Sodium Fluoride CAS No.7681-49-4 Sodium Fluoride Basic Information Sodium Fluoride Anticoagulant,Sodium Fluoride Allergy,Sodium Fluoride 99,Industrial Grade Sodium Fluoride Shandong YingLang Chemical Co.,Ltd , https://www.sdylhgtrade.com
Product Name: Sodium fluoride
CAS: 7681-49-4
MF: FNa
MW: 41.99
EINECS: 231-667-8
Mol File: 7681-49-4.mol
Sodium Fluoride Chemical Properties
Melting point: 993 °C(lit.)
Boiling point: 1700 °C
Density: 1.02 g/mL at 20 °C
Vapor pressure: 1.4 mm Hg ( 0 °C)
Fp: 1704°C
Storage temp.: 2-8°C
Solubility H2O: 0.5 M at 20 °C, clear, colorless
Form: powder
Color: White to off-white
Specific Gravity: 2.558
PH: 7.0-10.0 (25℃, 0.5M in H2O)
Odor: Odorless
Water Solubility: 4 g/100 mL (25 ºC)
Sensitive: Hygroscopic
Wheat stem bee
The scientific name *Cephus pygmaeus* Linnaeus belongs to the order Hymenoptera, family Stemoptera. This species is widely distributed across the country. Another related species, *C. fumipennis* Eversmann, known as the stem-winged wheat stem bee, is found in provinces such as Henan, Qinghai, and Gansu.
The primary host plants include wheat, barley, and other cereal crops. The larvae of these bees bore into the stems and culms of the plants, causing severe damage by consuming the inner tissues. In severe infestations, the stalks become hollowed out. As the larvae mature, they move into the rhizomes, cutting the stalks off from the root or leaving only a thin layer of the epidermis connected. The cut sections are neat, and the affected wheat becomes easy to bend, often leading to lodging.
Morphologically, adult *C. pygmaeus* have a body length of 8–12 mm. They are entirely black with long, filamentous antennae and transparent wing membranes. The front part of the body is dark brown, and females have yellow horizontal bands on abdominal segments 4, 6, and 9. Their abdomens are more rounded, and the ovipositor at the end has a zigzag shape. Male bees also display yellow bands on segments 3 through 9. On the ventral side of the first, third, fifth, and sixth abdominal segments, there are large light green spots. A pale green triangular mark is present on the back of the abdomen, and the overall body is uniformly slender. The eggs are about 1 mm long, elongated, and white and transparent. The last instar larvae measure 8–12 mm, with a milky white body, light brown head, and reduced thoracic structures. Their bodies are wrinkled, and the hind segment extends into a short chitinous tube. The pupae are yellowish-white and turn black when fully developed.
In terms of life habits, *C. pygmaeus* completes one generation per year. The mature larvae overwinter in the base of the stems or within the root pods. Adults emerge in April of the following year, with peak emergence occurring in mid-May and lasting for over 20 days. After emerging, female bees lay eggs in thin straw stalks, typically depositing 50–72 eggs per stalk. Most eggs are laid near the lower parts of the wheat stems. When laying eggs, females use their mandibles to create small holes in the stems and scatter the eggs along the inner walls. The egg stage lasts about 6–7 days, after which the larvae feed on the inner walls of the stems. By the third instar, they enter a feeding frenzy, often chewing through entire stems and gradually moving downward toward the base, causing the wheat heads to turn white. Once mature, the larvae move into the roots and overwinter.
For control, several methods can be applied. First, after harvest, deep plowing and burning of wheat stubble can help reduce adult emergence. Second, crop rotation should be practiced as much as possible. Third, cultivating varieties with thick stalk walls or insect-resistant traits is recommended. In severely infested areas, spraying 90% trichlorfon crystals diluted 900 times or 80% dichlorvos EC diluted 1000–1200 times during the peak adult emergence period in late May can be effective. Alternatively, 1.5% dimethoate or 2.5% trichlorfon powder can be applied at 1.5–2.5 kg per 667 m². These measures can significantly reduce infestation levels and protect crop yields.