Primer design for identifying economically important Liriomyza species (Diptera: Agromyzidae) by multiplex PCR

Leafminer flies, especially, Liriomyza huidobrensis, Liriomyza sativae and Liriomyza trifolii, are quarantine species in many countries. Their morphological similarity makes identification difficult. To develop a rapid, reliable, sensitive and simple molecular identification method using multiplex PCR, we newly sequenced the mitochondrial cytochrome oxidase I (COI) genes of Liriomyza bryoniae, Liriomyza chinensis, L. huidobrensis, L. sativae, L. trifolii, Chromatomyia horticola and four parasitoid species. We aligned them with all the COI sequences of the leafminer flies found in the international DNA nucleotide sequence databases (DDBJ/EMBL/GenBank). We then designed species‐specific primers to allow us to differentiate between L. bryoniae, L. chinensis, L. huidobrensis, L. sativae, and L. trifolii.     

Molecular evidence of cryptic species within the Liriomyza huidobrensis (Diptera: Agromyzidae)

Phylogenetic relationships among populations of the polyphagous pea leafminer, Liriomyza huidobrensis (Blanchard), were investigated using DNA sequence data. Maximum parsimony analysis of 941 bp of mitochondrial cytochrome oxidase I and II genes showed that L. huidobrensis contains two well-defined monophyletic groups, one composed of specimens from California and Hawaii and one composed of specimens from South and Central America together with populations that have been recently introduced into other parts of the world. The differentiation between the two clades within L. huidobrensis is equivalent to that seen between other agromyzid species, suggesting that L. huidobrensis as currently defined contains two cryptic species. This finding is consistent with field observations of differences in pest status and insecticide resistance between L. huidobrensis populations. Until additional studies are complete, no changes in L. huidobrensis taxonomy are proposed. However, researchers and quarantine officials may wish to consider the findings of the current study in designing research, pest management, and quarantine programs for L. huidobrensis.     

Phytosanitary irradiation of Liriomyza trifolii (Diptera: Agromyzidae)

Agromyzid leafminers are economic and quarantine pests of a variety of vegetables, flowers, and ornamental foliage. Methyl bromide fumigation is often used as a phytosanitary treatment when quarantined agromyzids are found in shipped commodities; alternative treatments are sought. Ionizing radiation is a viable alternative that is increasing in use worldwide. A dose of 400 Gy is accepted by USDA-APHIS for all insects (except Lepidoptera pupae and adults) on all commodities. Efforts to lower this dose and make it acceptable to other countries involve determining radiotolerance of families of major quarantine pests. Agromyzidae is one such family for which no useful information on radiotolerance exists. This research sought to determine the dose required to control a major agromyzid pest, Liriomyza trifolii (Burgess) and was performed on L. trifolii collected in Weslaco, TX, reared on Phaseolus vulgaris L. and Capsicum annuum L. and irradiated in the late puparial stage. The measure of efficacy was prevention of F1 mine formation. Puparia collected from Gossypium hirsutum L. and reared on P. vulgaris were more radiotolerant than those collected and reared on C. annuum. A dose of 214 Gy may prevent F1 mine formation of L. trifolii. This research used a variation of probit analysis where the direct response of the treated individual is not measured, but the response of the F1 generation is. This type of analysis is useful in phytosanitary irradiation research where the measure of efficacy often involves a response of the F1 generation.     

Egg-collection equipment for Liriomyza leafminers (Diptera: Agromyzidae)

Egg-collection equipment for Liriomyza leafminers was designed using a small glass tube with a glucose solution supported between two thin films. Adult female Liriomyza trifolii (Burgess), which were previously reared on kidney bean for 2–4 days, laid abundant eggs in 5 or 10% glucose solutions. Hatchability of the eggs in the solutions was greater than 80%. The equipment was used successfully to collect eggs from another leafminer species, Liriomyza sativae Blanchard.     

Kairomone attractant for the leafmining fly, Liriomyza bryoniae (Diptera, Agromyzidae)

A field test carried out in an industrial greenhouse in Lithuania revealed the attractiveness of synthetic methyl salicylate (MeSa) towards an economically important leafmining tomato pest, Liriomyza bryoniae (Kaltenbach) (Diptera, Agromyzidae). The behavioural reaction of the flies depended very much on the simultaneous presence of both olfactory and visual stimuli. The attractiveness depended on the colour of a sticky trap: MeSa attracted significantly more flies (ca. 2.2 times) when placed in yellow traps than in aluminium foil colour ones, when catches in such traps were compared to a corresponding control. L. bryoniae is the first species within the Agromyzidae family attracted by MeSa. The attractant was attributed to kairomones, as the compound is known as a plant-produced volatile. MeSa can be an effective extra-tool for increasing the attractiveness of traps. It should be evaluated in future whether such trap/bait combination is effective for the mass trapping of L. bryoniae leafminers in greenhouses (closed area).     

The Turkish Agromyzidae (Diptera), with descriptions of four new species

A total of 117 agromyzid leafminers are known to occur in Turkey, among which Agromyza phylloposthia, Pseudonapomyza pyriformis, Liriomyza cardariae and Phytomyza geminata are described as new to science. A faunistic account of the Agromyzidae in Turkey is given.     

温度对美洲斑潜蝇及南美斑潜蝇种群增长的影响

在恒温条件下观察了美洲斑潜蝇和南美斑潜蝇实验种群的发育、存活及繁殖情况,拟合了两种斑潜蝇发育速率与温度之间的关系模型,求出了各发育阶段的发育起点温度及有效积温,组建了不同温度下两种斑潜蝇实验种群的生殖力表,计算了主要的生命表参数.结果表明,温度对两种斑潜蝇的发育、存活、繁殖均有显著的影响,且两种斑潜蝇对温度的适应特性有着明显差异.美洲斑潜蝇适应的温度范围较广,相对较高的温度有利于种群的发育、生存及繁殖;而南美斑潜蝇适应的温度范围相对较窄,且适温范围明显偏低,高温不利于种群的增长;在各自的适温条件下,两种斑潜蝇都有很强的种群增殖能力.     

福建省发现加藤斑潜蝇（双翅目：潜蝇科Diptera：Agromyzidae）

1995年在调查潜叶蝇种类时，在菊花上发现加藤斑潜蝇，属中国大陆首次报道，本文对其形态特征进行描述。     

Description and biology of two new species of Neotropical Liriomyza Mik (Diptera,Agromyzidae), mining leaves of Bocconia (Papaveraceae)

Liriomyza mystica Boucher & Nishida, sp. n., and Liriomyza prompta Boucher & Nishida, sp. n. are described from Costa Rica. Both species were reared from leaves of Bocconia frutescens L. (Papaveraceae). The latter species was also reared from B. arborea S. Watson. Larvae of L. mystica mine primary veins of large, relatively old, mature leaves, and L. prompta mine blades of small to large, mature leaves. These represent the first record of agromyzids feeding on Bocconia. Biological information is also given and illustrated.     

美洲斑潜蝇室内饲养研究

筛选了室内饲养美洲斑潜蝇的适宜寄主植物,进行了饲养密度及成虫补充营养糖的浓度试验。结果表明：初生菜豆PhaseolusvulgarisL.苗是室内饲养的适宜寄主植物,用该种植物饲养,幼虫饲养密度低于1头／cm2,则幼虫成活率大于90％,饲养密度提高,则幼虫成活率降低,每平方厘米初生叶饲养1头幼虫是适宜的饲养密度,成虫补充营养糖或蜜糖的浓度以8％为宜。     

Influence of Liriomyza species (Diptera: Agromyzidae) and their host plants, on oviposition by Opius dissitus females (Hymenoptera: Braconidae)

Two factors, among others, influence the oviposition of Opius dissitus Muesebeck. The first was the host species, the second the plant upon which the pest host larvae develop. O. dissitus females prefer Liriomyza trifolii (Burgess) larvae over those of L. huidobrensis (Blanchard). O. dissitus females were more attracted to the larvae of L. trifolii or L. huidobrensis when these were present on courgette rather than tomato or lettuce.     

Host plant-related parasitism and host feeding activities of Diglyphus isaea (Hymenoptera: Eulophidae) on Liriomyza huidobrensis, Liriomyza sativae, and Liriomyza trifolii (Diptera: Agromyzidae)

Host plant species can affect the behavior and attributes of parasitoids, such as host searching, oviposition, and offspring fitness. In this study, parasitism, host feeding, and sex ratios of Diglyphus isaea (Walker) (Hymenoptera: Eulophidae) on Liriomyza huidobrensis (Blanchard), Liriomyza sativae Blanchard, and Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) larvae reared on Phaseolus vulgaris L., Pisum sativum L., Solanum lycopersicum L., and Vicia faba L. were determined. In no-choice tests, L. huidobrensis had the highest rate of parasitism when reared on P. vulgaris (46%), L. sativae when reared on V. faba (59%) and P. vulgaris (59%), and L. trifolii when reared on S. lycopersicum (68%). Host feeding in no-choice tests ranged between 2% and 36% and was highest on L. trifolii reared on V. faba. Results of choice tests showed a significant interaction effect for host plant and Liriomyza species on parasitism and host feeding. Within plant mixtures, L. sativae reared on P. vulgaris had the highest rate of parasitism (31%), followed by L. trifolii on S. lycopersicum (29%) and L. huidobrensis on V. faba (28%). Host feeding was highest on L. trifolii reared on S. lycopersicum (14%) and lowest on L. huidobrensis reared on P. sativum and S. lycopersicum (1%). In some instances, plant mixtures resulted in a higher proportion of females of D. isaea than single plant species. The highest proportion of females was obtained in plant mixtures on L. huidobrensis and L. trifolii on V. faba (71 and 72%, respectively). This study suggests that planting crop mixtures can potentially lead to higher proportions of females, thus improving parasitism and host feeding, depending on Liriomyza and host plant species.     

Polyandry and Reproduction in the Serpentine Leaf Miner Liriomyza trifolii (Diptera: Agromyzidae)

We investigated the hypotheses that Liriomyza trifolii is a polyandrous species and that multiple mating is required to maximize female fecundity. In addition, the hypothesis that male copulating frequency reduces female fecundity was examined. Using sterile and fertile males, we found that L. trifolii females mate more than once during their life span, and that multiple mating is required to maximize female fecundity. A similar amount of sperm was transferred during five successive male copulations with an equal insemination probability. However, the probability of reproduction failure was strongly correlated with the male copulating sequence. Moreover, the failure rate of sperm transfer was found to be 6.8%. In light of these results, possible selection pressures driving for polyandry in L. trifolii are discussed.     

Analysis of acoustic stimulus to Liriomyza trifolii (Diptera: Agromyzidae) through Electroantennogram (EAG) technique

The study utilized the Electroantennogram (EAG) technique as biological acoustic stimulus to Liriomyza trifolii (Diptera: Agromyzidae). Pure tone sounds and courtship songs were tested in the excised head of test specimens. Significant EAG stimuli were detected when released at 20 Hz pure tone sound together with the courtship song having long pulse train patterns of Cryptonevra inquilina and Lipara japonica (Chloropidae). For their biological effectiveness, movement behaviors were analyzed with stimulus taken from EAG recordings. No attraction effect was observed even with and without acoustic stimulus. However, movement activities were transformed by information entropy and observed to be clearly different when selected acoustic stimuli were broadcast. The combination of response to EAG and behavioral observation would be useful to determine effective movement modification through acoustic stimulus in insect pests that are necessary toward the development of an acoustic pest management tool in agriculture.     

Feeding, oviposition and survival of Liriomyza trifolii (Diptera: Agromyzidae) on Bt and non-Bt cottons

The effects of Bt transgenic cottons (Bt-I expressing cry1Ac and Bt-II expressing cry1Ab and cry2Ab or cry1Ab and cry1Fa) and non-Bt cottons on feeding, oviposition and longevity of adults, and development and survival of Liriomyza trifolii larvae were studied under laboratory conditions; and infestation on four Bt and two non-Bt cotton traits were investigated under field conditions. Laboratory choice and no-choice tests showed that L. trifolii adults were capable of distinguishing between Bt cottons and non-Bt cottons. In a choice test on younger plants (4-5 leaves), the adults were found more often and made more feeding punctures (FP) on non-Bt cottons than on Bt cottons. On older plants (8-9 leaves), adults made the most FP on non-Bt cotton followed by those on Bt-II cottons and the least on Bt-I cotton. The females oviposited more eggs (6.7 eggs per leaf) on non-Bt cotton than on Bt-I (1.7 eggs per leaf) and Bt-II (0.8 eggs per leaf) cottons on younger plants and oviposited similar numbers of eggs (0.7-1.3 eggs per leaf) on non-Bt and Bt cottons on older plants. In a no-choice test, the females also fed more FP on non-Bt cottons than on Bt cottons on both younger and older plants. The females oviposited more eggs (15.6 eggs per leaf) on non-Bt cotton than on Bt-I (8.2 eggs per leaf) and Bt-II (6.5 eggs per leaf) cottons on younger plants and similar numbers of eggs (2.5-3.3 eggs per leaf) on non-Bt and Bt cottons on older plants. Larval and puparial survivals were not different among Bt and non-Bt cottons. The occurrence and damage of leafminers on cottons in the field showed that L. trifolii infested more plants and leaves and had more mines on non-Bt cotton than on Bt cottons.     

The movement and dispersal of Liriomyza trifolii (Diptera: Agromyzidae) in a chrysanthemum greenhouse

Investigation of the dispersal of Liriomyza trifolii in a 1–2 ha chrysanthemum greenhouse indicated that the average distance flown by female flies was greater than that flown by male flies. However, flies of both sexes were found at the furthest distance from the release point (102 m) which indicates that flies in the greenhouse could be considered to be a single inter-breeding population. When the data were fitted to a generalised distance-dispersal model, examination of the parameters revealed density decreased with distance more rapidly for males than females. Also, the model showed that males tended to be slightly more attracted to each other than were females. The applicability of these results to the development of pest management systems for L. trifolii is discussed.     

Role of plant volatiles in host plant location of the leafminer, Liriomyza sativae (Diptera: Agromyzidae)

Abstract The role of plant volatiles in host plant location of the leafminer Liriomyza sativae Blanchard was studied. Four types of antennal sensilla were identified on the funiculus by scanning electron microscopy: trichoid, basiconic, clavate and grooved sensilla. An olfactory pit, containing groups of sensilla, was present on the ventral side of the funiculus. No sexual difference was detected in sensilla diversity and distribution. In behavioural assays, both males and females were attracted by the odour of the bean Phaseolus vulgaris L. They had distinct EAG responses to the bean odour. No significant sexual difference was found in behaviour or EAG responses.
Electroantennograms were recorded from female L. sativae to 14 plant volatile compounds. The most distinct EAG responses were obtained for: (1) the general green leaf volatiles 1-hexanol (E)-2-hexen-1-ol, (E)-3-hexen-1-ol and its isomers, (Z)-3-hexen-1-ol, the acetate (E)-3-hexenylacetate and the aldehyde hexanal; and (2) limonene, a compound associated with tomato, which is a key host plant of this insect. Other volatile compounds associated with host plants, such as α-pinene, myrcene, β-caryophyllene, and eugenol did not elicit responses. The ability of this insect to locate a host plant appears to be augmented by the perception of a combination of host-specific and general green leaf volatiles. A modification of the EAG recording method of Dipteran species was provided.     

Parasitoid associated with Liriomyza huidobrensis (Diptera: Agromyzidae) outbreaks in tomato fields in Brazil

1. The knowledge of natural factors that affect pest populations is essential in predicting the occurrence of pest outbreaks and in developing integrated pest management programmes. Natural enemies, climatic elements and host plants are among the most important factors affecting pest dynamics.
2. Tomato (Solanum lycopersicum) is the second most consumed vegetable worldwide. The pea leaf miner Liriomyza huidobrensis (Diptera: Agromyzidae) is a major pest to the tomato in Brazil.
3. This study aimed to determine the main natural factors that regulate L. huidobrensis populations in tomato fields in Brazil.
4. Liriomyza huidobrensis densities were evaluated by directly counting the number of active mines on the basal leaf of the middle section of the plant canopy, and predators and parasitoids were assessed using the leaf‐beating‐against‐a‐tray technique. Eight commercial tomato fields were assessed over two years. The phenological growth stages of the tomato plants (vegetative and reproductive) were noted during the assessments.
5. Liriomyza huidobrensis populations peaked between the middle and end of the planting season.
6. Opius sp. (Hymenoptera: Braconidae) was the main natural enemy of L. huidobrensis.
7. Our results suggest that phenological growth stage and Opius sp. are associated with population dynamics of L. huidobrensis in tomato fields.
8. Therefore, integrated pest management programmes should aim to preserve populations of the parasitoid Opius sp.

     

Pea leafminer Liriomyza huidobrensis (Diptera: Agromyzidae) uses vibrational duets for efficient sexual communication

The pea leafminer (Liriomyza huidobrensis) is a notorious pest of vegetables and ornamental plants worldwide. Despite a large number of studies on its biology and ecology, the courtship behavior and sexual communication of this species remain unclear. Here, we studied vibrational communication in the sexual interaction of the pea leafminer. On host plant leaves, females and males behaviorally displayed the bobbing-quivering alternation, which finally led to copulation. Moreover, records of laser vibrometry revealed threesignal duets underlying the behavioral alternation. Sexually mature males spontaneously emitted calls (MCs) to initiate the duets. The females rapidly responded to MCs by emitting replies (FRs) that are longer in duration. The FRs further triggered male replies (MRs) in their search for potential partners. Leafminer-produced vibrational signals convey efficient information to partners and generate pair formation on stretched substrates, such as plant leaves and nylon mesh, but cannot elicit responses on dense substrates, such as glass and plastic. Vibrational playbacks of both MCs and FRs can elicit replies in females and males, respectively. This study completely characterizes substrate-borne vibrational duets in a dipteran insect. The discovery of vibrational sex signals in the pea leafminer provides new insights for the development of novel approaches to control the pest and its relative species.