A Preliminary Study On Sustainable Management Of Bradysia Odoriphaga

Bradysia odoriphaga causes great damage to Chinese chives in China, and is controlled mainly by using chemical insecticides, causing pollution to environments and products. It is needed to find an alternative method for control the pest to chemical pesticides This paper presents the preliminary studies of biology, behavior, population dynamics and control methods of B. odoriphaga in Shouguang. The main results are as follows:The population dynamics of adult and larvae of B. odoriphaga in Shouguang annually were 6 peaks of population curve in a year: during early April, late April, the last ten days of May, early June, the middle of September and the middle of October. However, the higher peaks of curves occurring in spring. In spring, there were two peaks of larvae population dynamics: during last ten days of March and mid-April, and during autumn, there were also 2 peaks in last ten days of October and mid-November. Like adults, the population of larvae in spring was more than in autumn. The overwinter developmental stages of the maggot were at 3rd or 4th instar. The special distribution of B. odoriphaga larvae in soil was surveyed too. The larvae mainly distributed 0-5cm in depth of soil, and 0-5cm horizontally around the bulbs.The developmental duration of B. odoriphaga egg was shortest at 25℃, 3.7 days among the treatments at temperatures of 10℃, 15℃, 20, 25℃ and 30℃, whereas those of larvae and pupae were the shortest at 30°C 10.2d and 2.9d respectively, and grew faster with the increase of temperature. The female lay the most of quantity of eggs at 25 ℃. The sex ratios (female to male) were 1.51,1.58 and 1.83 at 25℃,30℃ and 35℃ respectively, The phototaxis of the maggot adults was tested with different color discs and most favorite to light-wave at 449nm.Based on the results of studies on phototaixs, yellow sticky traps were firstly used to monitor population dynamics of B. odoriphaga, and combination with the population dynamics of larvae, it was found the intervals between first peaks of curves of populations adult and larvae-were 15d, while 7d between the second peaks, and 7d between the third peaks.Some insecticides including nicotine, abametic, and cyromazin for control of B. odoriphaga were selected both in lab and field trials. The results of field trials with insecticides in spring were better than those in autumn, and suitable dosages of insecticides to control B. odoriphaga were determined too.