Padi Pests Malaysia
Padi Pests and Insects in Malaysia.
The major insect/pests to be tested with our products are (a) Apple Snail; (b) Rice Bug; and (c) Rice Black Bug.
> APPLE SNAILS.
Two species, Pomacea canaliculata and Pomacea maculata (under Investigation), commonly known as Golden Apple Snails, are highly invasive and cause damage to rice crops. They were introduced to Asia, from South America, in the 1980s as potential food for people, but it unfortunately became a major pest of rice.
What it does - Golden apple snails eat young and emerging rice plants. They cut the rice stem at the base, destroying the whole plant.
Why and where it occurs - Snails are able to spread through irrigation canals, natural water distribution pathways and during flooding events.When water is absent, apple snails are able to bury themselves in the mud and hibernate for up to six months. When water is re-applied to fields, snails may emerge. They damage direct wet-seeded rice and transplanted rice up to 30 days old. Once the rice plant reaches 30−40 days, it will become thick enough to resist the snail.
How to identify - To distinguish golden apple snails from native snails, check its color and size. Golden apple snails have muddy brown shell and golden pinkish or orange-yellow flesh. They are bigger and lighter in color compared to native snails. Its eggs are bright pink in color.To confirm snail damage, check for missing hills, cut leaves, and cut stems.
Why is it important - The golden apple snail is considered a major problem of rice. If no control measure is taken, they can completely destroy 1 sq. meter of field overnight. This damage could lead to more than 50% yield loss.
How to manage - The critical time to manage golden apple snails is during land preparation and crop establishment or planting ... specifically, first 10 days after transplanting (DAT) and during the first 21 days after direct wet-seeding. After this, the crop is generally resistant to snail damage and snails are actually beneficial by feeding on weeds.
Community snail management - To best control the snail, communities should work together to reduce snail numbers in their area :-
> Conduct mass snail and egg collection campaigns, involving the whole community, during land preparation and planting or crop establishment;
> Keep fields drained as much as possible during the vulnerable stages of the rice plant (below 30 days) or transplant 25−30 day old seedlings from low density nursery beds; and
> Encourage natural predators.
Biological control - (a) Red ants feed on the snail eggs while ducks (and sometimes rats) will eat young snails. (b) Several wild bird species have also adapted to feed on golden apple snails and domestic ducks can be put into fields during final land preparation or after crop establishment when plants are big enough (e.g. 30−35 Days); and (c) Snails can also be harvested, cooked and eaten or sold as animal feed. However, it is important to take extra care and cook the snails thoroughly, as they are known carriers of the rat lungworm.
Cultural control - (a) Handpick snails and crush egg masses. This is best done in the morning and afternoon when snails are most active. Place bamboo stakes to provide sites for egg laying that allows easy collection of snail eggs for destruction. You can also use attractants or plants that attract snails, such as papaya and cassava leaves, to make hand picking easier; (b) Manage water - Apple snails have difficulty moving in less than 2 cm of water. Keep water level below 2 cm during the vulnerable stages of the rice plant. Construct small canals or canalettes (e.g. 15−25 cm wide and 5 cm deep) after the final land preparation. Pull a sack containing a heavy object around the edges of rice paddies or at 10−15 m intervals. Canalettes facilitate drainage and act as focal points for snails making manual collection or killing easier; (c) Use toxic plants - Place toxic plants, such as tobacco leaves, heart leaf false pickerelweed and citrus leaves in strips across the field or in canalettes; (d) Prevent field entry - Know your water flow. Snails can invade fields from canals, rivers, and reservoirs. Place a barrier where water enters and exits the field. Place a wire or woven bamboo screen or mesh bag on the main irrigation water inlet and outlet to prevent snail entry; and (e) Transplant - Transplanted rice is less vulnerable than direct seeded rice. Plant healthy and vigorous seedlings. Raise seedlings in low density nursery beds, i.e. less than 100g seeds per sq. meter and delay transplanting (e.g. transplant 25−30 day-old seedlings). To reduce missing hills from snail damage, multiple seedlings per hill can be planted.
Chemical control - (a) Sometimes chemical control may be needed if other practices fail. Check locally available products that have low toxicity to humans and the environment. Nitrogen fertilizer is harmful to the apple snail when applied in 2 cm of water; (b) Apply products only to low spots and canalettes rather than to the whole field. Always ensure safe application; (c) Apply products only to low spots and canalettes rather than to the whole field. Always ensure safe application; and (d) If used, molluscicides should only be used immediately after transplanting or during the seedling establishment phase in direct seeded rice; and only for rice younger than 30 days old.
> RICE BUGS.
The most common species of rice bug are Leptocorisa oratorius. Pictured in this background.
What it does - Rice bugs damage rice by sucking out the contents of developing grains from pre-flowering spikelets to soft dough stage, therefore causing unfilled or empty grains and discoloration. Immature and adult rice bugs both feed on rice grains.
Why and where it occurs - High rice bug populations are brought about by factors such as nearby woodlands, extensive weedy areas near rice fields, wild grasses near canals, and staggered rice planting. The insect also becomes active when the monsoonal rains begin. Warm weather, overcast skies, and frequent drizzles favor its population buildup. The population of the rice bug increases at the end of the rainy season. Rice bugs are found in all rice environments. They are more common in rain fed and upland rice and prefer the flowering to milky stages of the rice crop. Adults are active during the late afternoon and early morning. Under bright sunlight, they hide in grassy areas. They are less active during the dry season. In cooler areas, the adults undergo a prolonged development in grasses. They feed on wild hosts for one to two generations before migrating into the rice fields at the flowering stages. The nymphs are found on the rice plant where they blend with the foliage. There, they are often left unnoticed. When disturbed, the nymphs drop to the lower part of the plants and the adults fly within a short distance.
How to identify - Check the plant for feeding damage, such as (a) Small or shriveled grains; (b) Deformed or spotty grains; (c) Empty grains, and (d) Erect panicles.
The symptoms can be confused with the damage caused by nutrient deficiency or flower thrips. To confirm rice bug infestation, check for presence of insect (a) Oval, shiny and reddish brown eggs along midrib of leaf; (b) Slender and brown-green nymphs and adults feeding on endosperm of rice grains; and (c) Offensive smell.
Why is it important - Both the adults and nymphs feed on grains at the milking stage. They can be serious pests of rice and sometimes reduce yield by as much as 30%.
How to manage - Remove weeds from fields and surrounding areas to prevent the multiplication of rice bugs during fallow periods. Level fields with even applications of fertilizer and water encourage rice to grow and develop is at the same rate. Planting fields, within a village, at the same time (synchronous planting) also helps reduce rice bug problems. Capturing rice bugs, in the early morning or late afternoon, by net can be effective at low rice bug densities, though labor intensive. Encourage biological control agents: Some wasps, grasshoppers and spiders attack rice bugs or rice bug eggs. Indiscriminate insecticide use disrupts biological control, resulting in pest resurgence
> RICE BLACK BUGS.
What it does - Black bugs remove the sap of the plant. They can cause browning of leaves, deadheart and bugburn. Their damage also causes stunting in plants, reduced tiller number, and formation of whiteheads. On severe cases, black bugs weaken the plant preventing them from producing seeds. As shown in this background picture.
Why and where it occurs - The insect is common in rain fed and irrigated wetland environments. It prefers continuously cropped irrigated rice areas and poorly drained fields. Damages are observed more frequently in dry season rice crops and densely planted fields. Black bug flight patterns are affected by the lunar cycle; on full moon nights, large numbers of adults swarm to light sources. Staggered planting of the rice crop and excessive nitrogen also favor the buildup of the pest. During non-rice periods, the presence of alternate breeding site favors population increase.
How to identify - Check leaves for discoloration. Black bug damage can cause reddish brown or yellowing of plants. Leaves also have chlorotic lesions. Check for decreased tillering. Bugburn symptoms show wilting of tillers with no visible honeydew deposits or sooty molds. Plants are also stunted; and can develop stunted panicles, no panicles, incompletely exerted panicles, and unfilled spikelets or whiteheads at booting stage. Check for deadhearts. Deadhearts can also be caused by stemborer. To confirm cause of damage, pull infected plants. In black bug damage, infected plants cannot be pulled at the bases. Heavy infestation and "bugburn" is usually visible after heading or maturing.
Why is it important - Black bug feeds on the rice plant from seedling to maturity growth stages. Ten black bug adults per hill can cause losses of up to 35% in some rice.
How to manage - To prevent black bug infestation Use resistant varieties. Contact your local agriculture office for up-to-date lists of varieties available. Maintain a clean field by removing the weeds and drying the rice field during plowing. Plant rice varieties of the same maturity date to break the insect’s cycle. Use of mercury bulbs as light traps for egg-laying adults, light trapping of insects should start 5 days before and after the full moon. Encourage biological control agents, such as small wasps (parasitize the eggs), ground beetles, spiders, crickets, and red ants (attack the eggs, nymphs, and adults), coccinellid beetles, ducks, toads (feed on eggs and nymphs), fungi species (attacks nymphs and adults).
To control - During early infestation, raise the water level in the field for 2−3 days to force the insects to move upwards. Flood the fields. This can cause higher egg mortality. After harvest, plow fields to remove remaining insects