20191--Mrinmoy Das

Indian Journal of Entomology 83(2021) Online published Ref. No. e20191 DoI No.: 10.5958/0974-8172.2020.00259.X

EFFICIENCY OF LIGHT SOURCES IN TRAPPING LEPIDIOTA MANSUETA

Mrinmoy Das1, Badal Bhattacharyya*, Sudhansu Bhagawati and Elangbam Bidyarani Devi

Department of Entomology, Assam Agricultural University, Jorhat 785013, Assam 1Central Integrated Pest Management Centre, State Bio Control Laboratory, Agartala 799003, Tripura *Email: [email protected] (corresponding author)

ABSTRACT

Efficiency of six light sources viz., light emitting diode (LED), Solar LED, compact fluorescent lamp (CFL), mercury, ultraviolet (UV) and tungsten bulbs in trapping of adult Lepidiota mansueta Burmeister was evaluated in Majuli river island of Assam during 2015-17. Results revealed that the maximum number of (781.2; sex ratio: 3.7:1) got trapped in solar LED light trap and found to be significantly superior over the other light sources. With CFL bulbs, the maximum number of beetles were trapped in 15-watt bulb (725.3; sex ratio: 4.1:1). In mercury and UV lamp it was 389.2 and 199.1 beetles with a male: female sex ratio of 4.4:1 and 4.4:1, respectively. Relatively less beetles were attracted to the light traps with tungsten and normal LED bulbs. Based on these observations, a modified battery-operated LED light trap was designed and its performance was compared with solar LED and 15-watt CFL bulb during 2017. The modified battery-operated light trap trapped 427.3- 469.3 beetles as compared to the ones with solar LED (641.0) and 15-watt CFL bulb (582.0).

Key words: White grubs, Coleoptera, scarabaeid, Majuli river island, light traps, sex ratio, solar LED, light intensity, modified battery operated LED light trap

Lepidiota mansueta Burmeister is a species of pockets. Both the sexes of L. mansueta beetles exhibit white grub belonging to the family positive phototaxis and hence trapping and their mass under the order Coleoptera. This species own a typical destruction by operating light traps during the peak biennial lifecycle which is the first of its kind from emergence period during April was considered as a North East India and also possess a unique distinction practical, cost-effective and ecofriendly novel approach as the first report of Indian phytophagous white grub vis-a-vis adult management (Bhattacharyya et al., species with nonfeeding adults (Bhattacharyya et 2013). In view of this, field experiments were carried al., 2015). Third instar grubs were observed to cause out at the endemic fields of Majuli during 2015-17 to substantial damage to many field crops in Majuli island assess the effectiveness of different light sources in of river Brahmaputra, Assam and also in some major trapping of L. mansueta beetles. sugarcane growing areas of Haridwar and the adjacent areas of Ganga river of Uttarakhand (Bhattacharyya MATERIALS AND METHODS et al., 2013). The most severely affected crops were Field experiments were carried out to know the potato, sugarcane, Colocasia and green gram, and the efficiency of six light sources in trapping L. mansueta extent of damage varied from 42-48, 15-20, 35-40 adults at Majuli river island (26.0016°N, 94.2243°E) and 30-35%, respectively in Majuli (Bhattacharyya of Assam during 2015-16. Tungsten bulbs (40, 60 and et al., 2011). The species spent its entire life cycle 100 watt), compact fluorescent lamp (CFL-11, 15 and under the ground except for a very short period of 2-3 20-watt), mercury bulb (160 watt), ultra violet lamp weeks during the month of April in which the adults (UV), light emitting diode (LED-5, 10 and 15 watt) come out of the ground for mating and oviposition. and solar LED bulbs were the sources of light. The The management of adult beetles during the period efficiency of light sources were assessed following the after premonsoon showers became inevitable in the methodology given by Ramamurthy et al. (2010). To endemic areas. Moreover, in white grub endemic areas operate tungsten, CFL, mercury and LED bulbs, bulbs in Majuli, community action programmes were aimed were fitted in a locally designed light trap supplied by since 2010 for collecting adult beetles in huge numbers Networking Centre, All India Network Project on Soil by scouting and operating light traps at its endemic Pests, Durgapura, Jaipur, Rajasthan. The 2 Indian Journal of Entomology 83(2021) Online published Ref. No. e20191 effectiveness of UV light was assessed by using the through CFL bulb, mercury bulb, UV lamp, tungsten light trap obtained from the Pest Control India Pvt. Ltd, and LED bulb. Maximum attraction of beetles in solar Bangalore. The solar LED light traps were received LED light traps could be attributed to the emission of from the National Institute of Agrobiological Science, longer wavelength which were perceivable to but Tsukuba, Japan. Except solar LED, other light traps indistinguishable to human eyes (Poiani et al., 2014). were operated by a mini electricity generator (Honda Moreover, the solar LED light source used in the present 750v) and the light intensity was measured manually study emitted blue coloured light with minimum light by using HTC Lux meter (LX-101A) at 19.30 hr. Light intensity (33.5 Lux) which dispersed in all the directions traps were installed randomly at a distance of 20 m and exhibited a strong attraction for the beetles. The at three endemic villages viz., Bhimpara (26.0055ºN, observations are in agreement with Cowan and Gries 94.0683ºE), Juginidhari (26.0055ºN, 94.0724ºE) and (2009), according to whom the blue light was more Bhakatchapori (26.0089ºN, 94.1496ºE). Beetles trapped effective in trapping moths as compared to green, orange in each replication was counted and collected in separate or red light. Light traps operated with CFL bulb 15-watt containers and brought to the laboratory. The sex of registered 725.3± 8.9 number of beetles trapped (male: the beetles was confirmed by dissecting the individual 582.7± 3.1, female: 142.6± 3.2; light intensity: 1215.0 beetles. The experiment was conducted in completely Lux) followed by CFL bulb 20-watt (total: 564.4± 6.8, randomized design with three replications and data male: 457.1± 3.3, female: 107.4± 1.9; light intensity: analyzed as per Gomez and Gomez (1984). A “modified 1662.3 Lux). The least number of beetles were trapped battery operated LED light trap” was also designed to in light traps operated with LED bulb 15-watt (total: fix the limitations as observed with the aforementioned 143.6± 5.1, male: 122.0± 5.1, female: 21.6± 2.5; light light traps in trapping the beetles and its performance intensity: 895.2 Lux). These results are in conformity was compared with solar LED and CFL 15-watt bulb with the findings of Poiani et al. (2014) who reported fitted light traps by Paired ‘t’ test during 2017. that the probability of capturing insects with a CFL bulb was 3x more as compared to the LED bulbs since RESULTS AND DISCUSSION CFL bulbs emitted white light with shorter wavelengths The efficiency of light sources in orienting L. that might have attracted more nocturnal insects as mansueta beetles based on pooled data (2015 and 2016) compared to the LED bulbs. is presented in Table 1. The maximum trapping was Mercury light trap registered significantly maximum in the solar LED light trap (total: 781.2± 7.9, male: numbers of beetles trapped (total: 389.2± 5.5, male: 613.5± 4.7 and female: 167.6± 3.7) which was found 317.1± 3.7, female: 72.5± 2.8; light intensity: 2403.8 to be significantly superior over the light traps operated Lux) as compared to UV lamp operated light trap (total: Table 1. Efficiency of light sources in trapping ofL. mansueta adults (2015, 2016 and pooled) Treatments Light trap catch (Nos.) Mean Sex Light Total Female Male Ratio Intensity (Mean*±SD) (Mean*±SD) (Mean*±SD) (Male: Female) (Lux)

T1 : Tungsten bulb (40 watt) 217.8± 6.2 31.2± 2.5 186.6± 3.9 6.0: 1 560.8

T2 : Tungsten bulb (60 watt) 266.6± 4.6 36.8± 1.8 229.8± 2.5 6.2: 1 855.0

T3 : Tungsten bulb (100 watt) 343.2± 6.3 43.3± 2.4 299.9± 3.8 7.0:1 1711.7

T4 : CFL Bulb (11 watt) 348.2± 4.1 60.6± 3.6 287.6± 3.6 4.8: 1 961.7

T5 : CFL Bulb (15 watt) 725.3± 8.9 142.6± 3.2 582.7± 3.1 4.1: 1 1215.0

T6 : CFL Bulb (20 watt ) 564.4± 6.8 107.4± 1.9 457.1± 3.3 4.3: 1 1662.3

T7 : Mercury bulb (160 watt) 389.2± 5.5 72.5± 2.8 317.1± 3.7 4.4: 1 2403.8

T8 : UV lamp 199.1± 4.6 31.9± 2.2 136.8± 3.2 4.4: 1 1899.7

T9 : LED Bulb (5 watt) 215.9± 4.6 35.5± 2.7 180.4± 4.2 5.1: 1 571.7

T10 : LED Bulb (10 watt) 174.3± 4.8 27.2± 2.0 147.1± 2.6 5.4: 1 1221.7

T11 : LED Bulb (15 watt) 143.6± 5.1 21.6± 2.5 122.0± 5.1 5.7:1 895.2

T12 : Solar LED 781.2± 7.9 167.6± 3.7 613.5± 4.7 3.7: 1 33.5 S.Ed(±) 4.85 2.19 3.04

CD0.05 10.02 4.52 6.28 *Average of three replications Efficiency of light sources in trappingLepidiota mansueta 3 Mrinmoy Das et al.

199.1± 4.6, male: 136.8± 3.2, female: 31.9± 2.2; light intensity: 1899.7 Lux). Superiority of mercury light traps in trapping insects under the order Coleoptera, Hemiptera and Hymenoptera as compared to black and UV light traps had been reported by Ramamurthy et al. (2010). No significant difference between mercury vapour traps and the UV light in trapping scarab beetles in a tropical forests of Costa Rica (García-López et al., 2011). Among the three tungsten bulbs (40, 60 and 100-watt) tested, the maximum numbers of beetles were trapped in light trap operated with 100-watt bulb (total: 343.2± 6.3, male: 299.9± 3.8, female: 43.3± 2.4; light intensity: 1711.7 Lux) followed by in 60-watt (total: 266.6± 4.6, male: 229.8± 2.5, female: 36.8± 1.8; light intensity: 855 Lux) and 40-watt (total: 217.8± 6.2, male: 186.6± 3.9, female: 31.2± 2.5; light intensity: 560.8 Lux). In this present study, it was observed that mercury and tungsten bulbs were more easily heated as compared to other light sources and revealed 2403.8 and 560.8-1711.7 lux light intensity, respectively. Sex ratio was also was varied among the trappings, and the most effective sex ratio (male: female) was registered in case of solar LED light source (3.7: 1) indicating a good Fig. 1. General view of the modified battery operated LED catch of males per female followed by in CFL 15-watt light trap (4.1:1) and CFL 20-watt bulbs (4.3:1). Comparatively Details of the modified battery operated LED light trap- Source of more male biased sex ratio was recorded in tungsten light: Lantern (Make: Havells) with 16 nos. high power 3.2-watt (6.0:1-7.0:1), LED (5.1:1-5.7:1), UV (4.4:1) and surface mounted device LED having 350 Lux intensity. The light mercury bulb sources (4.4:1). source has in built rechargeable lithium ion 2200 mAh battery and the total height of the Lamp is 30 cm. General specification Being non-feeding in behaviour, the adults of L. of modified trap: Total height: 145 cm, upper top cover diameter: mansueta possess very poor flight activity and hence a 40 cm, distance between top cover and funnel: 20 cm; funnel considerable number of beetles could not either reach diameter: 50 cm; funnel to tank distance: 15 cm; tank diameter: or enter the tank of the light traps. Hence, there was a 40 cm; tank length: 30 cm; pore diameter: 2 cm; length of the need to increase the catchment area of the trap to orient iron stand: 80 cm; diameter of the holder of the iron stand: 42 cm; length of catchment tray: 90 cm; breadth of catchment tray: and collect more number of beetles. Furthermore, poor 90 cm; depth of the catchment tray: 25 cm and raised inward electrical connectivity and irregular power supply edge portion of the catchment tray: 6 cm. in most of the endemic areas of Majuli also caused This observation confirmed the findings of Watson hindrance in operating the light traps continuously. (1979), who also amplified the catchment area of the Realizing the above facts, efforts were made to design trap by using a portable child’s swimming pool and a “modified battery-operated LED light trap” (Fig. 1). found approximately 4.6x increase in trapping of black The performance of the modified trap was also assessed Heteronychus arator as compared to normal with Solar LED and CFL 15-watt bulb fitted light traps trapping through conventional Robinson’s light trap. during 2017 (Table 2). It was clear from the results that the beetles trapped (total: 427.3- 469.3, male: Experience gained through operating the light traps 344.3- 376.7, female: 83.3-92.0; light intensity: 324.7- by exploring different light sources in the L. mansueta 330.0 Lux) in the modified battery operated LED light endemic areas established that the farmers with enough trap was found to significantly differ with light traps resources can opt for Solar LED light trap costing operated with CFL 15-watt bulb (total: 582.0± 11.5, approximately Rs. 35,000-40,000/ trap. Farmers also male: 456.7± 6.1, female: 124.7± 5.0; light intensity: can operate light trap with CFL 15-watt bulb (cost: Rs. 1210.5 Lux; paired ‘t’ value: 15.15) and solar LED light 6000-7000/ trap) for the mass collection and destruction trap (total: 641.0± 9.0, male: 502.3± 4.0, female: 138.7± of beetles in the endemic villages with uninterrupted 4.5; light intensity: 33.4 Lux; paired ‘t’ value: 17.39). power supply. However, the farmers with limited 4 Indian Journal of Entomology 83(2021) Online published Ref. No. e20191

Table 2. Comparison of modified battery-operated LED light trap with solar LED and CFL bulb 15 watt fitted light trap in trapping L. mansueta adults during 2017 Treatments Light trap catch (Nos.) Mean Sex Light Total Females Male Ratio Intensity (Mean*± SD) (Mean*± SD) (Mean*± SD) (Male: Female) (Lux) A. Comparison of modified battery operated LED light trap with solar LED light trap Solar LED light trap 641.0± 9.0 138.7± 4.5 502.3± 4.0 3.6:1 33.4 Modified battery operated LED 469.3± 11.0 92.0± 4.6 376.7± 7.6 4.1:1 324.7 light trap Paired ‘t’ value (P=0.05) 17.39 8.96 22.41 B. Comparison of modified battery operated LED light trap with CFL bulb 15 watt fitted light trap CFL Bulb (15 watt) 582.0± 11.5 124.7± 5.0 456.7± 6.1 3.7 :1 1210.5 Modified battery operated LED 427.3± 9.5 83.3± 4.0 344.3± 6.7 4.1 :1 330.0 light trap Paired ‘t’ value (P=0.05) 15.15 8.53 15.56 resources and residing in areas with poor electrical international conference on : chemical, physiological, connectivity can opt for modified battery-operated LED biotechnological and environmental aspects, Poland. 36 pp. light trap with a cost of Rs. 4000-5000/ trap. Moreover, Bhattacharyya B, Pujari D, Bhuyan U, Handique G, Baruah A A L H, Dutta S K, Tanaka S. 2015. Seasonal life cycle and biology the modified battery-operated LED light traps does not of Lepidiota mansueta (Coleoptera: Scarabaeidae): a serious depend on weather conditions in comparison with Solar root‑feeding pest in India. Applied Entomology and Zoology LED light traps and hence best suited for the marginal 50(4): 435-442. farmers of Majuli. Bhattacharyya B, Pujari D, Handique G, Baruah A A L H, Dutta S K, Das M. 2013. Monograph on Lepidiota mansueta (Coleoptera: ACKNOWLEDGEMENTS Scarabaeidae). Directorate of Research (Agri.), Assam Agricultural University, Jorhat. 30 pp. Financial help received from the Indian Council of Cowan T, Gries G. 2009. Ultraviolet and violet light: attractive orientation Agricultural Research, New Delhi is duly acknowledged. cues for the Indian meal moth, Plodia interpunctella. Entomologia Experimentalis et Applicata 131(2): 148-158. Authors are also indebted to Dr. A. S. Baloda, Network García-López A, Micó E, Zumbado M A, Galante E. 2011. Sampling Coordinator, All India Network Project on Soil scarab beetles in tropical forests: The effect of light source and Arthropod Pests, RARI, Jaipur, Rajasthan for his night sampling periods. Journal of Science 11(95): 1-14. help and guidance. Authors also acknowledge Dr. Gomez K A, Gomez A A. 1984. Statistical Procedures for Agricultural Seiji Tanaka, Ex-Senior Researcher, Laboratory of Research. Wiley-Interscience, New York. 680 pp. Insect Behaviour, National Institute of Agrobiological Poiani S, Dietrich C, Barroso A, Costa Leonardo A M. 2014. Effects Sciences, Tsukuba, Japan for providing the solar of residential energy-saving lamps on the attraction of nocturnal insects. Lighting Research and Technology 0: 1-11. LED light traps. Thanks are due to all the Lepidiota Management Farmers’ Group of Majuli river island, Ramamurthy V V, Akhtar M S, Patankar N V, Menon P, Kumar R, Singh S K, Ayri S, Parveen S, Mittal V. 2010. Efficiency of different Assam for providing logistics for the field study. light sources in light traps in monitoring insect diversity. Munis Entomology and Zoology Journal 5 (1): 109-114. REFERENCES Watson R N. 1979. Use of a modified light trap to improve catches of black beetle, Heteronychus arator (Coleoptera: Scarabaeidae) and Bhattacharyya B, Bhuyan U, Baurah A A L H, Pujari D, Saud R K. 2011. black field cricket,Teleogryllus commodus (Orthoptera: Gryllidae). Lepidiota mansueta Burmeister (Coleoptera: Scarabaeidae). A new New Zealand Entomologist 7 (1): 92-97. severe key pest in Majuli Island, Assam. Proceedings. Seventh (Manuscript Received: July, 2020; Revised: September, 2020; Accepted: September, 2020; Online Published: January, 2021) Online published (Preview) in www.entosocindia.org Ref. No. 20191