Eco. Env. & Cons. 26 (November Suppl. Issue) : 2020; pp. (S156-S161) Copyright@ EM International ISSN 0971–765X Biotoxicity analysis of different doses of Beauveria bassiana (Balsamo) Vuillemin against Nymph of Odontotermes obesus (R.) Anjana Intodia1*, Arti Prasad2 and Bharati Veerwal3 1*Govt. Meera Girls College, Udaipur, Rajasthan, India 2Department of Zoology, Mohan Lal Sukhadia University, Udaipur, Rajasthan, India 3Maharana Pratap Govt. P.G.College, Chittorgarh, Rajasthan, India (Received 31 March, 2020; Accepted 14 May, 2020) ABSTRACT Termites are soil-dwellers and carry out various activities in hidden-quarters without being detected. They pose a serious threat to agricultural, horticultural crops, forestry trees, and wooden structures. Use of entomopathogenic fungus can be a ecofriendly approach as comparable to chemical insecticides for control of various castes of termites. Entomopathogenic fungi are important natural enemies of arthropods and can be used as biological control agents. Bio efficacy of different concentrations of entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin were evaluated against nymphs of termite Odontotermes obesus (R.) in laboratory conditions. The treatment results clearly revealed that the rate of mortality was increased with concentration and exposure period of treated dose of Beauveria bassiana on nymph of termite. Key words : Biotoxicity, Beauveria bassiana, Nymphs, Odontotermes obesus Introduction cultural crops, agroforestry, stored timbers, books and records, woodworks in buildings and stored Termites are well organized social insects present in products containing cellulose (Rashmi and terrestrial environments that feed on cellulose. Sev- Sundararaj, 2013). Worldwide, the anticipated loss eral termite species play a great ecological role in due to termite damage is about 50 billion US$ yearly contributing appreciably to most of the ecosystems (Subekti et al., 2015), although estimates vary con- (Roonwal, 1978a). Their actions result into recycle of siderably by the cropping systems followed in dif- macronutrients such as Carbon and Nitrogen and ferent environmental regions. The losses caused in tunneling habits helps in soil aeration, porosity India alone run into several hundred million rupees (Singha et al., 2010). Out of 300 species of termites per year, and the world loss must be more than known so far from India, about 35 have been re- $10,000 Million. ported damaging agricultural crops and buildings. Entomopathogenic fungi are important natural Termites have been reported worldwide as one of enemies of arthropods and can be used for biologi- the most important group of insects that cause sig- cal control. More attention has been given to fungal nificant and serious damages to crops, structures pathogens of insects, which are widespread in na- and buildings (Lee and Chung, 2003). Termites ture and are being exploited to control pests cause extensive damage to agricultural and horti- through introduction and augmentation (Goettel et (1*Associate Professor, 2Professor, 3Assistant Professor) INTODIA ET AL S157 al., 2005 and Gokçe & Er, 2005). Entomopathogenic Culture of Beauveria bassiana (Balsamo) Vuillemin fungi differ from other insect pathogens because Beauveria bassiana (Balsamo) was collected from they are able to infect through the host’s integu- Maharana Pratap University of Agriculture and ment, so ingestion is unnecessary and infection is Technology, Udaipur Rajasthan and subcultured on not limited to chewing insects (Fuxa, 1987). Termites Sabouraud Dextrose Agar (SDA) media, in the labo- could be effectively controlled by using pathogenic ratory. A spore suspension was prepared by har- microbes. Their habitats, which are humid and of a vesting conidia from the SDA plates just before ap- relatively constant temperature, are ideal for micro- plication. Conidial count was done using Neubauer bial growth, while crowded conditions and social Improved Haemocytometer under a microscope for interaction in termite nests encourages transmission conidia/mL of dilution and recorded separately. of the fungus (Delate et al., 1995). Anand et al. (2009) has reported that the fungal Inoculation pathogen Beauveria bassiana infects pupae of Thirty nymphs were placed on different petri plates Spodoptera litura in a dose–dependent manner for that contained 1 mL conidial suspension of B. each of the formulations investigated which agree bassiana at different concentration of 4.5 x108, 4.5 with the findings of the present investigation. They x107, 4.5 × 106 and 4.5 × 105 conidia/mL on also reported that Beauveria bassiana was more infec- Whatman’s filter paper disc (9 cm × 1 mm) and 1 tive and resulted in maximum average percent mor- mL of control suspension solution which contained tality among the three species viz. Metarhizium sterile water. The nymphs were exposed to conidial anisopliae, Beauveria bassiana and Lecanicillium sp. suspension for 24 hours. The treated nymphs were under investigation. The life cycle of a termite be- then transferred in sterile glass Petri dishes (10 cm gins with an egg, it goes through incomplete meta- in diameter), lined with sterile moistened Whatman morphosis, with egg, nymph and adult stages. filter paper. A wood piece was placed in the petri Nymphs go through a series of moult as they grow. plate for food. Both experimental and control petri Nymphs first moult into workers, and then some dishes were kept at 28°C ± 2°C and relative humid- workers go through further moulting and become ity 75± 5 percent in BOD in the dark. soldiers or alates (Neoh and Lee, 2011). If we control nymph we can also control termite colony. Results In the present investigation, bioefficacy of differ- ent concentrations of entomopathogenic fungus Bioefficacy of different concentrations of Beauveria bassiana (Balsamo) Vuillemin were evalu- entomopathogenic fungus Beauveria bassiana ated against nymphs of termite Odontotermes obesus (Balsamo) Vuillemin were evaluated against (R.) in laboratory conditions. nymphs of termite Odontotermes obesus (R.) in labo- ratory conditions. The treatment results revealed Materials and Methods that highest concentration (4.5 × 108 conidia/mL) was significantly superior over the rest of the treat- Termite collection ments (29.92 percent mortality) at 24 hours of treat- Underground nests of Odontotermes obesus (R.) lo- ment time (Table 1). 4.5 × 106 and 4.5 × 105 conidia/ cated at crop fields were opened up, termites con- mL were at par in terms of toxicity when analyzed sisting of workers, soldiers and nymphs together statistically (CD 5 percent= 4.27). with nest material were collected in a tray and Similar trend of effectiveness was observed at 48 brought to the laboratory. The termites along with and 72 hours of treatment period. Highest concen- the nesting mound soil were put in plastic contain- tration maintained its superiority even at 96 hours ers and were observed in the laboratory for 1-2 after exposure by registering significantly highest months. The rearing container was covered with (95.84 percent) mortality of nymph over rest of the lids. Water was added to the containers every 3-7 treatments. Second lower concentration 4.5 × 107 days to maintain moisture. These termites were kept conidia/mL (79.17 percent mortality) proved to be in petri dishes containing wet filter paper for 24 h next best to lower two treatments and differed sig- before inoculation. nificantly from remaining treatments (CD 5%= 7.31). Cent percent mortality was observed at the S158 Eco. Env. & Cons. 26 (November Suppl. Issue) : 2020 Table 1. Biotoxicity of Beauveria bassiana (Balsamo) Vuillemin on nymphs of Odontotermes obesus (R.) Treatment Cumulative mean percent mortality ± SE 24 Hrs 48 Hrs 72 Hrs 96 Hrs 120 Hrs 144 Hrs Control 5.83±1.60 10.84±2.50 15.84±0.86 17.50±0.83 19.17±1.60 19.17±1.60 4.5×108 Conidia/mL (T1) 29.92±1.29 47.50±2.85 71.67±3.47 95.84±2.10 100.00±0.00 100±0.00 4.5×107 Conidia/mL (T2) 23.33±1.36 38.33±3.97 61.67±2.15 79.17±2.85 95.00±1.67 100.00±0.00 4.5×106 Conidia/mL (T3) 17.50±1.60 33.33±1.36 50.83±1.59 73.33±3.60 94.17±0.84 100.00±0.00 4.5×105 Conidia/mL (T4) 14.17±2.50 26.67±3.04 45.00±2.89 64.17±4.17 90.00±1.36 100.00±0.00 S.E.m ± 1.725 2.871 2.376 2.951 1.254 0.713 CD (P=0.05) 4.27 7.12 5.89 7.31 3.11 1.77 CD (P=0.01) 6.35 10.57 8.74 10.86 4.61 2.62 highest concentration (4.5 × 108 conidia/mL) after df =4) which means that there was no significant 120 hours and for rest of the treatment after 144 differences between the observed and predicted hours as compared to 19.17 percent in control (Fig. proportion of mortality. The values of lower and 1 6 1). upper limit of LC50 were 2.51×10 and 9.90 × 10 conidia/mL and values of lower and upper limit 9 28 LC90 1.47 × 10 and 1.90 × 10 conidia/mL respec- tively. These results were also supported by graphi- cal representation (Fig. 2). Probit analysis was conducted to calculate LT50 and LT90values, in hours, for each concentration of fungus. Goodness of fit tests for each concentration showed that the results were the best fit to the data of all available distributions. The Chi square values for different concentrations were 6.17, 5.04, 6.31 and 10.55 which was nonsignificant. LT50 and LT90 values for 4.5 × 108 conidia/mL concentrations were 37.45 Fig. 1. Graphical representation for the biotoxicity of and 88.58 hrs. respectively, and 95 percent confi- Beauveria bassiana (Balsamo) Vuillemin against nymphs of Odontotermes obesus (R.) Further ANOVA also supported the results (Table 2). The mortality values were significantly increased depending on the increasing time period of treatment when the termite nymphs were ex- posed to different concentrations of fungus.