Red gram podfly

Morphology of Melanagromyza obtusa, Red gram podfly

1. ACHARYA N.G RANGA AGRICULTURAL UNIVERSITY Agricultural college, Bapatla Course No :ENT 501 Course Title :INSECT MORPHOLOGY Topic : Morphology of Redgram Podfly ( Melanagromyza obtusa ) Submitted to, Dr. B. Ratna kumari Assistant professor Department of entomology Agricultural college Bapatla. Submitted by, P. Vijay babu BAM 18- 41.

2. RED GRAM PODFLY Melanagromyza obtusa

3. Contents:- Important notes Taxonomic position Morphology Head - sclerites , compound eyes, antennae, mouth parts. Thorax - wing venation and leg modifications Abdomen - various structures and modifications of abdomen. Biology and management References

4. 1. Importance notes:- In Agricultural Entomology, the pigeonpea pod fly appears in a list of “the more notable pest species of Agromyzidae ” (Hill, 1994). In Agricultural Insect Pests of Temperate Regions and Their Control, the pigeonpea pod fly appears in a list of “important leaf miner ( Agromyzidae ) pests” (Hill, 1987). The FAO document “Plant Pests of Quarantine Importance to the Caribbean” mentions, “Can be very serious. Up to 100% pod damage and up to about 85% seed damage reported in India. In Latin America, pigeonpea is both a backyard garden crop and an export crop grown for canning green seeds (Shanower et al., 1999).

5. 2. Taxonomic position Phylum : Arthropoda Class : Insecta Order : Diptera Family : Agromyzidae Full Name : Melanagromyza obtusa Malloch 1914 Synonym : Agromyza obtusa Malloch (Sigh & Ipe , 1973) Common name: Pigeonpea Pod Fly (Shanower et al., 1999) Bean Pod Fly; Pod Fly (FAO/RLAC, 1989)

6. 3. HEAD The head is distinct from the thorax, with a marked narrowing at the neck . Adult agromyzids can be recognized by the distinctive  sclerotization  of the head.  The upper part of the  frons , above the  ptilinal suture is lightly sclerotized and lacks  setae .

7. The lower part of the frons and the dorsal area of the head tends to be much more heavily sclerotized and setaceous.  Thus, the frontal vitta often forms a distinctive patch on the head, different in colour and texture from the rest of the head.  The  compound eyes  are usually oval and fairly small, although in some species, they are larger and more circular . The  chaetotaxy  is well developed, especially on the head. 

8. The post vertical orbital bristles on the head are always present and divergent, inner and outer vertical bristles on the head are well developed . They have ocellar bristles, frontal bristles (two to eight pairs of frontal bristles, the lower one to three pairs curve inward, the other pairs backward), vibrissae (in some cases weakly developed), and oral bristles are always present.

9. Antennae:- The basal segment of the antennae is very short; the second antennal segment is not grooved. The third antennal segment is always large, usually round (not elongated but sometimes with a sharp point) and usually with swollen, and the almost bare or pubescent arista never is plumose. 

10. Mouth parts:- The mouthparts are sponging type and proboscis is usually short and thick, rarely elongated and geniculated  . The maxillary palps are single-segmented and porrect.  At the end of the labium, there are large sponge like organs called  labella .

11. The labella is a very complex structure that contain many grooves known as pseudotrachea . This structure is very important as it suck up liquids like a sponge . Once liquid food is drawn by the pseudotrachea, it will pass through the food channel into the oesophagus .

12. 2. Thorax:- The thorax has well-developed dorsocentral bristles, postalar bristles, supra- alar bristles, and acrostichal and intra- alar bristles. The scutellum has two to four bristles.  The  chaetotaxy  of the pleura is also of taxonomic significance.

13. The characters taken into consideration are presence or absence, the number, and the position of setae and groups of hairs on the, Mesopleuron – anepisternal or mesopleural bristles sternopleuron – sternopleural bristles proepisternum and proepimeron – proepisternal and proepimeral bristles, or propleural bristles Pteropleuron – anepimeral or pteropleural bristles Hypopleuron – meral or hypopleural bristles.

14. Wings:- All Diptera are equipped with only one pair of functional wings, which are on the mesothorax (front).   The wings on the metathorax are transformed into the  halteres  or rocker arms.  The halteres are club-shaped organs, used to balance the insect in flight

15. Wing venation:- W ing-veins are costa , subcosta , radial, medial and cubital .  The costa has one break which is at the end of the subcosta .  The subcosta is apparent (faint) and joins vein 1 well short of the costa , or terminates before it (vein Sc is complete or incomplete, apically ending in vein R1  .

16. Legs:- A few bristles are on the legs, but bristles on tibia 2, are of taxonomic significance . Tibiae are without a dorsal pre-apical bristle.   Hind tibiae are without strong bristles in the basal 4/5.  The front femora are without a conspicuous spine beneath . The relatively thin legs have precisely arranged bristles which also function in chaetotaxy. 

17. The dorsum of the tibia (especially) and the femur is often identified by a double line of very small bristles .

18. 3. ABDOMEN:- The morphology of the abdomen is substantially determined by morpho-anatomic adaptation, in both sexes, as a function of the reproduction.  In general, the 10 urites are reduced to a lower number of urites because of structural modifications of the first urite and the last.

19. In females, the last urites become thinner and stretch forming a flexible telescopic ovipositor . This morphological adaptation is often accompanied by sclerotisation of the terminal eighth urite, so that the ovipositor is able to penetrate through the tissues of the organism which will accommodate the eggs and larvae.

20. Eggs and larva:- The egg is oval-shaped, white or yellowish . The Diptera larva is apodous (with no legs ) . The head is usually devoid of eyes, has chewing mouthparts , modified antennae with up to six segments, more or less developed or reduced to papillae.

21. PUPA:- The pupa is variable, from barrel shaped, to a more elongated shape ( coarctate type). The outer surface can segmentation and is more or less smooth or wrinkled.  The colour varies from black to brown to yellowish white.

22. ADULTS:- The adult is a medium-sized green species with a large ocellar triangle (Spencer, 1973). On the abdomens of the females, the basal cone of the ovipositor is conspicuously elongated (Spencer, 1973).

23. Females copulate within 24 hours after emergence and oviposition quickly follows (Spencer, 1973). When fed with honey, the adult stage lasts for approximately 12 days; without feeding, only half as long (Shanower et al., 1999).

24. DAMAGE SYMPTOMS:- Dark brown encrustation on the pod wall Dry pods showing  pin head size hole , Seeds  shrivelled, striped and partially eaten

25. MANAGEMENT:- Chemical Control: Hill (1987) notes that several insecticides, such as diazinon and chloropyrifos , are effective against dipterans Several studies showed that two or three applications are more effective in reducing pod fly infestations than single applications of the same insecticide (Shanower et al., 1998). Because of (1) the high cost of insecticides used in repeated sprays, (2) the comparatively low value of the crops, and (3) the cryptic nature of the pest, control by insecticides may not be feasible.

26. Cultural Activities:- Because of its restricted host range (Shanower et al., 1999) crop rotation will probably influence populations of pigeon pea pod flies. The maturation date of pigeon peas in India greatly influenced the quality and quantity of damage caused by the pigeon pea pod fly. Pigeonpea cultivars maturing at the end of November had 4% seed damage; cultivars maturing in mid-February had 11% seed damage. cultivars maturing in the last week of April had 35% seed damage (Shanower et al., 1998).

27. Natural Enemies:- More than 14 species of parasitic hymenoptera attack the larval stage. The two most important taxa are Euderus spp . and Ormyrus spp. (Shanower et al., 1999; Shanower et al., 1998).

28. PREDICTED CONSEQUENCES:- The ARS is seeking a pigeonpea variety that will mature in 120 to 150 days. This variety will be introduced into the wheat rotation. The pigeonpea variety will be planted just after the wheat has been harvested (usually in June) and will be harvested before the replanting of wheat (usually in October) (Weaver, 1998). In Latin America, pigeonpea is both a backyard garden crop and an export crop grown for canning green seeds (Shanower et al., 1999).

29. REFERENCES: Ahmad, T. 1938. The tur pod fly, Melanagromyza obtusa , a pest of Cajanus cajan . Indian Journal of Agricultural Sciences 8(1):63-76. Delfino , M. D. and Hardy, D. E. 1967. A Catalog of thje Diptera of the Oriental Region. The University Press of Hawaii, Honolulu, HI. Hill, D. 1994. Agricultural Entomology. Timber Press, Portland, OR. Shanower, T. G., Lal , S. S., and Bhagwat , V. R. 1998. Biology and management of Melanagromyza obtusa ( Malloch ) ( Diptera : Agromyzidae ). Singh. S. 1971. Agromyzidae Exploration in India. School of Entomology, St. John’s College, Agra, India.

30. Submitted to, Dr. B. Ratna kumari, Assistant professor, Dept. of entomology, Agricultural college, Bapatla. Submitted by, P. Vijay babu, BAM-18-41, Msc .Ag 1 st year, Dept. of entomology, Agricultural college, Bapatla.