates the course of temperaturevelocity curve (Davidson, 1944). The values of average percentage development in one day which are presented within normal zone of development were fitted to a straight line by method of least square (regression line). 3- Theoretically, the point where the velocity line crosses the temperature axis is the threshold of development ( C). The thermal units required for development of each stages was determined according to the equation of thermal summation (Blunk, 1923). Y (T t) = K where: Y, is the developmental duration in days, T, is the experimental temperature in degree centigrade, t, is the threshold temperature for development in degree centigrade and K, is the thermal units (degree-days).

3 Younes & Akel, Effect of on Development and Reproduction of Peach Fruit Fly, Bactrocera zonata 257 RESULTS: A. Effect of different temperatures on some biological aspects of the peach fruit fly Bactrocera zonata in relation to degree days:- The aim of the present study is to establish the velocity constants; i.e. the relation between temperature and the developmental rate which give a quantitative expression for this relationship, using thermal summation. 1- Effect on the egg stage: The embryonic development (incubation period) of B. zonata eggs declined gradually as the temperature increased from 20 to 30 C (Table 1). The threshold of egg development (t o ) was found to be 8.1 C when temperature ranged between 20 and 35 C (Fig 1). The averages of thermal units in degree-days (DD's) required for embryonic development were 53.55, 53.74, 52.56, and DD's at 20, 25, 30, and 35 C, respectively, with an average of DD's. The developmental rate was closed at the constant temperatures ranged between 20 and 35 C. The values of the developmental rate at the tested temperatures ranged between 20 and 30 C, are remarkable good fit to the calculated temperature velocity line having formula: Y = x. of 25 and 30 C are considered the most favorable zone for the egg hatching. Table 1. Effect of temperature on incubation period, development rate, hatch rate and thermal units of Bactrocera zonata Incubation period ( days ) mean Development Hatch rate % Thermal units * ( D D s ) ± ± ± ± F 4.48** 64.97*** *** n.s L.S.D n.s = Non significant *=Thermal units (DD s) were based on a developmental threshold (t 0) of C for Bactrocera zonata eggs. ** = Significant Effect on the larval stage: The average larval durations of B. zonata varied from 14.2 days at 20 C to 7.01 days at 35 C (Table 2). Significant differences were observed between the mean larval durations at the different constant temperatures. The developmental rates of B. zonata larvae gradually increased with the increase in the tested temperatures. These rates were 7.04, 9.71, 12.98, and 14.27% at 20, 25, 30, and 35 C, respectively. The lower development threshold (t o ) for larval stage was 6.1 C (Fig. 2). The mean values of thermal units required for larval development till pupation were , , and (DD's) at 20, 25, 30, and 35 C, respectively, with an average of (DD's) as determined by the thermal summation equation: K = Y (t-to). The average value of thermal units at optimum zone of temperatures (25 to 30 C) was degree-days (DD's). Generally, the four recorded values for developmental rate of larvae till pupation at tested temperatures, were also remarkable good fit to the calculated temperature-velocity line having the formula: Y = x The highest pupation rate of B. zonata larvae was 95.45% at 30 C, which was considered the optimum and favorable temperature. Table 2. Effect of temperature on larval duration, development and pupation rates and thermal units of Bactrocera zonata Larval duration (days) mean Development Pupation Thermal units * ( D D s ) ± ± ± ± F 59.33*** 5.11** ** L.S.D *=Thermal units (DD s) were based on a developmental threshold (t 0) of C for Bactrocera zonata larvae. ** = Significant Rate of development (days) Rate of development (days) C Fig. 1. Linear regression of the relationship between the developmental rate of Bactrocera zonata eggs and different constant temperatures 0 C Fig. 2. Linear regression of the relationship between the developmental rate of Bactrocera zonata larvae and different constant temperatures

4 Effect on the pupal stage: The pupal duration declined with an increase in temperature (Table 3). However, the developmental threshold (t o ) as illustrated in figure 3 was C. The thermal units requird for pupal duration completion till the adult emergence were , , , and degree-days at 20, 25, 30, and 35 C, respectively. The average of the total thermal units was (DD's) as determined by the thermal summation equation; K = Y (t 11.75). Table 3. Effect of temperature on pupal duration, development rate, thermal units, emergence rate and sex ratio of Bactrocera zonata Pupal Development duration ( days ) mean Thermal units * ( D D s ) Emergence rate ( % ) Sex ratio ± : ± : ± : ± : F 48.56*** 10.49** 4.45** 10.08** - L.S.D *=Thermal units (DD s) were based on a developmental threshold (t 0) of C for Bactrocera zonata pupae. ** = Significant ; *** = highly significant Rate of development (days) C Fig. 3. Linear regression of the relationship between the developmental rate of Bactrocera zonata pupae and different constant temperatures The pupal developmental rate at the range of temperature of 20 to 35 C are remarkable good fit to the calculated temperature velocity line using formula: Y = X. The pupal developmental rate was 7.14, 10.52, 14.26, and 17.21% at 20, 25, 30, and 35 C, respectively. The highest rat of adult emergence was 97.42% at 30 C which was considered the optimum and favorable temperature. The sex ratio ( : ) of - - Egypt. J. Exp. Biol. (Zool.), 6(2): (2010) emerged adults was female biased at all temperatures except at 30 C. of 20 C induced prolongations in the pre-oviposition period of female emerged from eggs exposed to this temperature as compared with other tested temperatures (Table 4). However, inverse effect was observed in oviposition periods at all temperatures. The mean average oviposition periods of female adults emerged from eggs exposed to 20, 25, 30, and 35 C were 9.8, 13, 29.8, and 28.4 days, respectively. Table 4. Effect of exposure of eggs to temperature on the pre-and ovipositional periods of the emerged females Pre-oviposition period (days) Oviposition period (days) Min. Max. Min. Max ± ± ± ± ± ± ± ± 5.41 F 40.00*** 23.04*** 24.39*** 64.89*** 24.38*** *** L.S.D of 30 C was considered as favorable temperature as compared with 20 C, where the mean number of eggs laid per female was and 62.8 eggs, respectively. The optimum and favorable temperature for egg fertility was between 25 and 30 C, where the mean average of egg hatching was 186 and 174.8, respectively. On the other hand, lower and higher temperatures (20 and 35 C.) were considered unfavorable temperatures, where the mean averages of egg hatch were 24.6 and 87.8, respectively (Table 5). Table 5. Effect of exposure of eggs to temperature on the fecundity and fertility of emerged females No. of eggs laid / female No. of hatched eggs Min. Max. Min. Max ± ± ± ± ± ± ± ± F 431*** 602*** 747*** 198.7*** *** *** L.S.D

5 Younes & Akel, Effect of on Development and Reproduction of Peach Fruit Fly, Bactrocera zonata 259 B. Effect of types on some biological aspects of B. zonata under laboratory conditions: There were no significant differences among the mean average of pre-oviposition period relative to the type (Table 6). The mean pre-oviposition periods of females copulated repeatedly, delayed and copulated once were 20.67, 21.71, and days, respectively. On the other hand, the oviposition periods of B. zonata female were affected by the type of and the differences between these types were statistically significant. The highest oviposition period ranged between 29 and 38 days with an average of days in case of repeated and the lowest one was recorded for females copulated once, where this period ranged between 9 and 14 days with an average of days. The oviposition period of females which copulated after 14 days post-emergence ranged between 12 and 23 days with an average of days. Table 6. Effect of type of Bactrocera zonata on the pre-and ovipositional periods Types of Repeated Pre-oviposition period (days) Min. Max ± 0.53 a Delayed * ± 0.99 a Copulated ** once ± 0.36 a Oviposition period (days) Min. Max ± 1.18 a ± 1.57 b ± 0.59 c F n.s n.s *** *** *** L.S.D n.s = Non significant * = Copulation between male and female flies was started 14 days post emergence. ** = Male and female flies were separated from each other 48 hours post emergence. In females copulated more than once the minimum and maximum numbers of eggs laid per female were and , respectively (Table 7). The corresponding figures in delayed were and with an average of eggs per female. The mean average of eggs deposited per female copulated once was There was no significant difference between females copulated once and others of delayed. Repeated induced an encouraged the females to deposit remarkably higher numbers of eggs than the two other types. Repeated induced significant increase in the percentage of egg hatching, compared with the other two types of (Table 7). Table 7. Effect of type of Bactrocera zonata on the fecundity and fertility Types of Repeated No. of eggs laid / female Hatchability % Min. Max ± 79.9 a Delayed * ± 5.97 a Copulated once ** ± 9.22 a Min. Max ± 1.22 a ± 3.59 b ± 2.31 b F *** *** L.S.D * = Copulation between male and female flies was started 14 days post emergence. ** = Male and female flies were separated from each other 48 hours post emergence. DISCUSSION: Data obtained indicated that the immature stages of B. zonata developed successfully within a temperature range between 20 and 35 C. Moreover, temperature thresholds of eggs, larvae and pupae were 8.1, 6.1 and 11.7 C, respectively. while, the thermal units for eggs, larvae and pupae ranged between and 53.8, and , and and degree days, respectively. These findings are in general agreement with those obtained by Mohamed (2000). Similarly, Duyck et al. (2004) concluded that there was a strong and positive relationship between temperature and the developmental rate of eggs, larval and pupal stages of B. zonata. The rate of adult emergence peacked at 25 C. The present results are in consistent with observations recorded by Mohamed (2003), who reported that the incubation period and hatchability rates were 4.81 days and 67.0% under constant temperature and humidity (25 C and 70% R.H.) for B. zonata. The author found that the larval duration and survival of this pest were 8.87 days and %, respectively,when the larvae were reared at the same conditions. Also, pupal duration was 9.57 days and survival of the pupal stage was 84.37%. Several investigators studied the relationship between constant temperatures and developmental rates of different insect species (Gergis et al. (1990); Hashem et al and Dahi 2003). clearly affected adult emergence, ovipositional periods, fecundity and fertility of females emerged from eggs exposed to different constant temperatures. Similar results were obtained by El-Aw et al. (2003) and Binary and Agarwal (2005) on B. zonata; Shoukry and Hafez (1979) on Ceratitis capitata; Vargas et al. (2000) on C. capitata and Younis et al., (1988) on Earias insulana.

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7 Younes & Akel, Effect of on Development and Reproduction of Peach Fruit Fly, Bactrocera zonata 261 Bactrocera zonata (Saund) (Diptera:Tephritidae) : ± 70 ( 35,30,25,20) %.. 30 % %71.18.( 30-25) %97,42