J. BioI. Control, 15: 97- 100,2001 Research Note Biology and predatory potential of Micraspis univittata (Hope), a coccinellid predator recorded in sugarcane ecosystem S.EASWARAMOORTHY, R. NIRMALA and G. SANTHALAKSHMI Division of Crop Protection Sugarcane Breeding Institute Coimbatore 641007. Tamil N adu, India E-mail: [email protected] ABSTRACT: In a survey for natural enemies in sugarcane fields at Harinagar, West Champaran district, Bihar, the coccinellid, Micraspis univittata (Hope) was recorded for the first time in sugarcane ecosystem. The biology of the coccinellid and its predatory potential were worked out at Sugarcane Breeding Institute, Coimbatore, using the sugarcane aphid, Melanaphis sacchari (Zehnt.) as the laboratory host. The mean duration of development of M. univittata was lS.S± 0.6 days and the adult longevity was 37.7 ± 7.7 days. The predatory potential of grubs was 373 ± 39.6 aphids while the adults preyed on 3659.1 ± 865.9 aphids. The grubs and adults also preyed upon different stages of other sugarcane pests like shoot and internode borers. But they failed to feed on nymphs of whiteOies and eggs and nymphs of pyrilla. KEY WORDS: BioJogy,Micraspis univittata, predatory potential, sugarcane aphids In India, thirty three species of coccinellids 1978). With a view to work out the biology and are reported to occur in the sugarcane ecosystem feeding potential of this coccinellid, a study was (Easwaramoorthy et ai., 1988). They are found to conducted at Sugarcane Breeding Institute, predate mainly on different stages of soft bodied Coimbatore, using sugarcane aphid Melanaphis hemipterans, coccids, eggs and young larvae of sacchari (Zehnt.) as host and the results are lepidopteran borers and mites (Butani, 1958; presented in this paper. In addition, the other prey Sankaran and Mahadeva, 1974; Bindra and Brar, range of the coccinellid in the sugarcane 1978). During a recent survey in the sugarcane ecosystem was determined using sugarcane shoot fields of MIs Harinagar Sugar Mills, Harinagar, and internode borers, whiteflies, mealybugs and West Champaran District, Bihar, for the natural pyrilla. enemies of Plassey borer, Chilo tumidicostalis (Hampson) in September 1999, the coccinellid, The biology of the coccinellid was studied Micraspis (=Verania) univittata (Hope) was found (n=10) at 28 ± 4°C and 70 ± 10 per cent relative to occur for the first time in sugarcane humidity. Freshly laid eggs were placed in glass ecosystem. Earlier. Verania sp. and V. discolor F. vials (15cm I x 2.5cm dia) and the incubation were found to feed on nymphs and puparia of period was recorded. After hatching, the grubs whiteflies, Aleurolobus barodensis (Mask.) were reared individually on sugarcane aphids (Bulani, 1958) and V. aUardi Muls. on eggs of provided ad libitum. Moultings and successive Pyrilla perpusilla (Walker) (Bindra and Brar, developmental period of each instar of the grub EASWARAMOORTHYeral. and pupal period were noted. Adult gestation The number of aphids preyed by M. period and longevity were determined. For univittata grubs increased steadily with age and studying the feeding potential, the newly hatched successive moultings except for the second instar. grubs (n=13) were fed with known number of The average feeding potential of first, second, third aphids. Observations were made at 24h interval and fourth instar grubs was 53.7 ± 7.1,46.1 ± 3.3, and the unfed aphids were removed. Fresh batch 82.2 ± 14.3 and 191 ± 34.5 aphids, respectively. of aphids were offered to the grubs everyday until During the entire period of development a single pupation and upon emergence the adults (n=10) grub preyed upon 373 ± 39.6 aphids (Fig.la). were fed with known number of aphids everyday The predatory potential of adults was until death. observed over a period of 47 days. The mean The eggs were barrel shaped, creamy yellow number of aphids consumed by an adult varied and laid on the leaf surface in clusters containing from 45.0 to 139.3 aphids per day. The feeding 14 - 18 eggs close to the aphid colonies. The potential was at its peak when the beetles were 21 unfertilised eggs were laid individually or - 41 days old. A single adult preyed on a mean of sometimes in groups containing less than 10 eggs. 3659.1 ± 865.1 aphids (1512 - 4601) during its Mean fecundity was 71.3 eggs (33 - 108 eggs) laid lifetime (Fig. 1 b). in 5 - 7 clusters. Egg laying period lasted for 8 - 14 days. The egg period lasted for 2.4 ± 0.5 days. The preliminary host range studies showed The grub stage had four instars and each instar that the grubs and adults of M. univittata can feed lasted for 3.9 ± 0.3, 2.0 ± 0.0, 2.2 ± 0.4 and 4.0 ± on the eggs and young larvae of shoot borer, Chilo 0.6 days, respectively. The mean pupal period infuscatellus Snellen and internode borer, lasted for 4.3 ± 0.6 days with a pre-pupal period C. sacchariphagus indicus (Kapur). They do not of about one day. The mean duration of feed on nymphs and adults of the leaf hopper, development was 18.8 ± 0.6 days. The pre­ Pyrilla perpusilla (Walker) and nymphs and oviposition period of adult female varied from 5 - puparia of whiteflies, Aleurolobus barodensis 10 days. The adults lived for a period of 19 - 48 (Mask.) and Neomaskellia bergii Sign. days with a mean of 37.7 ± 7.7 days (Table 1). Micraspis spp. are found to feed on a variety of aphids (Nasiruddin and Islam, 1979; Agarwala Table 1. Mean developmental periods of et al., 1988; Rao et al., 1997). M. discolor larvae M. univittata on M. sacchari were found preying on nymphs and adults of N. iugens in rice fields (Samal and Misra, 1985). Stage of the predator Duration (days) M. crocea (Mulsant) is reported to feed on the eggs Egg 2.4±O.5 of Cnaphalocrocis medinalis (Guenee) and Bradley (Bandong and Grub Marasmia patnalis Litsinger, 1986) and on the pentatomid a) First instar 3.9±O.3 Scotinophara coarctata (Fabr.) (Perez et al., 1989) in rice fields in Philippines. In Malaysia, b) Second instar 2.0±O.0 M. discolor is found to prey on larvae of C. c) Third instar 2.2±O.4 medinalis (Mun, 1982). In groundnut, M. vincta is found to feed on Spodoptera litura (F.) d) Fourth instar 4.0±O.63 (Bhanukiran et ai., 1998). The available literature Pupa 4.3±0.64 shows that Micraspis spp. have their host range in Hemiptera and Lepidoptera as observed in the Toal developmental period 18.8±0.6 present study for M. univittata. The non­ Adult longevity 37.7±7.7 acceptance of Pyrilla in the present study may be due to its larger body size in relation to predator 98 Biology and predatory potential of M. univittata, a coccinellid predator 65 150,-----------------------------, 55 130 ~ j4:5 110 '=' 35 i 90 0 g 25 co 70 ~ 15 50 ;5 0 2 4 6 10 12 Days after hatching Days after hatching (a) Predatory potential of grubs (b) Predatory potential of adults Fig.I. Feeding potential of M. univittata adults and grubs on M. sacchari size and that of whiteflies due to its hard cuticle to conduct this study and Dr. Poorani, Project and waxy coating. But this is in contrast to the Directorate of Biological Control, Bangalore, for earlier observations made by Butani (1958) that identification of the coccinellid. The senior author Verania sp. and V. discolor feed on the nymphs is thankful to the authorities of MIs Harinagar and adults of A. barodensis. Sugar Mills, Bihar, for the facilities provided to carry out the survey work. 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