Stem Borer
The stem borer is the most destructive insect for the date palm tree in the United States & India. The adult male date palm stem borer is 20-39 mm in length, while the females are typically longer than the males. The stem borer beetle is reddish-brown in color and coated with short pubescence. The stem borer’s eyes are perceptive. The antennae of the stem borer have twelve segments and are as long as the stem borer body. The rear edge of the last sternite is straight in the male and round with a little depression in its center in the female. The eggs are white and stretched, measuring approximately 35-43 mm in length and less than 2 mm in width. The hatchlings are long and tube-shaped, measuring approximately 45-50 mm in length.
Symptoms of Stem-Burer Bug
Large (2-3 cm) holes in the upper trunk are the most evident indicator of damage caused by Dinapate wrighii, the huge palm borer. In this region, you can find numerous exhibition rooms. In extreme circumstances, the palm’s trunk may become brittle and its crown may fall off. The larvae’s feeding may cause the death of the bud or meristem.
- Both adult palm borer insects and the larval feeding damage they cause are immediately identifiable.
- Sawdust is visible in the crown and trunk of the tree.
- The chewing causes holes to be worn into the leaves.
- The palm borer excavates galleries in the stem of the palm.
- As a result, the stems get twisted, and incorrect leaf bud development occurs.
- The afflicted palm plants dry out and die.
Identification of Stem-Borer
Adults can attain a length of 2 inches and range in color from black to dark reddish brown. As with most bostrichids, this individual has a prominent snout tuck, concealing its mouth and jaws from above. The crown of the skull resembles a balloon. Eggs range from white to golden in hue and measure approximately 1/16 of an inch in length. The female lays the eggs in a chamber she has bitten out of a piece of wood, typically at the leaf\’s base. Thick, golden, and frequently concealed in trees, larvae are difficult to notice. When threatened or exposed, they can reach a length of 1.5 inches while crawling in a C-shape. Pupae develop in a chamber one inch beneath the bark of trees.
Damage Symptoms of Stem Borer
Date palms of India and California fan palms are prone to infection by the palm borer. Both adults and larvae target the trunk and the base of the leaf crown as their principal points of attack. Females will develop a chamber towards the base of the leaf crown, which will be partially filled with a soft, thick, and moist material composed of fibers, feces, and sap. Along a tree trunk, wood-boring larvae can create tunnels in either direction. As they emerge, newly independent adults frequently chew holes in tree trunks. Typically, infested palms exhibit fading leaves and die prematurely. With sufficient wind, fragile palms can fall over. The gigantic palm borer is a nuisance but not a serious problem as a secondary pest. It preys on hosts that are dead, dying, or under tremendous stress, such as transplant recipients.
Life Cycle of Stem Borer
On date palm fibers, females lay approximately 140 eggs. larvae emerge around two to three weeks later. They dug through the trunk in search of food and shelter. Approximately 2.5 weeks are necessary for the pre-pupa stage. During this stage, the cocoon is made. The pupal stage can last anywhere from 1.5 to 2.5 months, depending on when the insect begins spinning its cocoon. July and March would both work. Hibernation of stem borer larvae can last up to two years. Due to this, the larval stage can endure between one and two years. The total length of a yearly life cycle is approximately 13 months and up to 23 months for a biennial cycle. Summer is when stem borer moths are most prevalent.
Stem Borer Chemical Control Method
It has been determined that the systemic insecticides Confidor 200SL (Imidacloprid) and Actara 240SC (Thiamethoxam) are both effective against date palm tree stem borer infestations. In controlled field experiments, three methods were tested: direct spraying, trunk injection, and off-season drenching. The larvae of the Indian Rhinoceros Beetle, Oryctes agamemnon arabicus (ARB), were shown to be unaffected by a direct spray of a 5-liter solution (1 ml confidor per liter water) per tree or (1ml Actara per tree treating only the crown tree) on the trees.
Injection of 10 ml per palm tree with a concentration of a standard solution (10 ml confidor per liter water) caused 100% mortality of ARB larvae, but injection of 40 ml per palm tree with the same dose resulted in approximately 85.8% mortality. In contrast, a 25-liter drench applied to each tree with either 25 milliliters (ml) of Confidor or 5 milliliters (ml) of Actara resulted in larval mortality rates of 80% and 75%, respectively. The results of this study justify the use of Confidor 200 SL (Imidacloprid) or Actara 240 SC (Thiamethoxam) as chemical control for palm stem borers in IPM programs after yield collection.
Stem Borer Biological Control & IPM
Since ancient times, the date palm has been a major fruit crop in the desert regions of the world, including Southwest Asia, North Africa, Mexico, Australia, South America, India, and the United States. Numerous insect pests pose a threat to palm trees, the most severe of which is the stem borer. The whole lifetime of this parasite happens within the host tree, making it exceedingly difficult to eliminate. The use of pheromones to affect insect behavior, crop and field hygiene, the removal of contaminated fronds and offshoots, and the elimination of concealed breeding areas are all components of an integrated pest management (IPM) approach for controlling this pest. IPM also includes regulatory policies such as local and international quarantine, as well as cultural approaches such as boosting in-groove humidity and palm density, applying pesticides sparingly, and using biological control agents such as entomopathogenic fungus and nematodes.