Bioecology of Blossom Midge of Jasmine, Contarinia maculipennis Felt (Cecidomyiidae: Diptera) in Different Jasminum Cultivars

Jasmine is a well-renowned flower around the world especially in the tropics because of its unique fragrance. Jasminum sambac, Jasminum auriculatum, Jasminum grandiflorum, and Jasminum nitidum are the four cultivable species of Jasminum. Blossom midge, Contarinia maculipennis Felt (Cecidomyiidae, Diptera), a dipteran pest, has attained the status of a major pest causing severe economic loss by reducing the marketable quality of the flowers. To compare the lifecycle of the notorious midge in all the cultivable Jasminum species, a detailed laboratory study was conducted at the Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore, India. The observations on life cycle parameters of blossom midge, C. maculipennis, revealed that the life cycle consists of egg, maggot, pupa, and adult. The life cycle and duration of each stage are found to be the shortest on J. nitidum and the longest on J. sambac.


Introduction
The genus Jasminum, belonging to Oleaceae or Olive family, contains over 200 species of vines or shrubs with opposite leaves and fragrant flowers [1]. The name "jasmine" or "jessamine" is derived from the Arabic and Persian "yasmin" or "yasaman" and originally referred to the species of Arabian jasmine (Jasminum sambac (L.) Ait) [2]. This plant, with its extremely fragrant flowers, is native to southern Asia, but it has been cultivated in the Middle East for centuries [3]. Jasminum is the generic name of shrubs and vines in the olive family (Oleaceae). Although more than 200 species are known, 40 species have been identified in India, and 20 species are cultivated in South India [4][5][6], of which only three species are used for commercial cultivation namely, J. sambac (Gundumalli/Madurai Malli), Jasminum auriculatum (Mullai), and Jasminum grandiflorum (Jathimalli/ Pitchi). The angel jasmine, Jasminum nitidum, with sweetly fragrant, snow-white, pinwheel-shaped flowers is recently introduced for commercial cultivation in Tamil Nadu, India. The leaves are opposite, 5-12 cm long, with 5-11 leaflets in pinnate form. The flowers are produced in open cymes, and the individual flowers are white having corolla with a basal tube 13-25 mm long and five lobes 13-22 mm long. The flower's fragrance is unique and sweet. It is widely cultivated as an ornamental plant in warm temperate and subtropical regions. The Jasmine Concrete and Jasmine Oleoresin (sold as Jasmine Absolute) were extracted by solvent extraction method. Both products have a huge demand in the fragrance industry (Figure 3). Methyl jasmonate isolated from the jasmine oil of J. grandiflorum has led to the discovery of the molecular structure of the jasmonate plant hormones [9].

Jasminum nitidum
This twinning climber has slender stems and forms a dense habit. The dark glossy green leaves are lance shaped, and the fragrant white star-shaped flowers appear throughout summer in clusters (Figure 4). The angle-winged jasmine is grown for its flowers and glossy foliage. It is planted in small or large gardens for its fragrance or to grow over lattice or a pergola. It is suitable for coastal sub-tropical regions and establishes in 1-2 years. It is also used in containers and grown under glass in cold climates. Once established, it has a high-water requirement and responds to an occasional deep watering particularly during dry periods [10].
The production of jasmine is affected by various factors, among which insect pests are the most devastating factor. The major pests affecting jasmine are jasmine bud worm (Hendecasis duplifascialis Hampson), leaf webworm (Nausinoe geometralis Guenee), gallery worm (Elasmopalpus jasminophagus Hampson), leaf roller (Glyphodes unionalis Hübner), and the two spotted mite (Tetranychus urticae Koch). Of these, bud worm and blossom midge gain major economic importance, as they cause excessive damage to the buds, which is the economic part of the plant [11]. The midge maggots enter into the buds at the base of the corollas resulting in swelling and shrivelling at the base of the buds. The maggots feed inside unopened flower buds, causing deformed, pink discolored buds and blossoms. In case of severe infestations, buds dry prematurely leading to bud drop or blossom drop, thereby the marketable quantity of the flowers is greatly reduced [12] (Figure 5).
Management of this pest has become a menace for the jasmine growers. The knowledge on life history of the pest as well as the life table on different varieties is essential for developing IPM in better management of any pests. The knowledge of the sequence of developmental stages, their duration, and number of generations and method of overwintering is essential to know the 'weakest link' in the life cycle. This would help to aim control measures effectively at the most vulnerable stage of the pest. The biology of jasmine midge is attempted in the four cultivable jasmine

Materials and methods
In the laboratory, 10 pairs of adult midges were introduced into the rearing cage (50 × 45 × 45 cm). A 250 ml conical flask filled with water plugged with adsorbent cotton and inserted with fresh J. sambac branches with flowers and buds was kept inside the cages to facilitate oviposition. The buds were checked for eggs, and the life history was studied. The lower surface of the rearing cage was filled with moist sand and planted with three-fourth mature flower buds to facilitate pupation of the maggots. The egg, maggot, pupal, and adult longevity periods were recorded. Jasmine branches with flowers were replaced daily with fresh branches.
The biology was also studied by rearing them in J. auriculatum, J. grandiflorum, and J. nitidum buds by placing the respective branches in the conical flask with flowers and buds (Figure 6).
To study the biology in different Jasminum species, the midges were cultured in J. sambac, J. auriculatum, J. grandiflorum, and J. nitidum placed inside Petri dishes, and the following parameters were recorded.

Results and discussion
The life span of blossom midge, C. maculipennis, was studied on four cultivable Jasminum species namely, J. sambac, J. auriculatum, J. grandiflorum, and J. nitidum in the laboratory. The life cycle of blossom midge consisted of egg, larval, pupal, and adult stages (Figure 7). The extensive details of life stages were studied in all the four Jasminum sp. and furnished in Table 1. The different life stages were detailed in the following paragraphs.

Eggs
The eggs were elongated and cylindrically laid on the inner whorls of the petals in groups of 10-13 during night times. The eggs hatched in 1-2 days. The average egg period was 1.3, 1.2, 1.1, and 1.1 days in J. sambac, J. auriculatum, J. grandiflorum, and J. nitidum, respectively.

Maggot
The larval stages of midges are called maggots. There were totally four larval instars. The maggots were narrow with pointed anterior and posterior ends. The maggots on eclosion were dull white in color and turned yellow as the development progressed. The maggots scraped the petals, stamen, and stigma and suck sap from the flower buds. The larval period lasted for 4-5 days. The average larval period observed in J. sambac, J. auriculatum, J. grandiflorum, and J. nitidum was 4.4, 4.2, 4.1, and 3.9 days, respectively.

Pupa
The maggots turned orangish yellow before pupation. Pupation occurred in the top superficial layer of soil in a thin white case. The pupal period lasted for 7-8 days. The average pupal period was 7.5, 7.3, 7.2, and 7.0 days in J. sambac, J. auriculatum, J. grandiflorum, and J. nitidum, respectively.

Discussion
The average egg, maggot, pupal, and adult period were 1.3, 4.4, 7.3, and 2.0 days in J. sambac. The findings were in agreement with previous reports that cecidomyiid eggs hatched in 1.4 days, and the larval stage lasted 4-5 days, and adults emerged in 7-8 days [13]. Previous research works studied on the life stages of C. maculipennis and evolved the same results [14]. While comparing the biology in different Jasminum species, the egg period was highest (1.3 days) in J. sambac and least (1.1 days) in J. grandiflorum and J. nitidum. The trend was similar to other stages also. The total life cycle was highest (15.4 days) in J. sambac and least (13.4 days) in J. nitidum [15]. The longest duration of midges on J. sambac revealed the presence of physical factors like bud shape and size or chemical factors like high phenols, lower protein, and sugars that impair the faster growth and development. Host plants adversely affect the biology of the phytophagous insect, reducing the size, longevity, fecundity, and increasing mortality or alternatively may indicate that midges do not prefer to feed on J. auriculatum, J. grandiflorum, and J. nitidum.

Conclusion
The life cycle studies of blossom midge on four cultivable Jasminum sp., J. sambac, J. auriculatum, J. grandiflorum, and J. nitidum revealed that the life cycle consists of egg, maggot, pupal, and adult stages. The life cycle and duration of each stage are found to be the shortest on J. nitidum and the longest on J. sambac.
The use of moderately resistant varieties as a part of IPM strategy can enhance the biological and chemical tools of insect pest management. One of the techniques to decrease the pest damage is the use of the cultivars or species, which shows higher resistance to insect pests such as J. nitidum and J. grandiflorum in areas where incidence of jasmine mites was high. J. grandiflorum is a commercially cultivated species of Jasmine, well known for its mesmerizing fragrance as well as usage for concrete recovery. But, J. nitidum is a new Jasminum species with star-shaped fragrant flowers newly introduced for commercial flower cultivation. Hence, utilizing this least preferred species in breeding programs of jasmine will yield better varieties with greater degree of resistance to jasmine pests.
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