Effects of deciduous fruit species on the growth, development and reproduction of Bactrocera dorsalis

Abstract:【Objective】In order to study the host adaptability of Bactrocera dorsalis on deciduous fruit species in the North, and provide reference for the monitoring and control of B. dorsalis, the host adapt-ability of B. dorsalis fly to six types of northern deciduous fruit trees was studied, and the growth and reproduction of B. dorsalis on different hosts were observed.【Methods】Different fresh host fruits were cut into small pieces and placed in Petri dishes. On the day of egg hatching, a small brush was used to gently pick the newly hatched larvae of B. dorsalis into a plastic petri dish (5 cm in diameter), 5 for each dish, and a piece of fresh fruit was put in the dish before it was covered. Observation was made twice at both 9:00 and 21:00 every day, the data of egg hatching, larval survival, instar, pupation and eclosion were recorded, and the fruit was supplemented when eaten up or the rotten fruit was replaced.100 eggs per treatment were done for 3 times. Put the adults into the insect cage for mating. Take 30 pairs of adults and put every 10 pairs into one insect cage (20 cm×20 cm×20 cm) and put adult feed for adult feeding. At 20:00 every day, the survival of adults and the number of eggs laid were observed and recorded. Adults laid eggs on the plastic cup wall and the spawning date was marked every day. Take the eggs laid within 12 hours, place them on the fruit block in the plastic culture dish, cover the dish, place them in the artificial climate box, and observe the hatching of the eggs. All experiments were con- ducted at (28±1) ℃, RH 75%±5% and photoperiod 16L: 8D.【Results】Among the six different host  fruits, the growth period of the eggs of the B. dorsalis on kiwifruit was the shortest, which was (0.68±0.22) d; the growth duration on pomegranate was the longest, which was (1.11±0.01) d; the develop-ment period of larva was the shortest on pomegranate, which was (7.21±0.05) d; the development peri-od of larva was the longest on apple, which was (16.37±0.27) d; the development period of pupal stage was the shortest on pomegranate, (9.82±0.04) d, which was markedly shorter than the other five host plants; the development periods from egg to pupa increased successively on pomegranate, kiwifruit, peach, jujube, pear and apple, which were 18.15 d, 19.61 d, 22.24 d, 22.57 d, 24.30 d and 27.42 d, re-spectively; the whole generation cycle increased gradually on peach, pomegranate, apple, kiwifruit,pear and jujube. The development period of the 1st instar larvae of B. dorsalis on pomegranate was the shortest, which was (0.93±0.06) d; the development period on apple was the longest, being (2.27±0.07) d; the second instar larvae on pomegranate and kiwifruit were (1.11±0.05) d and (1.10±0.25) d respec-tively; it was longer on jujube and pear, which were (2.90±0.09) d and 2.82±0.06 d respectively; the du- ration of 3rd instar larval was the shortest on pomegranate, which was (5.18±0.02) d. The hatching rate of the eggs of the B. dorsalis on pear was the highest, which was (63.00±8.83)%, jujube was (42.67±4.11)%, and the lowest rate on peach was (21.33±2.36)%. The pupation rate of larvae was the highest on pomegranate, which was (96.39 ± 1.70)% ; kiwifruit and peach were (67.39 ± 2.44)% and (66.96 ±3.39)%, respectively; apple was the lowest, being (42.15±0.84)%. After eating pomegranate, the surviv-al rate of larvae was the highest, which was (79.67±3.68)%; kiwifruit was the second, being (52.67±3.09)%; the survival rate of larvae feeding on apple was the lowest, which was (26.33±0.94)%. The emergence rate of B. dorsalis feeding on kiwifruit at larval stage was the lowest, being (48.92±4.55)%. In the whole growth cycle, the survival rate of larvae and pupation rate were mainly affected. As a result, the overall survival of pomegranate fed B. dorsalis was surprisingly higher than that of other fruits.The early oviposition stage of female adults of B. dorsalis with pomegranate as host was markedly lon-ger than that of other hosts, which was (17.77±0.60) d; however, the pre spawning duration of B. dorsalis with peach as host was significantly shorter than that of other fruits, which was (11.61±0.72) d. Dur-ing the growth process, the oviposition duration of B. dorsalis fed on jujube was the longest, which was(50.13±5.11) d, and the average oviposition per female was 1 105.90±54.91; the spawning period of B.dorsalis fed on apple was the shortest, which was (38.27±1.41) d, and the spawning number per female was 556.23±35.28. The number of eggs per female of B. dorsalis fed on pomegranate was 1 197.63±51.48; the number of eggs per female of B. dorsalis feeding on peach was the least, which was 401.50±90.24. The net proliferation rate and intrinsic growth rate of pomegranate host were significantly higher than those of other hosts. Under the appropriate conditions of (28±1) ℃, RH 75%±5%, photoperiod 16L:8D and ample food, the maximum instantaneous growth rate of B. dorsalis population with stable age group was 0.131 7±0.002 7, the maximum population proliferation per generation was 858.98± 27.38 times, the average duration of a generation was 51.30±0.82 days, and the population of B. dorsa-lis increased the most every day (1.140 8±0.003 1 times).【Conclusion】As is known to us, among the six host fruits, pomegranate was more suitable for the growth of B. dorsalis larvae, and it was beneficial for female adults to lay eggs. In the actual field prevention and control, we should combine the host adaptability of B. dorsalis with the means of prevention and control, and do a good job in the monitor- ing and control on deciduous fruit trees in the north.