Larval nutritional-stress and tolerance to extreme temperatures in the peach fruit fly, Bactrocera zonata (Diptera: Tephritidae).

Within the factors affecting insect tolerance to extreme environmental conditions, insect nutrition, particularly of immature stages, has received insufficient attention. In the present study, we address this gap by investigating the effects of larval nutrition on heat and cold tolerance of adult Bactrocera zonata - an invasive, polyphagous fruit fly pest. We manipulated the nutritional content in the larval diet by varying the amount of added yeast (2-10% by weight), while maintaining a constant sucrose content. Adults derived from the different larval diets were tested for their tolerance to extreme heat and cold stress. Restricting the amount of yeast reduced the efficacy of the larval diet (i.e. number of pupae produced per g of diet) as well as pupal and adult fresh weight, both being significantly lower for yeast-poor diets. Additionally, yeast restriction during the larval stage (2% yeast diet) significantly reduced the amount of protein but not lipid reserves of newly emerged males and females. Adults maintained after emergence on granulated sugar and water for 10 days were significantly more tolerant to extreme heat (i.e. knock-down time at 42 oC) when reared as larvae on yeast-rich diets (8% and 10% yeast) compared to counterparts developing on a diet containing 2% yeast. Nevertheless, the composition of the larval diet did not significantly affect adult survival following acute cold stress (exposure to -3°C for 2 hrs.). These results are corroborated by previous findings on Drosophilid flies. Possible mechanisms leading to nutrition-based heat-tolerance in flies are discussed.

Old residents and new arrivals of Rhagoletis species in Europe.

The genus Rhagoletis (Diptera: Tephritidae) comprises more than 65 species distributed throughout Europe, Asia and America, including many species of high economic importance. Currently, there are three Rhagoletis species that infest fruits and nuts in Europe. The European cherry fruit fly, Rhagoletis cerasi (may have invaded Europe a long time ago from the Caucasian area of West Asia), and two invasive species (recently introduced from North America): the eastern American cherry fruit fly, R. cingulata, and the walnut husk fly, R. completa. The presence of different Rhagoletis species may enhance population dynamics and establish an unpredictable economic risk for several fruit and nut crops in Europe. Despite their excessive economic importance, little is known on population dynamics, genetics and symbiotic associations for making sound pest control decisions in terms of species-specific, environmental friendly pest control methods. To this end, the current paper (a) summarizes recently accumulated genetic and population data for the European Rhagoletis species and their association with the endosymbiont Wolbachia pipientis, and (b) explores the possibility of using the current knowledge for implementing the innovative biological control methods of sterile insect technique and incompatible insect technique.

Spatio-Temporal Distribution of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) and Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) in a Cotton Production Area.

Helicoverpa armigera (Hübner) and Pectinophora gossypiella (Saunders) are major pests of cotton in Greece and elsewhere. Analysing male captures in pheromone traps over two seasons, in two cotton producing sites in central Greece, the spatial and temporal variation in population dynamics were examined. In 2007, captures of male H. armigera increased in late July and maintained at high levels for 1 month and declined at the end of August. For P. gossypiella, male captures remained at low levels during summer, increased late in August, peaked at mid of September and declined toward the end of the season. In 2008, trap captures of both species increased sharply by the end of June and remained at relatively high levels until August and September for P. gossypiella and H. armigera, respectively. Spatial analysis produced a spatial trend map over space, a temporal stability map over time and a spatial and temporal trend map for both species, which could lead in separating the field into management zones, and direct control to areas that exhibit high densities of the pest population and are stable over time.

Diapause termination of Rhagoletis cerasi pupae is regulated by local adaptation and phenotypic plasticity: escape in time through bet-hedging strategies.

Persistence and thriving of univoltine, herbivore insect species of the temperate zone rely on obligate diapause response that ensures winter survival and synchronization with host phenology. We used a stenophagous fruit fly (Rhagoletis cerasi) with obligate pupae diapause to determine genetic and environmental effects on diapause intensity of geographically isolated populations with habitat heterogeneity. Pupae from two Greek and one German populations with various gene flow rates were exposed at five constant chilling temperatures (0-12 °C) for different durations and then incubated at a high temperature until all adults have emerged. Pupae diapause intensity differs among Greek and German populations, suggesting an adaptive response to habitat heterogeneity (mostly differences in phenology patterns of local host cultivars). Moderately warm winter temperatures, such as 8 °C, promote diapause termination in all three populations. Insufficient chilling (short duration or warmer temperatures) regulates the expression of prolonged dormancy. Interestingly, extended chilling (longer than required for terminating diapause) 'return' pupae to another (facultative) cycle of dormancy enabling adults to emerge during the next appropriate 'window of time'; a strategy first time reported for univoltine insects. Consequently, diapause duration of R. cerasi is determined both by i) the adaptive response to local climatic conditions (annual dormancy) and ii) the plastic responses to interannual climatic variability resulting in two types of long life cycles within populations, prolonged and facultative dormancy as response to insufficient chilling and extended exposure to chilling, respectively. Long life cycles are expressed as a part of dormancy bet-hedging strategies of R. cerasi populations.

Management of protein intake in the fruit fly Anastrepha fraterculus.

This work tested if carbohydrates and proteins ingestion is regulated in the South American fruit fly, Anastrepha fraterculus, to optimize survival and reproduction. Adult food treatments were established by providing sugar and hydrolyzed yeast in various combinations either alone or mixed at a standard 3:1 ratio (sugar:hydrolyzed yeast). Individual food consumption was assessed and related to survival patterns. The effects of adult feeding on fecundity and fertility patterns were investigated in groups of flies. Sugar consumption was the lowest in the treatment where it was provided with hydrolyzed yeast at a fixed 3:1 ratio. Consumption of hydrolyzed yeast did not differ between this treatment and the one in which this solution was complemented with one solution of sugar. It seems that a mixture of sugar and hydrolyzed yeast at a fixed ratio of 3:1, respectively, restricts extra ingestion of sugar; most probably because of negative response of the fly to overconsumption of protein. Survival was affected by the treatments, being lower in those cases where protein was at the fixed ratio. Group experiments revealed that protein restriction expanded longevity and decreased egg production. In contrast, egg production was enhanced when flies were kept continuously with a mixture of yeast and sugar plus an extra source of sugar, and this was not in detriment of survival. Our results suggest that fixed sugar-protein ratios in which protein is in excess affects fitness components such as longevity and reproduction. These findings are discussed from a theoretical and applied perspective in the context of pest control by means of the sterile insect technique.

Cytogenetic analysis of the Ethiopian fruit fly Dacus ciliatus (Diptera: Tephritidae).

The Ethiopian fruit fly, Dacus ciliatus, is an important pest of cucurbits, which recently invaded the Middle East. The genetics and cytogenetics of D. ciliatus have been scarcely studied. Such information is, however, an essential basis for understanding the biology of insect pests, as well as for the design of modern control strategies. We report here the mitotic karyotype and detailed photographic maps of the salivary gland polytene chromosomes of this species. The mitotic metaphase complement consists of six pairs of chromosomes, including one pair of heteromorphic sex (XX/XY) chromosomes. The heterogametic sex is ascribed to the male. The analysis of the salivary gland polytene complement shows a total number of five long chromosomes (10 polytene arms), which correspond to the five autosomes of the mitotic nuclei, and a heterochromatic mass corresponding to the sex chromosomes. Banding patterns, as well as the most characteristic features and prominent landmarks of each polytene chromosome are presented and discussed. Chromosomal homologies between D. ciliatus and Bactrocera oleae are proposed by comparing chromosome banding patterns and by in situ hybridization of the hsp70 gene.

Cross-amplified microsatellites in the European cherry fly, Rhagoletis cerasi: medium polymorphic-highly informative markers.

The European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is a major pest of cherries in Europe and parts of Asia. Despite its big economic significance, there is a lack of studies on the genetic structure of its natural populations. Knowledge about an insect pest on molecular, genetic and population levels facilitates the development of environmentally friendly control methods. In this study, we present the development of 13 microsatellite markers for R. cerasi, through cross-species amplification. These markers have been used for the genotyping of 130 individuals from five different sampling sites in Greece. Our results indicate that (i) cross-species amplification is a versatile and rapid tool for developing microsatellite markers in Rhagoletis spp., (ii) the microsatellite markers presented here constitute an important tool for population studies on this pest, and (iii) there is clear structuring of natural European cherry fly populations.

Systemic mechanisms of individual reproductive life history in female Medflies.

This paper is the second one in a series of two papers hypothesizing and testing systemic grounds of reproductive life history in the female fruit fly. In the first paper, we analyzed mechanisms of individual fecundity scheduling and have drawn the following conclusions. Individual fecundity in female flies is endowed as a flat pattern with a steady-state period of a constant rate of egg-laying. An individual female reveals three stages in her adult life history: maturation, maturity, and senescence. The first stage is a transient period of achieving a steady state at maturity, which can be maintained until the senescence stage. Thus, an individual fecundity pattern has no maximum. The maximums observed experimentally are averaging-caused artifacts. Two natural causes of deaths exist in flies, senescence-caused ones and premature deaths, probably due to a reproductive overload. In this paper, to confirm these findings, we use individual daily scores of egg-laying in four populations of Mediterranean fruit flies. Based on fecundity scores, we divide each Medfly population into four classes, namely zero-egg, short-, medium- and long-lived egg-layers. We demonstrate that, indeed, the three above findings definitely exist in Medflies. Our procedure allows the efficient storage of individual fecundity in parametric form, with only five numbers for each fly. Finally, this protocol will allow a more precise analysis of fecundity-energy trade-offs in flies carrying appropriate longevity mutations.

Early detection and population monitoring of Ceratitis capitata (Diptera: Tephritidae) in a mixed-fruit orchard in northern Greece.

Population monitoring of the Mediterranean fruit fly,Ceratitis capitata (Wiedemann), was studied in 1998 in a mixed-fruit orchard in northern Greece, using International Pheromone McPhail traps (IPMT) baited with the female targeted attractants ammonium acetate, putrescine, and trimethylamine, and Jackson traps baited with the male specific parapheromone trimedlure. Special emphasis was placed on detecting the low initial adult population resulting from surviving overwintering larvae as early as possible in the spring and early summer. Traps were suspended on various host trees, using trap grid densities of either 15 or 1.5 traps per hectare. The first adults detected were females captured on 24 June in IPMT traps suspended on apricot trees, which are among the earliest maturing hosts in the area. From the end of July, the most effective trap was the IPMT trap placed on peaches, which followed apricots in the fruit ripening sequence. IPMT traps captured predominately females (approximately 80% of the total captures) and by far outperformed Jackson traps in early detection (the first males in Jackson traps were captured in August) as well as in total captures until mid-October. After mid-October, however, more flies were captured in Jackson traps. Comparing the performance of two trap grid densities on apple trees (the common host in the two grids), we found that in the high-density trap grid the first adults were detected 1 wk earlier than in the low-density trap grid. Our findings for this locality suggest that trap type and plant species on which traps are suspended are of key importance in early detection and population monitoring of C. capitata.

Evaluation of trap types and food attractants for Rhagoletis cerasi (Diptera: Tephritidae).

Trapping experiments were conducted during the period of flight activity of the cherry fruit fly Rhagoletis cerasi L. in the area of Thessaloniki, northern Greece, during the years 1993-1997 to test several traps alone and in combination with different food attractants. Yellow sticky-coated visual traps were more effective than McPhail-type traps baited with different food attractants. Of the visual traps, the most effective was the yellow Rebell trap. The Rebell trap, provided with a dispenser containing a slow release formulation of ammonium acetate attached to the lower part of the trap, was found to be the most effective of all treatments tested, capturing approximately 50% more R. cerasi flies than the Rebell trap without any attractant. Ammonium carbonate dispensers did not increase the performance of Rebell traps. More mature females were captured in Rebell traps baited with or without ammonium acetate than in McPhail-type traps baited with ammonium acetate. This study demonstrates that Rebell traps baited with an ammonium acetate dispenser can provide a more effective tool for monitoring and mass trapping of R. cerasi than the currently used unbaited Rebell traps.

Ultrasonographic classification and phacoemulsification of white senile cataracts.

OBJECTIVE: To classify the white senile cataracts and report the results of phacoemulsification of white cataracts. DESIGN: Prospective, noncomparative case series. PARTICIPANTS: One hundred eyes were included. INTERVENTION: White cataracts were examined biomicroscopically before surgery, and their acoustic structure was analyzed with standardized A-scan echography. White cataract surgery was performed with phacoemulsification via a superior temporal near-limbus corneal approach using a bimanual divide-and-conquer or stop-and-chop technique. Patients were followed after surgery for a period of 9 months. MAIN OUTCOMES MEASURES: The A-scan acoustic structure of white cataracts; successful accomplishment of capsulorrhexis; mean phacoemulsification time, power, and energy; intraoperative and postoperative complications of phacoemulsification; and visual acuity at 9 months after surgery. RESULTS: White senile cataracts were categorized into three different types. Type I included intumescent, white cataracts with cortex liquefaction and high internal acoustic reflections (44 eyes), type II included white cataracts with voluminous nuclei, little amount of whitish solid cortex, and low internal acoustic reflections (49 eyes), and type III included white cataracts with fibrosed anterior capsule and low internal echospikes (7 eyes). Circular capsulorrhexis was completed in 79 eyes and was significantly less successful in eyes with type I intumescent, white cataracts compared with type II white cataracts (P = 0.0034). Mean phacoemulsification time and energy were higher in type II and type III white cataracts. Posterior capsule rupture occurred in ten eyes, and three of these eyes were complicated by vitreous loss. In 95 eyes, the posterior chamber lens was implanted in the capsular bag and in five eyes in the sulcus. After surgery, a transient corneal edema developed in 31 eyes. At the final 6-month examination, the mean postoperative visual acuity was 20/30. CONCLUSION: Current phacoemulsification techniques can safely manage eyes with senile white cataracts. The increased risk of difficulty with continuous capsulorrhexis in type-I and type-III white cataracts and the substantial nuclear hardness in type-II and mainly type-III white cataracts would suggest that current phacoemulsification techniques might not be as successful in these patients as they are in ordinary earlier cataracts.