New insecticide molecules and entomopathogens against Hadda beetle, Henosepilachna vigintioctopunctata infesting vegetable cowpea

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1 Full paper Indian Journal of Plant Protection Vol. 42. No. 4, 2014 ( ) 333 New insecticide molecules and entomopathogens against Hadda beetle, Henosepilachna vigintioctopunctata infesting vegetable cowpea M H Kodandaram, Jaydeep Halder and A B Rai Division of Crop Protection, Indian Institute of Vegetable Research, Varanasi , Uttar Pradesh, India. E mail: kodandaram75@gmail.com Abstract Laboratory and field experiments on the efficacy of novel insecticide molecules and entomopathogens to hadda beetle, Henosepilachna vigintioctopunctata were conducted at Indian Institute of Vegetable Research, Varanasi for two seasons during Chlorantraniliprole g a.i /ha and thiacloprid g a.i. /ha exhibited ovicidal action with lowest per cent egg hatching. Imidacloprid g a.i. /ha and thiacloprid a.i. /ha were found to be most effective against grub and adult stages of hadda beetle and recorded highest per cent mortality when tested by leaf residue method. Among the biopesticides viz., Metarhizium anisopliae (1x10 8 cfu/g) and neem oil provided highest protection over control and indicated compatibility and synergistic activity at 1:1 combination. Emamectin benzoate 5 10 g a.i. /ha and thiodicarb 75 a.i. /ha proved to be the most effective with highest reduction in pest population of 75.3 and 73.9%, respectively under field conditions. Keywords: Cowpea, Henosepilachna vigintioctopunctata, bioefficacy, new insecticides, entomopathogens Introduction Among leguminous vegetables, cowpea (Vigna unguiculata) is a cheap and nutritious vegetable grown mainly for tender pods throughout India and South East Asia. It is mostly cultivated in Uttar Pradesh, Bihar, Orissa, West Bengal, Chhattisgarh, Gujarat and Odisha. Among different insectpests attacking the cowpea, hadda beetle, Henosepilachna vigintioctopunctata (Fab.) is a minor pest (Van Halteren, 1971). But recently, in northern parts of India this pest has become a major one and attacks cowpea during vegetative stage of the crop. Being polyphagous in nature, this pest also attacks other vegetable crops like potato, brinjal, tomato and cucurbits. In severe infestations, both the grub and adult stages scrape the chlorophyll, skeletonize the leaves, which lead to formation of a papery structure on the infested leaf, poor growth of the plants and reduce the yield to a considerable extent (Murthy, 1958 and Rajagopal and Trivedi, 1989). Generally, conventional insecticides belonging to organophosphates and synthetic pyrethroids are used to control the hadda beetle in solanaceous vegetables (Kumar and Kumar, 1998; Sheikh Khursheed and Desh Raj, 2013). The newer insecticide molecules presently available have several advantages over conventional insecticides like high selectivity to target pests, excellent efficacy at low rates or dosage, cause less harm to natural enemies and environment (Kodandaram et al., 2010). All these merits render them as relatively safe and fit well into integrated pest management (IPM). To our knowledge, there are no reports available on the field effectiveness of new insecticide molecules against hadda beetle in cowpea. Hence, present study was taken up to evaluate the efficacy of some of the novel insecticide molecules, entomopathogens and plant origin insecticides against hadda beetle, infesting cowpea under laboratory and field conditions. Materials and methods Laboratory studies The grubs and adult hadda beetles were collected from cowpea fields of Indian Institute of Vegetable Research (IIVR) farm and were reared in laboratory on their natural host at 27 ± 1 o C and 60 ± 5 % RH. The eggs, grubs and adult beetles from laboratory maintained cultures were taken for the bioassay studies. The new insecticides molecules viz., chlorantraniliprole 18.5 SC, flubendamide SC, indoxacarb 14.5 SC, spinosad 2.5 SC, imidacloprid 17.8 SL, thiacloprid 21.7 SC and talc based formulation of entomopathogens viz., Beauveria

2 334 Insecticide molecules and entomopathogens against Hadda beetle M H Kodandaram et al., 1x10 8 cfu/g, Metarhizium 1 x 10 8 cfu/g and Lecanicillium lecanii (previously known as Verticillium 2 x 10 8 cfu/g and Pseudomonas 1 x 10 8 cfu/g and neem 2.5% used in the present study were obtained as commercially available formulations from their respective sources of supply. Different insecticides were evaluated at their recommended doses after dilution in the distilled water. Concentration of neem oil was prepared by dissolving in emulsifying water containing Triton X-100 as an emulsifier. All the microbial biopesticides were 5 g/l of water and neem oil was sprayed alone and in their 1:1 combinations. To determine the ovicidal action of newer insecticides, one day old 50 eggs of H. vigintioctopunctata were dipped in the respective insecticides solutions for 5 seconds and then air dried. The treated eggs were transferred to Petri dishes (diameter 90 mm) and kept for hatching under high humidity (75 ± 5% RH) conditions. For control, the eggs were dipped in distilled water. Data on hatching of treated eggs and mortality of hatched grubs was recorded at 48 and 72 hours after treatment. The efficacy of insecticides and entomopathogens against grubs and adults was evaluated using the following bioassay methods. Direct spray method. The test insects were randomly selected and placed in the Petri dishes and one ml of each concentration of the test insecticides and entomopathogens was directly sprayed at a pressure of 340 g cm -2 under Potters tower. The sprayed Petri dishes containing treated larvae were air dried for about 5 minutes and fresh untreated cowpea leaves were given as food. In case of control the grub and adults were sprayed with distilled water. Leaf residue method. Cowpea leaf discs of approximately 5 cm diameter were dipped in the different insecticide solutions for 20 seconds and then air-dried. Leaf discs dipped in the distilled water were maintained as control. The treated leaf discs were then transferred to Petri dishes and ten adult beetles were released in each Petri dish and were allowed to feed on the treated leaf. Dry film residue. A film of each insecticide was prepared on both the surfaces of Petri dish by depositing 1 ml of concentration by gentle swirling and later dried for 10 minutes under electric fan. Adult beetles were introduced into Petri dish and untreated cowpea leaves were given as food. For control the Petri dishes were treated with the distilled water. In all the three bioassay methods, each treatment including control was replicated thrice. Ten test insects were released in each treatment. All the treated insects were kept at 27 ± 1 o C and 70 ± 5 % RH and in case of insecticides mortality of grubs and adults was recorded 24 and 48 h after treatment and for microbial biopesticides, 5 days after treatment. Field study A field experiment was conducted during Kharif season of 2010 and 2011 in RBD design at the IIVR farm. Cowpea (cv. Kashi Kanchan) was sown in plots of size of 5m x 3m with a spacing of 45 cm 15 cm and all standard agronomic practices were followed except plant protection. There were six treatments viz., emamectin benzoate 5 10 g a.i. / ha, indoxacarb ml a.i. /ha, spinosad ml a.i. /ha, thiodicarb 75 a.i. /ha, flubendamide ml a.i. /ha and untreated control. All the treatments were replicated thrice. Two foliar sprays of each treatment was applied at 25 days after transplanting at an interval of 15 days. Observations were recorded on the number of adults per plot at 3, 7, 10 days after spray (DAS). The data collected were transformed and statistically analysed through ANOVA. Results and discussion Ovicidal action The ovicidal effect of different insecticides on eggs of hadda beetle is presented in Table 1. Among different insecticides, thiacloprid g a.i. /ha and chlorantraniliprole g a.i /ha were most effective against eggs of hadda beetle with lowest per cent hatching of 11.8 and 20.5, respectively. Similarly, highest per cent inhibition of egg hatching of 82.6 and 70.0 was observed in thiacloprid and chlorantraniliprole, respectively as compared to untreated control and the lowest inhibition was in spinosad treated eggs. However, 100 per cent mortality of hatched grubs was recorded in chlorantraniliprole, indoxacarb, imidacloprid and thiacloprid treated eggs of hadda beetle. Similar results were reported by Sahu et al., (2006), who observed ovicidal effect of thiodicarb on the eggs of epilachna beetle, Epilachna sparsa. Efficacy of insecticides on grubs and adults The data on the mortality of grubs and adults of hadda beetle (Table 2) at 24 and 48 hours after treatment revealed that imidacloprid g a.i/ha and thiacloprid a.i/ha were the best treatments against grubs with average per cent mortality of 90 and 86.7, respectively. Further, it was also found that the chlorantraniliprole a.i/ha, flubendamide a.i/ha and Indoxacarb g a.i/ha registered 65, 63.3 and 63.3 per cent mortality of treated grubs and were statistically at par with each other. Lowest grub mortality was recorded

3 Indian Journal of Plant Protection Vol. 42. No. 4, 2014 ( ) 335 Table 1. Ovicidal effect of newer insecticides on eggs of hadda beetle Dose Per cent Per cent inhibition Per cent mortality Treatments (a.i/ha) hatching over control of hatched grubs Chlorantraniliprole 18.5 SC Flubendamide SC Indoxacarb 14.5 SC Spinosad 2.5 SC Imidacloprid 17.8 SL Thiacloprid 21.7 SC Control SEm± CD (P=0.05) Table 2. Effect of new insecticides on grubs and adults of hadda beetle by direct spray method Per cent mortality Grubs Adults Treatments 24 HAT 48 HAT Avg. 24 HAT 48 HAT Avg. Chlorantraniliprole 18.5 SC Flubendamide SC Indoxacarb 14.5 SC Spinosad 2.5 SC Imidacloprid 17.8 SL Thiacloprid 21.7 SC SEm± CD (P=0.05) in spinosad 2.5 SC@ 17.5 a.i/ha. In case of adults, imidacloprid g a.i/ha and thiacloprid a.i/ha were most effective with the average per cent mortality of and 95. Chlorantraniliprole a.i/ha and flubendamide a.i/ha were least effective against adults of hadda beetle. In both the stages of hadda beetle the mortality increased with increase in time. Sahu et al., (2005) evaluated relative toxicity of some insecticides and found fipronil, diflubenzuron, triazophos, thiodicarb and cartap hydrochloride more toxic as compared to carbaryl against grubs of epilachna beetle, Epilachna sparsa. Among the newer insecticides evaluated, imidacloprid g a.i /ha and thiacloprid a.i /ha proved to be most effective against adults of hadda beetle by all the three methods of applications. The per cent mortality in imidacloprid treated adults was 95,100, 90 and thiacloprid was 93, 100, 89 for direct spray, leaf residue and film residue methods, respectively. Our present findings are in conformity with, Sahu et al., (2005 ) who also reported that the five insecticides viz., fipronil, diflubenzuron, triazophos, thiodicarb and cartap hydrochloride exhibited 1.87 to 7.94 times higher toxicity in leaf dip method than that in direct spray method against the third instar grubs of epilachna beetle, Epilachna sparsa. Efficacy of entomopathogens and neem oil Marked differences in the efficacy of microbial insecticides alone and their combinations with neem oil were observed against grubs of hadda beetle (Figure 1). Among the different entomopathogens, the black muscardine fungus, M. anisopliae was found to be highly effective in controlling the second instar grubs of E. vigintioctopunctata imparting 62% mortality after 6 days after treatment followed by B. bassiana (60.3%). However, neem oil had the highest protection over control (66.4%) amongst all the tested

4 336 Insecticide molecules and entomopathogens against Hadda beetle M H Kodandaram et al., % Protection over control (SEm+) B. bassiana M.anisopliae L.lecanii P.fluorescens B.thuringiensis Neemoil Bb+NO Biopesticides Ma+NO Ll+NO Pf+NO Bt+NO Figure 1. Efficacy of entomopathogens and neem oil against grubs of hadda beetle biopesticides under laboratory conditions. Interestingly, combination of all the microbial biopesticides with neem oil at 1:1 ratio gave greater mortality than their individual biopesticides. The highest mortality of 77.5% grubs was recorded in the combination of M. anisopliae and neem oil followed by L. lecanii and neem oil combination with 72% mortality, indicating compatibility and synergistic activity between the entomopathogens and neem oil. Our present findings are in accordance with the observation of Swaminathan et al., (2010) who observed that neem oil 5% caused 60% adult mortality under laboratory conditions. In another study Vishwakarma et al., (2011) reported that M. 3 g/l gave 70.71% reduction in epilachna beetle population infesting bottle gourd. Compatibility between M. anisopliae and neem oil was reported against nymphs and adult females of red cotton bug, Dysdercus cingulatus by Halder et al., (2013). Field efficacy Data on the field efficacy of newer molecules against hadda beetle is presented in Table 3. The results clearly indicate that all the treatments reduced pest population significantly over untreated control at 3, 7 and 10 days after application. However, emamectin benzoate 5 10 g a.i. /ha and thiodicarb 75 g a.i. /ha proved to be the most effective treatments with highest overall mean reduction of 75.3 and 73.9% in pest population, respectively, being statistically at par with each other, but significantly superior to other treatments. The next best treatments were indoxacarb and spinosad. Whereas, flubendamide was statistically at par with the indoxacarb and spinosad after first round of application but after second spray it was least effective. Patnaik et al., (2004) reported that foliar application of thiamethoxam g a.i. /ha was effective against epilachna beetle, H. vigintioctopunctata in brinjal under field conditions. Recently, Sheikh Khursheed and Desh Raj (2013) evaluated the efficacy of some conventional insecticides and biopesticides and found that lambda- cyhalothrin and carbaryl were most potent and effective against H. vigintioctopunctata in bittergourd. Thus, from the above findings it can be concluded that novel molecules like chlorantraniliprole g a.i. /ha, imidacloprid g a.i. /ha, thiacloprid a.i. /ha, emamectin benzoate 5 10 g a.i. /ha and the biopesticides viz., M. 1 x 10 8 cfu/g and neem oil can be effectively utilized for the control of different life stages of hadda beetle, H. vigintioctopunctata. Moreover, the present study may also help in rational selection of novel insecticide molecules, microbial and botanical insecticides, which can be taken advantage for developing integrated pest management (IPM) programme for cowpea. Acknowledgements The authors are thankful to the Director, Indian Institute of Vegetable Research, Varanasi, India for encouragement, support and providing infrastructural facilities in conducting these studies. References Halder J, A B Rai and M H Kodandaram Compatibility

5 Indian Journal of Plant Protection Vol. 42. No. 4, 2014 ( ) 337 Table 3. Field efficacy of newer insecticide molecules against hadda beetle Reduction in population over control (%)* Dose First spray Second spray (gm/ml) Before Overall Treatments a.i/ha spray 3DAS 7DAS 10DAS Avg. 3DAS 7DAS 10DAS Avg. efficacy Emamectin Benzoate 5 SG (57.7) (58.2) (60.0) (58.6) (61.8) (59.5) (64.1) (61.7) (60.2) Indoxacarb SC (41.5) (50.3) (60.9) (50.7) (57.6) (54.4) (49.5) (53.8) (52.2) Spinosad SC (39.6) (52.6) (62.0) (51.1) (60.4) (50.8) (50.8) (54.1) (52.6) Thiodicarb WP (49.1) (52.6) (64.0) (54.9) (63.4) (64.4) (64.1) (64.0) (59.3) Flubendamide SC (52.4) (43.9) (53.5) (49.9) (54.7) (42.7) (38.1) (45.1) (47.5) SEm± CD (P=0.05) Figures in the parentheses are arc sin transformed values; DAS = Days after spray; * Pooled mean of three replications of neem oil and different entomopathogens for the management of major vegetable sucking pests. National Academy Science Letters 36 : Kodandaram M H, Rai A B and Jaydeep Halder Novel insecticide for management of insect pests in vegetable crops - Review. Vegetable Science 37 : Kumar S and Kumar J Laboratory evaluation of some insecticides against strains of hadda beetle, Henosepilachna vigintioctopunctata (Fab) resistant to malathion and endosulfan. Pest Management and Economic Zoology 6 : Murthy D V An unusual mode of feeding by epilachna beetle on brinjal. Mysore Agricultural Journal 33 : 80. Patnaik H P, Mohapatra L N and Maity B K Effectiveness of thiamethoxam 25 WG against the insect pests of brinjal under field conditions. Journal of Plant Protection and Environment 1 : Sheikh Khursheed and Desh Raj Efficacy of insecticides and biopesticides against hadda beetle, Henosepilachna vigintioctopunctata (Fabricius) (Coleoptera: Coccinellidae) on bitter gourd. Indian Journal of Entomology 75 : Swaminathan R, Manjoo S and Hussain T Anti-feedant activity of some biopesticides on Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae). Journal of Biopesticides 3 : Van Halteren P Insect pests of cowpea, Vigna unguiculata (L.) in the Accra plains. Ghana Journal of Agriculture Science 4 : Vishwakarma R, Prasad P H, Ghatak S S and Mondal S Bio-efficacy of plant extracts and entomopathogenic fungi against Epilachna beetle, Henosepilachna vigintioctopunctata (Fabricius) infesting bottle gourd. Journal of Insect Science 24 : Rajagopal D and Trivedi T P Status, bio-ecology and management of epilachna beetle, Epilachna vigintioctopunctata (Fab.). Tropical Pest Management 35 : Sahu B B, Senapati B and Mohapatra L N Relative toxicity of some insecticides to epilachna beetle, Epilachna sparsa. Journal of Plant Protection and Environment 2 : Sahu B B, Senapati B and Mohapatra L N Ovicidal effect of thiodicarb on the eggs of epilachna beetle, Epilachna sparsa. Insect Environment 12 : Received : Accepted :