Abundance Of Leafminer Research Articles

Physical barriers and corridors in urban habitats affect colonisation and parasitism rates of a specialist leaf miner

1. Urban environments are fragmented habitats characterised by the presence of physical barriers, which may negatively affect dispersal and colonisation by insect herbivores and their natural enemies. Conversely, plants growing along pavements may function as dispersal corridors, helping to moderate the harmful effects of resource patch isolation on organism movement and population persistence. 2. We experimentally tested the effects of walls as physical barriers to the dispersal of the leaf miner Liriomyza commelinae Frost and colonisation of its host plant, Commelina erecta L., in urban habitats. We also evaluated whether plants along pavements could act as corridors for this species. 3. We exposed experimental host plants to the leaf miner in houses with front gardens and back yards, the latter being completely surrounded by walls. The front gardens had walls but none separating them from the pavement. Previously mined plants were also exposed to parasitoids in the yards to determine parasitoid attack. 4. Liriomyza commelinae took longer to colonise back yards with higher walls, and the abundance of mined plants along pavements reduced the colonisation time. Leaf-miner abundance was marginally affected by the yard type, and was lower in back yards. Cumulative parasitism rates decreased with increasing distance at which mined plants were placed from pavements. 5. Constructions act as physical barriers, having a negative impact on colonisation of host plants by leaf miners. The function of pavements as corridors seems to depend on the abundance of mined plants. Parasitism may be affected by distance from the corridor rather than physical barriers or other potential hosts.

Abundance of Citrus Leafminer Larvae on Citrus and Citrus-related Germplasm

The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is a key pest in most citrus-growing regions worldwide. Adult citrus leafminers oviposit primarily on young elongating flush of Citrus as well as other Rutaceae and some ornamental plants. Larvae feed on the epidermal cell layer of developing leaves and injury to leaves provides a pathway for infection by the bacterium Xanthomonas citri subsp. citri (Hasse), the causal agent of Asiatic citrus canker. In this study, we quantified abundance of citrus leafminer larvae on progeny of 87 seed parent genotypes of Citrus and Citrus relatives (family Rutaceae) in the field in East–central Florida to identify those that have low abundance of leafminers. Progeny from the 87 parent genotypes varied in abundance of the leafminer. Progeny of 15 parent genotypes had a high mean abundance of more than six leafminers per flush shoot. All but one of these genotypes were in the Citrus genus. Progeny of 16 parent genotypes had zero, or nearly zero, leafminers, but none were from the Citrus genus. However, many of these 16 genotypes were from genera closely related to true citrus (subtribe Citrinae) and are sexually compatible with Citrus. Progeny of two parent genotypes in the subfamily Toddalioideae and Glycosmis pentaphylla (Retz.) Corr. also had a low abundance of leafminer. Glycosmis pentaphylla also is a poor host for the Asian citrus psyllid, Diaphorina citri Kuwayama, and has biochemical resistance to the citrus weevil, Diaprepes abbreviatus (L.), so this genotype as well as others identified as poor hosts for the leafminer may prove useful in breeding programs aimed at reducing the abundance of multiple insect pests on citrus.

Effects of urbanisation on the parasitoid community of a leafminer

Urbanisation may have detrimental effects on communities of parasitoids, affecting their species richness, abundance, and species dominance. Here we investigated the influence of the degree of urbanisation on parasitoid communities of Liriomyza commelinae (Frost) (Diptera: Agromyzidae), a leafminer of Commelina erecta L. (Commelinaceae), in the city of Córdoba, Argentina. To study changes in species richness, the specific composition of parasitic complexes and their degree of impact on the leafminer, 18 sampling sites from the centre to the outskirts of the city were selected and different variables indicative of urbanisation were quantified in each site. During January and February of 2005 and 2006, all mined leaves found in each plant patch were collected and the following variables were estimated: proportion of mined patches, abundance of the leafminer, total parasitoid species richness, total parasitism rates and parasitism due to the most abundant parasitoid species. The percentage of mined patches and leafminer abundance increased with urbanisation degree. Estimates of parasitoid species richness were not influenced by urbanisation degree but increased with species richness of mined plants. Changes in the specific composition of species along the urbanisation gradient were observed. Although parasitism by one of the species studied was higher in more urbanised sites of the city, the total parasitism rate of L. commelinae was not affected by urbanisation degree, species richness of mined plants or leafminer abundance. It appears that urbanisation benefits the herbivore species here studied but not through altering parasitoid activity. Changes in parasitoid community composition reflex dissimilar tolerance to environmental conditions displayed by different parasitoid species.

STUDI LALAT PENGOROK DAUN LIRIOMYZA SPP. PADA PERTANAMAN BAWANG DAUN, DAN PARASITOID OPIUS CHROMATOMYIAE BELOKOBYLSKIJ & WHARTON (HYMENOPTERA: BRACONIDAE)

Studies on Leafminer Liriomyza spp. in Green Onion Fields, and Parasitoid Opius chromatomyiae Belokobylskij & Wharton (Hymenoptera: Braconidae). Field studies were conducted to determine population abundance of leafminers and their parasitoids in green onion fields in Puncak, West Java. In addition to that, laboratory studies were carried out to determine demographic parameter of Opius chromatomyiae as well as response of parasitoid to increasing host density. Results revealed that green onions were infested by two species of leafminers, Liriomyza huidobrensis and Liriomyza chinensis. Leafminer flies emerged from Erwor leaves (54.5) were significantly higher than those of RP leaves (18.65) (P = 0.0005). However, number of leafminer flies caught on sticky traps was not statistically different (P = 0.297). Two species of parasitoid, Hemiptarsenus varicornis and O. chromatomyiae, were associated with leafminers in green onion fields. Higher number of parasitoids emerged from Erwor leaves (13.68) as compared to RP (6.90) (P =0.0007 ). However, level of parasitization were 24.36% on Erwor and 28.45% on RP, and was not significantly different (P = 0.387). Laboratory studies indicated that net reproduction (Ro) of O. chromatomyiae was 28.55, generation time (T) 15.96 days, intrinsic growth rate 0.21, and total of reproductive value 223.64. The stable age distribution of parasitoid were 37.93% eggs, 24.92% larvae, 20.36% pupae and 16.78% adults. The parasitoid showed functional response type II to increasing host density, with a = 0.08 and Th = 2.58.

No simple sum: seasonal variation in tannin phenotypes and leaf-miners in hybrid oaks

Parent-hybrid asymmetries in the biosynthesis of defense chemistry are believed to affect the distribution of herbivorous insects within plant hybrid zones. While tannins are often produced as complex, dynamic mixtures, the ecological effects of biological and ontogenetic variation in tannin metabolism within hybrid zones are poorly understood. Here, we examine correlations between the seasonal variation of absolute and relative concentrations of individual ellagitannins and total proanthocyanidins in the Quercus gambelii × Q. grisea hybrid complex and a community of leaf-mining Lepidoptera (Gracillariidae, Heliozelidae, Nepticulidae, Tischeriidae), and examine the interactive effects between tannins on leaf-miner abundance. We found strong seasonal variation in oak tannin phenotypes, but two general phenotypes are characteristic of oaks of the Q. gambelii × Q. grisea complex, based upon biosynthetic variation in high molecular weight ellagitannins. Leaf-miner community structure was significantly correlated with the dominant tannin phenotypes in the Q. gambelii × Q. grisea hybrid zone in mid-summer (July, August). Additionally, leaf-miner density was significantly negatively correlated with the ratio of vescalagin-derivatives and total proanthocyanidins in August and September. Overall, hybridization affects biological and ontogenetic variation in ellagitannin and proanthocyanidin biosynthesis within the Q. gambelii × Q. grisea hybrid complex and this variation correlates with herbivore distribution and abundance. Future studies of phenolic chemistry in plant-herbivore interactions in hybrid zones should include a more rigorous quantification of tannin phenotypes as complex, temporally dynamic mixtures.

Abundance of leafminers and leaf area loss by chewing herbivores in hybrids between Quercus crispula and Quercus dentata

We examined responses of phytophagous insects to hybrids between Quercus crispula Blume and Quercus dentata Thunberg in a natural population in northern Japan. The abundance of leafminers and leaf area loss by chewing insects in hybrids were intermediate between those in the parental species (additive mode), close to those of either of the parental species (dominance mode), or similar to those of both parental species (no difference). Hybrids were neither more susceptible nor resistant to the insect herbivores we monitored. In Phyllonorycter (Gracillariidae) species, which are specialized to either of the parental oak species, the mortality of sap-feeding early instar larvae did not differ between hybrids and the parental species. The abundance of four leafminer taxa was correlated with environmental conditions (i.e., distance from the coastal edge of the forest or the timing of budbreak) as well as genetic factors.

RESISTANCE AND SUSCEPTIBILITY OF MILKWEED: COMPETITION, ROOT HERBIVORY, AND PLANT GENETIC VARIATION

Beetles in the genus Tetraopes share a long evolutionary history with milkweeds (Asclepias spp.), feeding on roots as larvae and leaves as adults. Despite their extreme specialization on milkweed, Tetraopes require drying grass stems as oviposition sites, even though they do not consume grass. The natural history of the interaction suggests that herbivory may be likely only when milkweeds are in close proximity to grasses. Theory also predicts that two stresses on plants, competition and herbivory, may have non-additive negative impacts on correlates of fitness. In field experiments conducted over two years, I followed the consequences of grass competition and beetle attack for herbivory, growth, and reproduction of milkweed, and reciprocal effects of milkweed on grass in common gardens. To assess the effect of milkweed traits on beetles, I conducted a quantitative genetic experiment using full-sibling families of milkweed and measured the effects of putative resistance traits on the abundance of Tetraopes adults. Milkweeds growing next to grass were initially unaffected in growth but suffered 10% greater leaf herbivory by adult Tetraopes than did milkweeds growing alone. This effect was caused by direct attraction of beetles to grass, not by a competitive modification of milkweed's phenotype. In late summer of the first growing season, when Tetraopes naturally oviposits, I experimentally added larvae to milkweed roots with and without grass competition. Within a month, I detected an interaction between competition and herbivory: neither had an individual impact, but jointly they reduced milkweed growth. In spring of the second growing season, when Tetraopes had completed development, I again found strong evidence for a non-additive effect of competition and herbivory together, severely reducing plant growth compared to their individual effects. Root herbivory induced a plant response that reduced the abundance of leaf-mining flies by 40%, but only for milkweeds with grass competition. Neither competition nor herbivory affected the production of defensive latex, cardenolides, or carbon, but they interacted to affect leaf nitrogen content. Thus, although trait-mediated indirect interactions were implicated in the effect of competition and root herbivory on leaf miner abundance, I did not uncover the mechanism. In the final harvest, beetle herbivory reduced reproductive characters (fruit production, fruit mass, aboveground biomass) by 20– 30%, whereas competition had negligible effects. The net interaction effect for grass was competitive, with a 23% reduction in grass biomass caused by milkweed in the absence of herbivory. However, the presence of beetle herbivory on milkweed roots completely alleviated the competitive effect of milkweed on grass. Thus, the associational effect of grass on milkweed resulted in milkweed suffering the non-additive effects of competition and herbivory, whereas grass enjoyed competitive release by facilitating its neighbor's herbivore. Many traits of milkweed (e.g., growth, reproduction, and several resistance traits) showed variation among 23 full-sibling families, indicating that competitive ability and resistance may be subject to natural selection. A multiple regression analysis on family means revealed that leaf trichome density and nitrogen content were negatively genetically correlated with abundance of Tetraopes adults, but probability of flowering and plant height were positively associated. Leaf miners were most strongly negatively affected by latex and trichomes. Thus, complex interactions among competition, root herbivory, and plant genetic variation affect the herbivore and plant community and may result in diffuse coevolution between milkweed and its herbivores. I present a general model that predicts the conditions in which plant–plant interactions result in net competition or facilitation.

カシワ・ミズナラ・種間雑種での潜葉性昆虫相と外食性被食率の比較

カシワ・ミズナラ・種間雑種での潜葉性昆虫相と外食性被食率の比較

PARASITISME HEMIPTARSENUS VARICORNIS (GIRAULT) (HYMENOPTERA: EULOPHIDAE) TERHADAP LALAT PENGOROK DAUN LIRIOMYZA HUIDOBRENSIS (BLANCHARD) (DIPTERA: AGROMYZIDAE) PADA TANAMAN KACANG ENDUL (PHASEOLUS VULGARIS L.) DI CILOTO, JAWA BARAT

Parasitism of Hemiptarsenus varicornis (Girault) (Hymenoptera: Eulophidae) on leafminer fly Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) on kacang endul (Phaseolus vulgaris L.) in Ciloto, West Java. The objective of this research was to elucidate the relationship between leafminer and its parasitoid abundants. The research was conducted in Ciloto (Cianjur), West Java in 1999. The miner infested leaves of kacang endul were collected and placed in plastic bowls. The emerged parasitoids from those leaves were counted. The result indicated that the level of parasitism of H. varicornis during the plant growth stage ranged from 39 to 50%. The perfect density dependent between percentage parasitism and the leafminer abundance was experimentally proved.

Community dynamics of leafminers (Diptera: Agromyzidae) and their parasitoids (Hymenoptera) in a natural habitat from Central Argentina

We examined the temporal community dynamics of leafminers (Agromyzidae: Diptera) and their mainly polyphagous parasitoids in a natural habitat from Central Argentina. Changes in community composition are shown by changes in dominant species and similarity coefficients. Abundance of leafminers was highest in winter, and was not related to their species richness. Abundance and species richness were correlated in the parasitoid community. Temporal variation in parasitoid diversity and abundance were positively correlated with species number and density in the host community. Apparent parasitism was greater when parasitoid species richness was high and parasitoid community dominance was low.

Decreased Leaf-Miner Abundance in Elevated CO 2 : Reduced Leaf Quality and Increased Parasitoid Attack

Decreased Leaf-Miner Abundance in Elevated CO 2 : Reduced Leaf Quality and Increased Parasitoid Attack

Leaf-Mining Insects and Fluctuating Asymmetry in Elm Ulmus glabra Leaves

Fluctuating asymmetry, which represents small, random deviations from bilateral symmetry, arises as a result of an inability to control development under genetically and environmentally stressful conditions. Herbivory is also particularly common in plants growing under stressful conditions. It was hypothesized that herbivory would be particularly prevalent in plants with leaves demonstrating high degrees of fluctuating asymmetry. This prediction was tested for the leaf-mining insect, Rhynchaenus rufus, which commonly attacks elm Ulmus glabra. Leaves with mines were significantly more asymmetrical in the width of their two halves and the distance between side-ribs, than the nearest neighbouring leaf without a mine. Elm trees with a high incidence of leaf mines had significantly more asymmetric leaves than the nearest neighbouring elm tree with a low incidence of leaf mines. This was the case regardless of whether affected or unaffected leaves were compared. The incidence of leaf mines across trees was positively related to the degree of leaf asymmetry of the tree. Developmental stability of leaves, as measured by fluctuating asymmetry, was therefore associated with susceptibility to one kind of herbivory in elm trees. Leaves of elm trees watered with a large amount of fertilizer were more asymmetric than leaves of trees just provided with water, suggesting that one kind of stress increased the level of leaf asymmetry. The relationship between foliar asymmetry and herbivory appeared to be causal since increased asymmetry caused by the fertilizer treatment gave rise to an increased abundance of leaf miners.

Abundance and mortality of a specialist leafminer in response to experimental shading and fertilization of American holly.

Phytomyza ilicicola (Diptera: Agromyzidae), a univoltine specialist leafminer, typically reaches higher population densities on cultivated host planted in sunny, urban sites than it does on native trees in the forest understory. I tested the hypothesis that environmental factors, more specifically differences in light intensity and soil fertility, are responsible for this observed pattern, either by affecting leaf morphology or nutritional quality, or indirectly through early leaf abscission. Clonal trees were planted at a common site and experimentally shaded and fertilized for 14 months before being exposed to oviposition by adult flies. Differences in leaf thickness, nitrogen and water status, and in the abundance, developmental rate, survival, pupal weights and abscission-related mortality of leafminers were compared among trees. Leaves from experimentally shaded trees were larger and thinner, with only two palisade cell layers as compared to three to four layers in leaves from unshaded trees. Crystals, probably of calcium oxalate, are abundant in the abaxial cell layer, and it was hypothesized that these might set mechanical constraints on larvae feeding within shaded leaves. However, there was little or no difference in leafminer abundance, developmental rate, survival to pupation, area of finished mines, or pupal weight between shaded and unshaded trees. Leafminers compensated for feeding within thinner, shaded leaves by consuming portions of the abaxial and adaxial palisade layers and leaving a thinner roof on the mine. Furthermore, there was no difference in thickness between leaves with successful or aborted mines in either shade or sun. Leaves from fertilized trees contained 37% higher total nitrogen than those from unfertilized control trees. Fertilization did not significantly affect leafminer abundance, developmental rate, mine area or pupal weight, but survival to pupation was slightly lower on fertilized trees. Abscission-related mortality of P. ilicicola was much higher in full sun than for shaded trees, opposite of what would be predicted if early abscission per se were a primary determinant of relative abundance between habitats. These results indicate that structural constraints on leafminer larvae within shaded leaves, differences in leaf nitrogen related to soil fertility, and/or differential mortality resulting from early leaf abscission are probably not the proximate causes of density variation of this leafminer between woods and urban habitats.

The Absolute Abundance of Leaf Miners on Plants of Different Successional Stages

On confirme la theorie selon laquelle on observe une forte abondance typique des phytophages en rapport avec les premiers stades de succession vegetale par comparaison avec les stades ulterieurs de la succession et, pour la meme espece vegetale, une plus forte abondance sur les plantules par rapport aux plantes matures

Leafminers on Oak: The Role of Immigration and In Situ Reproductive Recruitment

The roles of overwintering reproductive recruitment and intertree immigration are examined for leaf—mining insects on oak trees. Full—exclusion caged trees that exclude immigrants, litter exclusion caged trees that exclude overwintering recruits, and control trees were sampled to determine leafminer abundance and species richness. Full—caged trees had little overwintering recruitment, and populations went extinct during the season's first generation. Litter exclusion trees recruited as many species as did control trees, but had lower leafminer densities. However, further experiments indicate that the lowered densities were a caging artifact. This result suggest that most leafminer populations on oak trees are maintained by yearly reimmigration from safe overwintering sites and not from in situ reproductive recruitment. Therefore, the distribution and abundance of leafminers on oak should not be viewed as the turnover of reproductive populations on individual trees, but rather as the immigration and failed colonization of species whose movements encompass several trees.

Border Effects of Serpentine Leaf Miner Abundance in Potato Fields

Border Effects of Serpentine Leaf Miner Abundance in Potato Fields