Comparative population dynamics of Drosicha mangifera at three different stations of Jammu region (Fig.)
Comparative population dynamics of Drosicha mangifera at three different study stations viz. Udheywala (District Jammu), Kharot (District Kathua) and Majalta (Ditrict Udhampur) shown in fig. When the popuation of Drosicha mangifera at 3 different stations were compared, the results inferred that the highest population density was observed at Udheywala followed by Kharot and then followed by Majalta.
On comparing the infestation rate in Udheywala and Kharot stations (t=0.64, df=18, p=0.53), it was found that the infestation in these two stations is not significant. Similarly the infestation between stations Kharot and Majalta (t=0.29, df=18, p=0.77), Udheywala and Majalta (t=0.90, df=18, p=0.38) (Table 15) is also not significant which may be attributed to almost similar weather conditions of three studied stations.
Table 23: Mean of Drosicha mangifera population at different stations
(Fig. ) Comparative population dynamics of Drosicha mangifera at three different stations of Jammu region
Bactrocera dorsalis (Hendel, 1912)
Biological and all other associated activities of the pest of Mango have been studied in detail by the present author in the study areas during her studies under the following headings.
Field observations revealed that mating occurs in the early morning hours. At the time of copulation, the male fly mounted on the back of the female forming a grip on its body with the help of pro and meso thoracic legs, while the met thoracic pair is used for balancing itself on substratum. The author observed that mating pair if gets disturbed, they flee away together in this posture to a secluded place and continue the process. The wings of both sexes remained folded during the act of copulation. Lal and Sinha, 1960 in Bactrocera cucurbitae observed that copulation takes place at dusk and males were found to be more active than females.
Selection of fruit stage for oviposition:
The present author recorded that both unripened and ripened fruits are selected by the female for oviposition. The tender fruits and the overripe fruits are not favored for oviposition. The present authors observation go in line with the observation of Sharma (2001) who also reported that the fruits which are about to ripen i.e. whose color changes from slightly yellow to green are suitable for oviposition. Chhetry (2009) recorded more or less similar observations on citrus.
Further, the present author analyzed that the over ripened fruits are not suitable for oviposition. Besides this, the fruits which are already infested with maggots were not favored by new fertile female for oviposition. It might be due to the reason that the odor emitted by the overripe drupe and the maggots infested fruits resist female flies to oviposit on the fruits.
The present author observe that that the female fly before ovipositing scans one fruit after another for determining the presence of conspsecific larvae or to select an appropriate site for puncturing. After scrutinizing the host plant for some time, the female fly pierce its ovipositor inside the fruit, under the skin of the fruit and lays eggs in small batches. At the time of oviposition, the wings are placed laterally, fully stretched but moderately bend its abdomen while putting its ovipositor into the drupe surface. After ovipositing, with the help of hind pair of legs, the females were seen cleaning their ovipositor. More than one female may lay eggs in an individual fruit. A more or less similar observation was made by Sharma (2005) who also observed oviposition behavior of Dacus dorsalis in Guava in Jammu region. The present author noticed that besides actual ovipositional areas, there are numerous sites of puncturing. This is because if the first site of puncturing does not seem appropriate, the fly leaves the spot and moves to some other satisfactory area. Under in vivo conditions, it was observed that 4- 6 minutes was taken for oviposition. According to Chhetry (2009) on citrus plantations, oviposition lasted for 3-5 minutes. As the female fly oviposits on different fruits at a single time, therefore it is unable to determine the actual fecundity of the female. Likewise, Mathaji (2009) reported that after 2 to 3 visits, fly scrutinize the surface of fruit and finally selects the fruit for oviposition. Nevertheless, it is seen that at a single stretch the female fly laid 2-36 eggs. The occurrence of 2-5 eggs at one place was observed by Sharma (2005) inside the guava fruit. Melinand et al. (2016) however, studied that Bactrocera dorsalis in the south area laid 201 to 325 eggs with an average of eggs on mango while in the north area laid about 323 to 348 eggs with an average of 347.67 ± 5.71 eggs.
The female fly laid eggs in clusters below the skin of the host fruit by its ovipositor. Freshly laid eggs are barrel shaped, translucent white, not uniform, having longitudinal striations and are marginally rounded. Length of egg varied from 0.8- 1 mm with an average of 0.9±0.1mm. Average width of the egg was 0.22-0.02 and varied between 0.19-0.25 mm (Table 24). Although, Sharma (2005) reported egg length of 0.9-1.00 mm. Similar observations were made by Mathaji (2009) who found average length of egg 0.92 ± 0.07 mm in mango.
Incubation period varied from 2-5 days with an average of 3.3 ± 1.20 days. Sharma (2005) however, recorded that incubation period lasted for 2-5 days in summer and 4-8 days in winter while Chhetry (2009) recorded incubation period lasted for 7-10 days. The present study goes in line with Mathaji (2009) who found average incubation period as 2.68 ± 0.63 days on mango. Kalia and Yadav (2015) however, studied the incubation period of Bactrocera dorsalis on mango with an average of 1.7 ± 0.21 days. Likewise Melinand et al. (2016) observed the incubation of eggs with an average of 2.6 ± 0.5 days on mango.
The freshly and newly hatched maggot are transparent and prolonged whereas the full grown are creamy white. The anterior end of the larvae is pointed and is broader towards posterior end. Body is 11 segmented and the first segment is marginally black possessing black pharyngeal hooks. The first five segments suddenly increases in size while there is a meager increase in size from segment 6-10. Maggot posses paired spiracles. The length of the maggot varied from 1.45-7.00 mm with an average of 3.49±2.19mm and 0.49-3.80 mm in width with an average of 2.50- 1.30 mm (Table 24).
Due to the small size of the maggot, the number of larval instars could not be determined. Total larval period observed was 7-10.00 days with an average of 7.08 ± 1.5 days. However, Sharma (2005) during summer recorded larval period ranged between 5-6 days and during winter 9-32 days. Chhetry (2009) however has recorded the larval period to range between 14-35 days on citrus plants. A similar observation was made by Mathaji (2009) who found larval period average duration 7.44±1.16 days. On the contrary, Kalia and Yadav (2015) studied the larval period of Bactrocera dorsalis on mango with an average of 7.5 ± 0.16 days. More or less similar observations were made by Melinand et al. (2016) who found 7.97 ± 0.60 an average of larval period duration.
The present author observed that number of maggots inside the fruit depends upon the size of the fruit and the quantity of the fruit available inside the fruit. Usually, 15 to 55 maggots have been observed by the author. The fruits which are of small size have lesser number of larvae possibly due to the reason that small size fruit contain small amount of pulp which started degrading very quickly.