Field Evaluation of Fungal Pathogens Against White Grub, Holotrichia Serrata (Fab

Field evaluation of fungal pathogens against white grub, Holotrichia serrata (Fab.) in sugarcane

P. S.Tippannavar.,1 R. R. Patil2and Patil Sanjay B.3

1Agricultural Research Station, Sankeshwar

2 Dept of Entomology, College of Agriculture

3Agricultural Research Station, Sankeshwar

University of agricultural Sciences, Dharwad-580 005, Karnataka, India.

ABSTRACT

Field evaluation of two fungal pathogens viz., Metarhizium anisopliae and Beauveria bassiana at varied dosages and concentration werecarried out for two consecutive years during 2011 and 2012 at Sankeshwar, Karnataka, India. The results revealed that, chlorpyriphos 20 EC at 10 ml per l was highly effective treatment at all the intervals of observation i.e 7th, 14th, 28th, 45th and 60 days after treatment. However among the entomopathogens combination of Metarhizium anisopliaeat 25 kg/ha and Beauveria bassianaat25 kg/ha along with 25 kgs of FYM recorded 8.74, 4.83, 2.67 and 1.96 grubs per square meter area at 14, 28, 45 and 60 DAT. The next best treatment was Metarhizium anisopliaewhich at 25kg/ha along with 25kgs of FYM recorded least number of grubs i.e 9.24, 5.50, 3.06 and 2.21 at 14, 28, 45 and 60 DAT respectively. However Beauveria bassiana at 25 kg/ha along with 25 kg of FYM has recorded 9.32, 5.58, 3.41 and 3.16 grubs per ml at 14, 28, 45 and 60 DAT. Higher cane yield of 93.45 t/ha was recorded in chlorpyriphos treatment. The combination of Metarhizium anisopliaeat 25 kg/ha and Beauveria bassianaat 25 kg/ha recorded 89.62 t/ha and found on par with chloropyriphos and followed by Metarhizium anisopliaeat 25 kg/ha (87.68t/ha) and Beauveria bassianaat 25 kg/ha (84.83t/ha).

Key words: White grub, Metarhizium,Beauveria, Entamopathogenand Sugarcane

INTRODUCTION

The larvae of chaffer beetles are also known aswhite grubs and are among the serious pests of most of the cultivated crops (Veeresh 1983). White grubs have become an increasingly difficult pest in Belagavi district of Karnataka during the past six (few) years and some are recognized as the serious pests on sugarcane, groundnut, cereals pulses and vegetables (David et al., 1986). The yield loss due to white grubs reported to be as high as 100 per cent in Karnataka (Veeresh 1974), Tamil Nadu (Thamarai Chelvi et al., 2010) and 80 per cent in Maharashtra (Patil et al., 1988). Among the different species of Holotrichia (Hope) which are economically important and are known to attack a wide range of crops.

Several tactics have been adopted for the management of white grubs including cultural, mechanical, biological, chemical and integrated methods suggested by various workers (Manisegaran et al., 2011), Sahayaraj and borqio 2009, Srikanth and Singaravelu, 2011). Though the application to chemical is effective in combating the menace, practically it is proved as an uneconomical, difficult and associated with high cost, environmental pollution and other problems. Hence there is a strong need for the development of alternative tactics for the management of white grub, which are ecofriendly and economically feasible. About 90 genera and 700 species of fungi representing a large group of entomopathroals (Metarhizium spp, Beauveria spp., and Verticillium spp.) which are entomopathogenic have been reported. Among these Metarhizium is of greater role in the management of white grubs, Metarhizium anisopliae (Metschnikof) Sorkin can be effectively utilized as one of the components in the management of white grubs (Sajad Mohi-ud-din et al., 2006; Chroton, 2007).

The fungus is ecofriendly in nature, economic and self multiplicative in nature. Above all sugarcane ecosystem provides ideal micro climate for the fungus to multiply and congenial soil moisture, high humidity and high organic matter helps the fungus to perpetuate itself in sugarcane ecosystem.

MATERIALS AND METHODS

Field trials on evaluation of entomopathogens were carried out for two consecutive years during 2010-12 in white grub endemic area i.e., at Bellad Bagewadi of Hukkeri taluka. The trials were laid out in randomized block design with nine treatments and three replications.

The cane variety Co 86032 was planted during the month of October in both 2010 and 2011, with inter-row spacing of 90 cm over a plot size of 10 m  10 m for each treatment. All the recommended package of practices were followed except for the management of white grub viz., M. anisopliae and B. bassiana and their combinations. Various treatments (Table 1) as detailed were imposed.

Chlorpyriphos 20 EC at 10 ml per litre of water was prepared and the actual quantity required for the treatment was calculated for drenching the soil around the clump by making holes of 15 cm depth and 3 cm diameter with the help of crow bar. Neem cake was applied to soil near the root zone.

Observations were made a day before and 15, 30, 45 and 60 days after imposition of treatments on larval count in 1 m2 area. In each treatment five randomly selected spots were observed for larval population at different intervals. Finally, at harvest, number of millable canes (NMCs) and cane yield (t/ha) were recorded in all the treatments.

RESULTS AND DISCUSSION

Results on field evaluation of two entomopathogens M. anisopliae and B. bassiana and their combination during 2011 and 2012 was done and pooled data was presented (Table 2)and discussed as follows.

Pooled data indicated that at seven DAT, T8 recorded significant superiority over all other treatments with least larval count of 6.23. At 14 DAT, T8 maintained its significant superiority over all other treatments with only 3.13 grubs. Among the entomopathogens T6 recorded 8.84 larval count and was significantly superior over all other treatments. However, T1 and T2 recorded 9.80 and 9.99 grubs and were at par with each other. Higher grub number was recorded in control plot and the order of superiority with respect to larval number was T8< T6<T1<T2<T3<T5<T4<T7<T9.

However, Manisegaran et al. (2011) reported that, application of M. anisopliae at 4 x 109 conidia/ha was found effective against sugarcane white grub, H. serrata.next to chemical treatment with chlorpyriphos on 60th DAT. Chlorpyriphos at 3 lt/ha recorded higher cane yield of 110.5 t/ha and M. anisopliae at 4 x 109 conidia/g recording 100.6 t/ha and is in complete agreement with the present findings.

Observations at 28, 45 and 60 DAT recorded supremacy of T8 over rest of the treatments with 2.14, 0.89 and 0.60 grub load, respectively. However, among the entomopathogens T6 was significantly superior over all other treatments with a grub load of 4.85, 2.70 and 1.98, respectively. In the present investigation M. anisopliae at25 kg/ha and B. bassianaat 25 kg/ha with FYM (250 kgs/ha) was effective by recording lower larval number resulting in higher cane yield followed by M. anisopliae and B. bassianaat 4x108 conidia comparable with chlorpyriphos 20 EC at 10 ml/1 (T8). Easwaramoorthy et al. (2005) reported that B. brongniartii when applied at 1.6 x1014 spores/ha produced significantly higher infection rate in third instar grubs of H. serrata to sugarcanecrop. Similarly, Rachappa, (2004) reported that M. anisopliae at 1x1013 conidia per ha was found as effective as chlorpyriphos in reducing H. serrata population in sugarcane resulting in higher cane yield. T1 recorded 6.08, 3.08 and 2.24 grubs at 28, 45 and 60 DAT and was significantly superior over rest of the treatments. Present investigation is in agreement with Yadav et al. (2004) who reported the efficacy of both M. anisopliae and B. bassiana alone or with 5, 10 or 15 g compost in a pot culture experiment. The efficacy increased with increased rate of compost application. M. anisopliae in combination with compost resulted in higher mortality of H. consanguinea fully justifying the present study against H. serrata.

Number of millable canes (‘000 ha-1)

Higher number of NMC’s (74.53) were recorded in T8 and was on par with T6 (72.12) and T1 (70.01). However, T2 (68.37), T3 (66.53), T5 (65.14) and T4 (63.79) were the next best treatments with respect to NMC count.

Cane yield (t/ha)

Higher cane yield of 93.45 t/ha was recorded in T8 and was on par with T6. T1 and T2were thenext best treatments with 87.68 and 84.83 cane yield. T3, T4 and T5 recorded 79.74, 79.15 and 77.50 t/ha and were significantly superior to T7 (64.15) and T9 (38.04) t/ha.

Field evaluation studies revealed significant superiority of T8 at all the intervals of observation by recording least larval number effecting higher NMC and cane yield. Among the entomopathogen treatments T6 was the most effective recording minimum number of grubs at all the intervals of observations and resulted at par cane yield with T8 followed by T1 and T2. However, T5 recorded modest number of grub count and cane yield respectively.

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Table 1: Entomopathogens evaluated in the field against Holotrichia serrata grub

Table 2: Pooled data on field evaluation of entomopathogens against white grub Holotrichia serrata

Figures in parentheses are x+1 transformed values, means showing similar alphabets do not differ significantly by DMRT

DAT-Days after treatment, NMC = Number of millable Canes, UTC = Untreated check