Browsing by Author "M. Sujithra"

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    Assessment of bio‑formulations of indigenous strains of Bacillus thuringiensis, Metarhizium robertsii and Metarhizium majus for management of the rhinoceros beetle, Oryctes rhinoceros L., in field
    (2023) C. Manjunatha; V. Velavan; R. Rangeshwaran; M. Mohan; A. Kandan; G. Sivakumar; A. N. Shylesha; M. K. Prasanna Kumar; D. Pramesh; M. Sujithra; H. K. Ranganath; S. N. Sushil
    Among all the coconut pests, rhinoceros beetle causes acute and serious damage to coconut palm. Management of this pest is very difficult due to its nocturnal activity, and also, it damages the emerging leaf inside the bud. Management of rhinoceros beetle using entomopathogens will be of great importance as it is economical and ecofriendly. Studies were carried out to decipher the biocontrol potential of indigenous entomopathogenic bacterium (Bacillus thuringiensis) and entomopathogenic fungi (Metarhizium robertsii and M. majus) against Oryctes rhinoceros in the field, individually as well as in combination, by soil drench as well as by topical spray method.
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    Evaluation of unmanned aerial vehicle for effective spraying application in coconut plantations
    (2024) R. Pandiselvam; Daliyamol; Syed Imran S; Vinayaka Hegde; M. Sujithra; P.S. Prathibha; V.H. Prathibha; K.B. Hebba
    Unmanned aerial vehicle (UAV) pesticide application in recent years owing to its importance such as time saving, reduction in human drudgery and also reduction in pesticides application rate. UAV has a great potential to address the problem involved in manual chemicals spraying in tall crops like coconut plantation where at present operation performed by manual climbing involves lots of drudgery and life risk. The current study aimed to understand the most influencing spraying parameters, such as spray height and spray time of the UAV sprayer on droplet characteristics such as spray droplet size, spray coverage and spray deposition at different layers (spindle, middle and bottom) of coconut tree canopy. The selected spray height (1, 2 and 3 m) and spray time (5, 8 and 11 s) significantly affects (p < 0.05) the droplet size (μm), spray coverage (%) and spray deposition (μl cm−2). In spray droplet size, the treatment T4, T5, T7 and T8 were recorded recommended droplet size of 50–400 μm in all layer of the coconut tree canopy. In spray coverage, the nearest value for recommended spray coverage of 10–20 % was observed for T1 and T5 treatment in all layer of the coconut tree canopy. The maximum penetration efficiency of 34.41 % had achieved at spray height of 2m and spray time of 8s (treatment T5). Based on performance of selected parameter, the spray height of 2 m and spray time of 8 s (treatment T5) was found best for spraying operation using UAV in coconut tree. The results showed the performance of the UAV offers best alternative for spraying operation on coconut tree and also this system will drastically reduce application time, labour requirement and improved the safety of coconut farmers.
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    Laboratory rearing of tea mosquito bug, Helopeltis theivora Waterhouse (Hemiptera: Miridae) on cocoa (Theobroma cacao L.)
    (2024) T. N. Madhu; E. K. Saneera; R. Thava Prakasa Pandian; Bhavishya; M. Chaithra; M. Sujithra; N. R. Nagaraja; B. J. Nirmal Kumar; S. Elain Apshara
    Tea mosquito bug (TMB), Helopeltis theivora is a most serious pest on cocoa worldwide that inflicts huge economic losses under epidemic situations. Laboratory colonies are necessary to perform year-round research to develop suitable management strategies for this pest. This study aimed to establish a population of TMB on suitable cocoa-feeding substrates under laboratory conditions. We used green cocoa pods and tender shoots as a food substrate and compared the biological parameters of H. theivora between them. The adult females preferred to lay more eggs on pods (32.20 ± 1.86 eggs/female) either singly or in a small group, and low fecundity was observed on shoots (20.75 ± 1.16 eggs/female). Meanwhile, egg hatching was highest on pods (92.48 ± 2.91%) than on shoots (74.08 ± 3.73%). This pest consists of five nymphal instars and the total nymphal duration was 13.53 ± 1.26 and 14.73 ± 0.85 days on pods and shoots, respectively. In addition, the per cent survival of H. theivora was highest on pods (78.66 ± 3.46) and lowest on shoots (51.85 ± 2.33). Significant differences were recorded in adult longevity and the mean life span of males and females were 13.17 ± 1.58 and 16.63 ± 1.64 days on pods; 11.10 ± 1.41 and 14.36 ± 1.53 days on shoots, respectively. Further, females lived longer than males in both substrates. Although, TMB will survive both on pods and tender shoots; rearing on pods could be more suitable and reliable to establish a sizable population of H. theivora under laboratory conditions.