Tomato Leafminer Tuta Absoluta Meyrick Research Articles

Investigating the effects of species niche shifts on the potential distribution of Tuta absoluta (Lepidoptera: Gelechiidae) by using global occurrence data.

Invasive species may occupy quite different environments in their invaded areas to native ones, which may intensively interfere with predicting potential distribution through ecological niche modeling (ENM). Here, we take the tomato leafminerTuta absoluta Meyrick (Lepidoptera: Gelechiidae), a tomato pest, as an example to investigate this topic. We analyzed niche expansion, stability, unfilling, and Schoener's D by principal component analysis (PCA)ordination method to examine its realized niche shifts and to explore how ENM approaches are affected by niche shifts. We used 5 datasets: Asian, African, European, South American, and global occurrence records in this study. Results showed that high niche unfilling for the species' invaded areas in Asia (20%), Africa (12%), and Europe (37%), possibly due to T. absoluta being in the early stages of invasion. High niche expansion was observed in Asia (38%) and Europe (19%), implying that some European and Asian populations had reached new climatic areas. African niche had the most niche stability (94%) and was equivalent to the native one in climate space (PCA ordination method), but the n-dimensional climate space framework showed that they were different. When projecting the native model to Asia and Europe, the native model performed poorly, implying that the niche shifts affected the transferability of the native model. ENM based on global data outperformed than other models, and our results suggested that T. absoluta has a large potential distribution in Asia, Mexico, South Europe, the United States, and Australia. Meanwhile, we recommend updating ENMs based on the species' invasion stage.

Efficacy of endophytic wild strains of entomopathogenic fungi against the tomato leafminer Tuta absoluta Meyrick) (Lepidoptera: Gelechiidae) in tomato plants

BackgroundTomato (Solanum lycopersicum L.) is a vegetable of great economic value. The tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a serious pest of tomato. Its control is difficult due to the protection of the larvae in the galleries they create its fast resistance development too many active ingredients and due to its many generations per year. Many entomopathogenic fungi (EPF) have been reported as endophytes for various plant pathogens and pests. In this study, the endophyticity of Beauveria bassiana Balsamo (Vuillemin) (Hypocreales: Cordycipitaceae) and Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) isolated from the soils of Crete against larvae of T. absoluta in tomato plants was examined.ResultsAs a result, the EPF isolates of Crete decreased both the distance of larval travel from the egg to the opening of the gallery and the weight of the T. absoluta larvae, but also colonized the tomato plants. The entomopathogenic fungi were isolated from tomatoes again. Mycelium began to appear 7 days later and had developed completely after 12 days at 25 ± 2 °C and in 95% RH. Interestingly, the period between the hatched egg and the emerged first instar T. absoluta larvae was affected significantly by the different treatments, but not by "repetition" or "plant". Interestingly, the distance was further significantly shortened after treatment with M. anisopliae isolate Crete and B. bassiana isolate Crete and the commercial strain. The development period of T. absoluta larvae varied significantly among the treatments, but not by repetition in time or plant. The treatments caused a significant variation in the weight of T. absoluta pupae. The lowest weight was recorded in the plants colonized by M. anisopliae isolate Crete.ConclusionsThe study demonstrated the ability of the B. bassiana and M. anisopliae from Crete to colonize the tomato plants and the wild strains of Crete affect the distance of larvae. With the presence of endophytic EPF, the period between the hatched egg and the emerged first instar T. absoluta larvae was decreased, as does the weight of the T. absoluta pupae.

Influence of Age, Host Plant and Mating Status in Pheromone Production and New Insights on Perception Plasticity in Tuta Absoluta.

The tomato leafminer Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is one of the most important pests of tomato worldwide. However, in spite of its tremendous economic importance, the success of environmentally friendly measures to control the pest is still limited. Study of physiological and behavioral parameters that affect pheromone production has provided useful information for pest management. Our results show no clear difference in pheromone production by females over the period from 2 h before to 2 h after the scotophase. However, pheromone production was clearly dependent on female age, with young females producing the highest amount of each pheromone component 10 days after emergence. In the presence of the host plant (physical contact and olfaction of the plant volatiles), virgin and mated females produced higher amounts of the major component of the pheromone (TDTA) than those in the absence of plant and those devoid of olfaction (antennectomized) but in physical contact with the plant. In electrophysiological experiments, TDTA elicited slightly lower responses on male antennae than the pheromone mixture. When stimulated at certain time intervals after the first exposure to TDTA, male antennae became more sensitive to the stimulus (sensitization effect). For the first time in an insect of the family Gelechiidae, we have found that females are able to detect their own pheromone (autodetection). Altogether, our results may represent a step forward in the knowledge of the chemical communication of this important pest.

Efficacy of Metarhizium anisopliae and Bacillus thuringiensis against tomato leafminer Tuta absoluta Meyrick (Lepidoptera: Gelechiidae)

Susceptibility of Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) populations to Metarhizium anisopliae and Bacillus thuringiensis (Bt) were evaluated under laboratory conditions. T. absoluta larvae were treated either individually or in combination with a single dose rate of B. thuringiensis (0.5 μL/L) and three conidial suspensions viz. 1x104, 1x106 and 1x108 spores/mL of M. anisopliae. Larval mortality, pupation, adult emergence, mycosis and sporulation varied depending on the application of different quantities of M. anisopliae alone and in combination with B. thuringiensis. Maximum mortality (100%) was achieved in 2nd instar larvae when M. anisopliae (1x108 spores/mL) and B. thuringiensis (0.5µL/L) were applied synergistically,while 4th instar larvae recorded a 95.45% mortality. Compared with the untreated checks, mortality, pupation and adult emergence of both 2nd and 4th instar larvae were significantly reduced with the combined application of M. anisopliae (1x108 spores/mL) and B. thuringiensis (0.5µL/L). Μycosis was most prevalent on 2nd and 4th instar larvae, exceeding 88 and 80% respectively,after exposure to 1×104 conidia/mL. The results indicate that the entomopathogenic fungi and the insecticidal protein produced by B. thuringiensis can be used in combination as biocontrol agents for the management of T. absoluta.

Arthropod pest complex and associated damage in field-grown tomato in Senegal

AbstractBiotic factors (including insect pests) constrain field-grown tomato production in Senegal. However, little information is available on the identity and life system of key pests. The objectives of this study were to: (i) update key pest records of field-grown tomato in the central vegetable-producing area along the northern coast of Senegal, known as the Niayes area; (ii) map their spatial and temporal incidence and (iii) understand insecticide use by growers to control the pests. A total of 98 tomato fields distributed in three zones along a north–south transect in the Niayes area were monitored over four crop cycles from 2012 to 2014. As expected, the tomato fruitworm Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) was the most destructive pest with an occurrence of 92% in sampled fields (90/98) and up to 38% damaged fruits in one field at the time of sampling. The proportion of damaged fruits did not differ among zones, but was significantly higher in the early dry season compared to the late dry season. The invasive tomato leafminer Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) was detected in 53% of sampled fields (52/98), mainly in the south of the Niayes area in the late dry season. Because of their ability to adapt to unstable environment and insecticides, this insect pest assemblage is a new challenge that farmers have to deal with while decreasing their use of broad-spectrum insecticides.

Propensity of Three Tunisian Populations of the Tomato LeafminerTuta absoluta(Lepidoptera: Gelechiidae) for Deuterotokous Parthenogenetic Reproduction

The tomato leafminer Tuta absoluta Meyrick 1917 (Lepidoptera: Gelechiidae) is a major pest of tomato Solanum lycopersicum Linnaeus 1753 (Solanales: Solanaceae) crops in Tunisia and the Western Palaearctic region. Current control programmes to manage this moth in greenhouses and open field tomato cultivations include, among others, pheromone-based strategies through male annihilation, mating disruption, and lure and kill technique. Despite recent advances in the efficiencies of pheromone lures and traps, low or moderate control has often been reported by researchers and growers. In 2012 the first known case of parthenogenesis in T. absoluta was reported in a French population of the pest. Although such reproduction mode was not proven to occur in nature, this discovery raised many concerns about the future of pheromones for the control of this moth, since their use is absolutely dependent on the assumption that the pest can only reproduce sexually. In this paper, we report the ability of three Tunisian populations of T. absoluta to reproduce asexually under laboratory conditions by assessing age-specific and total female fecundity, egg viability and adult longevity. Also, we discuss the possible implications for IPM programmes targeting this pest.