Applied Agricultural Entomology Insect pest of Corn

Applied Agricultural Entomology- Insect Pest of Corn

1. INTRODUCTION Maize (Corn), Zea mays , is an annual grass in the family Poaceae and is a staple food crop grown all over the world. The maize plant possesses a simple stem of nodes and internodes. A pair of large leaves extend off of each internode and the leaves total 8–21 per plant.

2. INTRODUCTION Corn is one of the Philippines’ most important staple crops, coming second only to rice in terms of land use and production. Globally, it also plays a vital role in food systems and local livelihoods. With more than a billion metric tons produced worldwide each year, corn is incredibly versatile. It’s used not only for human food and animal feed but also for ethanol, sweeteners like high-fructose corn syrup, starch, and even beverages and alcohol.

3. INTRODUCTION Maize can be attacked by a wide range of insects. Of the 47 insect species recorded feeding in corn, four are considered major problems in its production. These are the corn seedling maggots ( Atherigona oryzae Malloch.), the root grubs ( Leucopholis irrorata (Chev.)), the corn borer ( Ostrinia furnacalis Guenee ) and the corn earworm (Helicoverpa armigera Hubn .) .

4. Objectives To familiarized the major insect pest of corn To familiarized the life cycle of major insect pest of corn To describe the damage characteristics of major insect pest of corn To determine the control measures on damage of major insect pest of corn

5. INSECT PEST OF CORN

6. a. CORN EARWORM C.N: Corn worm S.N: Helicoverpa armigera armigera Order:(Lepidoptera: Noctuidae ) It is generally regarded as the more serious pest because of its greater capacity to develop resistance to insecticides, broader host range, and persistence in cropping areas from year to year.

7. Egg (2 - 4 ) days Adult Si x larvae stages (13 - 22 days ) Pup a (6 - 10 days ) Moths are tan, with one dark spot on the middle of each forewing, and a dark band at the end of each hind wing. Moths lay eggs singly on silks. Larvae vary greatly from yellow to green to pink. However, the head is always light brown and unmarked, and there are always microscopic spines covering the body.

8. SYPMTOMS They often feed near the ear tip but can move downward, damaging kernels along the way. This damage encourages fungal infection and can reduce grain quality at harvest.

9. DAMAGE Rows of feeding holes on leaves after they unfold at whorl stage: cut silk and hole at opening of ears from silking to soft dough stage.

10. Control measurement: Insecticides. Corn fields with more than 5% of the plants bearing new silk are susceptible to injury if moths are active. Insecticides are usually applied to foliage in a liquid formulation, with particular attention to the ear zone, because it is important to apply insecticide to the silk. Cultural practices. Trap cropping is often suggested for this insect; the high degree of preference by ovipositing moths for corn in the green silk stage can be used to lure moths from less preferred crops. Biological control . The bacterium Bacillus thuringiensis , and steinernematid nematodes provide some suppression. Soil surface and subsurface applications of nematodes also can affect earworm populations because larvae drop to the soil to pupate ( Cabanillas and Raulston 1996). Trichogramma spp. (Hymenoptera: Trichogrammatidae ) egg parasitoids have been reared and released for suppression of Helicoverpa zea in several crops. Host plant resistance . Numerous varieties of corn have been evaluated for resistance to earworm, and some resistance has been identified in commercially available corn.

11. B. CORN BORER C.N: Dalipog (Ilocano) S.N : Ostrinia furnacalis Order: (Lepidoptera: Crambidae ) The larvae of O. furnacalis attack all parts of the maize plant. Yield losses are greatest when damage occurs at the reproductive stages. Late-instar larvae bore into the stem or branches of host plants or webbed groups of florets or branches. They bore in the shank and cob in the ear or feed on silk or kernels. The stalk is the most common feeding site for final-instar larvae

12. CORN BORER LIFE CYCLE Egg (3 - 5 days ) Adult fi ve larval stag es (21 - 25 days ) Pupa (6 - 9 days )

13. SYPMTOMS Wilting and/or dying of the upper leaves. Ragged irregular holes The "dead heart" A considerable amount of "frass

14. damages Corn borers feed first on the leaves, then move to the tassels and pollen. Usually causes most damage to leaves at the mid‐whorl stages. Larvae in pollen. Corn damage & corn borer Leaf damage

15. CONTROL MEASURES: Natural Enemies-There are a number of natural enemies of Ostrinia of which the egg parasitoids, Trichogramma species, are reported to be the most efficient. Cultural Control -Remove the tassels from 75% of the plants; this i ) removes the caterpillars from the plants, and ii) takes away pollen that would otherwise have fed the caterpillars. Resistant Varieties- Resistant varieties have been selected/bred in a number of countries, so check if they are available in your country. Chemical Control-Synthetic insecticides are not recommended as they interfere with the parasitoids that control Ostrinia furnacalis . Biopesticides - Neem (water extracts from seed kernels) has been used in trials in Papua New Guinea and found to be effective. The research there found that removing the tassels from 75% of the plants, release of Trichogramma plasseyensis , an endemic species, and one application of neem gave satisfactory control of Ostrinia furnacalis .

16. C. CORN APHIDs C.N: Corn leaf aphids S.N: Rhapalipsiphum maidis Order: ( Homoptera : Aphididae ) Aphids are small insects, a few millimeters in length, with piercing sucking mouthparts. They are soft bodied and generally pear shaped with two protruding tubes called cornicles extending off the posterior dorsal part of their bodies. Young aphids are called nymphs. No pupal stage.

17. CORN APHIDS LIFE CYCLE Four Nymph Stages Adult (7 - 14 days The corn left aphids is a blue-green or grey, soft-bodied, spherical insect about the size of a pinhead [1/16 inch (1.6 mm) in length]. Female corn leaf aphids do not lay eggs, as do most other insects, but give birth to living young. These young, called nymphs, resemble the adults except that they are smaller and are sexually immature. Adults and nymphs can often be found clustered within the whorls or upper parts of corn plants over isolated or wide areas of a field.

18. SYPMTOMS Stunted growth Wilting Show yellow patches of discoloration Curling incomplete kernel development. tassels and silks are covered with honeydew.

19. damages Stunted growth due to removal of sap if attacked 2-3 weeks before tasseling; seedlings may wither and die if infested at early growth stages; leaf surface with sooty molds due to heavy deposits of heavy dew. Colonies of aphids found in Yellowing of leaves. Stressed upper leaves and tassel

20. CONTROL MEASURES: There are many natural enemies (lady beetles, lacewings, flower fly larvae, predatory midges, pirate bugs, Braconid wasps) that help reduce aphid numbers. Providing adequate irrigation during the silk stage can reduce or eliminate aphid damage. Inspect crops often and regularly; destroy leaves heavily infested with aphids by hand (or if necessary, use insecticides). If ants are present, find the nest, and destroy it with boiling water, if practical and plants are not at risk of damage, or use a pesticide. Without ants, predators and parasites will bring about natural control. Remove weeds from within and also outside the crop. Collect, burn or bury the remains of crops after harvest.

21. D. CORN SEEDLING MAGGOT C.N: Ngilaw (Ilocano) S.N: Atherigona oryzae Order: ( Diptera : Muscidae ) Eggs are white, darkening near the time of maturity, elongate, 1.25 mm long, laid on the leaf blades of seedlings, singly or in groups. Larvae grow to 9 mm, and are creamy-white becoming yellow with age. Pupation occurs at the base of the plant or in the soil. Pupae are contained in the last larval skin; they are reddish-brown, and about 4 mm long. The adult is a small, yellowish-grey fly, mostly 3-3.5 mm in length, with black head and thorax, and yellow abdomen with two to three pairs of black spots on the back.

22. CORN SEEDLING MAGGOT LIFE CYCLE Egg (1 - 3 days ) Adult (3 - 4 days ). 3 - 4 instars (7 - ) 10 days Pupa

23. SYPMTOMS Leaf feeding lesions, curling and breaking of young leaves, Wilting, draying and rooting of central shoot, infested seedlings shows stunted growth and later may produce side tillers

24. damages The maggots burrow into the seed, often destroying the germ. The seeds fail to germinate and plants do not emerge from the soil leaving large gaps in the stand. When infested seeds do germinate, the seedlings are weak and may die. Any condition that delays germination may increase damage from this pest. Destroyed germ of corn Larvae (maggot)

25. CONTROL MEASURES: Synchronous planting in contiguous areas Early planting in the growing season to escape high maggot population Clean culture including the removal of alternate host plantsSeed treatment with thiodicarb or carbofuran ST before planting.

26. E. CORN SEMILOOPER C.N: Dangan-dangan S.N: Chrysodeixis chalcites Order: (Lepidoptera: Noctuidae ) The semilooper larva is green in colour with several thin light lines running the length of the body. When crawling, it forms a characteristic loop or hump so is known as the semilooper .

27. CORN semilooper LIFE CYCLE Eggs (3 - 4 days ) Adult. Six larval stages Pupa (7 days) Eggs are pearl, white and spherical laid singly on leaves. Incubation period is 3 days. Larvae are greenish with lighter dorsal and lateral stripes and about 50 mm long. They have modes with lopping motion. The pupa is light green then turns reddish brown later. The pupation period takes place either in silver cocoon on lower leaf surface or in the soil and lasts for 7 days. The adult is brownish with golden bronze Y-shaped mark and white spot-on outer wings. Plant growth stages; Emergence (one leaf stage) top silking

28. SYPMTOMS skeletonization Leaf rolling

29. damages Elongated lesions or shedding of leaves due to feedings on soft leaf tissues but sparing the veins and midrib Corn silks are cut during silking stage Skeletonized corn leaf Corn semiloopers

30. CONTROL MEASURES: Choose a tolerance variety Avoid close plant spacing and late planting Monitor your plants at weekly intervals and check for the presence of larvae. Light and pheromone traps can be installed to check and kill the moth population. Collect and destroy larvae and adults to the extent possible. Plough your field after harvest to make the pest accessible to predators.

31. F. COMMON CUTWORM C.N: Arabas (Ilocano) S.N: Spodeptera litura Order: (Lepidoptera: Noctuidae ) The cutworm larvae feed on the roots and shoots, which are often cut off at ground level or at various other levels, or leaves or panicles may be detached. Cutworms can defoliate rice fields, generally in patches, from early vegetative growth to harvest. The cutworms are nocturnal; during the day, they hide in the upper layer (3-5 cm) of soil or occasionally on plants on cloudy days.

32. CORN cutworm LIFE CYCLE Egg (5 - 11 days ) Adult Larva (4 - 40 days ) Pupa (8 - 11 days ) The adult is about 20-25 mm long with wings (forewings are purplish-brown with numerous lines and spots and hind wings are whitish with narrow band along the center margins). The adult moths are nocturnal. The individual egg is pearly white, round, and has a ridged surface. Newly hatched larvae are tiny, about 1 mm long, and are greenish with a cylindrical body. The larvae pass through five instars to become full grown. The full-grown larva has a cylindrical body and is brown or brownish black tinged with orange.

33. SYPMTOMS include missing plant cut or wilted plants

34. damages Scrapping of leaf tissues by young larvae, leaving irregular grayish white patches on the leaves. Older larvae may cut stems and leaves, including veins and midribs Young plants may be completely defoliated by older larvae (third to sixth instars)

35. CONTROL MEASURES: Plow fields to remove weeds which may serve as alternate hosts. Collect egg masses and crush them Make small trenches around the field and put some cut grasses for shade. Collect hiding larvae during early morning Chemical spraying if severe infestation (use pyrethroids )

36. G. Oriental migratory locust C.N: Dudon S.N: Locusta migratoria manilensis Order: (Lepidoptera: Acrididae ) The Oriental migratory locust is slightly smaller than the African migratory locust. It can exist in two phases, solitary and gregarious. The solitary adults are either green or brown, but as the insects become more crowded together.

37. Oriental migratory locust LIFE CYCLE Eggs (10 - 24 days ) Adult nymph ( 5 or 6 instar ) The adult female Oriental migratory locust deposits a number of egg pods in the ground over the course of a few weeks. The eggs hatch 10 to 24 days later and the nymphs develop through 5 or 6 instars, taking between 26 and 61 days to fully develop.

38. SYPMTOMS The leaves are usually the first plant parts to be attacked and these can be chewed almost completely or if they are rather hard, the major veins, especially the midribs, are left. In cereals, varying proportions of the ripening grains are chewed back. Seed pods and fruits may also be attacked.

39. dAMAGE Leaves are irregularly chewed. In serious cases, whole plants sometimes stripped bare. Irregular chewed leaves

40. CONTROL MEASURES: To destroy locusts, the first and most important activity is to locate and destroy the locusts’ eggs in an organized manner by ploughing, harrowing and digging. Also digging 2′ x 2′ trenches around egg-laid areas will help entrap the nymphs, which are the flightless young of the locusts. As they move out after hatching, they are buried or killed with chemical sprays.

41. H. Corn plant hopper S.N: Peregrinus maidis Order:( Hemiptera : Delphacidae ) Peregrinus maidis , known as the corn planthopper , is a species of insect in the order Hemiptera and the family Delphacidae . It is widespread throughout most tropical and subtropical regions on earth. P. maidis are a commercially important pest of maize and its relatives. In addition to physical plant damage. P. maidis is the vector for several species-specific maize viruses, including maize stripe virus, maize mosaic virus and the non-pathogenic Peregrinus maidis reovirus .

42. CORN PLANT HOPPER LIFE CYCLE Eggs (5 - 12 days ) Adult. Four nymph stages ( 14 - 50 days ) Females lay 20-30 eggs within the midribs of their host-plant's leaves. Under normal conditions, development from hatchling to adult takes approximately 20 days. Normal development occurs between 20-27 °C and has five juvenile instar stages. Extreme temperatures (below 10 °C and above 30 °C) result in a loss of the fifth instar and a direct molt from fourth instar to adult, but full development is extended dramatically to 74 days. Rearing at a temperature of 15 °C results in an extra, sixth, instar and a 65-day development time. P. maidis occupies warm climates and is able to reproduce year round, but development is affected by temperature changes.

43. SYPMTOMS Wilting of leaves yellowing of the leaves stem weakness, and even death.

44. dAMAGE Infestations will physically damage the host plant because the insect breaks through the vascular tissue with its tibia spur and feeds on the sap exuded. The physical results on the plant includes wilting, yellowing of the leaves, stem weakness, and even death. In addition to physical damage, P. maidis can also introduce mold and infection to the plant while piercing the tissues. P. maidis feeding behaviour alone can result in a 10-15% crop loss.

45. CONTROL MEASURES: Remove weeds from the field and surrounding areas. o Avoid indiscriminate use of insecticide, which destroys natural enemies. Use a resistant variety. Contact your local agriculture office for an up-to-date list of available varities Use reflective mulch locate and destroy the locusts’ eggs in an organised manner by ploughing, harrowing and digging

46. I. ROOT GRUBS C.N: tateg SN: ( Leucopholis irrorata ( Chev .) Order: ( Coleoptera : Scarabaeidae )

47. ROOT GRUBS LIFE CYCLE Adult Larva(have 3 instar) Pupa Adult beetles lay eggs singly in the soil from May to June. The young grubs (1st and 2nd instar) feed on organic matter. The later instar (3rd) grubs feed on the root system of corn. Adults emerge out of the soil at the onset of rainy season. The complete life cycle of the white grubs is more or less one (1) yearReduction in yield due to infestation ranged from 14% to 50%.

48. SYPMTOMS yellowing of leaves Wilted discolored or dead seedlings may emerge when white grubs attack, gaps in rows where plants fail to emerge. Stunted growth

49. dAMAGE When full grown the grubs attack the roots of living plants causing stunted growth or death of the plant. The first indication of its infestation is yellowing of plants in patches in the field. This species is generally polyphagous, attacking corn and other species of grasses. This pest is not of regular occur ence in the field, but when infestation sets in, it becomes of major irnportance . Corn seedlings injured by white grub. Notice the purple color of the stems.

50. CONTROL MEASURES: No insecticides are recommended as rescue treatment Some cultural control techniques, such as crop rotation, weed control, mid-season plowing, and pasturing hogs on infested fields may provide partial control of white grubs.

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