Mediterranean Fruit Fly Populations Research Articles

Mediterranean fruit fly population phenological patterns are strongly affected by elevation and host presence

The Mediterranean fruit fly (medfly) (Ceratitis capitata, Diptera: Tephritidae), is an extremely polyphagous pest that threatens the fruit production and trading industry worldwide. Monitoring C. capitata populations and analysing its dynamics and phenology is considered of outmost importance for designing and implementing sound management approaches. The aim of this study was to investigate the factors regulating the population dynamics of the C. capitata in a coastal and semi-mountainous area. We focused on effects of topography (e.g. elevation), host presence and seasonal patterns of ripening on the phenological patterns considering data collected in 2008. The experimental area is characterized by mixed fruit orchards, and Mediterranean climate with mild winters. Two trap types were used for population monitoring. The female targeted McPhail type and the male targeted Jackson type. Traps were placed in farms located at different elevations and landscape morphology (coastal and semi-mountainous areas). The main crops included citrus, apples, peaches, plums, pears, figs, quinces and apricots. Adult captures were first recorded in May, peaked in mid-summer and mid-autumn and almost ceased at the end of the season (January 2008). Captures in the coastal areas preceded that of highlands by 15 days. Most of the adults detected during the fruit ripening of late stone fruit cultivars (first peak) and citrus (second peak). The probability of capturing the first adults preceded almost three weeks the peak of adult captures either considering the elevation or host focus analyses. The results provide valuable information on the seasonal population trend of C. capitata in mixed fruit Mediterranean orchards and can support the set-up of IPM systems in areas with various landscapes and different hosts throughout the fruit growing season.

Differential Cold Tolerance on Immature Stages of Geographically Divergent Ceratitis capitata Populations.

Cold tolerance of adult medflies has been extensively studied but the effect of subfreezing temperatures on the immature stages remains poorly investigated, especially as far as different populations are regarded. In this study, we estimated the acute cold stress response of three geographically divergent Mediterranean fruit fly populations originating from Greece (Crete, Volos) and Croatia (Dubrovnik) by exposing immature stages (eggs, larvae, pupae) to subfreezing temperatures. We first determined the LT50 for each immature stage following one hour of exposure to different temperatures. Then eggs, larvae and pupae of the different populations were exposed to their respective LT50 for one hour (LT50 = -11 °C, LT50 = -4.4 °C, LT50 = -5 °C for eggs, larvae and pupae, respectively). Our results demonstrate that populations responded differently depending on their developmental stage. The population of Dubrovnik was the most cold-susceptible at the egg stage, whereas in that of Crete it was at the larval and pupal stage. The population of Volos was the most cold-tolerant at all developmental stages. The egg stage was the most cold-tolerant, followed by pupae and finally the 3rd instar wandering larvae. This study contributes towards understanding the cold stress response of this serious pest and provides data for important parameters that determine its successful establishment to unfavorable environments with an emphasis on range expansion to the northern, more temperate regions of Europe.

Acute cold stress and supercooling capacity of Mediterranean fruit fly populations across the Northern Hemisphere (Middle East and Europe)

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), holds an impressive record of successful invasion events promoted by globalization in fruit trade and human mobility. In addition, C. capitata is gradually expanding its geographic distribution to cooler temperate areas of the Northern Hemisphere. Cold tolerance of C. capitata seems to be a crucial feature that promotes population establishment and hence invasion success. To elucidate the interplay between the invasion process in the northern hemisphere and cold tolerance of geographically isolated populations of C. capitata, we determined (a) the response to acute cold stress survival of adults, and (b) the supercooling capacity (SCP) of immature stages and adults. To assess the phenotypic plasticity in these populations, the effect of acclimation to low temperatures on acute cold stress survival in adults was also examined. The results revealed that survival after acute cold stress was positively related to low temperature acclimation, except for females originating from Thessaloniki (northern Greece). Adults from the warmer environment of South Arava (Israel) were less tolerant after acute cold stress compared with those from Heraklion (Crete, Greece) and Thessaloniki. Plastic responses to cold acclimation were population specific, with the South Arava population being more plastic compared to the two Greek populations. For SCP, the results revealed that there is little to no correlation between SCP and climate variables of the areas where C. capitata populations originated. SCP was much lower than the lowest temperature individuals are likely to experience in their respective habitats. These results set the stage for asking questions regarding the evolutionary adaptive processes that facilitate range expansions of C. capitata into cooler temperate areas of Europe.

Microsatellite based genetic diversity of Mediterranean fruit fly(Ceratitis capitata, Diptera: Tephritidae) populations from Southwest Turkey

Various pests cause economic losses in some agricultural products, especially in citrus fruits, which are grown in many countries and have a very important role in consumption and export. The Mediterranean fruit fly, Ceratitis capitata Wied. (Diptera: Tephritidae), which spreads throughout the Mediterranean basin, Europe, the Middle East, Central, and South America, and Australia, is considered the most destructive pest in the world. Turkey is an important part of the Eastern Mediterranean basin and, maybe plays a role in the colonization of this pest. This polyphagous species causes huge economic losses by negatively affecting yield and quality in many countries. In this study, population genetic structure and inter-population relationships of the Mediterranean fruit fly were studied by using eight microsatellite markers sampled from the Mediterranean and Aegean regions of Turkey. The results represent a high level of genetic diversity in the Mediterranean fruit fly populations in Turkey and there is no geographical clustering observed when the populations are evaluated in the geographical sense. As a result of the study for 7 provinces, the average number of alleles (n$_{a}$) was 6.95, the average number of effective alleles (n$_{e}$) was 3.58, the observed (H$_{o}$) and expected (H$_{e}$) heterozygosity values were 0.61 and 0.67, respectively. The gene flow (Nem) level among populations was found as Nem = 1.13. Higher genetic diversity values point out that Turkey may have an important role in the colonization of this organism.

Applying non-host criteria against Mediterranean fruit fly populations to obtain market access for West Australian avocados

ISHS XXX International Horticultural Congress IHC2018: VII International Symposium on Tropical and Subtropical Fruits, Avocado, II International Symposium on Jackfruit and Other Moraceae and II International Symposium on Date Palm Applying non-host criteria against Mediterranean fruit fly populations to obtain market access for West Australian avocados

Effect of host fruit, temperature and Wolbachia infection on survival and development of Ceratitis capitata immature stages.

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), holds an impressive record of successful invasions promoted by the growth and development of international fruit trade. Hence, survival of immatures within infested fruit that are subjected to various conditions during transportation seems to be a crucial feature that promotes invasion success. Wolbachia pipientis is a common endosymbiont of insects and other arthropods generating several biological effects on its hosts. Existing information report the influence of Wolbachia on the fitness traits of insect host species, including the Mediterranean fruit fly. However, little is known regarding effects of Wolbachia infection on immature development in different host fruits and temperatures. This study was conducted to determine the development and survival of immature stages of four different Mediterranean fruit fly populations, either infected or uninfected with Wolbachia, in two hosts (apples, bitter oranges) under three constant temperatures (15, 25 and 30°C), constant relative humidity (45-55 ± 5%), and a photoperiod of 14L:10D. Our findings demonstrate both differential response of two fruit fly lines to Wolbachia infection and differential effects of the two Wolbachia strains on the same Mediterranean fruit fly line. Larva-to-pupa and larva-to-adult survival followed similar patterns and varied a lot among the four medfly populations, the two host fruits and the different temperatures. Pupation rates and larval developmental time were higher for larvae implanted in apples compared to bitter oranges. The survival rates of wildish medflies were higher than those of the laboratory adapted ones, particularly in bitter oranges. The Wolbachia infected medflies, expressed lower survival rates and higher developmental times, especially the wCer4 infected line. High temperatures constrained immature development and were lethal for the Wolbachia infected wCer4 medfly line. Lower temperatures inferred longer developmental times to immature stages of all medfly populations tested, in both host fruits. Implications on the ecology and survival of the fly in nature are discussed.

CLIMEX and MED-FOES Models for Predicting the Variability in Growth Potential and Persistence of Mediterranean Fruit Fly (Diptera: Tephritidae) Populations

Abstract CLIMEX and MED-FOES models integrate climate and data on Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), biology and use it to define the environmental suitability for the pest at specific geographical locations. CLIMEX calculates growth indices as indicators of conditions that are suitable for medfly population growth. MED-FOES incorporates additional information on pest management interventions to simulate the process and timing of medfly eradication. CLIMEX simulations of climatic suitability in California and Florida indicated that the most favorable periods for medfly population growth are March through May and October through November, whereas the environment would be especially stressful during the summer months, except when irrigation is applied. With irrigation, California is highly suitable for medfly population growth during the summer months. Due to cool temperatures, medfly populations are likely to decline significantly in January through February in Los Angeles, Tampa, and Miami, and probably not survive in San Francisco. According to MED-FOES simulations, it possibly would take longer to eradicate medfly from California than Florida, particularly if the incursions are initiated in the summer months. Medfly annual growth indices for the ENSO La Niña years are relatively low for San Francisco and Los Angeles but above neutral for Tampa and very high for Miami. During the El Niño phase, the growth index remains unchanged for San Francisco, increases for Los Angeles, and decreases for Tampa and Miami. CLIMEX and MED-FOES models are useful for informing plans to manage invasion threats from medfly and other invasive insects.

Functional Genomics of a Symbiotic Community: Shared Traits in the Olive Fruit Fly Gut Microbiota.

The olive fruit fly Bactrocera oleae is a major pest of olives worldwide and houses a specialized gut microbiota dominated by the obligate symbiont “Candidatus Erwinia dacicola.” Candidatus Erwinia dacicola is thought to supplement dietary nitrogen to the host, with only indirect evidence for this hypothesis so far. Here, we sought to investigate the contribution of the symbiosis to insect fitness and explore the ecology of the insect gut. For this purpose, we examined the composition of bacterial communities associated with Cretan olive fruit fly populations, and inspected several genomes and one transcriptome assembly. We identified, and reconstructed the genome of, a novel component of the gut microbiota, Tatumella sp. TA1, which is stably associated with Mediterranean olive fruit fly populations. We also reconstructed a number of pathways related to nitrogen assimilation and interactions with the host. The results show that, despite variation in taxa composition of the gut microbial community, core functions related to the symbiosis are maintained. Functional redundancy between different microbial taxa was observed for genes involved in urea hydrolysis. The latter is encoded in the obligate symbiont genome by a conserved urease operon, likely acquired by horizontal gene transfer, based on phylogenetic evidence. A potential underlying mechanism is the action of mobile elements, especially abundant in the Ca. E. dacicola genome. This finding, along with the identification, in the studied genomes, of extracellular surface structure components that may mediate interactions within the gut community, suggest that ongoing and past genetic exchanges between microbes may have shaped the symbiosis.

Genetic structure of Mediterranean fruit fly (Diptera: Tephritidae) populations from Turkey revealed by mitochondrial DNA markers

Ceratitis capitata is one among the most destructive and economically important agricultural pests worldwide. Despite its economic significance, the population structures of this pest have remained relatively unexplored in the eastern Mediterranean basin. Using two mitochondrial markers, the present study aimed to examining the population genetic structure and diversity of C. capitata populations in Turkey, the region that covers a large part of the eastern Mediterranean area. Our results revealed that the Turkish Mediterranean fruit fly populations are characterized by low levels of genetic diversity and limited population differentiation. For comparison purposes, wemerged the sequences identified in the present study with the previously reported sequences from acrossthe world into the data matrix. The haplotype network showed that, unlike the African samples the Mediterranean samples and samples from the new world (America, Pacific region and Australia) did not show any clear pattern of geographical structuring, which indicates that the Mediterranean basin, particularly the eastern Mediterranean region populations, may have played a moreimportant role in the colonization of C. capitata populations to the new world. The results also revealed a close genetic relationship between the Turkish and Iranian populations, suggesting that the Iranian C. capitata populations probably originated from Turkey.

The Survival of Mediterranean Fruit Fly (Diptera: Tephritidae) Over Winter in Western Australia.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is one of the most economically important pest insects of fruit crops worldwide. Mediterranean fruit fly can cause up to 100% crop loss in susceptible fruit. In order to formulate best management practices, it is critical to understand how Mediterranean fruit fly overwinters in a given geographical location and bridge the gap between autumn and spring populations. In this study, we evaluated the overwintering potential of Mediterranean fruit fly immature and adult stages in two locations in Perth Hills, Western Australia. We also monitored wild adult Mediterranean fruit fly populations for 2 yr. Adults were present year-round with captures very low in winter to early spring relative to summer and autumn. Field experiments revealed that immature stages in apples (eggs/first instar) and soil (pupae) remained viable in winter, emerging as adults at the onset of warmer weather in spring. In field cages, adults survived 72-110 d, and female laid viable eggs when offered citrus fruit, though only 1-6% eggs survived to emerge as adults. Adults survived longer in field cages when offered live citrus branch. The findings suggest that all Mediterranean fruit fly life stages can survive through mild winter, and surviving adults, eggs in the fruit and/or pupae in the soil are the sources of new population that affect the deciduous fruit crops in Perth. We recommend that Mediterranean fruit fly monitoring is required year-round and control strategies be deployed in spring. Furthermore, we recommend removal of fallen fruit particularly apple and other winter fruit such as citrus.

Consequences of resistance evolution in a Cas9-based sex conversion-suppression gene drive for insect pest management

The use of a site-specific homing-based gene drive for insect pest control has long been discussed, but the easy design of such systems has become possible only with the recent establishment of CRISPR/Cas9 technology. In this respect, novel targets for insect pest management are provided by new discoveries regarding sex determination. Here, we present a model for a suppression gene drive designed to cause an all-male population collapse in an agricultural pest insect. To evaluate the molecular details of such a sex conversion-based suppression gene drive experimentally, we implemented this strategy in Drosophila melanogaster to serve as a safe model organism. We generated a Cas9-based homing gene-drive element targeting the transformer gene and showed its high efficiency for sex conversion from females to males. However, nonhomologous end joining increased the rate of mutagenesis at the target site, which resulted in the emergence of drive-resistant alleles and therefore curbed the gene drive. This confirms previous studies that simple homing CRISPR/Cas9 gene-drive designs will be ineffective. Nevertheless, by performing population dynamics simulations using the parameters we obtained in D. melanogaster and by adjusting the model for the agricultural pest Ceratitis capitata, we were able to identify adequate modifications that could be successfully applied for the management of wild Mediterranean fruit fly populations using our proposed sex conversion-based suppression gene-drive strategy.

Validation of a geographic weighted regression analysis as a tool for area-wide integrated pest management programs for Ceratitis capitata Wiedemann (Diptera: Tephritidae) on Terceira Island, Azores

ABSTRACTExtrapolation from quantitative sampling to the surrounding areas is an essential feature of many aspects of real world applications in pest management decision-making. However, these decisions are only as good as the accuracy of the methods that provided the information. The problem of estimating Mediterranean fruit fly population densities from trap grids is a specific case. The efficiency of three methods to estimate fruit flies trapped per day values for non-sampled areas in Terceira Island is evaluated, the inverse distance weighted, ordinary Kriging and the geographic weighted regression (GWR). Each method has its own specificities and merits. The results demonstrate that the GWR method is capable of estimating hotspots for the next season and can be used to identify ecological corridors over a non-sampled area. The high spatial heterogeneity and topographical conditions present on Terceira Island may explain why a more mathematically complex method is more reliable than simpler methods for use in possible future wide-area control program for medfly.

Analysis of Seasonal Risk for Importation of the Mediterranean Fruit Fly, Ceratitis capitata (Diptera: Tephritidae), via Air Passenger Traffic Arriving in Florida and California.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is one of the most economically damaging pests in the world and has repeatedly invaded two major agricultural states in the United States, Florida and California, each time requiring costly eradication. The Mediterranean fruit fly gains entry primarily in infested fruit carried by airline passengers and, since Florida and California each receive about 13 million international passengers annually, the risk of Mediterranean fruit fly entering the United States is potentially very high. The risk of passengers bringing the pest into Florida or California from Mediterranean fruit fly-infested countries was determined with two novel models, one estimated seasonal variation in airline passenger number and the other defined the seasonal and spatial variability in Mediterranean fruit fly abundance. These models elucidated relationships among the risk factors for Mediterranean fruit fly introduction, such as amount of passenger traffic, routes traveled, season of travel, abundance of Mediterranean fruit fly in countries where flights departed, and risk of the pest arriving at destination airports. The risk of Mediterranean fruit fly being introduced into Florida was greatest from Colombia, Brazil, Panama, Venezuela, Argentina, and Ecuador during January-August, whereas primarily the risk to California was from Brazil, Panama, Colombia, and Italy in May-August. About three times more Mediterranean fruit flies were intercepted in passenger baggage at airports in Florida than California, although the data were compromised by a lack of systematic sampling and other limitations. Nevertheless, this study achieved the goal of analyzing available data on seasonal passenger flow and Mediterranean fruit fly population levels to determine when surveillance should be intensified at key airports in Florida and California.

Delimiting survey and seasonal activity of peach fruit fly, Bactrocera zonata and Mediterranean fruit fly, Ceratitis capitata (Diptera: tephritidae) at El-Beheira Governorate, Egypt

Peach fruit fly (PFF), Bactrocera zonata (Saunders) and Mediterranean fruit fly (MFF) are the most destructive insect pests of fruit and vegetables in Egypt. The current study was carried out over two successive years; 2012 and 2013 in thirteen districts of El-Beheira governorate and aimed to conduct a delimit survey and monitor the seasonal activity of PFF and MFF populations. The results showed that the PFF was recorded in almost all of the examined districts except for Edko district. Moreover, the PFF was not found in El-Mahmodiya district throughout the second study period, while the MFF was spread throughout all tested districts at both years. Inter–site comparison revealed significant differences in the abundance of PFF and MFF across the tested districts during 2012 and 2013 seasons. A significant positive correlation was reported between the population activity of PFF and MFF through 2012 (r=0.34), while a non-significant positive correlation (r=0.24) was obtained in 2013. Population growth rate (r0) of PFF was higher than that of the MFF through the first interval of population increase through both 2012 and 2013 seasons; 1.02 and 0.17 for PFF, and 0.83 and 0.13 for MFF, respectively. The r0 values of the MFF was higher than the PFF through the second interval of increase through both tested seasons; 1.04 and 1.10 for MFF, and 0.16 and 0.21 for PFF. It could be concluded that these two insects exchange their role as a key-pest of fruit hosts along the tested seasons.

Detection of the Acetylcholinesterase Insecticide Resistance Mutation (G328A) in Natural Populations of Ceratitis capitata.

Wild Mediterranean fruit fly specimens collected from various regions worldwide were screened for the glycine to alanine (Gly->Ala) point mutation (G328A) in the acetylcholinesterase enzyme, presumably causing resistance to organophosphates. We found that the single nucleotide polymorphism (SNP) responsible for this amino acid change is located at the beginning of exon 6 of the Ccace2 gene. The identification of the exact location of the SNP permitted PCR primer design around this site and direct sequencing of the corresponding genomic region. We detected the resistance allele in natural Mediterranean fruit fly populations from Brazil and Spain, but not from other sites in four continents. The known treatment history of sites suggests that the resistance buildup is linked to organophosphate application in the field. The PCR-based detection provides a screening method useful for monitoring Mediterranean fruit fly insecticide resistance in local populations and improving pest management strategies accordingly.

Bait station devices can improve mass trapping performance for the control of the Mediterranean fruit fly.

The use of traps and other attract-and-kill devices in pest management strategies to reduce Mediterranean fruit fly populations has proved to be efficient. Nevertheless, many farmers are concerned about the effect of these devices on the trees where they are hung. Direct field observations have revealed that fruit damage is higher in trees with traps than in trees without them. This work evaluates the efficacy of different types of attract-and-kill device to protect fruit of the single tree on which the device is placed. Results suggested that trees with traps had at least the same fruit damage than trees without them. When traps were baited with protein hydrolysate, fruit damage was even higher than in trees without traps. However, fruit damage was significantly diminished when efficient bait station devices were used. Although mass trapping is able to control fruit fly populations as a control method, trees with some types of trap and bait are more susceptible to fly puncture. However, bait station devices reduce fruit damage in the single trees where they are hung. Bait stations are more efficient in fruit protection because fruit flies are affected as soon as they contact the device. Some recommendations for the use of the different attract-and-kill devices are discussed.

Response of Female Ceratitis capitata (Diptera: Tephritidae) to a Spinosad Bait and Polymer Matrix Mixture With Extended Residual Effect in Hawaii

The effectiveness of foliar applications of protein baits against pestiferous fruit flies (Tephritidae) can be adversely affected by a rapid loss of attractive volatile compounds and by rainfall due to the high water solubility of the baits. In a large coffee, Coffea arabica L., plantation in Hawaii with high and low populations of Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), the relative attractiveness of GF-120 NF Naturalyte Fruit Fly Bait as either a 40% (vol:vol) spray solution (= GF-120 NF) or as a formulated proprietary amorphous polymer matrix (= GF-120 APM) was compared. The GF-120 APM formulations contained either, 25, 50, or 75% of GF-120 NF (wt:wt). All baits were tested in association with visually attractive yellow bait stations as a way of standardizing the evaluations. With both high and low C. capitata populations, significantly more females were attracted to the fresh sprayed GF-120 NF than to any of the three fresh GF-120 APM formulations. The attractiveness of GF-120 sprayed decreased significantly after 1 wk, whereas 1-wk-old GF-120 APM formulations were as attractive as similar fresh formulations. GF-120 APM 75% aged for 3 wk outperformed similarly-aged sprayed GF-120 NF with comparatively high C. capitata populations. With low populations, both GF-120 APM 75% and GF-120 APM 50% aged for 2 wk outperformed the similarly aged sprayed GF-120 NF. Combined findings indicate that APM mixed with either 50 or 75% GF-120 applied to bait stations can be attractive to female C. capitata for up to 3 wk longer than the standard sprayed GF-120 NF.

Chemosterilant Bait Stations Coupled With Sterile Insect Technique: An Integrated Strategy to Control the Mediterranean Fruit Fly (Diptera: Tephritidae)

During 2008 and 2009, the efficacy of the combination of two Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), control techniques, sterile insect technique (SIT) and a chemosterilant bait station system (Adress), was tested in three crops: citrus (Citrus spp.), stone fruit (Prunus spp.), and persimmon (Diospyros spp.). Two thousand sterile males were released per ha each week in the whole trial area (50,000 ha, SIT area). For 3,600 ha, within the whole trial area, 24 Adress traps per ha were hung (SIT + Adress area). Ten SIT + Adress plots and 10 SIT plots in each of three different fruit crops were arranged to assess Mediterranean fruit fly population densities and fruit damage throughout the trial period. To evaluate the efficacy of each treatment, the male and female populations were each monitored from August 2008 to November 2009, and injured fruit was assessed before harvest. Results showed a significant reduction in the C. capitata population in plots treated with both techniques versus plots treated only with the SIT. Likewise, a corresponding reduction in the percentage of injured fruit was observed. These data indicate the compatibility of these techniques and suggest the possibility of using Adress coupled with SIT to reduce C. capitata populations in locations with high population densities, where SIT alone is not sufficiently effective to suppress fruit fly populations to below damaging levels.

Ancestral populations perform better in a novel environment: domestication of Mediterranean fruit fly populations from five global regions

Geographically isolated populations of a species may differ in several aspects of life-history, morphology, behavior, and genetic structure as a result of adaptation in ecologically diverse habitats. We used a global invasive species, the Mediterranean fruit fly to investigate, whether adaptation to a novel environment differs among geographically isolated populations that vary in major life history components such as life span and reproduction. We used wild populations from five global regions (Kenya, Hawaii, Guatemala, Portugal, and Greece). Adult demographic traits were monitored in F(2), F(5), F(7) and F(9) generations in captivity. Although domestication in constant laboratory conditions had a different effect on the mortality and reproductive rates of the different populations, a general trend of decreasing life span and age of first reproduction was observed for most medfly populations tested. However, taking into account longevity of both sexes, age-specific reproductive schedules, and average reproductive rates we found that the ancestral Kenyan population kept the above life history traits stable during domestication compared to the other populations tested. These findings provide important insights in the life-history evolution of this model species, and suggest that ancestral medfly populations perform better than the derived - invasive ones in a novel environment.

Seasonal and annual trends in field populations of Mediterranean fruit fly, Ceratitis capitata, in Mediterranean citrus groves: comparison of two geographic areas in eastern Spain

Seasonal and annual trends in Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) populations were analyzed to determine the factors that influence population fluctuations in the field. Adult flies were monitored along 2003-07 in two citrus areas in eastern Spain with similar climate, Valencia and Tarragona. Adults were present throughout the study period, even in winter. The initial annual population increase was related to previous winter and spring temperatures. Captures started to increase in April-May and usually reached a peak in July. This peak corresponded to the maximum capture period in Valencia, but not in Tarragona, where there was usually a second peak in autumn, with capture levels similar to the first peak. Gravid females were found throughout the year, even in overwintering populations of medfly. The availability of other host fruit species in the vicinity of the citrus groves may explain the differences in annual abundance and distribution of captures between the two areas studied.