Movement of Anastrepha fraterculus from native breeding sites into apple orchards in Southern Brazil

We report movements exhibited by adults of Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) from patches of native forests into apple orchards in Southern Brazil. Two mark-release-recapture experiments were conducted using wild flies. Released flies behaved as wild unmarked flies, and periods of peak captures of marked adults coincided with those of unmarked ones. In the first experiment (December 94), out of 2154 released adults, 7.1% were recaptured from day 2 through day 20 after release. Captures peaked from day 7–9 after release. Most marked flies (94.7%) were trapped within 200 m of the release point but eight adults (seven females and one male) were captured in traps placed in an apple orchard, 400–800 m from the release point. The vegetation found between forest and orchard consisted of pastures and annual crops. In the second experiment (January 95), a total of 3284 flies was released in an area where native host plants were abundant and located at ca. 900 m from an apple orchard. In all, 37.1% of marked flies were captured, 99.0% of them at a distance of less than 200 m from the release point. Four adults were captured in an apple orchard, 7 to 24 days after release. They may have reached the orchard through a large and continuous area of native forest. Our results unequivocally demonstrate that A. fraterculus adults are able to disperse from native forests where they originate and invade apple orchards, probably foraging for food and oviposition sites.     

Feeding behaviour of Bactrocera cacuminata (Hering) (Diptera: Tephritidae) on methyl eugenol: a laboratory assay

Abstract Many dacine (Diptera: Tephritidae) species are attracted to one of two chemical substances, 4-allyl-1,2-dimethoxybenzene (methyl eugenol (ME)) or 4-( p -hydroxyphenyl)-2-butanone (cue lure). Despite the fact that these chemicals or analogs occur naturally, their significance in the biology/ecology of the Dacinae has seldom been examined. In this study, we examine the patterns in feeding behaviour of Bactrocera cacuminata (Hering), a monophagous non-pest fruit fly, on ME. Based on a laboratory assay, we found that males of this species fed on ME multiple times within a single day and on multiple days. The pattern of repeat feeding was not related to time since previous feeding or duration of prior feeding. Our results contrast those obtained on a similar study on a related polyphagous species ( Bactrocera dorsalis (Hendel)). We discuss the implications of our findings with a view to explaining the functional significance of dacine response to these plant-derived chemicals.     

Pollination and breeding system of Eritrichium nanum (Boraginaceae)

 Flower development, pollination and breeding system of the high alpine cushion plant, Eritrichium nanum (Boraginaceae), were investigated in nine populations from the European Alps at altitudes of 2700 m–3200 m. Peak flowering period lasts longer than a month, from mid-June to the end of July. In contrast to statements in the literature that flowers are protogynous and nutlets remain in their calyx until spring we found a distinct protandry and nutlets being dispersed before mid-September. Various insects from 12 families, but mostly Diptera, frequently visited E. nanum flowers, with flies from the families Anthomyiidae and Muscidae being the predominant visitors. Under optimal conditions (max. solar radiation, min. wind force), visitation rates of 200 simultaneously observed flowers reached 32.5–46.7 insects per hour, i.e. 0.16–0.24 insects per flower per hour. However, the commonly observed Anthomyiidae and Muscidae clearly preferred the white-yellowish flowers of Saxifraga exarata and Saxifraga bryoides which are abundant at E. nanum sites and which are certainly also pollinated by species of these two fly families. The flowers of these Saxifraga species offer plenty of nectar and may compete for pollinators with E. nanum, when they are flowering in its proximity. However, various other insects like Pontia callidice and Psodos sp. (Lepidoptera) as well as Andrena sp. (Hymenoptera) and especially Eristalis tenax and closely related hoverflies showed a higher degree of flower constancy to E. nanum, often flying from a blue Eritrichium cushion to the next and hence causing outcrossing. The five fornices of E. nanum flowers which obstruct the tube containing stamens and nectar, are a feature which differs distinctly from the syndrome of fly-pollinated flowers with easily accessible nectar. Consequently pollination by flies in E. nanum seems to be caused mainly by the unfavorable ecological conditions at high altitudes, where flies are the most frequent insects. Bagging experiments showed that outcrossing and geitonogamy are the prevailing pollination modes, and autogamy, although possible, plays only a minor role. Received February 13, 2001 Accepted November 23, 2001     

Host-marking behaviour as a quantitative signal of competition in the walnut fly Rhagoletis juglandis

Abstract.  1. Walnut-infesting flies in the Rhagoletis suavis species group actively re-use hosts for oviposition despite engaging in a genus-typical host-marking behaviour which, in other Rhagoletis groups, deters oviposition. In a study of the walnut fly, R. juglandis (Cresson), alternative hypotheses for the putative marking behaviour were evaluated.
2. The oviposition site attraction hypothesis proposes that the host mark guides females to oviposition sites on occupied fruit. The competition intensity signal hypothesis proposes that the host mark is an indicator of the level of competition to be incurred if fruit are re-used.
3. In a field cage, females were presented simultaneously with fruit previously exposed to 25 females that were also allowed to oviposit and engage in the putative marking behaviour, and control fruit on which females were allowed only to oviposit. The occurrence of host marking reduced a female's propensity to oviposit from 46% to just over 10%, consistent with the competition intensity signal hypothesis only.
4. In a laboratory assay, the duration of host marking was correlated positively with the size of a female's clutch. This result, also consistent with the competition intensity signal hypothesis, suggests that the amount of marking pheromone on a fruit is a reliable indicator of the number of eggs already deposited within.
5. In a second field-cage experiment, females were allowed to mark on fruit for 0, 10, 20, or 30 min and fruit were presented to test females. Whether or not females alighted on a particular host was not affected by the duration of marking; however, the frequency of both ovipositor probing and egg deposition decreased with increasing duration of marking. Consistent with the competition intensity signal hypothesis, this result suggests that the host mark permits females to assess the level of competition that a clutch will incur within re-used fruit.     

Molecular identification of two species of myiasis-causing Cuterebra by multiplex PCR and RFLP

The myiasis-causing flies Cuterebra grisea (Coquillet) and Cuterebra fontinella (Clark) (Diptera: Oestridae) are normally parasites of mice, predominantly of the genus Peromyscus. The morphological similarities of these species and the existence of intermediate morphotypes bearing characters of both species make the identification of adults problematic; furthermore the identification of larvae is apparently not possible. This study presents two molecular approaches to discriminate between these species using specific band patterns: (i) species-specific primers designed in the cytochrome oxidase II (COII) region used in multiplex polymerase chain reaction (PCR) and (ii) restriction fragment length polymorphism (RFLP) on amplified segments of cytochrome oxidase I (COI) gene. Both methods were tested on Cuterebra larvae and on adult museum specimens. The two techniques showed a clear difference between C. grisea and C. fontinella, although species-specific primers were more successful than RFLP for degraded DNA. No intraspecific variation in RFLP and species-specific amplifications were detected for the two species of Cuterebra. The results exhibit discrepancies between molecular and morphological identification, suggesting that some of the adults were misidentified.     

Multiple symbiotes in larval black flies (Diptera: Simuliidae): associations of trichomycete fungi with ichthyosporeans, mermithid nematodes, and microsporidia

Studies of the interactions between two or more species of symbiotic microorganisms in a single host animal have lagged behind those involving interactions between hymenopteran or dipteran parasitoids. We screened the larvae of four species of black flies (Cnephia ornithophilia, Simulium furculatum, Simulium innoxium, and Simulium vandalicum) to determine if the colonization and prevalence of trichomycete fungi were influenced by ichthyosporeans, mermithid nematodes, microsporidia, or other species of trichomycetes. Differences in the layering of the peritrophic matrix of microsporidian-infected larvae, compared with that of uninfected larvae, were associated with greater levels of colonization by the midgut-inhabiting trichomycete Harpella melusinae. Colonization levels of different species of trichomycetes were significantly correlated with one another in only 2 of 11 cases. Aside from the consistent attachment of the trichomycete Simuliomyces microsporus to the ichthyosporean Paramoebidium chattoni, we found little evidence that prevalence and colonization levels of trichomycetes were influenced by other symbiotes, including other trichomycetes. This trend might reflect the physical separation of trichomycetes, which are gut specific, from other symbiotes. In addition, any combinations of symbiotes that were wholly incompatible would not have been observed in our field-collected material.     

North American face flies Old World origins: mitochondrial evidence

Analysis of a 513 base sequence of mitochondrial cytochrome oxidase I gene in Musca autumnalis De Geer (Diptera: Muscidae) from the U.S.A., England, Russia and Kazakhstan confirms that North American flies originated in Western Europe. Flies from the U.S.A., England and southern Russia shared most of their mitochondrial diversities, but face flies from Kazakhstan were substantially dissimilar, suggesting highly restricted gene flow and a species complex within the Palearctic.     

Human and other faeces as breeding media of the trachoma vector Musca sorbens

The fly Musca sorbens Wiedemann (Diptera: Muscidae) apparently transmits Chlamydia trachomatis, causing human trachoma. The literature indicates that M. sorbens breeds predominantly in isolated human faeces on the soil surface, but not in covered pit latrines. We sought to identify breeding media of M. sorbens in a rural Gambian village endemic for trachoma. Test breeding media were presented for oviposition on soil-filled buckets and monitored for adult emergence. Musca sorbens emerged from human (6/9 trials), calf (3/9), cow (3/9), dog (2/9) and goat (1/9) faeces, but not from horse faeces, composting kitchen scraps or a soil control (0/9 of each). After adjusting for mass of medium, the greatest number of flies emerged from human faeces (1426 flies/kg). Median time for emergence was 9 (inter quartile range = 8-9.75) days post-oviposition. Of all flies emerging from faeces 81% were M. sorbens. Male and female flies emerging from human faeces were significantly larger than those from other media, suggesting that they would be more fecund and live longer than smaller flies from other sources. Female flies caught from children's eyes were of a similar size to those from human faeces, but significantly larger than those from other media. We consider that human faeces are the best larval medium for M. sorbens, although some breeding also occurs in animal faeces. Removal of human faeces from the environment, through the provision of basic sanitation, is likely to greatly reduce fly density, eye contact and hence trachoma transmission, but if faeces of other animals are present M. sorbens will persist.     

欧洲杨、榛子、短叶松和黑云杉气体交换的日变化（英文）

对欧洲杨（Ｐｏｐｕｌｕｓ ｔｒｅｍｌｏｉｄｅｓ Ｍｉｃｈｘ．）和榛子（Ｃｏｒｙｌｕｓ ｃｏｒｎｕｔａ Ｍａｒｓｈ．）的叶片,短叶松（Ｐｉｎｕｉｓ ｂａｎｋｓｉａｎａ Ｌａｍｂ．）和黑云杉（Ｐｉｃｅａ ｍａｒｉａｎａ（Ｍｉｌｌ）ＢＳＰ）树枝气体交换日变化的特性进行了试验研究,以便于了解在北部气候条件下叶对环境变化的适应机理。气体交换采用便携式气体交换系统定时从旱晨到下午进行测定。在阳光充足的晴天,欧     

Do Gravid Black Flies (Diptera: Simuliidae) Oviposit at Their Natal Site?

We present information on an aniline dye marking method for black flies. In the laboratory, adults were sprayed with 2% aqueous solutions of four colors of aniline dyes; brilliant blue and methyl orange gave the best results in longevity trials. In field trials we were able to recapture 1.3% of newly emerged marked and released flies at oviposition sites. Mark–release–recapture experiments were designed to distinguish among three competing models concerning oviposition site selection by gravid female black flies: (1) larval site fidelity (“Do flies return to the site that they experienced as larvae?”), (2) adult site fidelity (“Do flies return to the site that they experienced as adults?”), and (3) no site fidelity (“Do flies oviposit at random, i.e., without regard to adult or larval experience?”). Models 1 and 2 were rejected. There is, however, no reason to reject Model 3, the no site fidelity model. Thus, we conclude that for members of the S. venustum/verecundum complex (i.e., S. rostratum, S. venustum, and S. truncatum) females find an “apparently suitable” waterway in which to oviposit; this may or may not be their natal site.