Effect of Weather Parameters on the Incidence of Thrips, Thrips tabaci Lindeman on Bt Cotton

The field experiments were conducted during kharif season of year 2014 & 2015 at Agricultural Research Station, Rajendranagar, Hyderabad, Telangana state, India to study the influence of weather parameters on the incidence of thrips population on Bt cotton. The results revealed that the peak incidence of thrips population was recorded on 35th Standard Week i.e., last week of August (32.87 thrips leaf–1) during kharif, 2014 and two peaks i.e., 35th Standard Week i.e., last week of August (33.93 thrips leaf–1) and 40th Standard Week i.e., the first week of October (40.40 thrips leaf–1) were recorded during kharif, 2015. Thereafter, its population declined gradually during both seasons. Correlations worked out between thrips population and weather parameters revealed that, one week (0.51*) and two weeks lag (0.65**) minimum temperature, one week lag (0.56**) morning relative humidity showed significant and positive influence, while one week lag (–0.44*) evaporation showed significant negative influence on thrips incidence. The prediction model developed for the thrips population revealed that the model explained the variation to an extent of 54 per cent in thrips incidence under the influence of minimum temperature and morning relative humidity.

Assessment of Bio-efficacy of Insecticides against Mites and Thrips Insect Pest of Chilli

A field experiment was conducted during kharif 2018-19 in Samajik Vigyan Kendra, Dr. B.R. Ambedkar University, Bordi, Sehore (M.P.) – INDIA. To assess the bio-efficacy of insecticides against mites and thrips insect pest of chilli pests. The bio-efficacy of three different insecticides, namely (i) Chlorfenapyr 240 SC - spray four time with different-different doses, (ii) Fipronil 5% SC and (iii) Imidacloprid 17.8 SL. One untreated plot was also used to investigate against Mites and Thrips. Among these insecticides, Chlorfenapyr 240SC doses 288 g.a.i/hac gram active ingredient per hactare) has reduced maximum mites and thrips population and it is most effective insecticides in chilli. The highest reduction of mites population recorded in treatment T4- (97.17%) followed by T3- chlorofenapyr (95.13%), T6- Imidacloprid (91.67%), T5- Fipronil 5% SC (85.35%), T2- chlorofenapyr (85.27%) and it was least in T1- chlorofenapyr (81.40%. Further, the thrips number was maximum reduced in treatment T4- chlorofenapyr (90.69%) followed by T3- chlorofenapyr (89.80%), T5- Fipronil 5% SC (89.51%), T6- Imidacloprid (74.18%), T2- chlorofenapyr (69.74%) and T1- chlorofenapyr (68.44 %). Hence, present study was clearly indicated that the treatment T4- chlorofenapyr 240SC@288 proved, the most effective insecticides. The cost benefit ratio was noted higher in Fipronil 5% SC@ 10 g.a.i ha-1 (3.20) followed by imidacloprid 17.8 SL @ 50 g.a.i ha-1 (2.99).

Effect of entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, on Thrips tabaci Lindeman (Thysanoptera: Thripidae) populations in different onion cultivars

Background Thrips tabaci Lindeman (Thysanoptera: Thripidae) is the key pest of onions that causes economic yield losses in commercial onion production in Pakistan. In this study, potential of the entomopathogenic fungi (EPF), Beauveria bassiana and Metarhizium anisopliae, as a bio agent was evaluated to manage buildup of thrips population on onion crop. Results Efficacy tests for EPF were conducted against T. tabaci infesting 3 different onion varieties (Phulkara, Swat 1, and Virio 7). Commercial formulations of B. bassiana strain GHA and M. anisopilae strain ESC-1, were evaluated at 4 different concentrations (108, 109, 1010, and 1011 conidia/ml) under field conditions for 2 years. The efficacy was assessed 3, 5, 7, and 10 days after spray application of the whole onion plant. Efficacy expressed as T. tabaci (nymphs and adults) percent population reduction in comparison to controls. Maximum corrected percent population reduction was observed in onion plants treated with B. bassiana 1011 conidia/ml, i.e., 86.62, 84.59, and 86% in Phulkara, Swat 1, and Virio 7 onion varieties respectively, after 10 days of spray application. While onion plants treated with M. anisopliae 108 conidia/ml showed minimum corrected percent population reduction, i.e., 69.42, 68.45, and 69.11% in Phulkara, Swat 1, and Virio 7 onion varieties respectively, after 10 days of spray. Conclusions Beauveria bassiana could significantly reduce thrips population and could provide a better long-term management of T. tabaci on onion. B. bassiana had a high toxic effect against offspring production of the T. tabaci under field conditions than M. anisopliae.

Biorational Management And Mycosis Studies Of Grape Thrips [Rhipiphorothrips cruentatus H.]

Field experiment was conducted to test the bioefficacy of various biorational insecticides against grapevine thrips at AICRP on Fruits, Department of Horticulture, MPKV, Rahuri, during 2017-18. Results revealed that standard check emamectin benzoate 5% SG consistently proved to be the most promising by recording the least thrips population (3.10/shoot). Among biorational insecticides neem oil 2% (4.09/shoot) proved as best treatment followed by, karanj oil (4.51/shoot) and neemazol (5.08/shoot). While entomopathogenic fungi Lecanicillium lecanii recorded less population (4.24/shoot) and emerged as best treatment as compared to the Metarhizium anisopliae (4.87/shoot) and Beauveria bassiana (5.34/shoot). However chlli methanolic extract (6.29/shoot), garlic methanolic extract (6.78/shoot), chilli water extract (6.85/shoot) and garlic water extract (7.08/shoot) are the least effective treatments. Incremental Cost Benefit Ratio (ICBR) in respect of different treatments ranged between 1.30 to 7.92. The highest ICBR of 1:7.92 was recorded in the treatment with emamectin benzoate 5 SG, and it was followed by Lecanicillium lecanii (1:6.34) and Metarhizium anisopliae (1:5.32). Although neem oil and karanj oil has great reduction of thrips population, but has less incremental cost benefit ratio i.e. 2.81 and 3.04, respectively, due to high dose and its cost. The mycosis test of three entomopathogenic fungi viz. Beauveria bassiana, Metarhizium anisopliae, Lecanicillium lecanii were studied on grape thrips. Mycosis by Beauveria bassiana was confirmed the pathogenicity of entomopathogenic fungi on grape thrips. Highly pronounced mycosis was observed by Metarhizium anisopliae on the dead bodies of thrips. Mycosis test of Lecanicillium lecanii was also proved on grape thrips (plate - 1, 2 and 3).

Thrips (Thysanoptera) associated with onion (Allium cepa L.) and Welsh onion (Allium fistulosum L.)

We determined the abundance, species composition, sex ratio and seasonal dynamics of thrips on one cultivar of Welsh onion (Allium fistulosum) and eight cultivars of onion (Allium cepa) in South Poland within three vegetation seasons (2014–2016). Nine species of Thysanoptera were identified on A. cepa and A. fistulosum. Irrespective of the onion cultivar, Thrips tabaci was the dominant species (64.4% of all collected thrips specimens), while Frankliniella intonsa also occurred in high numbers (28.3%). Conversely, Welsh onion was most often inhabited by F. intonsa (62.7%), although T. tabaci was also numerous (28.3%). The predatory Aeolothrips intermedius accounted for 4.5% on A. cepa and 2.9% on A. fistulosum. In the most numerous species, T. tabaci, F. intonsa and A. intermedius populations were formed mainly by females. The cultivar most colonised by thrips was Kroll of A. fistulosum. The tested cultivars of A. cepa demonstrated varying degrees of attractiveness to thrips in the subsequent years. The relationship between populations of T. tabaci, F. intonsa and A. intermedius changed in the subsequent months of the growing season. In June, mainly T. tabaci and F. intonsa occurred on onion plants, while from July, the percentage shares of F. intonsa and the predatory A. intermedius in the thrips population on many onion cultivars increased. The level of attractiveness of A. cepa related to onion thrips, which is reported as a main pest of onion, varies depending on the year and cultivar.

Establishing the presence of vine thrips in vineyards of Sveti Ivan Zelina

The vine thrips feed on vegetative and generative organs of the grapevine and cause damage in production. At the beginning of vegetation it sucks on the grapevine shoots and so they lag behind in growth. Later, it feeds on the leaves, and spotted necrosis is observed at the sucking sites. Later light yellow leaf coloration can be seen. Attack signs can also be noticed on the berries and since there is usually aesthetic damage table grape varieties suffer the most. Although the pest has been present in Croatia since the 1980s, little is known about the flight dynamics and the population size of this species. This study investigated the catch dynamics and population size of vine thrips in two vineyards (Gradunje and Vrškojice) in the area of Sveti Ivan Zelina. The thrips population was monitored during the vegetation season of 2018 by fluorescent yellow sticky traps (Csalomon®). In both vineyards pest presence was established at the beginning of May, and the last catches were recorded in the second half of September. According to the catch dynamics, the pest develops three generations in the investigated vineyards, and the highest number of thrips was recorded in the phase of growth and development of berries. Given the established thrips populations, its control is recommended, and in Croatia for this purpose only insecticide based on the active substance spinetoram has been registered.

Effect of physico-morphic characters and environmental factors on infestation of thrips (Thrips tabaci) on five onion cultivars

Resistance to plants is frequently associated with physical, morphological, physiological, biochemical, molecular and genetic characteristics of the plants. As very little information is available on the effects of physico-morphic characteristics and environmental factors on thrips (Thrips tabaci) infestation, therefore, in the present study such effects were evaluated on the infestation of thrips on five onion cultivars. Maximum number of adults and infestation of thrips was recorded on Marvi followed by Golden Orb while the adults and infestation was the minimum on Red Orb. Significant variations were observed in plant heights and girths among five onion varieties after 40, 70 and 100 days. Similarly, maximum yield was observed in case of Red Orb followed by F1 Mustang while the minimum yield was obtained with cultivar Marvi. The low temperature, high temperature and average temperature showed significant and positive correlations among all the cultivars. However, the average relative humidity showed negative and non-significant correlation for all the varieties. The correlation between physico-morphic characteristics and adult population was found significant for plant girth after 40 days while the correlations were non-significant for all the other factors. It is concluded from the present studies that Red Orb is comparatively resistant cultivar harboring the minimum thrips population. The highest yield was also recorded in case of Red Orb as compared to other tested cultivars and recommended for cultivation to enhance economic returns of farmers.

Insecticide resistance management against thrips (Thysanoptera: Thripidae) on onion in the central Rift Valley of Ethiopia

Two field experiments were conducted in the Central Rift Valley of Ethiopia in the hot and cool dry seasons of 2016/2017 with the objective to develop an insecticide resistance management program on thrips infesting onion. The first experiment dealt with the evaluation of four different insecticides namely profenofos, λ–cyhalothrin, imidacloprid, and spinetoram in different sequences on thrips population and their effect on yield. The second experiment examined the effect of admixing the surfactant organosilicone with imidacloprid, spinetoram and dimethoate. A Randomized Complete Block Design with three replications was used for both experiments. Data on number of thrips, bulb yield and economic returns were collected. The insecticide imidacloprid and spinetoram resulted in fewer numbers of thrips and higher yields than profenofos and λ –cyhalothrin. Application of the more effective insecticides when the thrips population was high followed by less effective insecticides resulted in better control and higher economic return. Surfactant added insecticides gave a fewer numbers of thrips and higher yields than the corresponding insecticides applied without surfactant. The sequential application of spinetoram and imidacloprid with less effective λ-cyhalothrin and profenofos by mixing with adjuvant are recommended for thrips control as an integral component of thrips management in the Central Rift Valley of Ethiopia.

Management Of Thrips Infesting Mung Bean Using Pesticides

The study was conducted to evaluate the effect of bio-pesticides and chemical insecticides namely Novastar 56EC, Stargate 48SC, Confidor 70WG, Actara 25aWG, Tracer 45SC, Ecomec 1.8EC, Bioneem plus 1EC to control thrips infesting mung bean in the experimental field of Sher-e- Bangla Agricultural University during November 2017 to February 2018. An untreated control observation was also evaluated. Efficacy of the treatments differed significantly and showed effective results in reduction of thrips population and infestation on mung bean at vegetative and reproductive growth stages of the plant. Stargate 48SC (clothianidin) was the most effective insecticide against the thrips species Megalurothrips usitatus and Thrips palmi with the highest reduction of population on top trifoliate leaves and terminal shoots (100.00 and 89.40%, respectively) at vegetative stage and reduction on flower buds and flowers (86.04 and 85.95%, respectively) at reproductive stage of mung bean. The lowest flower bud and flower infestation (7.22 and 3.41%, respectively) and shedding (4.21 and 1.06%, respectively) by thrips with the highest number of pod (23.80 plant-1), seed (10.20 pod-1), 1000 seed weight (48.40 g) and yield (1026.91 kg ha-1) were also found in Stargate 48SC treated plots followed by Confidor 70WG and Actara 25WG treatments. SAARC J. Agri., 17(2): 43-52 (2019)

The Role of Planting Patterns to Control Thrips from Red Chili Pepper Plants

Chili plants are commodities that are vulnerable to various types of pests, one of the main pests is thrips. This study aims to determine the role of cropping patterns to control thrips from red chili plants, which was carried out in the Maros Regency, South Sulawesi. Planting patterns applied were: 1) chili using plastic mulch without the combination of other plants and the use of pesticides, 2) chili using plastic mulch combined with corn plants, 3) chili without plastic mulch combined with watermelon plants, 4) chili without plastic mulch combined with watermelon and corn plants, 5) chili without plastic mulch combined with corn plants and 6) chili using plastic mulch and pesticides (according to farmers' treatment). The results showed that the highest population of thrips was found in the chili cropping pattern without plastic mulch combined with watermelon and corn plants with as many as 15 T. parvispinus and 32 T. palmi thrips. Meanwhile, the chili planting pattern using plastic mulch without the combination of other plants and with the use of pesticides had the lowest average amount of thrips population weighing at 5.1 T. parvispinus and 9.5 T. palmi. T. parvispinuspopulation was lower at the beginning of the observation (during the vegetative period) and tends to increase during the generative period of chili plants. T. palmi shows the opposite trend, its population tends to be high at the beginning of plant growth (vegetative phase) and decreases its population when the plant enters the generative period. Based on the data and facts found during the study, it is concluded that: 1). The chili cropping pattern without plastic mulch combined with watermelon and corn plants showed the highest average number of thrips population compared to the other cropping patterns. 2). The abundance of populations of the two thrips species showed different fluctuations, where T. parvispinus populations tended to increase in line with plant development and T. palmi decreased according to plant development. 3). In general, the application of intercropping cropping patterns has not yet appeared to play a role in reducing the abundance of thrips population but there is an opportunity to apply cropping patterns as a method to control thrips by selecting plants that are more suitable to be combined with chili plants.