Squid Ring,Squid Frozen Ring,Squid Tube Skinless Frozen,Low-Salt Squid Tube Zhoushan City Shuangying Aquatic Products Co., Ltd.  , https://www.shuangying-aquatic.com
Dictyostoma, a pest belonging to the family Diptera, is particularly harmful to leguminous crops. It was successfully controlled in Dalian during the 1970s and remained absent for about three decades. However, after the seed market opened up, the black maggots of bean stalks re-emerged and began spreading rapidly. Between 2005 and 2007, this pest caused significant damage in soybean fields in Liangjiadian and Xingshutun Towns within Jinzhou District of Dalian City, reducing soybean yields by 30% to 50%.
Morphologically, the black maggots of Dictyostoma are small in size with limited mobility. The adult fly measures about 2.5 mm in length, featuring a dark body, a blue sheen on the abdomen, dark red compound eyes, three antennae, and a blunt third segment. A central horn is present on the dorsal side, along with fine hairs and transparent wings that appear lavender in color.
In terms of behavior, the pest completes 2-3 generations per year in northern Liaoning, while in Dalian it can complete 3-5 generations annually. The larvae overwinter in the rhizomes and stalks of host plants. Eggs hatch in mid-June of the following year. Adults are not strongly attracted to light and are most active at temperatures between 25°C and 30°C. They tend to gather on the upper leaves of bean plants, piercing the leaf tips to feed on sap, causing small, scattered holes. After hatching, the larvae feed on the leaves, creating small, translucent tunnels. They then move toward the main veins, entering the petiole and stem, where they feed on the pith and xylem. When mature, the larvae bore a hole in the stem wall and pupate nearby.
The damage caused by Dictyostoma primarily affects crops like green beans, kidney beans, soybeans, red beans, mung beans, and other leguminous vegetables. Soybean production areas suffer the most, with yield losses ranging from 30% in mild cases to over 50% in severe infestations. The larvae hollow out the stems, disrupting water and nutrient transport, leading to plant death. In the seedling stage, damage can cause stunted growth, reduced cell development, and formation of abnormal rhizomes. Severely affected plants may become dwarfed, with hollow stems and falling leaves. Later-stage infestations lead to premature dropping of flowers, pods, and leaves, further reducing grain weight and overall yield.
The resurgence of Dictyostoma can be attributed to several factors. First, unregulated seed trading allowed infected seeds to enter the market without proper quarantine. Second, some seed distributors used low-quality edible soybeans as seeds, which often contained eggs. Third, consecutive warm winters from 2000 to 2007 provided favorable conditions for the survival of overwintering eggs. Lastly, fragmented land management practices led to continuous planting of soybeans, allowing pests to thrive and spread easily.
To manage this pest, strict seed quarantine measures must be enforced to prevent the spread of infested seeds. Establishing dedicated seed fields and ensuring proper cleaning and pest control during seed production can improve seed quality. Crop rotation should be practiced to break the pest's life cycle, and post-harvest cleanup of soybean residue is essential to reduce overwintering eggs. Chemical control options include spraying 50% phoxim EC diluted 1000 times, which offers over 90% control, or using 20% chrysanthemum EC diluted 3000 times combined with 20% synergistic cypermethrin EC, both of which have proven effective in controlling infestations. Early intervention is key to preventing large-scale outbreaks.