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Department of Entomology, S.V. Agricultural College, ANGRAU, Tirupati-517 502.
An extensive roving survey was conducted in different sugarcane growing districts of Andhra Pradesh at different cane developmental stages at bimonthly intervals during 2023-2024. Three shoot borers viz., Early shoot borer, Chilo infuscatellus, Inter nodal borer Chilo sacchariphagus indicus and Top shoot borer, Scirpophaga excerptalis were recorded from 60 farmer fields in four districts viz., Vizianagaram, Anakapalle, Krishna and Tirupati districts of Andhra Pradesh. Relative abundance and Diversity indices were calculated for each district based on population of shoot borers to understand the species composition of shoot borers in Andhra Pradesh. Vizianagaram recorded highest mean relative abundance of ESB (60.50%). While, Anakapalle recorded highest mean relative abundance of INB and TSB (40.20, 50.20). Anakapalle district recorded highest Shannon- Wiener index (1.01), Simpson index of Diversity (00.56) and Pielou’s evenness index (00.91) indicating the species richness and evenness as more number of three shoot borer species were collected here. Based on the diversity indices it could be concluded that the sugarcane shoot borers exhibited uniform distribution and higher diversity in Anakapalle district and aggregate distribution type and lowest diversity in case of Krishna, Vizianagaram and Tirupati districts of Andhra Pradesh.
KEYWORDS: Diversity indices, Distribution, Simpson index, Shannon-Wiener index Species richness and Evenness.
Sugarcane (Saccharum oficinarum L. : Poaceae) is an important commercial crop used for producing sugar, jaggery, ethanol, and various by-products. It is a source of income for millions of farmers and supports numerous ancillary industries such as sugar mills, ethanol production and biomass based power generation. It contributes significantly to the agricultural economy, especially in tropical and subtropical regions. Sugarcane is one of the important cash crops in India, contributing significantly to the agricultural economy and rural livelihoods. Worldwide sugarcane production has a vast and varied market and pivotal for industrial usage of sugar, biofuels, and spirits Brazil is the leading producer with a immerse production of 752.9 million tonnes, followed by India with 446.43 million tonnes. In India, 21% (56.48 lakh ha-1) of the agricultural land is used for sugarcane production and yields 22% the total sugarcane in the world with average productivity of 79.03 tonnes ha-1 (desagri.gov.in, 2023-24). In Andhra Pradesh, sugarcane was cultivated in an area of 0.66 lakh hectares with an annual production of about 2.10 million tonnes with an average productivity of 76.34 tonnes ha-1. The long duration with diverse environmental conditions under which sugarcane is grown in the world encounters broad spectrum of pests and diseases which have come to acquire a place of priority thereby causing economic loss to growers in terms of quality and quantity. Among them, borers are the major destructive pests which cause 8 to 10 per cent cane yield losses at farmer’s level and 10 to 15 per cent sugar recovery losses in sugar industries (Ahad et al., 2015). About 45 per cent of yield losses in sugarcane are due to infestation by borer pests alone. The different stages in sugarcane cultivation includes germination, tillering, early growth, grand growth and elongation (Rao et al., 2009). During these stages they are attacked by many pests and most importantly,ESB, Chilo infuscatellus, INB, Chilo sacchariphagus indicus and TSB, Scirpophaga excerptalis, Gurdaspur borer, Bissetia steniellus and Root borer, Polyocha depressella are the major shoot borer pests distributed in all the sugarcane growing areas of India (Gupta et al., 1993). Knowledge of the relative abundance of distinct shoot borer species infesting sugarcane is very crucial in estimating the targeted control which reduces indiscriminate pesticide use and safer for environmental and economic reasons. The diversity of shoot borers, their species richness and relative abundance in the different sugarcane districts of the Andhra Pradesh has not been fully assessed. In this connection a roving survey was conducted in different sugarcane growing districts of Andhra Pradesh at different growth stages of sugarcane during 2023– 2024 to know the sugarcane shoot borer species species diversity and their relative abundance.
A random roving survey was conducted in different 60 farmers fields located in 12 villages of four sugarcane growing districts of Andhra Pradesh viz., Vizianagaram (18.34° N & 83.21° E), Anakapalle (17.80° N & 82.96° E), Krishna (16.11° N & 80.93° E) and Tirupati (13.37° N & 79.32° E) during April 2023 to May 2024 (Figure
Destructive Sampling was done at different growth
stages of sugarcane viz., tillering, grand growth and harvesting. From each district, three villages and from each village, five farmers were selected for the survey. The survey techniques were followed as suggested by Rao et al., 2009. Shoot borer larvae were collected by destructive sampling method from ten randomly selected spots and from each spot 10 plants were selected for larval collection. The Shannon–Wiener’s, Simpson’s and Pielou’s evenness indices were used to determine the species diversity, richness and evenness. The Shannon– Wiener index was calculated to find out alpha of major species compared to the rare species. In taxonomic or ecological research, similarity indices provide quantitative bases of assessment in comparing species composition or biodiversity. The relative abundance and diversity indices were calculated using following formulae
where, H′=Shannon diversity index
∑=Sum from species 1 to species
J′=Evenness of allotment of individuals among the
species
Hmax=Maximum species diversity
(H’)=log2S
Species richness : The number of different species
found in particular environment or site.
The survey conducted in 60 farmers fields in 12 villages in four coastal districts of Andhra Pradesh. This study clearly indicated the presence of three major shoot borer species among the surveyed districts of Andhra Pradesh viz., ESB, C. infuscatellus, INB, C. sacchariphagus indicus and TSB, S. excerptalis by considering the morphological characters of larvae, adults and damage symptoms.
The nature and symptoms of damage were very distinc ti nsugarcan ea spe rth edamag ecause db ydifferent shoot borers. Early shoot borer, (C. infuscatellus) is severe at germination to tillering. The larvae is creamish with five violet stripes located dorsally and dorso laterally on its body with dark brown head. Adult Moth is small, slender, greyish brown or straw coloured with labial palpi projected upwards. Larva makes entrance hole at the ground level of sugarcane causes dead hearts which can be easily pulled out. The dead heart emits offensive smell, and it will be identified upto 45-50 days after sowing and in the set plantings rather than ratoon (Fig. 1).
Inter nodal borer (C. sacchariphagus indicus) affected the crop from cane formation to harvest. Moth is small, straw coloured. Forewings have a marginal dark line and the hind wings are whitish caterpillar has a white body with dark spots and a brown head. The larva bores at the nodal region and enters the stem. The tissues turn red and the hole is usually plugged with excreta. A larva may attack a number of nodes. Moth is medium sized, creamy white, slightly bigger than early shoot borer moth (Fig. 1).
Top shoot borer S. excerptalis female has tuft of orange red coloured hairs at the tip of the abdomen. In case of certain males, each of the forewings has a black spot. caterpillar is creamy white in colour with yellow head. Some of the caterpillar are white in colour and have black colour dorsal line with red colour head. A number of shot holes on affected leaves due to biting across the spindle, reddish brown charred dead heart that cannot be
easily pulled out at later stages of the crop are damage Survey in different growth stages of sugarcane in symptoms. Interference with apical growth gives rise to Andhra Pradesh revealed that 100% damage was due side shoots and critical bunchy top symptom (Fig.1).
From Table 2 it was clearly indicated that the Among the four surveyed districts of Andhra Pradesh Anakapalle district recorded the highest overall cumulative incidence was attacked by both ESB (35.50%) and INB (64.50%), whereas INB (57.50%) and TSB (42.50%) was recorded at harvesting (Fig.2). of three shoot borers of 41.58% followed by Krishna to INB during grand growth stage and vegetative stage was attacked by both ESB (35.50%) and INB (64.50%), whereas INB (57.50%) and TSB (42.50%) was recorded at harvesting (Fig.2).
A cursory examination from the 60 farmer fields (33.07%), Vizianagaram (30.82%). Least cumulative from 12 villages of 4 districts indicated Vizianagaram incidence was recorded in Tirupati district of 25.93%. recorded highest mean relative abundance of ESB
(60.50%) followed by Anakapalle (30.20%), Krishna speciesrichness and the evenness of the community (6.30%) and Tirupati (3.00%) respectively. Similar increase. The range of Simpson index of Diversity and trend of relative abundance in case of INB, TSB was Pielou’s evenness index ranges from 0 to 1. 0 and near also observed in which Anakapalle recorded highest values represents lower diversity and evenness whereas mean relative abundance (40.20, 50.20) followed by values near to 1 and 1 indicated the higher diversity and Krishna (25.50%, 25.30%), Tirupati (21.50%, 18.00%) evenness.and lowest abundance was recorded in Vizianagaram The results are in line with the findings of Lenonard (12.80%,6.50%) (Table 2).
The results are in line with the findings of Lenonard (12.80%,6.50%) (Table 2).and Gration (2015) who admitted that rice stem borer
Diversity indices were worked out for the four exhibitedbothuniformandaggregatetypeofdistributions.
surveyed districts based on the population of sugarcane Bonaventure et al. (2018) also conducted similar kind shoot borers collected in each district. From Table 3 it of investigation in irrigated lowland rice ecosystem in was evident that the species richness is same for all areas Kilombero, Tanzania and confirmed an aggregated as all three species of shoot borers viz., ESB, INB and dispersion pattern for stem borers. The current findings TSB present in all surveyed districts in A.P. Shannon- are in accordance with Rani et al. (2023) who reported the Wiener index was high for Anakapalle district (1.01) diversity of rice stem borers in AP, they also confirmed as the three species of shoot borers collected were high the aggregated dispersion patterns for rice stem borers in number compared to other districts which indicated in Andhra Pradesh. Ndemah et al. (2001) and Gounoue species richness in that particular area. Followed by and Schulthess (2004) also reported the aggregate spatial Krishna (00.82), Vizianagaram (00.81) and lowest was distribution behavior of lepidopteran rice stem borers. recorded in Tirupati (00.74). Simpson index of Diversity Arbab (2014) who reported random distribution of C. was also followed the same trend as Anakapalle district supressalis in rice fields in Iran. Widyaningrum (2015) recorded the high D value of 00.56 followed by Krishna also studied the arthropods biodiversity by employing (00.51), Vizianagaram (00.50) and least was recorded in diversity indices in Indonesia. Moolman et al. (2013) Tirupati (00.39). Pielou’s evenness index was also high reported a high diversity of stemborer parasitoids in in Anakapalle (00.91) as it comprised all the species of South Africa. Otieno et al. (2006) also reported the higher shoot borers with high number of larvae indicated the Shannon-Wiener index (1.67) in cropping systems for population swer eevenl ydistributed .Followed byKrishna lepidopteran stem borers in Kenya. Which supports the (00.75), Vizianagaram (00.74) and least diversity was current findings of diversity of sugarcane shoot borers in recorded in Tirupati (00.67). All the values of diversity Andhra Pradesh.
From this present study on the survey of shoot borers depicted the uniform and aggregated distribution patterns of shoot borers in surveyed districts of Andhra Pradesh. High species diversity and evenness reported from Anakapalle district followed by Krishna, Vizianagaram and Tirupati. Diversity indices were useful in predicting the species composition and their diversity in particular The range of Shannon-Wiener index is 0 to 1 locality which in turn used for to predict their abundance sometimes 1.5 to 3.5 (for high number of population) which is useful to manage insect pests efficiently. Shannon-Wiener index increases when both
The study is a part of the doctoral research work of the first author. The authors are highly grateful to Acharya N.G. Ranga Agricultural University, Lam, Guntur and S.V. Agricultural College, Tirupati for allocating the facilities for conducting the course of investigation, Agricultural dept. officials and Sugarcane Farmers who were co-operated and helped during survey.
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