1 . Powdered beetle pests ( Sitophilus zeamais Motsch . )
S. zeamais , " maize weevil " or powdered beetles undergo complete metamorphosis , from egg to imago stage ( adult beetles ) . Eggs are laid on any item that has a hole as deep as 1 mm , each hole is then sealed with the rest of the hoist . Egg stage 7 days . Larvae , no legs and clear white . When moving , somewhat shriveled larvae . Stage larvae 7-10 days . Pupa ( chrysalis ) , it looks as if an adult , pupal stage 7-12 days . Imago , his head forming elongated snout ( snout ) . Wings ( left and right ) has a rather pale -colored spots . Pronotum has a small indentation , round each other in a tight situation . The wings can be fully developed , so that the rear wing is used to fly . 3.50 to 5 mm in body length . Imago female can produce 300-400 eggs grains . The resulting egg can reach 575 points . This pest is polipag , besides damaging the corn can also damage the rice , rice etc. . Temperature range for the development of this pest is 17 - 34oC , with an optimum temperature of 25 - 30oC , humidity ranges are 45-100 % . Rapid population growth in material savings when their water content above 15 % . At high beetle populations tend to disperse powder .
Control :
For plant pests in field crops attacked by beetles that cause ear powder if open , so that the necessary management to minimize crop pests main stem borer and cob borers . Plants are drought and low fertilizer causes plants to become infected ear rot disease that can be attacked by beetles powder . Appropriate harvest when corn reaches physiological ripe characterized by the presence of a black coating on the tip of the inner seeds can reduce beetle infestation powder . Delayed harvest can cause increased damage in storage seeds .
Use of varieties that have good closure cornhusk favored by farmers , because farmers store maize in the form of cornhusk , helping to reduce the powdered beetle infestation . Resistant varieties have not been found and is still in the research stage assembly in CIMMYT - Mexico . Resistance mechanisms are known that have the seeds of violence and the high acid content .
- Hygiene ( cleanliness ) and Warehouse Management
Most pest warehouses tend to hide or hibernate after the warehouse is empty . Therefore, controlling pests in storage warehouses focused on hygiene . Hygiene is an important component in an integrated control strategy which intends to eliminate insect populations that can be carried over to the next storage period . Tactics used include cleaning all warehouse structure and burn all contaminated and discard seeds from the warehouse area . Additionally sacks former still contains residual seeds should be discarded . All structures must be repaired warehouse , including cracked walls where insects can hide , and give both insecticide treatments on the walls and ceiling of the warehouse . All of this work must be completed two weeks prior to the storage of the new harvest is done .
- Preparation stored corn grain drying
Of some important parameters that can affect the quality of the seed , which seed moisture content . Seed moisture content = 12 % can inhibit the development of beetle powder . On the moisture content of 8 % powdered beetles become important pests . On the water content of 15 % or more higher ground beetle population growth .
- Physical and mechanical control
Sorting can be done by separating the infected seeds damaged by insects with healthy seeds ( whole ) .
Vegetable materials used to protect seeds in storage varies depending on the region and its people as well as the availability of plants and methods of provision . Vegetable materials that can be used is the leaves of Annona sp . , Hyptis spricigera , Lantana camara , leaves of Ageratum conyzoides , Chromolaena odorata , roots of Khaya senegelensis , Acorus Calamus , flowers of Pyrethrum sp . , Capsicum sp . , And flour seeds of Annona sp . and Melia sp .
The use of entomopathogenic Beauveria bassiana with concentration 109 conidia / ml , at a dose of 20 ml / kg of seed mortality can reach 77.50 % . The use of natural enemies is a type of parasite larvae Anisopteromalus calandrae and Lariophagus distinguendus .
Chemically control is most effective , but harmful to consumers so it is only used for certain considerations such as for seed . Several insecticides are effective enough to beetle powder like genitrothion , iodofengas , which has the power protection pirimiphometil 0.5-1.5 months .
Fumigant is a chemical that the temperature and pressure in the form of gas , the concentration is sufficient to control pests . For effective fumigation , then the storage container must be airtight . Warehouse or storage containers that have been fumigated , should not be disturbed for at least one week . The most widely used fumigant that is metilbromid ( CH3Br ) and phosphine ( PH3 ) . Several reasons such as health and storage container that belongs to farmers are not airtight , causing fumigation method is not popular at farmer level .
- Structure of the warehouse and container storage
Storage container that does not allow for the exchange of air ( air-tight ) , such as metal silo , powder beetles can not thrive . If the silo is full of seeds , insect respiration resulting in the conversion of O2 to CO2 . Warehouse pest will die within 10 days in a sealed silo . In the zinc -covered wooden silo , powder beetle attack is lower than other storage containers such as sacks . At an airtight container such as a plastic -coated aluminum foil and plastic can are sealed powder coated paraffin beetle attack on corn seed is very low . At regular warehouse building consisting of walls or wood , powder beetles attack depends on the container used , but in closed warehouses adjustable temperature and humidity , powdered beetle attack can be eliminated .
2 . Tribolium castaneum Herbst .
This pest is known as the flour beetle ( " flour beetle " ) , have 3 antenna array enlarged end sections in particular , looks like a mace , wide - 9 vertebra to vertebra almost twice the 8th . This beetle is a cosmopolitan insect attack and found grains , seeds , flour , dried fruit , and an insect museum . The adults can be seen from the path that they wake up while moving through the powdery or granular foodstuffs . This pest is a pest of major importance or of rice and wheat products . In severe attacks , the product grayish yellow and moldy with a pungent odor . Imago body length of 3-4 mm , slightly flattened , oval shape and dark brown ( chestnut brown ) . Eggs a female can lay up to 450 eggs. Eggs are very small and white cylindrical shape , placed in flour or small fragments of granules . After hatch into larva ( larvae ) are cream-colored and covered with fine hairs , experiencing skin changes 6-11 times with varying larval period 3-12 weeks at a temperature of 30oC . The pupae without skin , the stage is 3-7 days depending on weather conditions . Year until 4-7 generation lasts 1-4 months . The optimum conditions for the development of this pest 35 - 37 ° C and 70 % Rh .
- Doing drying at certain times with perfect drying . Fumigant use can also be done, but must be careful, especially on a product that is consumed .
3 . Aspergillus flavus and Aspergillus parasiticus
This fungus is able to produce mycotoxins which are toxic metabolic compounds that can cause cancer in humans or animals . When present in corn kernels , the fungus Aspergillus resulting in power sprouts can decrease , change color , lose weight and volume , as well as changes in the chemical composition of seeds . Symptoms of Aspergillus on seeds, black or green , depending on the type of pathogen . Black color due to Aspergillus niger , Aspergillus flavus greenish color caused .
Control : made before from pre-harvest to post- harvest because this fungus infection since in the field , but it should be the seed storage moisture content = 13 % .
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