20295-- Ranganath T R

Indian Journal of Entomology 83(2021) Online published Ref. No. e20295 DoI No.: 10.5958/0974-8172.2021.00062.6

POPULATION DYNAMICS OF PESTS OF CASTOR

Ranganath T R*, Shivanna B K, Hugar A Y1, Jayalaxmi Narayan Hegde and Shashidara K C2

Department of Agricultural Entomology; 1Department of Agronomy; 2Department of Agricultural Engineering, College of Agriculture, University of Agricultural and Horticultural Sciences, Shivamogga 577204, Karnataka, *Email: [email protected] (corresponding author)

ABSTRACT

Field experiments were carried out to assess the diversity population dynamics of insect pests of castor during kharif 2018-2019 at Bhavikere, Karnataka. The results revealed eleven insect species feeding on different parts. The relationship between pests and weather parameters revealed that the incidence of Acathodelta janata and Spodoptera litura showed significant negative correlation with wind speed, and a significant positive one with maximum temperature. Conogethes punctiferalis, Empoasca flavescens and Nezara virudula had negative and significant relationship with minimum temperature, morning and evening relative humidity (RH) and rainfall; it exhibited a positive and significant correlation with maximum temperature. Liriomyza trifolii had a significant and negative relationship with maximum temperature, in contrast to a significant and positive one with morning and evening RH, rainfall and wind speed. None of the weather parameters had significantly influenced the incidence ofTrialeurodes ricini, merione, Dasychira mendosa and Helicoverpa armigera.

Key words: Population dynamics, castor pests, lepidopterans, leaf hoppers, plant bug, leaf miner, whitefly, weather parameters, correlation coefficients

Castor communis L. is an important non agronomic practices were followed as per the package edible oilseed crop grown in arid and semiarid regions, of practices (Anon., 2008) at AHRS, Bhavikere. The and it is a profitable crop (Patel et al., 2009). India is the observations on different growth stages of castor world leading principal producer of castor. The yield starting from one week after germination were made loss due to insect pests in castor is about 35-40%, with > at ten days intervals till harvest. Twenty plants were 100 insect pests. Of these about half a dozen such randomly selected and tagged to assess the incidence as sucking pests viz., leaf hoppers, whitefly and thrips, of insect pests. To assess the major lepidopteran pests and foliage feeders viz., semilooper, tobacco caterpillar, viz., semilooper, hairy caterpillar, tobacco caterpillar castor and borers like capsule borers are of and spiny caterpillar, the larval counts were made on economic importance (Basappa and Lingappa, 2001). randomly selected plants. In case of shoot and capsule The IPM involves the knowledge of pest ecology, and borer, incidence was recorded by counting the number information on incidence of pests of castor at different of infested capsules/ and total number of capsules on growth stages of the crop and its relation with weather ten randomly selected plants and % capsule damage parameters is essential. This will enable to find out under worked out. The incidence of leaf miner was recorded what weather conditions, particular pest would appear by counting the number of leaves infested on ten and thus help to forewarn the cultivators to resort to randomly selected plants and % infestation worked preventive measures against insect pests. This is the out. The incidence of sucking pests was estimated by main objective of the present study, and it explores the counting the number of leafhoppers, thrips and mites population fluctuation pattern of pests of castor crop at from three leaves/ plant on 20 randomly selected plants. Malnad region, with evaluation of the relationship with The leaves were selected as one from top, middle and weather factors. bottom on the main shoot. The thrips incidence was estimated by tapping the leaf on white card board. MATERIALS AND METHODS The plant bug was recorded by counting the number To study the incidence of various insect pests on of bugs on randomly selected tagged plants. The castor during kharif- 2018-19, the variety DCH-177 was status of the pest was considered based on number of sown in an area of 200m2 with a row spacing of 90 cm insects occurring. The data on weather parameters like and 60 cm between the plants. All the recommended temperature, relative humidity, rainfall, wind velocity/ 2 Indian Journal of Entomology 83(2021) Online published Ref. No. e20295 speed and sunshine hours were obtained and these were 8th) at maturity. These results agree with those of Singh correlated with incidence, and coefficients worked out. et al. (2002). The leaf miner was observed during initial growing period with a peak infestation (32.07%) on RESULTS AND DISCUSSION August 21st becoming nil from September 30th. These The observations revealed eleven insect pests on observations correspond with those of Manjunatha et the castor hybrid DCH-177 during 2018-19 as given in al. (2018). Table 1, with and Fig. 1 and 2 depicting the occurrence Table 2 provides the correlation coefficients of and intensity. These show that the incidence of the incidence with weather parameters. These reveal semilooper started during the early stage of the crop that the semilooper has a significant and positive th from August 11 onwards, with maximum counts (4.80 correlation with maximum temperature (r=0.539*); it th larvae/ plant) on October 20 . These observations has a negative and significant relation with wind speed corroborate with those of Suganthy (2007) and (Anon., (r=0.731**). The present findings are in agreement 2011). Spodoptera litura incidence started from with those of Umbarkar and Patel (2016). Spodoptera th September 10 onwards, reaching peak (4.15 larvae/ litura exhibits positive significant relationship with th plant) on October 20 ; these results are similar to those maximum temperature (r=0.514*), and a negative and of Ahir et al. (2017). The capsule borer incidence was significant one with wind speed (r=0.713**). These observed from the maturity stage of the crop from results correspond with those of Sailaja Rani et al. th ( October 10 5.84%), increased progressively attaining (2006) and Ahir et al. (2017) on onion and groundnut, th its peak (18.80%) on December 9 , thereafter a gradual respectively. A negative significant relation with decrease was noticed till the end of the growing period. minimum temperature (r=-0.635**), morning humidity These results corroborate with those of Manjunatha et (r=-0.534*), evening humidity (r=0.709**) and rainfall al. (2018). The incidence of leaf hopper was noticed (r=0.605**), and a positive significant one with st from August 21 onwards (0.33 leaf hoppers/ leaf), maximum temperature(r=535*) were observed with the th with a peak on December 9 (5.13 leaf hoppers/ leaf; incidence of capsule borer. These results are similar to thereafter it decreased to 2.33 leaf hoppers/ leaf (January those of Madhuri et al. (2006) and Patel et al. (2015). Table 1. List of insect pests observed on castor during 2018-19 S. No. Insect pest Scientific name Family Order Status 1 Grasshopper Attractomorpha sp. Pyrgomorphidae Orthoptera Minor 2 Tussock hairy caterpillar Dasychira mendosa (Hubner) Erebidae Minor 3 Semilooper Acathodelta janata (Linnaeus) Noctuidae Lepidoptera Major 4 Tobacco caterpillar Spodoptera litura (F.) Noctuidae Lepidoptera Major 5 Spiny caterpillar Ariandne merione (Cramer) Lepidoptera Minor 6 Leaf miner Liriomyza trifolii (Burgess) Agromyzidae Diptera Minor 7 Leaf hopper Empoasca flavescens (Fabricius) Cicadellidae Hemiptera Minor 8 Plant bug Nezara virudula (Linnaeus) Pentatomidae Hemiptera Minor 9 Whitefly Trialeurodes ricini (Misra) Aleyrodidae Hemiptera Minor 10 Shoot and capsule borer Conogethes punctiferalis (Guenn.) Pyralidae Lepidoptera Major 11 Gram caterpillar Helicoverpa armigera (Hubner) Noctuidae Lepidoptera Minor

35 30 Grasshopper B 30 (number/ plant) 25 Semilooper (larvae/ plant) 25 20 Leaf miner Tobacco caterpillar 20 (per cent leaf mine/ plant) (larvae/ plant) 15 15 Spiny caterpillar (larvae/ Empoasca flavescens 10 plant) 10 (no. of nymphs & adults/ Mean populationMean Tussock hairy caterpillar Mean population leaf) 5 5 (larvae/ plant) Plant bug 0 (no. of nymphs & 0 Gram caterpillar (larvae/ adults/ plant) plant) White fly Shoot and capsule borer (no. of nymphs & adults/ (% capsule damage/plant) JAN-08-2019 AUG-01-2018AUG-21-2018SEP-10-2018SEP-30-2018OCT-20-2018NOV-09-2018NOV-29-2018DEC-19-2018 three leaves)

Fig. 1, 2. Seasonal incidence of insect pests on castor Population dynamics of insect pests of castor 3 Ranganath T R et al.

Table 2. Correlation coefficients- insect pest incidence vs. weather factors Temperature (°C) Relative humidity (%) Rainfall Sunshine Wind speed Pest/variable Morning Evening Min. temp. Max. temp. (mm) hours (m/s) RH RH Attractomorpha sp. 0.222 0.512* -0.059 -0.193 -0.038 -0.003 -0.644** Liriomyza trifolii 0.453 -0.921** 0.522* 0.814** 0.666** -0.424 0.499* Empoasca flavescens -0.643** 0.580* -0.540* -0.742** -0.606* 0.304 -0.036 Nezara virudula -0.501* 0.683** -0.626** -0.733** -0.531* 0.421 -0.295 Trialeurodes ricini -0.241 0.228 -0.095 -0.308 -0.372 -0.057 0.043 Acathodelta janata 0.099 0.539* -0.280 -0.307 -0.177 0.154 -0.731** Spodoptera litura 0.088 0.514* -0.313 -0.303 -0.153 0.183 -0.713** Ariadne merione 0.366 0.278 0.004 0.029 -0.100 0.083 -0.824** Dasychira mendosa 0.298 0.263 0.168 0.042 0.288 -0.157 -0.443 Helicoverpa armigera -0.183 0.320 -0.265 -0.355 -0.395 -0.011 -0.273 Conogethes punctiferalis -0.635** 0.535* -0.534* -0.709** -0.605** 0.328 -0.005 Note: *Significant at p=0.05; **Significant at p=0.01; n= 18

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(Manuscript Received: July, 2020; Revised: September, 2020; Accepted: September, 2020; Online Published: February, 2021) Online published (Preview) in www.entosocindia.org Ref. No. 20295