Bio-efficacy of insecticidal spray schedule in chilli thrips

Introduction

Chilli (Capsicum annuum L.) belonging to family solanaceae is rightly called as wonder spice or universal spice originated from South Central America and is an important spice cum vegetable crop commonly used in Indian dietary and grown throughout India as well as in almost all parts of the tropical and subtropical regions of the world as a economically important vegetable, spice cum cash crops (Siri et al., 2020) [7] . Chilli is grown for its fruit, which is valued for its color, flavor, spice and vegetable nutrition, which is provided in its various products (Kumar et al., 2006) [6] . Based on the utility, different varieties are cultivated differing in flavour, pungency and colour. Chillies are a good source of nutrients like Vitamin A, Vitamin C, Vitamin B6, Potassium, Iron and Magnesium. Vitamin C was noticeably high in green chillies than in red chillies (Sparky, 2006) [18] . Red chillies are rich source of iron, potassium, magnesium, vitamin C, vitamin B6 and contain a small amount of beta-carotene (Idrees et al., 2020) [4] . Capsaicin, an active component of chilli, is responsible for the burning sensation and is used for medicinal purposes, having analgesic properties (Bosland et al., 2012) [2] . Thrips alone can cause the yield loss of 30-50 percent (Bhede et al., 2008) [1] . The level of infestation however depends upon the number of abiotic factors (temperature, relative humidity, sunshine hours and wind velocity) and biotic factors (natural enemies). Thus, it becomes necessary to formulate economically effective insect pest management strategy. Pesticides are considered as powerful tools to provide protection against insect pests but excessive use of pesticides also induces resistance development in target pests as well as killing beneficial organisms such as pollinators and natural enemies (Pedigo and Rice, 2006) [15] . When few products are labelled for an individual pest within a particular crop system, chemical control options are limited. Therefore, the same products are used repeatedly and continues selection pressure is placed on the target pest. There are both financial and environmental losses associated with the development of resistant populations. More often use of synthetic chemicals is one of the most common and popular methods of controlling major insect pests of chilli crop and in recent times, a large number of newer insecticides are available in the market for use in this class (Manjunatha et al, 2018) [10] . Therefore it is necessary to study the effect of different insecticides and evaluate them in spray schedules for formulating effective and economical management strategies of insect pests. Thus, the present investigation is designed to evaluate the effect of different insecticides by formulating spray schedule against major pests of chilli with reference to the Bio-efficacy of insecticides against chilli thrips".

Materials and Methods

The field experiments was conducted at Research Farm, and laboratory of Division of Agriculture Entomology, College of Agriculture, Latur (MS), India during Kharif 2022 in Randomized Block Design with 7 treatment and 3 replication. Latur is situated at 18 0 23 ' 5. 65 '' North Latitude, 76 0 34 ' 51.50'' East Longitude and at an Altitude of 515 m above the mean sea level (MSL) and has subtropical climate. The place lying in Northern transitional zone (Zone -8) with hot dry summer and cool winter. The observations on thrips was recorded regularly in the treated as well as in control plot throughout the period of investigation in all experiments just before first spraying (Pre) and 1, 3, 5, 7 and 14 days after spraying (DAS). Observations were recorded to assess thrips population from five leaves, one from top and two each from middle and bottom of randomly selected five plants from each net plot for whereas from five terminal leaves for thrips (Pathipati et al. 2012) [14] .

Results and Discussion

The findings obtained in the present investigations on different aspects of studies on bio-efficacy of insecticides against chilli thrips was undertaken at Department of Agricultural [11] assessed the bio-efficacy of new generation molecules and biorationals against T. parvispinus. The results suggested that new molecules viz., broflanilide 30 SC (18.60g a.i/ha) and fluxametamide 10 EC (40 g a.i/ ha) were found highly effective in reducing the thrips population on chilli crop, followed by spinetoram 11.7 SC (60 g a.i/ha) and tolfenpyrad 15 EC (150 g a.i/ha). Lakshmi and Kumar (2021) [8] proved that on the basis of mean percentage reduction over control in thrips population, the treatment spinosad (91.41%) proved to be most effective treatments followed by imidacloprid 0.05 ml/lt (87.62%), Pymetrozine 0.2 ml/lt (83.98%), emamectin benzoate 0.4g/lt (80.59%), Acetamiprid 0.05g/lt (70.62%) andacephate 0.75 g/lt (62.67%). Nagaraju and Kumar (2022) [12] revealed that among the different treatments Fipronil 5 percent SC (94.06%) proved to be the most effective treatment followed by spinosad 45 percent SC (93.16%), imidacloprid 17.8 percent SL (92.27%), profenophos 50 percent EC (84.37%).

Mandal and Mondal (2022) [9] proved that the lowest population of thrips was observed in Broflanilid 20 percent SC @ 25 g a.i. ha -1 and it was statistically superior over Dinotefuran 20 percent SG @ 30 g a.i. ha -1 , Profenofos 50 percent EC @ 500 g a.i. ha -1 and Azadirachtin 3 percent @ 15 g a.i. ha -1 .While, nonsignificant differences in insect populations were recorded among spinosad 45 percent SC @ 73 g a.i. ha -1 , Fipronil 5 percent SC @ 50 g a.i. ha -1 , Spirotetramat 15.31 percent OD @ 60 g a.i. ha -1 , tolfenpyrad 15 percent EC @ 150 g a.i. ha -1 , imidacloprid 17.80 percent SL @ 25 g a.i. ha -1 , Thiamethoxam 25 percent WG @ 25 g a.i. ha -1 , λ-cyhalothrin 5 percent EC @ 15 g a.i. ha -1 and Difenthiuron 50 percent WP @ 300 g a.i. ha -1 , respectively. The newer molecule, Broflanilid 20 percent SC @ 25 g a.i. ha -1 was found most efficacious against the chilli thrips among the treatments, and this molecule can be recommended to effectively manage the chilli thrips. Kumar et al. (2016) [5] revealed that, the spinosad 45 SC @ 0.4 ml was found most effective in reducing the population thrips @ 0.55/plant and it give highest marketable green chilli yield. Shinde et al. (2018) [16] results revealed that the spinosad 45 SC 0.014% was recorded highest reduction of Scirtothrips dorsalis population i.e. 1.41 mean thrips population per plant. Patil et al.

(2018) [13] reported that the spinosad 0.5ml /lt recorded highest reduction of thrips population (79.79%) followed by Imidachloprid 0.5ml /lt (76.81%) Kumavat et al. (2015) [7] results revealed that two sprays of imidacloprid 17.8 SL at 22.5 g a.i./ha at seven days interval was most effective and significantly superior to all other treatments which caused 91.05 percent mean reduction in aphid population. Ghosh et al. (2020) [3] revealed that the imidacloprid resulted the best suppression of whitefly population (81.48% suppression).

Conclusion

The study on the bio-efficacy of insecticides against chilli thrips revealed that the spray schedule involving fipronil 0.5 SC, tolfenpyrad 15 EC, and cyantraniliprole 10.50 OD was the most effective in reducing thrips population. It performed better than other insecticide combinations, including spinosad 45 SC + broflanilide 300G/L SC + flubendamide 20 WG. These treatments significantly reduced thrips infestation, supporting their use for effective pest management in chilli cultivation.

References

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