American Tomato Research Articles

Efficacy of integrated pest management tools evaluated against Tuta absoluta (Meyrick) on tomato in India

South American tomato moth, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is an invasive pest on tomato and other solanaceous crops. In general, 20 to 30 % yield loss is caused by this pest and sometimes it may result in 100% damage, if timely management interventions are not followed. Though the pest was reported in India during 2014, presently it has spread to several tomato growing states. In the present study various IPM tools have been evaluated against this pest. As a long-term strategy of resistance breeding, genotype screening was carried out for identification of resistance sources from wild and cultivated tomato genotypes showing resistance/tolerance against T. absoluta . Among the evaluated wild and cultivated tomato genotypes, Solanum pennellii (Accession, LA 1940) was identified as a resistant source against T. absoluta both under choice and no-choice bioassays and is being used for resistance breeding. Various entomopathogens ( Bacillus thuringiensis , Metarhizium anisopliae , Beauveria bassiana and M. rileyi ), egg parasitoids ( Trichogramma chilonis , T. pretiosum and Trichogrammatoidea bactrae ), light traps, pheromone traps, synthetic insecticides, botanical origin insecticides were also evaluated for their relative efficacy. Among the egg parasitoids T. pretiosum and among synthetic chemicals, spinetoram 12 SC@ 1.25ml/l were found very effective for the management of T. absoluta . Yellow light traps were found as an effective component for integrated management of T. absoluta . Azadirachtin 5% EC at the tested concentrations showed highest mean radial growth (24.67 mm) with relatively less inhibition (16.51%) of M. anisopliae indicating these combinations can be effectively utilised in the eco-friendly management of T. absoluta . We reported natural incidence of M. anisopliae on T. absoluta larvae, causing up to 35 per cent mortality during 2016-17.

Susceptibility of the egg parasitoid Trichogramma achaeae (Hymenoptera: Trichogrammatidae) to selected insecticides used in tomato greenhouses

The South American tomato moth Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a pest species of great economic importance in tomatoes, both in greenhouses and in open-air crops. This importance has increased in recent years because it has been introduced in many countries in Europe, Africa, and Asia. Insecticides different active ingredients and biological control agents are being used in the control of this pest species. This implies the need to make both groups compatible within IPM programmes. Therefore, the objective of this work was to study the compatibility between different insecticides and the use of the egg parasitoid Trichogramma achaeae Nagaraja and Nagakartti (Hymenoptera: Trichogrammatidae). Three groups of trials were carried out under laboratory and greenhouse conditions. Ten insecticides with the following active ingredient were evaluated: abamectin, azadirachtin, Bacillus thuringiensis, chlorantraniliprole, emamectin, flubendiamide, indoxacarb, methomyl, spinosad, and spiromesifen. In the results, three groups of insecticides were established based on their compatibility with the use of biological control: The first group (abamectin, B. thurigiensis, flubendiamide, indoxacarb and spiromesifen) showed a high degree of compatibility with egg parasitoid releases. The second group (azadirachtin and chlorantraniliprole, and methomyl) presented compatibility problems. Finally, the last group (emamectin, methomyl, and spinosad) did not apper to be compatible. The results found will allow a better application of IPM programmes in tomato crops for the control of this pest species.

Gene silencing by RNAi via oral delivery of dsRNA by bacteria in the South American tomato pinworm, Tuta absoluta.

RNA interference (RNAi) has been evaluated in several insect pests as a novel strategy to be included in integrated pest management. Lepidopterans are recognized to be recalcitrant to gene silencing by RNAi. As such, double-stranded RNA (dsRNA) delivery needs to be adjusted to assure its stability until it reaches the target gene transcript for silencing. Gene silencing by RNAi offers the potential to be used in the control of Tuta absoluta (Meyrick), one of the main insect pests of tomato (Solanum lycopersicum) worldwide. Here, we tested the delivery of dsRNA expressed in Escherichia coli HT115(DE3) and supplied to larvae in an artificial diet by screening target genes for silencing. We tested six target genes: juvenile hormone inducible protein (JHP); juvenile hormone epoxide hydrolase protein (JHEH); ecdysteroid 25-hydroxylase (PHM); chitin synthase A (CHI); carboxylesterase (COE); and arginine kinase (AK). Based on larval mortality, the duration of the larval stage in days, pupal weight, and the accumulation of the target gene transcript, we demonstrated the efficacy of bacterial dsRNA delivery for the functional effects on larval development. Providing dsRNA targeted to JHP, CHI, COE and AK by bacteria led to a significant decrease in transcript accumulation and an increase in larval mortality. Bacteria expressing dsRNA targeting essential T. absoluta genes supplied in artificial diet are efficient to screen RNAi target-genes. The oral delivery of dsRNA by bacteria is a novel potential alternative for the control of T. absoluta based on RNAi. © 2019 Society of Chemical Industry.

Assessing inoculative releases of Pseudapanteles dignus (Hymenoptera: Braconidae) for the biological control of Tuta absoluta (Lepidoptera: Gelechiidae)

Augmentative biocontrol implemented through inoculative seasonal releases of one or more biological control agents has proven to be a reliable crop protection approach in greenhouse and open field crops. The South American tomato pinworm, Tuta absoluta, is a key tomato pest worldwide. In this context, the effectiveness of the American-native larval endoparasitoid Pseudapantales dignus in reducing T. absoluta populations, in a semi-field set-up under greenhouse crop conditions, was assessed. In individual plants enclosed in cages, five host (T. absoluta):parasitoid (P. dignus) relative densities (2:1; 4:1; 4:2; 10:3 and 10:5) were evaluated through inclusion techniques. Controls for each treatment were included. Parasitization was allowed for 48 h; then leaves with signs of moth injury were removed and taken to the laboratory for rearing the host larvae until its pupation or the formation of P. dignus cocoons. Percentages of parasitism were calculated for each treatment and compared using a generalized linear model (GLM) with binomial link function. Pseudapanteles dignus females failed to parasitize at a host density of 2 larvae per plant; meanwhile at the other host densities tested, it reached from 23 to 61% parasitism. The greater percentage of parasitism was observed at host:parasitoid relative densities of 10:3. This field experiment showed evidence that the efficiency of this biocontrol agent decreases at low host densities, probably influenced by a reduction in host localization stimuli. Besides, at higher P. dignus release rates, parasitism decreased due to self-limitation of adult females by mutual interference when searching for hosts. Pseudapantales dignus has a significant potential for use in biological control programs.

Susceptibility of Cypriot Tuta absoluta populations to four targeted insecticides and control failure likelihood

AbstractTuta absoluta, known as the South American tomato pinworm, is one of the most disastrous pests of tomato cultivations, presently menacing tomato cultivations worldwide. In 2006, T. absoluta invaded Spain from South America. Since then, it was rapidly spread to most European, African and Asian countries. Such alien invasive species can minimize crop production, whereas the increasing use of insecticides raises various environmental concerns as well as on control costs, control failure and the toxicity to non‐target organisms. The S. American tomato pinworm is mostly controlled by chemical insecticides, and failure to control it is not a rare phenomenon. Resistance to numerous insecticides has been reported and is mainly due to the fact that farmers do not follow a sustainable resistance management scheme. Several examples have been reported from several countries where the tomato pinworm is present. In order to develop a successful insecticide resistance management (IRM) strategy for any major pest, one needs to identify the baseline toxicity to insecticides and then monitor susceptibility levels. In Cyprus, the current status of susceptibility levels to the main insecticides that are used to control T. absoluta has never been studied before. Herein, nine Cypriot populations of the pest were subjected to laboratory bioassays between 2016 and 2018 using the main insecticides applied against it. We found that the insecticides chlorantraniliprole and indoxacarb could not control the Cypriot T. absoluta populations anymore, with a resistance ratio (RR) >28 and 3–23, respectively. Furthermore, mortality achieved by those two insecticides was 20.6%–72% for chlorantraniliprole and 27.5%–78% for indoxacarb. However, the insecticides emamectin benzoate and spinosad are very effective, since mortality to both of them ranged between 99.5% and 100%.

Side effects of insecticides commonly used against Tuta absoluta on the predator Macrolophus basicornis

Macrolophus basicornis (Stal) (Hemiptera: Miridae) is a promising biological control agent against tomato pests, mainly the South American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). Nevertheless, the amount of pesticides used in tomato crops could compromise the effectiveness of M. basicornis in pest control. Thus, the present research aims to evaluate the lethal and sublethal effects of five insecticides (spinetoram, chlorantraniliprole + abamectin, triflumuron, tebufenozide, and abamectin) commonly used in tomato crops on M. basicornis. Third instar nymphs were exposed to dry residues of insecticides on tomato seedlings, and adults were directly sprayed using a Potter precision tower. Abamectin caused the highest mortality rate (79.98%) of M. basicornis nymphs. Females exposed to spinetoram during the nymphal stage showed a reduction in tibia length. Except for spinetoram, all other insecticides significantly influenced adult longevity. All insecticide treatments caused a reduction in female offspring. However, the growth of males and females (F1 generation) issued from adults treated did not differ significantly from the control. In the predator flight bioassay, males in the first evaluation showed a reduction in flight activity following exposure to chlorantraniliprole + abamectin and to tebufenozide. Overall, all insecticides tested caused negative effects on M. basicornis.

Garden Variety: The American Tomato from Corporate to Heirloom

Garden Variety: The American Tomato from Corporate to Heirloom

RNAi in Tuta absoluta management: effects of injection and root delivery of dsRNAs

The South American tomato pinworm, Tuta absoluta, is considered worldwide as one of the most important tomato pests. Insecticide resistance reported on the moth and the awareness about the negative impact of agrochemicals on the environment and human health have raised the demand for new control tools. Among these, RNA interference (RNAi) can represent a valid tool to be included into new control strategies against this pest. Here we report the results of trials aimed at evaluating the effects of dsRNAs targeting acetylcholinesterase (AChE), nicotinic acetylcholine alpha 6 (nAChRs), ryanodine (RyRs) receptors by injection and root delivery. In the injection procedure, 2 and 5 µg of dsRNA were able to reduce the gene expression in a range of 62.7–75.4%, inducing a maximum mortality rate of 92.59%. The dsRNAs administered at 5 µg by root absorption revealed the potential of this delivery system to affect the gene expression (47–69% reduction) and the mortality (ranging from 67.1 to 80.5%) of treated specimens. The delivered dsRNAs (both injected and root administered) affected the weight of both T. absoluta pre-pupae and pupae. The selected AChE, nAChRs and RyRs genes can be suitable targets for T. absoluta control by means of in planta delivery dsRNAs.

Temperature and tomato variety influence the development and the plant damage induced by the zoophytophagous mirid bug Nesidiocoris tenuis

Nesidiocoris tenuis (Hemiptera: Miridae) is an important biocontrol agent of several key arthropod pests, including the South American tomato pinworm, Tuta absoluta (Lepidoptera: Gelechiidae). However, it can cause economic damage owing to its herbivory. Risk assessment on plant for the predator under different temperature thresholds is necessary for managing its phytophagy in tomato cultivation. We investigated the predator plant damage and its development under the influence of temperature and tomato variety. Ten commercial tomato varieties of different types (round red, small cherry, date baby plum, piccadilly plum and marmande beefsteak) were tested in the laboratory under five constant temperatures (15, 20, 25, 30 and 35 °C). The amount of fourth-instar nymphs moulted into adults and stem necrotic rings induced by the feeding activity was evaluated. The plant damage differed among the varieties and increased significantly across the temperatures up to 30 °C, with a slight decline at 35 °C. Temperature and variety significantly affected the nymphal development with an increasing number of moulted adults at increasing temperature, but with slight differences among tomato varieties. Our findings provide valuable information on the mirid response to the tested abiotic and biotic factors, which can help in the management and exploitation of N. tenuis as a biocontrol agent in tomato crop.

Trichome and biochemical basis of resistance against Tuta absoluta in tomato genotypes

AbstractSouth American tomato moth, Tuta absoluta, a serious pest of tomato (Solanum lycopersicum) in tropics and subtropics, is rapidly spreading world over. Twenty one wild/cultivated/advanced breeding lines of tomato were screened for resistance to T. absoluta under greenhouse conditions (choice bioassay) and promising genotypes were evaluated further for their antibiosis activity through no choice bioassay under in-vitro conditions. From 21 genotypes screened, six wild accessions viz., S. pennellii (LA 1940); S. chilense (LA 1963); S. arcanum (LA 2157); S. lycopersicum (LA1257) and S. corneliomulleri (LA 1292, LA1274) were relatively resistant to T. absoluta based on mean percent damage and were further studied under in-vitro conditions. These genotypes recorded relatively more larval mortality, prolonged larval and pupal duration with reduced adult emergence of T. absoluta. Among these six genotypes, S. pennellii (LA-1940) showed resistance both under choice and no choice bioassays with higher number of type IV trichomes, highest total flavonoids and phenols. In general, glandular trichomes (GTs) (type I, IV, VII) showed negative correlation in different genotypes of tomato with reference to larval number/plant, percent damage and adult activity, whereas type V (non-GTs) showed negative correlation with number of larvae/plant.

Insecticide resistance in the tomato pinworm Tuta absoluta: patterns, spread, mechanisms, management and outlook

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is an invasive pest difficult to control. Insecticide application is quite common and remains the prevalent control method particularly in open-field cultivation systems. As a result, insecticide resistance to many chemical classes of insecticides has been described both in South America and in Europe. The development of insecticide resistance is relatively fast in this species, and the main mechanisms involved are altered target-site sensitivity and/or enhanced detoxification, depending on the chemical class. However, insecticide resistance mechanisms do not differ between South America and Europe and are mainly due to simple genotype variations leading to high levels of resistance. The presence of resistance alleles at low frequency, especially against newer chemistry, is of major concern, as they tend to spread with the invasions making tomato pinworm particularly difficult to control. The monitoring methods and management programmes developed for the species benefited from the pro-activity of the Insecticide Resistance Action Committee and its country groups, particularly in Brazil and Spain. Bioassay methods were developed, resistance monitoring activities initiated and resistance management guidance was provided. The implementation of integrated control programmes and appropriate resistance management strategies as part of such programs is of utmost importance to keep tomato pinworm infestations under economic damage thresholds, thus guaranteeing sustainable yields.

Evaluation of Beauveria bassiana isolates against South American tomato moth, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Evaluation of <i>Beauveria bassiana</i> isolates against South American tomato moth, <i>Tuta absoluta</i> (Meyrick) (Lepidoptera: Gelechiidae)

Hierarchical and optimization methods for the characterization of tomato genotypes

ABSTRACT The correct characterization of germplasm banks is fundamental for breeders to succeed in breeding programs. Several studies have sought to obtain genotypes with resistance to pests. However, there is no consensus about which methodology is the most appropriate to characterize a germplasm bank of tomato with different levels of resistance to pests. The objective of this study was to compare methods of multivariate analysis for the evaluation of genetic diversity in tomato genotypes with different levels of resistance to pests. The experiments were conducted at the Vegetable Experimental Station of the Federal University of Uberlândia - Monte Carmelo campus (18º 42’ 43.19” South latitude and 47º 29’ 55.8” West longitude, 873 m altitude), in the period from April 2013 to November 2016. Sixteen genotypes were evaluated from the interspecific cross between LA-716 (S. pennellii) versus pre-commercial line (UFU-057) followed by backcrossing and self-fertilization, along with the pre-commercial line UFU-057 (recurrent parent) Santa Clara and the wild accession S. pennellii (donor genitor). The contents of acylsugar, foliar trichomes, South American tomato pinworm and leaf miner repellency tests were analyzed. The experimental design was the randomized block design totaling 76 plots (19 genotypes x 4 blocks). It was concluded that there was genetic variability among the evaluated genotypes. The method of graphic dispersion by principal components revealed a greater power of discrimination. Genotypes UFU-057F2RC27#4.3, UFU-057F2RC28#2.2 and UFU-057F2RC27#4.7 contain the highest levels of acylsugar, resistance to Liriomyza spp. and T. absoluta.

Occurrence of South American Tomato Leaf Miner (Tuta absoluta) and Current Management Practices Adopted by Farmers in Lalitpur District, Nepal

A study was carried out to document occurrence of Tuta absoluta and current management practices adopted by farmers in Lalitpur district (Lele VDC) where a total of 70 respondents were interviewed using random sampling method. The study comprises three target groups viz. structured questionnaire survey of farmers growing tomatoes (50); structured questionnaire survey of traders involved in tomato business (10); and lastly farmers’ field survey to determine the extent of Tuta absoluta damage in leaves (10). The results revealed in the field Tuta absoluta is the most devastating insect pest and has done the highest 72% losses in the farmer field which is the heavy loss for the farmers and as a result, production of tomato has decreased in 2016 as compared to 2015. However while all the respondents claimed to have faced pest problem only 20% of the respondents were aware about Tuta absoluta. The survey also showed that 70% of the respondents were using para-pheromone lure (TLM lure) while 10% were using para-pheromone lure + light trap, 60% were using botanicals and bio-pesticides like Neem, Bacillus Thuriengensis in alternative ways and 20% were using chemicals like Chlorantraniliprole 18.5% SC (Alcora), Botanical pesticides (Dadaguard), Emamectin benzoate (EMAR 5% WDC), Cyromazine 10% SC (King hunter), Flubendiamide 39.35% SC (FAME 480 SC) without considering their environmental and health risks. All recommended Tuta absoluta control strategies such as pheromone trapping for monitoring as well as suppression, chemical and biological control were not available or known by growers. Trader’s survey showed on an average of 11.7 percent of fruits damage in market where as in farmers field survey revealed an average of 3 percent loss in net house and 10.3 percent loss in open field.

Integrated Management of South American Tomato Leaf Miner [Tuta Absoluta (Meyrick)]: A Review

Tuta absoluta (Meyrick) is one of the newly introduced insect pest of tomato in Nepal, which was first detected by Entomology Division, Nepal Agricultural Research Council from a commercial tomato grower of Balaju, Kathmandu on 16th May 2016. The pest occurs all-round the year within the temperature range of 20-27° C, and therefore, the environment of mid hills and plains of Nepal is suitable for sustaining the pest except during the winter season. T. absoluta pest mainly attacks Solanaceous crops, especially evident in tomato, however, it is also found in non-solanaceous crops. Larva of the pest is devastating causing damage in fruit, leaves and stem, and reducing tomato production by 80-100% in open field as well as in plastic house, if no control measures are carried out. Chemicals, like Spinosad, Chlorantraniliprole and Novaluron are recommended in Nepal for controlling this pest, but studies have revealed the inefficacy of chemical control measures due to wide host range, faster reproducing ability and development of pesticide resistance. Therefore, Integrated Pest Management (IPM) with mass trapping of the pest using pheromone trap, biological control by predator, parasitoid, entomopathogenic microbes, including cultural practices are imperative for the effective control of this pest.

Geographical Distribution of South American Tomato Leaf Miner Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) in Nepal

South American tomato leaf miner, Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) is an invasive insect pest of tomato (Lycopersicon esculentum Miller) both in field and controlled environment conditions. T. absoluta is native to South America, it was detected first time in Nepal from Kathmandu during May, 2016. Survey was conducted at 46 locations of 31 districts in terai and mid hills of Nepal during February to June 2018. T. absoluta was detected from 45 locations of 30 districts surveyed. T. absoluta which was detected from Kathmandu, Lalitpur, Bhaktapur, Kavre and Dhading districts in 2016 has now been spread into 33 districts across the Nepal. Apart from 33 districts T. absoluta might be present in other districts which were not surveyed during the study. Farmers generally manage T. absoluta through indiscriminate use of chemical pesticides. So, extensive research is needed in future to develop integrated pest management technique which is suitable and sustainable for its management in Nepalese context.

Monitoring South American Tomato Leaf Miner, Tuta absoluta (Meyrick) and Assessment of Management Practices Adopted in Kavre, Nepal

The study was carried out from April-August, 2017 to monitor the population of Tuta absoluta and to assess the management practices being adopted in Kavre, Nepal. Study consisted of two major parts: monitoring of insect population and farmer’s survey. The population of T. absoluta ranged from 51 to 972 in each Wota -T trap. The highest population of the insect in traps were recorded in Dhulikhel followed by Panauti and Banepa. Majority of tomato growers (78%) reported T. absoluta as the most problematic among other pests, diseases and disorders. The data from E-Plant clinic at Panchkhal revealed the degree of severity of T. absoluta in tomato crop. Tomato growers have adopted cultural, physical, mechanical, para-pheromone lures, quarantine, botanical and chemical methods for the management of this pest. Majority of them relied on chemical pesticide (94%) followed by cultural practices (86%) and Tomato Leaf Miner (TLM) lure (66%) based on cumulative percentage of respondents. Use of TLM lure was found as the best in terms of its effectiveness, safety, and practicability. Thus, Integrated Pest Management strategies are essential to limit the significant loss and reduce dependency on chemical pesticides in future.

Effectiveness of Different Types of Traps For Management of Tuta absoluta in Nepal

Among the various potential vegetables, tomato is one of the high value crops, with growing market demand and higher level of return per hector. South American Tomato leaf miner, Tuta absoluta is one of the main constrains in tomato production in Nepal. Field experiments were conducted from June to October 2017 to determine the attractive action of trap colours against T. absoluta management in Lele VDC, Lalitpur, Nepal. Experiments were setup using different types of traps (Delta trap, Wota-T trap and solar light trap) each with pheromone capsule i.e. TLM lure. Particularly, in this experiment the influence of color (orange, white, yellow and green) in delta trap, height adjustment from ground level - 1 feet, 2 feet, 3 feet and 4 feet) in Wota-T trap and; locally prepared light traps of led bulb, solar light trap with high power of 65 lumens and solar light trap with low power of 25 lumens to capture Tuta moth were tested. For the evaluation of effectiveness of different types of traps, number of Tuta moths captured were recorded. The results demonstrated that T. absoluta moths can distinguish between the colours. White colored delta trap captured maximum mean number of Tuta moth (22) followed by green (16), yellow (13) and orange (10). Similarly, Wota- T trap when placed at different height, trap placed at ground level captured maximum mean number of Tuta moths (15) followed by One ft (12), Two ft(11), Three ft(8) and Four ft(2). Among the different types of light trap solar light trap with high power of 65 lumens captured maximum mean number of Tuta moth’s (5) followed by solar light trap with low power of 25 lumens (3) and locally prepared light trap with led bulb (2). Significant differences between mean moth catches by different colored delta traps, wota-T trap placed at different height and different types of light traps were observed. Based on the study conducted with in a season it were found that trap color, trap height and light trap types are the characteristics that strongly affect the response of T. absoluta moths to pheromone-baited traps. From the study it is clear that, these traps can be used as one of the best sex pheromone based management strategy for the management of T. absoluta moths. Further research is recommended for better understanding of the effect of trap colour on the diversity and abundance of non target insects captured

Occurrence, biology, natural enemies and management of Tuta absoluta in Africa

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a devastating invasive pest of tomato crops in several areas around the world including Africa. Here, we comprehensively review and discuss the relevant scientific knowledge on its occurrence, biological and ecological aspects, fortuitous insect natural enemies, and potential advantages and constraints of pest management scenarios adopted against this pest in tomato crops in both Northern and Sub-Saharan Africa. We conclude the manuscript with a comprehensive research agenda providing future priorities towards sustainable control of this important tomato pest.

Tuta absoluta continues to disperse in Asia: damage, ongoing management and future challenges

Since its initial detection in Turkey in 2009, the invasive destructive pest South American tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has started its new invasion journey to east and invaded most Asian countries. This pest currently causes extensive damage to tomato production and potentially threatens key production areas such as China. To provide an overview of current status of T. absoluta in Asia, we have briefly reviewed the damage and economic impacts by this pest locally and discussed why this species has spread so rapidly among the countries. Moreover, ongoing integrated pest management options are summarized in newly invaded areas with an emphasis of discussing the potential control failures by chemical insecticides. Future research efforts on developing promising management technologies are recommended. Finally, we suggest building a cross-regional network to enhance the sustainable control of this pest.