Store grain pests A Lecture By Mr Allah Dad Khan
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This document provides descriptions of various grain pests, including moths, beetles, and weevils. It discusses the life cycles, physical characteristics, and damage caused by angoumois moth, granary weevil, lesser grain borer, boll weevil, flour weevil, rice weevil, bean weevil, wheat weevil, rose weevil, confused flour beetle, flat grain beetle, Indian meal moth, flour beetles, saw-toothed grain beetle, warehouse beetle, and warehouse moth. The descriptions aim to help identify and understand these common pests of stored grains.
Store grain pests A Lecture By Mr Allah Dad Khan
- 1. Store Grain Pests By Mr. Allah Dad Khan Provincial Coordinator IPM KPK MINFAL Islamabad
- 2. Stored-grain Insects often cause as much loss after harvest as crop pests cause during the growing season. Insects cause losses by direct feeding damage and also deterioration and contamination of grain. Six steps to prevent and control of insect damage are: keep bins clean and repaired; use residual sprays; store only clean, dry grain; aerate the grain; protect the grain; and inspect the grain regularly.
- 3. DESCRIPTION The angoumois moth is yellow-brown with darker markings. Its wingspan is 12- 20mm. Females lay up to 250 eggs on or near the surface of stored grain. The eggs hatch into a caterpillar which bores into grain kernels remaining inside until mature. It then eats its way out of the grain, leaving characteristic exit pin holes on the grain surface. Unlike most other moth pests, no surface web is formed. The life cycle may be completed in as little as five weeks. As well as reducing the weight of grains, Angoumois moth infestations impart an unpleasant smell and taste to the cereal.
- 6. DESCRIPTION When disturbed it sits very still for several minutes. An adult lays up to 450 eggs singly in holes chewed in cereal grains. Each egg hatches into a white, legless larva, which eats the grain from the inside. The larva pupates within the grain and the adult then chews its way out. The exit holes are characteristic signs of weevil damage. The life cycle takes about one month under summer conditions and adults may survive for a further eight months. The granary weevil is a small dark brown-black beetle about 4mm long with a characteristic rostrum (snout) protruding from its head. It has biting mouth parts at the front of the rostrum and two club-like antennae.
- 7. DESCRIPTION The lesser grain borer is the most serious pest of stored grain in Western Australia. It is a dark brown cylindrical beetle about 3mm long. The head is hidden by the thorax when viewed from above. Females lay up to 500 eggs scattered loosely through the grain. The eggs hatch to produce curved white larvae with brown heads and three pairs of legs. The larvae burrow into slightly damaged grains and eat out the starchy interior. After pupating the adults emerge from the grain, leaving large irregular exit holes. The life cycle takes from three to six weeks depending on the temperature. Adults may live up to two months.
- 10. DESCRITION Life cycle of weevils depends greatly on the species. For some, in spring, the adult weevils lay their eggs on the ground near the host plant. When the eggs hatch, the larvae burrow into the ground and feed on the roots. Since the larvae are underground, people seldom see them. Many of the larvae spend the winter in the ground and emerge as adults the following spring. However, the adults that emerge during the summer or fall may invade homes for shelter. Some, like the Asiatic oak weevil, are attracted to light, so they are drawn to homes at night. Others may be attracted by the warmth from the house.
- 12. DESCRIPTION is a type of beetle that is known to cause severe damage to cotton crops. The boll weevil measures an average length of 6 mm. It feeds on the buds and flowers of the cotton plant.
- 13. DESCRIPTION Wherever flour is present, the beetle known as the flour weevil (Family Tenebrionidae) follows. They are not able to feed on whole grains. These beetles are not actually weevils.
- 14. DESCRIPTION —While it is true that the rice weevil (Sitophilus oryzae) is harmless in itself, it hurts human beings on a larger magnitude by compromising food supplies. What it lacks in stinging or biting, it makes up for in causing destruction on a potentially massive scale
- 15. DESCRIPTION The bean weevil the farmers’ scourge. Technically, they belong to the cadre of seed beetles and are not true weevils.
- 16. DESCRIPTION Commonly called the granary weevil, the wheat weevil holds notoriety for its destructive potential in agriculture. Historically, it is known as one of the most formidable pests.
- 17. DESCRIPTION The rose weevil is a serious threat to all horticulturists. Its snout can drill through flower buds. These weevils cause irreparable harm by feeding on petals.
- 18. DESCRIPTION ). Both the adult and larvae are large and easy to see. Both stages feed mainly on the germ of stored grains, but may also attack milled cereal products. The larvae leave stored grain in the fall and burrow into woodwork, such as wooden bins or boxcars, to hibernate. They may also burrow into packaged cereal products, thus providing an entrance for other cereal pests
- 21. DESCRIPTION The confused flour beetle closely resembles the rust- red flour beetle in appearance and life history except for the antenna segments which do not have a distinct three-segmented club at the end. It is more often found in flour mills than on farms, as it prefers more finely divided materials.
- 23. DESCRIPTION Flat grain beetles are small reddish brown insects about 1.5mm long with long antennae and a flattened body. Eggs are laid throughout the stored grain and develop into tiny larvae with characteristic tail horns, biting mouth parts and three pairs of legs. They feed on damaged grain and wheat embryos. Pupation takes place in a cocoon. A complete life cycle takes from 4-5 weeks and adults may survive up to one year.
- 25. DESCRIPTION Indian meal moth (Plodia interpunctella) The adult Indian meal moth is grey with distinctive brownish-red tips to the forewings. The female lays up to 200 eggs near the grain surface as it slowly passes from grain to grain spinning a silk thread. Severe infestations may form a surface web on the grain heap. Larvae attack the wheat germ, then pupate in a cocoon which may be found in cracks and crevices of buildings. The insects quickly emerge as adult moths. A generation takes as little as four weeks under warm conditions.
- 28. DESCRIPTION Flour Beetles go through a complete metamorphosis, just like a fly or a flea and lay tiny eggs that are clear to white in color. These eggs hatch into tiny creamy colored - brownish white larvae. Once the larvae are mature and developed,, they will take on a yellowish tint and are about 3/16 of an inch long. The larvae then goes through a transformation phase and becomes a pupae. The pupae is actually a soft shell inside which the matured larvae develops and fully matures into a fully grown adult beetle capable of reproduction and widespread infestations.
- 30. DESCRIPTION The saw-toothed grain beetle is common on Western Australian farms. Adults are dark brown to black with six tooth-like projections on each side of the thorax. They lay up to 500 eggs loosely spread through the infested grain; eggs hatch to produce larvae which feed externally on grain dust and sometimes wheat embryos. The mature larvae pupate within a silken cocoon. A complete generation may take place in as little as three weeks but the adults may live up to nine months. They frequently hide in cracks and crevices of buildings and machinery.
- 31. DESCRIPTION This beetle was first found in Western Australia in 1989 and that infestation was eradicated. It has now spread to about a dozen locations in Western Australia but has never established to damaging populations. The warehouse beetle is a pest of stored grain in its own right, but the greater threat is the impact on trade that it could have by masking an incursion of the world's worst pest of stored grain — the khapra beetle. Warehouse beetle and khapra beetle require microscopic examination to distinguish them
- 32. DESCRIPTION The warehouse moth is a drab grey moth with a 10-12mm wingspan. It usually only infests the surface of stored grain. Moths live for only about two weeks, but during that time lay up to 200 eggs. These are distributed loosely on the grain surface. Larvae hatch out of the eggs and wander over the grain surface leaving a trail of silk which may form a thick mat covering the surface of the infested grain. Mature larvae pupate in a silk cocoon among the grain or on the walls of the building. The life cycle takes at least four weeks.