Thrips Development Research Articles

Population dynamics of wheat and predatory thrips in winter wheat agrocenosis in the forest-steppe of the Samara region

The current paper has presented the three-year study results (2021–2023) on recording the population dynamics of wheat and predatory thrips during the spring-summer vegetation period of winter common wheat in the forest-steppe of the Samara region. The purpose of the study was to determine the dynamics of the seasonal development of wheat and predatory thrips according to the phenophases of the development of winter common wheat in the forest-steppe of the Samara region. For this purpose, there were carried out the calculations using the mowing method with an entomological net on winter wheat crops in different phenophases of development, and the population of species and thrips were determined in the laboratory under a binocular. According to weather conditions, 2021 and 2023 were characterized as dry and hot, 2022 was characterized as cool with plenty of precipitation in the first half of the winter wheat vegetation period. The population dynamics of wheat and predatory thrips varied depending on the weather conditions of the spring-summer period of the year. In the hot years of 2021 and 2023 there were 2 periods of increase in population. In 2021, the period of maximum population of wheat thrips was observed from a heading stage to a flowering stage (1016 and 1048 specimen per 100 sweeps of the net) and in the phase of milky-wax ripeness (426 specimen per 100 sweeps of the net). In 2022, the population of wheat thrips on plants increased gradually, the peak was noted once during the flowering stage, amounting to 1084 specimen per 100 sweeps of the net. In 2023, a population increase was observed in the heading stage (1782 specimen per 100 sweeps of the net) and the phase of milky-wax ripeness (421 specimen per 100 sweeps of the net). In the hot years of 2021 and 2023 there were 2 periods of increase in predatory thrips’ population; the maximum number of entomophages was observed during the heading stage and amounted to 87 and 61 specimens per 100 sweeps of the net, respectively. In the cool year of 2022, there was one population increase during the flowering stage and amounted to 14 specimens per 100 sweeps of the net. In the phases of heading and flowering of plants, there were predominantly adult insects (imago), and in the phases of milky and milky-wax ripeness, there were predominantly found larvae of different ages. The weather conditions in 2021 and 2023 turned out to be more favorable for the development of wheat and predatory thrips than in 2022.

Efficacy of insecticides against wheat thrips Haplothrips tritici Kurd. in winter wheat crops

Goal. To develop an effective system of winter wheat protection against wheat thrips Haplothrips tritici Kurd. Determine the technical effectiveness of insecticides Karate Zeon 050 CS, SC (lambda-cyhalothrin, 50 g/l); Match 050 ES, CE (lufenuron, 50 g/l); Enjio 247 SC, CS (thiamethoxam, 141 g/l + lambda-cyhalothrin, 106 g/l); Talstar, 10% CE (bifenthrin, 100 g/l); Mospilan, VP (acetamiprid, 200 g/kg); Inazuma, VG, (acetamiprid, 100 g/kg + lambda-cyhalothrin, 30 g/kg) in the Southern Steppe of Ukraine.
 Methods. The experiment was set up on winter wheat crops in 4-, 5- and 8 replications in 4x replication. The plots were arranged by the method of randomized blocks. The pest was counted by sampling 20 ears of wheat, which were placed in paper bags, tightly closed, delivered to the laboratory and counted live and dead adults by analyzing each ear for all samples from each experiment. Larvae were counted by the method of distillation using selectors.
 Results. To control the number of thrips, the effectiveness of the insecticide Engio 247 SC, CS at four application rates (0.05, 0.1, 0.15 and 0.2 l/ha) and Karate Zeon 050 CS, SC; Inazuma, VG; Match 050 ES, CE; Mospilan, VP; Talstar, 10% CE was studied. As a result of observations of changes in the number of thrips during 2017—2019, it was found that its appearance on winter wheat crops occurs from May 08 to 24. Peculiarities of weather conditions influenced the dynamics of thrips numbers. The duration of individual phases of wheat thrips development by years depending on the GTC was studied. The studies revealed the main patterns of wheat thrips population development and showed the possibility of controlling its number with the help of various insecticides.
 Conclusions. The use of insecticides Match 050 ES, CE; Karate Zeon 050 CS, SC; Talstar, 10% CE; Mospilan, VP; Inazuma, VG at consumption rates of 0.3 l/ha, 0.2, 0.1, 0.075, and 0.24 l/ha, respectively, on winter wheat crops against wheat thrips in the phase — «beginning of earing» (VVSN 51) effectively controls the number of thrips and provides technical efficiency of 93.7—96.1%. The use of the insecticide Engio 247 SC, KS at consumption rates of 0.05 l/ha, 0.1, 0.15 and 0.2 l/ha provides technical efficiency of this drug against pest larvae at the level of 90.2%, 94.7, 95.9 and 96.4%, respectively.

Effect of <i>BT</i> and Non-<i>BT</i> Cotton on Biology of <i>Thrips Tabaci</i> and Its Management Using Insecticides

The development of Thrips tabaci was studied on transgenic BG I, BG II, non-Bt, and desi cotton cultivars. The oviposition period was minimum on desi cotton, FDK 124 (11.67 days) as compared to BG II (RCH 650) and non-Bt cotton (LH 2076). Female longevity was minimum on FDK 124 (17.50 days) followed by RCH 650 (23.17 days) and LH 2076 (21.83 days). Maximum female longevity was recorded on BGI cotton cultivar RCH 308 (26.83 days). Nymphal, pupal period, and total development period were minimum on FDK 124 (8.17, 2.33, and 34.00 days) as compared to Bt and non-Bt cotton cultivar, LH2076. Based on the higher oviposition period, female longevity, fecundity, and nymphal period, Bt cotton hybrids were found to be more favourable for thrips development in comparison to non-Bt cotton cultivars and desi cotton . The new generation insecticide, spinetoram 11.7SC @ 425g/ ha was most effective and also found to be safe to the predators.

Effects of Different Parts of the Rose Flower on the Development, Fecundity, and Life Parameters of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae).

Frankliniella occidentalis (Pergande) is an important horticultural pest that causes serious damage to rose plants, which is one of its preferred foods. In this study, rose petals, rose flowers, and 10% honey solution + kidney bean pods were chosen as foods to assess their influence on the growth, development and fecundity of F. occidentalis. The results showed that developmental time of immature F. occidentalis with the following trend: rose flowers <10% honey solution + kidney bean pods < rose petals < kidney bean pods. The longevities of both female and male adults were lowest when feeding on the rose petals and were highest when feeding on rose flowers. The fecundity was in the following order: rose flowers >10% honey solution + kidney bean pods > rose petals > kidney bean pods. The net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of F. occidentalis feeding on rose petals and kidney bean pods were lower than those feeding on rose flowers and 10% honey solution + kidney bean pods. The development, longevity, fecundity, and parameters have significantly changed since F1 generation after feeding with the three food types. The results indicated that different parts of rose flowers had a significant effect on the development of thrips, and nectar and pollen had a positive effect on thrips population increase and reproduction.

Population Development and Determination of Infestation Rate of Greenhose Tomato Pests in Karatay and Meram (Konya) Districts

The study was carried out during the 2018-2019 growing season under greenhouse conditions to determine the population development and infestation rates of Thrips, Leafhopper species, and Tuta absoluta damaging greenhouse tomatoes in Karatay and Meram (Konya) districts. For this purpose, 10 greenhouses of tomato were selected from the two districts. Delta-type sexual pheromone trap, blue and yellow sticky traps were hung in each greenhouse. The traps were placed in the greenhouses alongside tomato seedlings. The pests caught in these traps were counted weekly and recorded. The infestation rate of 25 plants was selected randomly from each greenhouse and their pest infestation was examined. As a result of this study, Thrips species in the districts were found in the early stage of the plant in blue traps and were recorded to be 29 and7 pests per week in Karatay and Meram respectively. Leaf hooppers species emerged in yellow sticky traps during the last stages of plant phenology; and in 2018-2019, a maximum of 5-4 pests per week was determined, respectively. Tuta absoluta, on the other hand, had a high population at the end of the season; in 2018-2019, a maximum of 636-571 adult pests per week were caught oon the traps, respectively. In 2018-2019, whereas the infestation rate of Thrips and Leafhopper species were 0%, the infestation rate of T. absoluta was 18.66% and 18.76%, respectively.

Effect of wavelength on development and demographic parameters of Scolothrips longicornis fed on two-spotted spider mites

The wavelength of light can affect reproduction and development of arthropods. In the present study, we examined the reproduction and development of predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch (Trombidiformes: Tetranychidae) eggs, under five wavelengths: white (all wavelengths), blue (475 nm), green (580 nm), yellow (620 nm) and red (675 nm), at 25 ± 0.5 °C, 16L: 8D and 60 ± 10% rh. Light wavelength did not significantly influence female and male preadult duration, male adult duration, and male total longevity. White and blue light yielded the longest oviposition periods. All life table parameters varied significantly among treatments. The intrinsic rate of increase (rm d−1) was lowest in red light wavelength (0.112 ± 0.009) and highest in white wavelength (0.171 ± 0.008) and blue light wavelength (0.168 ± 0.008). The present research demonstrates that white light conditions positively influence S. longicornis with shorter development time and improved reproductive performance. This information will be beneficial in mass production of S. longicornis for biocontrol programs involving T. urticae.

Effect of temperature on the development and reproduction of Thrips flavus (Thysanoptera: Thripidae)

Abstract In Northeast China, thrips have long been considered a secondary pest of soybean until recent years. No study has provided clear reports regarding the effects of temperature on the development and reproduction of Thrips flavus Schrank (Thysanoptera: Thripidae). Our aim was to study whether the population dynamics of T. flavus were affected by temperatures. Thus, the development, reproduction and growth of T. flavus populations reared on soybean leaves were studied at five different constant temperatures. The temperature and rate of development from eggs to adults were linearly related between 19 and 31°C. The developmental threshold temperature and effective accumulated temperature were 11.60°C and 273.89 degree‐days for the whole generation. The viability of adult survival decreased with the increase in temperature between 19 and 31°C. The value of life expectancy of females ranged from 7.47 days (at 31°C) to 16.66 days (at 22°C), while the life expectancy value of males ranged from 5.33 days (at 19 and 31°C) to 17.0 days (at 25°C). The mean fecundity per female was highest at 19°C, with 7.85 eggs/day. The intrinsic rate of increase was the highest (0.102) at 31°C. The results obtained indicate that temperature is a key factor associated with the development and reproduction of T. flavus on soybean.

First report of insulin receptor in thysanoptera and its expression variation with development of western flower thrips, Frankliniella occidentalis

• A unique insulin receptor is identified in Frankliniella occidentalis . • The insulin receptor is expressed in all developmental stages. • Expression of the receptor is negatively correlated with the thrips development. Insulin signaling is required for insect development. Insulin-like peptides and their signalings have been extensively assessed in various insects. However, little is known about them in Thysanoptera. This study identified the first insulin receptor in Thysanoptera using western flower thrips, Frankliniella occidentalis . A single Fo-InR ( F. occidentalis insulin receptor) gene is encoded in its genome. A predicted amino acid sequence (1,645 residues) was highly (>70% homologies) matched to known insect InRs. However, it did not cluster with other known insect taxonomic groups. Domain analysis suggested an intracellular protein kinase and an extracellular ligand-binding regions. All developmental stages from larva to adult expressed Fo-InR . Starvation up-regulated its expression levels at all developmental stages except pupal stage. Different diet conditions resulting in different developmental rates altered expression levels of Fo-InR . There was a negative correlation between developmental rate and Fo-InR expression levels, especially at adult stage. Results of this study suggests a physiological role of insulin signaling in F. occidentalis development.

SPREAD AND HARMFULNESS OF THE THRIPS TABACI LIND IN APPLE PLANTATIONS OF THE KRASNODAR TERRITORY

The results of daily phytosanitary monitoring of fruit plantations and literature data on biology, ecology, harmfulness of tobacco thrips (Thrips tabaci Lind.) are presented. In the apple agrocenoses of the Kuban and Black Sea zones of Krasnodar Territory, an increase in the harmfulness of representatives of the order Thysanoptera is observed. An increase in the number of tobacco thrips was noted, which led to a decrease in the quality of fruits. In the growing season of 2018, isolated symptoms of fruit damage by phytophagous were noted, in the growing season of 2019, fruit damage reached up to 2 %, in 2020 — 5-30 %. It was revealed that during the flowering period the number of T. tabaci Lind was 1-2 specimens per inflorescence; at the end of flowering, the amount of the pest increased by 5 times. High temperatures and lack of precipitation led to an outbreak of the pest population; in the first decade of June, 15 to 40 individuals were fixed per leaf. A high degree of damage to the tops of shoots, leaves and fruits was observed, the tissue in the feeding places of the pest was deformed, discolored, acquiring the appearance of whitish spots, which grew during the growth and ripening of fruits. It is known that the intensive development of thrips takes place in dry and hot years; the optimum temperature for the development of T. tabaci Lind is +25 °C. As a result of our monitoring, it was revealed that the maximum amount of the pest was observed during the period when high temperatures and low relative air humidity were noted — June and early July. The greatest number of the pest was found in areas bordering the fields of grain and tilled crops, while the number of phytophages at the time of registration reached 45 individuals per leaf and more. It should be noted that when the air temperature rises above +35 °C, the development of the phytophage stops, and the mortality rate of all stages sharply increases. To ensure a stable phytosanitary situation in fruit agrocenoses and prevent loss of fruit quality from damage by thrips, it is necessary to develop a set of measures to control the number of pests.

Life History of Thrips hawaiiensis (Morgan) Reared on Flower of “Saba” Banana (Musa acuminata x balbisiana Colla)

Thrips hawaiiensis (Morgan) is a pest of banana, mango, and pomelo. The study aimed to determine the development and reproductive capacity of thrips under laboratory condition. To start the culture, female thrips were collected from Beltran “Saba” banana plantation in Tuao, Cagayan, Philippines. Thrips were reared on fresh banana flowers in glass containers covered with cotton gauze pad sealed with rubber bands at temperatures of 25 ± 1.0 to 32 ± 2.0 °C, relative humidity of 78–99%, and photoperiod of 12:12 h (L:D). Forty (40) eggs laid within 8 h by first-generation female were observed from 05 Oct–16 Nov 2020. Three (7.5%) males and 37 (92.5%) females emerged from unfertilized eggs. Male average egg incubation, first instar, and second instar larval, prepupal, and pupal days were 1.33 ± 0.47, 1.33 ± 0.47, 1.33 ± 0.47, 1.00 ± 0.00, and 1.33 ± 0.47, respectively. Male average total development period and lifespan were 8.67 ± 0.62 and 9.33 ± 0.94, respectively. Female average egg incubation, first instar larva, second instar larva, prepupa, and pupal periods were 1.24 ± 0.43, 1.24 ± 0.43, 2.38 ± 0.48, 0.59 ± 0.20, and 2.38 ± 0.48, respectively. Female average total development period from egg to adult emergence and lifespan from egg to post oviposition until the adults are dead were 8.89 ± 0.52 and 23.19 ± 7.07, respectively. Female average pre-oviposition, oviposition, and post-oviposition periods were 1.05 ± 0.38, 12.27 ± 6.69, and 0.95 ± 1.20, respectively. The average number of eggs laid by each female was 196.92 ± 75.70. Female second instar larva and pupa development period were longer – which could be due to the bigger body size – and the average lifespan was twice as long as that of male. T. hawaiiensis is a short-lived, asexual insect with high fecundity; based on the life span of female thrips studied, between 7–8 thrips generations could be developed annually.

Structural, Physiological and Biochemical Alterations on the Galled-Stem of Tamarix nilotica

Tamarix nilotica (Tamaricaceae) is an important wild medicinal plant. It inhabits semi-arid environment, where it is often one of the most important plants suitable for insects’ infestation. Thrips (Thysanoptera: Insecta) infect T. nilotica causing galls that affect plant growth and development. The present work therefore was undertaken to study the morpho-anatomical, biochemical, and physiological aspects induced by insect infestation. Zeatin (Zn), gibberellins (GA3), salicylic acid (SA), 24-epibrassinolide (BR), and abscisic acid (ABA) were increased in the infected stems relative to the healthy ones. Galled-stem shown increased thickness of periderm and phellem layers whereas large portion of vascular cylinder disappeared leaving a large C shaped cavity where the mature insect nested. Gall sites had declined chlorophyll contents which were associated with a decrease in the emission of chlorophyll a fluorescence. While total soluble sugars, sucrose, total free amino acids, total soluble protein and minerals contents as well as the activities of SOD, CAT, PX, PO, APX, and AO significantly reduced in the infested Tamarix stems , polysaccharides, proline, MDA and H2O2 have been increased compared with the healthy ones. Galled-stems exhibited increased antiradical activity (expressed as IC50) which was concomitant with accumulation of phenolics, tannins, alkaloids, flavonoids and enhanced PAL. Six endophytic fungi inhabited Tamarix galls. Development of thrips galls on T. nilotica stems drastically impacts the host structure and its cellular metabolism as well as induction of an oxidative stress. The roles and impacts of endophytic fungi on insect induced galls still need further exploration.

Abundances of thrips on plants in vegetative and flowering stages are related to plant volatiles

AbstractWestern flower thrips (WFTs), Frankliniella occidentalis Pergrande, and onion thrips (OTs), Thrips tabaci Lindeman, are two cosmopolitan insect pests of agricultural and horticultural plants. Understanding the occurrence and development of thrips on plants is crucial for identifying suitable plants that can be used for developing a “push‐pull” strategy against thrips. In this study, the dynamics of WFTs and OTs on plants (Allium fistulosum L., Medicago sativa L., Luffa cylindrica (L.) Roem., Ocimum basilicum L., and Schizonepeta tenuifolia (Benth.) Briq.) were investigated for two consecutive years (2018–2019). Throughout the survey, the abundances of both thrips species were strongly associated with plant species and plant phenology; both thrips species were present at relatively high densities on M. sativa but very low densities on O. basilicum and S. tenuifolia. Populations of both thrips species greatly increased during plant flowering. A Y‐tube olfactory test was used to study the effects of plant volatiles in mediating thrips behaviour and showed that volatiles of M. sativa were attractive to both thrips species whether emitted by the plant in the vegetative or flowering stage, while volatiles of O. basilicum and S. tenuifolia were repellent to thrips. Additionally, because of the presence of a high number of floral chemicals, both thrips species exhibited a greater preference for volatiles emitted by plants in the flowering period over those emitted by plants in the vegetative period. Our observations indicate that plant species and flowering status play an important role in the abundance dynamics of thrips and that the volatiles of flowering plants attract thrips more strongly than volatiles emitted by vegetative plants. These findings can facilitate the screening of attractive/unattractive plants for developing push‐pull strategies to control thrips.

Predicting the Potential Invasive Range of Klambothrips myopori (Thysanopetra: Phlaeothripidae).

Temperature-driven development of myoporum thrips, Klambothrips myopori (Thysanopetra: Phlaeothripidae), was examined at seven constant temperatures (15, 17, 20, 25, 30, 34, and 35.5°C) on Myoporum laetum Forst (Lamiales: Scrophulariaceae). Thrips successfully completed development to adult stage between 15 and 35.5°C. One linear and three nonlinear models were fitted to describe developmental rates of K. myopori as a function of temperature, and for estimating thermal constants and bioclimatic thresholds (Tmin, Topt, and Tmax). The Briere-1 model performed best in describing the developmental rate of cumulative life stages. Two ecological niche models, CLIMEX and Maxent, were used to predict the geographic distribution of K. myopori in its native range and globally. Overall predictions of environmental suitability differed greatly across models. The CLIMEX model accurately predicted known invasive and native localities, while the Maxent model failed to predict the native localities and parts of the invasive range. Based on the CLIMEX model, K. myopori has the potential to establish in many regions of the globe.

Development of the thrips repellent

Development of the thrips repellent

Food decisions of an omnivorous thrips are independent from the indirect effects of jasmonate-inducible plant defences on prey quality

Plant defensive substances can affect the quality of herbivores as prey for predators either directly or indirectly. Directly when the prey has become toxic since it ingested toxic plant material and indirectly when these defences have affected the size and/or nutritional value (both quality parameters) of prey or their abundance. To disentangle direct and indirect effects of JA-defences on prey quality for predators, we used larvae of the omnivorous thrips Frankliniella occidentalis because these are not directly affected by the jasmonate-(JA)-regulated defences of tomato. We offered these thrips larvae the eggs of spider mites (Tetranychus urticae or T. evansi) that had been feeding from either normal tomato plants, JA-impaired plants, or plants treated with JA to artificially boost defences and assessed their performance. Thrips development and survival was reduced on the diet of T. evansi eggs relative to the diet of T. urticae eggs yet these effects were independent from the absence/presence of JA-defences. This indicates that the detrimental effects of tomato JA-defences on herbivores not necessarily also affects their quality as prey.

Thrips developmental stage-specific transcriptome response to tomato spotted wilt virus during the virus infection cycle in Frankliniella occidentalis, the primary vector

Tomato spotted wilt virus (TSWV) is transmitted by Frankliniella occidentalis in a circulative-propagative manner. Little is known about thrips vector response to TSWV during the infection process from larval acquisition to adult inoculation of plants. Whole-body transcriptome response to virus infection was determined for first-instar larval, pre-pupal and adult thrips using RNA-Seq. TSWV responsive genes were identified using preliminary sequence of a draft genome of F. occidentalis as a reference and three developmental-stage transcriptomes were assembled. Processes and functions associated with host defense, insect cuticle structure and development, metabolism and transport were perturbed by TSWV infection as inferred by ontologies of responsive genes. The repertoire of genes responsive to TSWV varied between developmental stages, possibly reflecting the link between thrips development and the virus dissemination route in the vector. This study provides the foundation for exploration of tissue-specific expression in response to TSWV and functional analysis of thrips gene function.

Non-consumptive predator effects on a primary greenhouse pest: Predatory mite harassment reduces western flower thrips abundance and plant damage

Prey react to the presence of predators in suite of ways that reduce predation risk, but may also negatively affect fitness. Non-consumptive effects (NCEs) of predators on prey are likely important components of biological control and moderators of plant damage in agricultural systems. Yet, few studies have investigated their effects in crops relying on augmentative release of natural enemies for protection. Here, we investigated NCEs of the predatory mite Neoseiulus cucumeris on a non-prey life stage of western flower thrips (Frankliniella occidentalis), one of the most damaging pest of greenhouse crops in the world. Second instar thrips were exposed to 2 adult female mites on a leaf disk for 24h. Over a 20min observation period, we saw a 22% reduction in thrips feeding behavior in the presence of predatory mites compared to thrips alone. Thrips feeding was often interrupted by attempted mite attacks, which averaged 4 attacks per thrips over 20min. After 24h, this reduced leaf damage by 51% in the predator treatment compared to the control. This result held true in experiments on whole plants, with damage reduced by 38% in the presence of mites. No significant reduction in feeding activity or damage was observed when larval thrips were exposed to non-predatory mites, conspecifics, or leaves which had previously held large numbers of predatory mites. The presence of mites did not alter thrips development time or final adult size. However, survival to adulthood was decreased by 54–78% in the presence of mites, suggesting a lack of nutritional reserves necessary to complete development. This study demonstrates that NCEs of predatory mites can induce a trophic cascade by reducing pest feeding and fitness. Such beneficial effects of natural enemies are often overlooked in simple predation and efficacy studies.

Onion thrips, Thrips tabaci (Thysanoptera: Thripidae), overwintering in South Auckland, New Zealand: the importance of the local bionomic data/temperature model and biosecurity implications

Onion thrips flights in winter and early spring 1999 were monitored in South Auckland using sticky traps and trap plants. A pair of yellow sticky traps and 10 ‘thrips-free’ onion pot plants per site were changed every 2 weeks. Thrips were detected on traps and plants in June, September and October. Sticky traps were the most reliable method for detecting thrips flights. Wild plants were inspected four times and revealed that thrips bred all winter. There was no diapause. Seedlings that had sprouted in mid July had second instar larvae by 4 October 1999. The nearest source was self-set plants in an adjacent field. Three published temperature models for onion thrips development were compared. Generation times were similar in summer, but very different in winter. The Texas model with minimum developmental threshold of 11.5 °C had the longest winter generation time and required a thrips flight by early August for second instar larvae to develop in the crop by 4 October, whereas the South Auckland model (threshold 8.7 °C) required flights by early September. Thrips flights were detected by traps in September but not August 1999. For cosmopolitan pests that are very variable genetically, it is important to generate local biological data. The biosecurity implications of this variability are discussed.

Comparison of two populations of Pseudophilothrips ichini (Thysanoptera: Phlaeothripidae) as candidates for biological control of the invasive weed Schinus terebinthifolia (Sapindales: Anacardiaceae)

Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae) (hereafter Schinus), is one of the worst invasive species in Florida and Hawaii. The thrips Pseudophilothrips ichini Hood (Thysanoptera: Phlaeothripidae) is being considered as a potential biological control agent of Schinus. Two populations of this thrips were collected in the weed's native range; one from central-east Brazil (Ouro Preto thrips) and a second from north-east Brazil (Salvador thrips). Temperature requirements, adult fecundity and impact on different plant haplotypes by P. ichini were examined in the laboratory. Complete development of thrips from both populations occurred at temperatures ranging from 20 to 30°C. Two approaches were used to model the predicted distributions of the thrips populations in the USA: the physiological model (NAPPFAST) based on cold tolerance and the ecological niche model based on climatic variables (MaxEnt). The physiological model predicted that both populations of P. ichini may establish in similar areas of the USA, overlapping with the distribution of Schinus. However, the niche model predicted that only the Ouro Preto thrips could establish in the USA. The difference in model predictions suggests an apparent preadaptation of the Salvador thrips to lower temperatures than those experienced at the locations they were collected in Brazil. The Ouro Preto thrips had similar fecundity on two Florida Schinus haplotypes, whereas lower fecundity on haplotype A was found for the Salvador thrips. Based on these results, the Ouro Preto population may be better adapted to the climatic conditions and plant haplotypes found in Florida. Moreover, greenhouse studies indicated that Schinus growth was greatly reduced by thrips feeding, which may result in lower weed reproduction and densities in the field.

Adoption of IPM Approach-An Ideal Module against Thrips (Thrips tabaci Linderman) in Onion

Onion (Allium cepa L.) is an important export oriented vegetable among the cultivated Allium crops in India. Onion Thrips (Thrips tabaci Linderman) is the key biotic factor for reducing yield loses in both onion as vegetable crop as well as seed crops. Besides direct damage to both foliage and bulbs, thrips can also indirectly aggravate purple blotch and act as a vector for viral disease such as Iris yellow spot. In absence of high levels of host plant resistance to Thrips tabaci and development of resistance towards number of pesticide of late, there is an urgent need to look at other IPM options for effective management. A field study was conducted under the All India Network Research Project on Onion and Garlic, at the College of Horticulture (OUAT), Sambalpur, Odisha, India during the winter season 2010-11 to 2012-13 to find out the most effective eco-friendly IPM modules for management of thrips in onion. The treatment consists of M1: IPM module, M2: Farmers’ Practices and M3: Control, laid out in RBD. The results obtained over three years indicated that both M1 and M2 not only significantly reduced the thrips population (21.68 and 21.02 thrips plant-1) but also increased total marketable yield (25.86 and 25.70 tha-1), respectively over the control, M3 (39.13 thrips plant-1and 20.58 tha-1) . Higher BC Ratio was recorded in M1 (3.26) than M2 (2.70). It is concluded that adoption of the IPM module approach consisting of planting of border crop of two rows of wheat and one row of maize, 10-15 days prior to planting of onion seedling, dip treatment with Carbosulfan and need based insecticides spray, when thrips population exceed ETL (30 thrips/plant-1) not only reduces the thrips infestation but also increases the bulb yield with quality of onion bulbs.