Article

Contribution to the study of the biology and ecology of the leaf-miner Liriomyza trifolii and its control by neem

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Abstract

The serpentine leaf-miner Liriomyza trifolii is a new proliferous and polyphagous agricultural pest in Mauritius, attacking crops, ornamentals and weeds. Urgent chemical control measures had to be developed in order to save total crop loss, in particular potato, tomato, haricot beans, crucifers and onions. This insect is resistant to most insecticides. In view of formulating an integrated management programme, this paper reports on some aspects of practical importance concerning the biology and ecology of the leaf-miner, the incidence of damage, and the possibility of its control by natural plant products such as extracts of neem (Azadirachta indica). Steam distillates of neem leaves seriously affect larvae and pupae upon treatment by contact at as low a dose as 0.3% of the extract. Field treatments of onion plantations with aqueous neem extracts (0.5%) gave good protection to the crop. The current control measures are briefly considered.

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... A leaf miner preference that belonged to the genus Liriomyza for the different varieties of plants back to the presence of Trichomes, which its distribution and density varies among the leaves and are important factors in the election of the host by adults (Fagoonee andToory, 1984, Knodel et al., 1985). Many researchers have *Author for correspondence : E-mail: zeinahtaha1991@yahoo.com indicated that Trichomes produce secondary metabolic compounds, including glycoalkolodis, Phenols and Flavonoids compounds, which are a defensive compound against many insects (Goffreda et al., 1990, Elliger et al., 1981. ...
Research Proposal
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A field study was carried out on eggplant (Solanum melongena L.) and Squash (Cucurbita pepo L.) crops under the conditions of the plastic house in the Plant Protection Department / College of Agricultural Engineering Sciences / University of Baghdad, to determine which is the most preference from the leaf miner Liriomyza spp. As well as its relation with the secondary compounds existing in the plant that's well-known for its importance in the defense system of the plant. The results showed a significant difference in the leaf miner Liriomyza spp. preference to infection over eggplant (S. melongena L.) and Squash (C. pepo L.), Squash was the most preference from the insect and the general average of insect population density on Squash throughout the growing season was 39.2 individual / 10 leaves compared with eggplant which was 7.83 individual / 10 leaves. The study results also showed a variation in the leaves content of eggplant and Squash of secondary compounds (Phenols, Flavonoids, Tannins and Alkaloids) and their different concentrations when the infestation with the insect, as it is increase when it increases and decrease when it decreases with as a defensive means. Finally, the study findings showed the presence of Tannins was in very small quantities below the level of sensitivity over the Squash leaves, which is not preferred by insects and it is one of the compounds that known as their toxic effect to insects, while eggplant resistance to the insect was attributed to its high content of Phenols, Tannins, total Alkaloids and Flavonoids compared to Squash.
... In addition, it must be noted that there is another possibility to explain the highest parasitism for small larvae. The larval feeding rate, i.e., the rate of mine development, increases as the occupant larvae grow [51], which may decrease the probability of being attacked per unit length of mine. If this could be the case, the parasitism level would be lowered for large larvae. ...
Article
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Because insect herbivores generally suffer from high mortality due to their natural enemies, reducing the risk of being located by natural enemies is of critical importance for them, forcing them to develop a variety of defensive measures. Larvae of leaf-mining insects lead a sedentary life inside a leaf and make conspicuous feeding tracks called mines, exposing themselves to the potential risk of parasitism. We investigated the defense strategy of the linear leafminer Ophiomyia maura Meigen (Diptera: Agromyzidae), by focusing on its mining patterns. We examined whether the leafminer could reduce the risk of being parasitized (1) by making cross structures in the inner area of a leaf to deter parasitoids from tracking the mines due to complex pathways, and (2) by mining along the edge of a leaf to hinder visually searching parasitoids from finding mined leaves due to effective background matching of the mined leaves among intact leaves. We quantified fractal dimension as mine complexity and area of mine in the inner area of the leaf as interior mine density for each sample mine, and analyzed whether these mine traits affected the susceptibility of O. maura to parasitism. Our results have shown that an increase in mine complexity with the development of occupying larvae decreases the probability of being parasitized, while interior mine density has no influence on parasitism. These results suggest that the larval development increases the host defense ability through increasing mine complexity. Thus the feeding pattern of these sessile insects has a defensive function by reducing the risk of parasitism.
... Female L. trifolii deposit eggs in host leaf tissues; the larvae tunnel within the leaf and feed on the leaf mesophyll. Since mine width increases with larval growth (Fagoonee & Toory 1984; see alsoFig. 1a), the width of a particular mine section indicates which larval instar (firstethird) has made it (Ayabe & Ueno 2004). ...
Article
The complex pattern of mines made by leafminers is postulated to hinder the host-searching behaviour of parasitoids, and if this is true, parasitoids should have evolved strategies of searching mines in a way that will achieve the highest efficiency. We investigated the possible deterrent effect of mine pattern complexity on a parasitoid searching for a host within a patch, and the searching behaviour used by the parasitoid to shorten search time. For this, we used the leafminer Liriomyza trifolii (Diptera: Agromyzidae) and its generalist parasitoid Hemiptarsenus varicornis (Hymenoptera: Eulophidae). Observations of the parasitoids showed that searching time increased on mines with complex patterns and crosses. We also found that the parasitoids used a specific searching strategy: they made multiple trackings to find the host and each tracking was terminated with a constant mine-leaving rate per unit time irrespective of mine complexity. With an individual-based model, we also found that while search time to host encounter increased with mine complexity, the optimal mine-leaving rate that attained the most efficient search did not vary with mine complexity, indicating that making multiple trackings with an optimal constant rate was advantageous in terms of search time for any search on a mine over a range of levels of complexity. Furthermore, the mine-leaving rate estimated from the behavioural observations was consistent with the optimal rate obtained in the simulations. Multiple-tracking behaviour by H. varicornis is the best way for foraging for hosts whose feeding pattern varies from simple to more tortuous.
... Present observation is also partly supported by Fagoonee . [6] who have observed that the extent of infestation, in each season, peaks at the mid-season. However the infestation was found to be confined to the lower half of the individual plant. ...
... Before laying eggs, females check the suitability of leaves for offspring development van Lenteren 1986, Parrella 1987). Immediately after hatching, the larva begins mining the leaf mesophyll layer until it completes feeding and emerges from the leaf (Fagoonee and Toory 1984). Larval development time is inversely related to temperature (Leibee 1984, Parrella 1987, Lanzoni et al., 2002. ...
Conference Paper
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Liriomyza trifolii is one of the most serious insect pests of vegetable crop in Florida. Adult female punctures the leaf with the help of ovipositor and feeds on plant sap. Female lays eggs in these punctures. An adult female can lay 35-39 eggs per day, a total of 200-400 in lifetime. Immediately after hatching, larva starts mining the leaf and feeds on mesophyll layer of the leaf until the larva emerges from the leaf. L. trifolii infests host crops at the beginning of germination until harvest. In the four crops, squash (Cucurbita pepo), cucumber (Cucumis sativus), Tomato (Solanum lycopersicum) and cabbage (Brassica oleracea), in the early stage of germination, population abundance was commonly low and the distribution pattern of adults and feeding mines were regular as compared with snap bean (Phaseolus vulgaris). In general, the abundance of L. trifolii was higher in bean (P. vulgaris) than in squash (C. pepo) than in cucumber (C. sativus) than in tomato (S. lycopersicum) and was the lowest in cabbage (B. oleracea). This information of the present research studies carries great value in developing a pest management decision. Based on this information growers will be able to develop a site selective insecticide management program.
... Eggs are deposited into the leaf puncture and develop inside the leaves. The mining activity of larvae causes damage to the mesophyll layer of the leaf and the feeding rate increases rapidly as the larvae develop (Fagoonee & Toory 1984). The mature larvae exit the leafmine and drop to the ground to pupate in the soil. ...
Article
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Seasonal population densities of Liriomyza trifolii (Burgess) and its parasitoid Opius dissitus (Muesebeck) were studied at 3 snap bean (Phaseolus vulgaris) sites in south Florida from 2010 to 2011. L. trifolii population density presented a seasonal preference, and was significantly abundant during Dec 2010 (17.9 ± 1.5 adults per 5 leaves) and Jan 2011 (30.3 ± 2.7 adults per 5 leaves) when the temperature was relatively low (∼ 3 °C). Its parasitoid, O. dissitus showed a pattern of population density similar to L. trifolii, and was abundant during December 2010 (4.5 ± 0.45 adults per 5 leaves) and January 2011 (5.4 ± 0.73 adults per 5 leaves). A direct density dependent relationship was found between O. dissitus parasitism and L. trifolii. Spatial distribution patterns of L. trifolii and O. dissitus were evaluated at these 3 bean sites. Both L. trifolii and O. dissitus showed an aggregated (clumped) distribution pattern when their densities were high during Dec 2010 to Jan 2011, but a regular (uniform) distribution pattern when their densities were low during Sep 2010 and Feb 2011.
... It was noted earlier that the life history stages of both D. begini and L. trifolii were aged on a daily basis; however, the number of susceptible larvae of L. trifolii changes continuously as they are found and attacked. For this reason, the attack equations are solved for every 30-min period during a lO-h daily activity cycle (see Oatman & Michelbacher 1958, Parrella et al. 1983, Fagoonee & Toory 1984, and Parrella 1984 regarding Liriomyza activity cycles). The model has 19 parameters built directly into it, some of which have multiple age-dependent forms, and the values used in the simulations are given in Table 1. ...
Article
Implementation of augmentative biological control is often hindered by the inability to obtain accurate information on natural enemy release rates that will ultimately yield a salable crop within economic constraints. The purpose of this study was to develop and evaluate a computer model that attempts to predict augmentative releases of the parasitoid Diglyphus begini (Ashmead) (Hymenoptera: Eulophidae) to use for biological control against the serpentine leafminer Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) infesting greenhouse-grown cut chrysanthemums. The model attempts to determine the appropriate release rate necessary to reduce leafminer densities below 1 larvae per 1,000 chrysanthemum leaves within 40 d after planting, after which time aesthetically important foliage forms on chrysanthemums. In the construction of this deterministic model, three simplifying assumptions have been made: (1) there is no insect movement between the greenhouse and outside, (2) greenhouse temperatures are a constant 27°C, and (3) the greenhouse represents a homogeneous environment. Model simulations indicated that successful biological control was unlikely when parasitoid releases are initiated later than 14 d after planting regardless of the release rate. The simulations also demonstrated that D. begini release rates are not linearly related to L. trifolii densities, and that a parasitoid release strategy is not simply the determination of a proper wasp/leafminer ratio. Validation studies of the model's predictions provided mixed results. Following the release rates generated by the model, L. trifolii larval densities were not significantly greater than I per 1,000 leaves 40 d after planting. However, the model did not always track the succession and magnitude of leafminer population fluctuations with statistical accuracy. Two factors probably contributed to these errors in prediction: (1) the assumptions inherent to the model were not met during the validation trials, and (2) the leafminer subroutine of the model could not accurately predict L. trifolii densities in the absence of D. begini. In spite of these errors, leafminer damage to the harvested foliage was significantly lower in the treatments receiving D. begini releases than in the control treatments. In addition, when the model was tested in a commercial cut chrysanthemum greenhouse, L. trifolii was successfully controlled by releases of D. begini, resulting in the production and harvest of a salable cut chrysanthemum crop without the use of any pesticides. Finally, postvalidation reconstruction of the model, to include temperature-dependent variation in life history parameters, increased the predictive power of the model.
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We examined the feeding pattern of the monophagous leaf miner Agromyza phraginitidis Hendel (Diptera: Agromyzidae) on Phragmites australis (Poaceae). The females of A. phragmitidis deposit their eggs in a clutch, mostly in the proximal part of the leaf, under the epidermis between 2 adjacent veins. When the larvae emerge, they immediately start feeding toward the leaf tip, and each larva forms an individual mine between 2 veins. The larvae are selective feeders; they feed mainly on the nutrient rich mesophyll between the veins. Tissues of low nutritional value (e.g., vascular tissues, sclerenchyma strands, and the epidermal tissues) are avoided. After the 1st instar, however, the larvae become too large to fit between the veins and are forced to cross them. Therefore, they consume the vasculate or a small part of it, depending on the sclerification of the vein type. We conclude that vein sclerification and arrangement are the most important factors influencing the feeding pattern and the resulting mine shape of the larvae of A. phragmitidis. This study strongly suggests that vein sclerification and arrangement, especially in grass leaves, may act as an effective barrier against herbivores or may reduce feeding rates, or both.
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Avaliou-se o efeito de extratos aquosos de folhas e de ramos da planta inseticida Trichilia pallida sobre o desenvolvimento e oviposição da traça-do-tomateiro, Tuta absoluta. Acompanhou-se o desenvolvimento do inseto em folhas de tomateiro (Lycopersicon esculentum, cv. Santa Clara) previamente submersas nos extratos nas concentrações de 0,1; 1,0 e 5,0%. Também foi avaliado o efeito dos extratos de folhas a 1,0 e 5,0%, pulverizados sobre ovos do inseto, e a não-preferência para oviposição, com chance de escolha, em folhas de tomateiro com e sem esse extrato a 5%. Verificou-se que os extratos de folhas e de ramos prejudicam o desenvolvimento do inseto afetando principalmente a fase larval, aumentando a duração e reduzindo a viabilidade deste período. O extrato de folhas apresenta maior atividade que o de ramos, reduzindo a viabilidade larval a valores próximos a 20%, já na concentração de 1%. O extrato de folhas a 5% não apresenta efeito ovicida mas, o substrato tratado pode tornar-se menos preferido para oviposição.
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Field trials were conducted for three years (1997-1999) to study the effectiveness of different neem formulations against the major insect pests complex and on yield of okra (Hibiscus esculentus), tomato (Lycopersicon escculentum), and onion (Allium cepa). Neem kernel powder was applied into the soil (NKPS), sprayed as water extract on the target plants (ANKE) or applied as water extract into the soil (ANKES). The registered German formulated neem seed extract ( NeemAzal), includes Azadirachtin as main active principle, and, the Japanese trade product (Sumicidin) were also used for comparison. The experiments were conducted in the Shambat area of Khartoum in the Sudan. ANKE showed significant increase on yield of okra during the two seasons 1997 (162%), 1998 (52%), tomato 1998 (74%). An increase by 28% of Okra 1999 was also obtained (nicht significant). Against the insect pests of okra, the product reduced the number of cotton aphids Aphis gossypii, white fly Bemisia tabaci (Genn.), the number of plants infested by the larvae of the spotted boll worm Earias vittella and the number of leaves damaged by the adults of the flea beetle Podagrica puncticollis significantly. A reduction by 35% of the number of aphids on okra grown in the year 1999 was also recorded. Against the insect pest complex of tomato, ANKE reduced the number of the leaves damaged by the larvae of the leaf miner Liriomyza trifolii significantly, while it reduced the number of aphids by 40%, and the number of white fly by 33% under the control. The product increased the weight of onion grown in the year 1999 by 15% over the control. A reduction by 21% and 26% of the number of cotton thrips T. tabaci on onion grown on the year 1998 and 1999 respectively, was also recorded. NeemAzal increased the yield of okra grown in the years 1997, 1998, and 1999 significantly. It succeeded also in the significant reduction of number of aphids on okra grown in the year 1998 and 1999, the number of plants infested with the larvae of spotted boll worm and the number of leaves damaged by the adults of flea beetle. It reduced the number of white fly not significantly by 58%. On tomato, NeemAzal increased the yield by 38% over the control (nich significant). It reduced the number of the leaves damaged by the larvae of the leaf miner and white fly significantly, while it reduced the number of aphids only by 10% under the control. On onion, NeemAzal showed similar results as that of ANKE. NKPS increased the yield of okra grown in the year 1997 by 32% and the yield of tomato by 46%. On okra grown in the year 1998, it reduced the number of white flies and leaves damaged by the adults of flea beetle significantly, while it reduced the number of aphids only by 19%. On tomato, it reduced the number of white fly by 13% as compared with the control. ANKES reduced the number of white fly on okra grown in the year 1998 significantly. The results of NKPS and ANKES indicate a systemic movement of neem compounds from the root to the leaves. Sumicidin gave almost the same results as ANKE and NeemAzal in significant reduction of the number of tomato leaves damaged by the larvae of the leaf miner. Against white fly on tomato, Sumicidin showed the same results as NeemAzal in significant reduction of the number by 60%, but better as ANKE, which showed non-significant reduction by 40%. Against aphids on tomato, Sumicidin gave significant reduction of the number by 60%, while the reduction by ANKE and NeemAzal was not significant by 40% and 10% respectively. Although Sumicidin showed generally better results as the three-neem products (NeemAzal, ANKE and NKPS) against the target insect pest of tomato, all neem products gave yield higher than it did. On onion plants, Sumicidin showed better, but not significant effects on the weight and against cotton thrips than NeemAzal and ANKE. The results are summarized in Table 14, 15, and 16. A strong positive effect on the growth rate, vigor, plant height and number of leaves of okra and tomato plants treated with ANKE and NeemAzal were observed.
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Parasitoids have developed a variety of searching strategies to maximize their searching efficiency. To increase the efficiency, leafminer parasitoids first search for host mines, which are linear and visually conspicuous, and then search for host larvae situated at the end of the mines by tracking the mines. We hypothesized that the leafminer parasitoids have the ability of directional orientation toward larvae as opposed to orienting randomly and tested this hypothesis by using the leafminer Liriomyza trifolii (Burgess) (Diptera; Agromyzidae) and its parasitoid Hemiptarsenus varicornis (Girault) (Hymenoptera: Eulophidae). Direct observations of parasitoid behavior revealed that female parasitoids mostly selected the correct direction immediately after mine encounter. However, they did not select correctly when the host had been parasitized, or when the point of the mine encounter was far from the host larva, suggesting the possibility of sound-based search. Curiously, the success of encounter rates was not influenced by the directions that the female had selected. This was because the female turned to the correct direction during her search even after selecting the wrong direction. Thus, female H. varicornis can recognize which end of the mine the target larva lays upon mine encounter or during the foraging bout. The importance of the ability of recognizing the correct direction by the parasitoid and the possible mechanism involved in this ability is discussed.
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Applied as a soil drench to chrysanthemums, 0.4% crude neem extract caused significant mortality of late instars and pupae of Liriomyza trifolii (Burgess)in both research and commercial greenhouses. Insecticidal effects of drenching lasted for 3 weeks. Drenching did not inhibit female feeding or oviposition. Repeated drenching did not significantly inhibit plant growth. Mortality (89%) of prepupae reared from untreated plants occurred when the prepupae were placed on neem-drenched soil.
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Chapter
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The development periods and areas of the leaf mines by larvae Liriomyza trifolii (Burgess) were studied in the experimental greenhouse. The mean development periods of the mines was 3.4 days (58.9 DD), and the mean area of individual mines was 0.6 cm2. Incidence of the foliar leaf mines was examined three times in the commercial tomato greenhouse. The mine numbers in each tomato leaflet varied from 1 to 9, but the leaflets with 2 mines were the most frequent case. The area of individual mine remained relatively constant regardless of the increase of mine numbers per leaflet (0.37-0.41 cm2). There was a significant relationship between the total mine number and total leaf area mined (r2=0.72). Counting the total mines provides the baseline information for the decision making and assessing yield loss in the tomato greenhouses.
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بهدف مسح صانعات الأنفاقمن عائلة Agromyzidaeعلى بعض نباتات الزينةوالخضا والأعشاب.جمعتنباتات مختلفةمصابةبصانعات الأنفاق وسجل عدد الحشاات الناتجة وشخصت حسب المفاتيح التصنيفية.أكدت نتائج الدااسة تسجيل نوعين من الحشاات المنبثقةمنالأنفاق هي :ChromatomyiahorticolaGoureauوLiriomyza sativaBlanchard.انحصاتالإصابةللنباتات خلال فصل الابيع فيبداية آذاا/مااسوالنصف الأول من نيسان/أبايل.أثبتت الدااسة أن الوجود النسبيللنوع Chromatomyiahorticolaبلغ 100%على نباتات السناايا.)ppsCineraria(وحلق السبع/فمالسمكة).LAntirrhinum majus(وأم الحليب/اللبينة).sppEuphorbia (.والخباز).ppsMalva(.فيحينبلغالوجود النسبيللنوع Liriomyza sativa100%على نباتات الخياا.)LsativusCucumis(والحندقوق.sppMelilotus.إختلفت نسبة بزوغ الحشاات البالغة للنوعينباختلاف العائلات النباتية حيثكانت أعلى نسبة بزوغ للنوع Chromatomyiahorticolaعلى نباتات السنااياوأم الحليب وبلغت56.6و 48.3%،على التوالي،وكانت أقلها على نباتات حلق السبع والخبازحيث بلغت 20%،أما النوع Liriomyza sativaفقد بلغت نسبة بزوغ الحشاات البالغة 75%على نبات الخياا و15%على نبات الحندقوق
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The leafminer, Liriomyza trifolii Burgess, a polyphagous agricultural pest, can attack crops at different stages of development; some are attacked at the beginning of the crop cycle and others at the end of the cycle. Experiments on the differential susceptibility of the bean Phaseolus vulgaris and the potato Solanum tuberosum plants were done to get some information about factors which influence host selection by the leafminer. The distribution and density of leaf trichomes, as well as the nutritional status of the host plants, were found to be important in host selection. High trichome density acts as a physical deterrent to Liriomyza flies, just as senescing primary bean leaves induce non-acceptability. When given a choice, flies prefer bean to potato leaf discs, though the latter possess less trichomes. Other factors (chemical attractants and some nutrient components) might therefore also be involved in the complex host selection behaviour of L. trifolii.
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A field experiment conducted at Regional Agricultural Research Station, Lam, Guntur during 1998-99 crop season for evaluating different insecticides against serpentine leaf miner, Liriomyza trifolii (Burgess) on tomato revealed that plant products NSKE 5 per cent and Neemazal 0.5% were effective against the leaf miner among the insecticides tested and produced significantly higher yields. Further, laboratory trials against prepupae and pupae of the leaf miner also confirmed the above results.
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