The Effect of Soil Depth on Pupation of Bactrocera dorsalis Collected from Chilli

Abstract

Fruit flies including genus Bactrocera undergo a process of pupation in the soil. The depth of the soil may affect the success of pupation. This study aimed to evaluate soil depth's effect on the success of Bactrocera dorsalis (Hendel) pupae in becoming imago, survival, normality and development time. The experiment in the laboratory consisted of eight treatments of pupation depth (0, 4, 10, 20, 30, 40, 50 and 60 cm). Pupae were put in mica tubes with a diameter of 5 cm and poured with soil granules. Replications were done four times. The survival of B. dorsalis was significantly affected by soil depth. As the depth of the soil increased, the likelihood of becoming an imago reduced. The survival rate was lowest at a depth of 30 cm (2%±2) and the success rate for becoming an adult was best at a control depth of 0 cm (60%±5.9). Additionally, it was discovered that as pupation depth increased, the imago's survival rate decreased. The control group had a greater imago emergence survival rate (51%±4.1), whereas no pupa survived at a depth of 30 cm in the other groups. All soil depths except for 30 cm had normal imago, however, all other soil depths had anomalous imago. The range of the average development time was 8.02 to 12.57 days. The length of pupal development is influenced by the depth of pupation. At depths between 0 and 4 cm, pupal development took fewer than 10 days on average, but from 10 to 60 cm, it took more than 10 days. The regression analysis's findings point to the equation y = -4.9524x + 35.54. According to prediction results, a depth of 50.4 cm may be the point at which the emergence of adult B. dorsalis is successfully suppressed. This study recommends covering rotten fruit to inhibit the growth of fruit flies or burying it in the ground to a depth of more than 50 cm (in dry conditions) to increase the effectiveness of fruit fly management.