Ceratitis Capitata Research Articles

Diminish the chances of Mediterranean fruit fly Ceratitis capitata eggs surviving by suppressing the expression of the heat shock protein 27 gene (Hsp27).

The hypothesized role of stress-inducible heat shock proteins is to act as a buffer against environmental variations and affect fitness in suboptimal conditions. Our study examining the functions of heat shock protein 27 (Hsp27) in the eggs of the Mediterranean fruit fly (Ceratitis capitata). We utilized double-stranded RNA, specifically targeting the Hsp27 gene, to reduce its expression and assessed the consequent impact on egg viability. The investigation included the examination of early eggs (less than 6 hours post-laying) and late eggs (more than 42 hours post-laying), using varying concentrations (0.02, 0.1, and 0.2 µg/µL) of Hsp27 dsRNA. Control groups of eggs were dsRNA of ATPase, Cctra-2, or phosphate buffer solution (ph-B-S). Down-regulating Hsp27 dsRNA reduced the hatching rate of the eggs compared to the hatching rate in the control groups, especially in the ph-B-S group. The early eggs were more affected than the late eggs after soaking with Hsp27 dsRNA, where the Hsp27 dsRNA decreased the hatching rates to 12.91% early. The tested concentration of 0.2 µg/µL of Hsp27 dsRNA was achieved with the most significant reduction of 2.75 in egg viability. The sex ratio of insects hatched from treated eggs was investigated after hatching. After the down-regulation of Hsp27, there was no significant effect of the Hsp27 down-regulation on the sex ratio.

Field evaluation of female- and male-targeted traps for Ceratitis capitata (Diptera: Tephritidae).

Mediterranean fruit fly (Medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a globally significant economic pest for which lure based trapping can be used to monitor established populations and for surveillance. Either female- or male-targeted traps can be used; however, recommendations on which to apply are inconsistent and many programs rely on male-targeted traps. Here, we compare the performance of male-targeted traps (Lynfield Trap with Trimedlure) and female-targeted traps (Biotrap Globe trap with the 3-component lure-TMA Plus) in apple orchards in south-west Western Australia over 2 years (September 2019 to September 2021). Male-targeted traps caught more Medflies overall than female-targeted traps, although the difference was minor. However, female-targeted traps were better at attracting Medfly early in the season when populations were small; and were more likely to capture at least one fly when their paired male-targeted trap caught none. Conversely, male-targeted traps were more likely to capture Medflies late in the season and were more likely to catch high numbers of Medflies. Consequently, female-targeted traps may be better at detecting Medfly early in the season, and male-targeted traps may be better at detecting Medfly abundance late in the season, at least in apple orchards. Our results suggest that either or both trap-types could be used for monitoring Medfly populations, with the optimal solution being dependent on the intended application.

Covert RNA viruses in medflies differ in their mode of transmission and tissue tropism.

The presence of RNA viruses in insects has been extensively covered. However, the study of host-virus interaction has focused on viruses that cause detrimental effects to the host. In this manuscript, we uncovered which tissues are infected with covert RNA viruses in the agricultural pest Ceratitis capitata, and which is the preferred transmission route of these viruses. Our results showed that vertical and horizontal transmission can occur simultaneously, although each virus is transmitted more efficiently following one of these routes. Additionally, our results indicated an association between the tropism of the RNA virus and the preferred route of transmission. Overall, these results set the basis for understanding how viruses are established and maintained in medfly populations.

On the impact of re-mating and residual fertility on the Sterile Insect Technique efficacy: Case study with the medfly, Ceratitis capitata.

The sterile insect technique (SIT) can be an efficient solution for reducing or eliminating certain insect pest populations. It is widely used in agriculture against fruit flies, including the Mediterranean fruit fly (medfly), Ceratitis capitata. The re-mating tendency of medfly females and the fact that the released sterile males may have some residual fertility could be a challenge for the successful implementation of the SIT. Obtaining the right balance between sterility level and sterile male quality (competitiveness, longevity, etc) is the key to a cost-efficient program. Since field experimental approaches can be impacted by many environmental variables, it is difficult to get a clear understanding on how specific parameters, alone or in combination, may affect the SIT efficiency. The use of models not only helps to gather knowledge, but it allows the simulation of a wide range of scenarios and can be easily adapted to local populations and sterile male production. In this study, we consider single- and double-mated females. We first show that SIT can be successful only if the residual fertility is less than a threshold value that depends on the basic offspring number of the targeted pest population, the re-mating rates, and the parameters of double-mated females. Then, we show how the sterile male release rate is affected by the parameters of double-mated females and the male residual fertility. Different scenarios are explored with continuous and periodic sterile male releases, with and without ginger aromatherapy, which is known to enhance sterile male competitiveness, and also taking into account some biological parameters related to females that have been mated twice, either first by a wild (sterile) male and then a sterile (wild) male, or by two wild males only. Parameter values were chosen for peach as host fruit to reflect what could be expected in the Corsican context, where SIT against the medfly is under consideration. Our results suggest that ginger aromatherapy can be a decisive factor determining the success of SIT against medfly. We also emphasize the importance of estimating the duration of the refractory period between matings depending on whether a wild female has mated with a wild or sterile male. Further, we show the importance of parameters, like the (hatched) eggs deposit rate and the death-rate related to all fertile double-mated females. In general, re-mating is considered to be detrimental to SIT programs. However, our results show that, depending on the parameter values of double-mated females, re-mating may also be beneficial for SIT. Our model can be easily adapted to different contexts and species, for a broader understanding of release strategies and management options.

Life history and overwintering in multi‐ and univoltine species of family Tephritidae in a subtropical region of northwestern Argentina

AbstractAmong phytophagous insects, life history often evolves as a strategy to cope with seasonality in host plant availability. Whereas specialization often leads to dormancy, aestivation, or longevity, polyphagous species bridge between periods of host availability by exploiting alternative host plants. The aim of the present work was to characterize the life histories of four species of specialist and generalist uni‐ and multivoltine frugivorous fruit flies – Ceratitis capitata Wiedemann, Anastrepha fraterculus Wiedemann, Rhagoletis blanchardi Aczel, and Rhagoletotrypeta pastranai Aczel (all Diptera: Tephritidae) – inhabiting in sympatry in Las Yungas phytogeographical province in Tucumán (northwestern Argentina). For this purpose, infested host plant fruits were sequentially collected during two consecutive years, and flies recovered from these fruits were subjected to demographic experiments to establish longevity and overwintering mechanisms. The results indicated that life cycles were tightly related to host fruit availability, where multivoltine species sequentially exploit different host plants over the year, whereas univoltine species must undergo pupal dormancy to reach the next host fructification period and may extend the duration of dormancy when climatic conditions are acyclic and unpredictable. The present study may broaden knowledge about diapausing Tephritidae in subtropical regions and may contribute to an increased conceptual basis for the improvement of pest control strategies, such as the sterile insect technique (SIT).

Infestation and evaluation of damage of the Mediterranean fruit fly (Medfly), Ceratitis capitata (Wied.) (Diptera: Tephritidae) on Citrus in Southern Tunisia

Infestation and evaluation of damage of the Mediterranean fruit fly (Medfly), Ceratitis capitata (Wied.) (Diptera: Tephritidae) on Citrus in Southern Tunisia

Evaluation of Fruit Flies (Diptera: Tephritidae) Attractants in Northeastern Ethiopia

A study was conducted in South Wollo and North Wollo administrative zones of northeastern Ethiopia in 2018; Torula yeast, protien hydrolase, methyl eugenol, trimed lure and terpinyil acetate were evaluated for adult fruit fly species complexes trapping. Four fruit fly species was trapped; Bactrocera dorsalis, Ceratitis cosyra, Ceratitis capitata and Ceratitis fasciventris. Bactrocera dorsalis was the most abundant species accounted for 97.9% of the total trapped adults. The number of B. dorsalis C. cosyra and C. capitata showed a significant difference among trapping locations and attractants; The highest number of B. dorsalis was trapped with methyl eugenol at Kalu (722.2 flies/ trap/ week); C. capitata was higher at Habru which was guava and coffee dominated habitat while C. cosyra was relatively higher at Kobo which is mango dominated; more adults were trapped in male lure traps (97.03%) than food-based attractants (2.97%); food-based attractants could be valuable alternatives for detection and monitoring of fruit flies.

The maxillary palps of Tephritidae are selectively tuned to food volatiles and diverge with ecology

The maxillary palp is an auxiliary olfactory organ in insects, which, different from the antennae, is equipped with only a few olfactory sensory neuron (OSN) types. We postulated that these derived mouthpart structures, positioned at the base of the proboscis, may be particularly important in mediating feeding behaviors. As feeding is spatio-temporally segregated from oviposition in most Tephritidae, this taxonomic group appears quite suitable to parse out sensory breadth and potential functional divergence of palps and antennae. Scanning electron microscopy and anterograde staining underlined the limited palpal olfactory circuit in Tephritidae: only three morphological subtypes of basiconic sensilla were found, each with two neurons, and project to a total of six antennal lobe glomeruli in Bactrocera dorsalis. Accordingly, the palps detected only few volatiles from the headspace of food (fermentation and protein lures) and fruit (guava and mango) compared to the antennae (17 over 77, using gas-chromatography coupled electrophysiology). Interestingly, functionally the antennae were more tuned to fruit volatiles, detecting eight times more fruit than food volatiles (63 over 8), whereas the number of fruit and food volatile detection was more comparable in the palps (14 over 8). As tephritids diverge in oviposition preferences, but converge on food substrates, we postulated that the receptive ranges of palpal circuits would be more conserved compared to the antennae. However, palpal responses of three tephritid species that differed in phylogenetic relatedness and ecologically niche, diverged across ecological rather than phylogenetic rifts. Two species with strongly overlapping ecology, B. dorsalis and Ceratitis capitata, showed inseparable response profiles, whereas the cucurbit specialist Zeugodacus cucurbitae strongly diverged. As Z. cucurbitae is phylogenetically placed between B. dorsalis and C. capitata, the results indicate that ecology overrides phylogeny in the evolution of palpal tuning, in spite of being predisposed to detecting food volatiles.

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.

Does the Neotropical‐native parasitoid Ganaspis pelleranoi successfully attack the worldwide invasive pest Drosophila suzukii?

AbstractThe Asian Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a harmful invasive pest widespread throughout Argentinian fruit‐producing regions. It coexists with both pests, the sub‐Saharan African Ceratitis capitata (Wiedemann) and the Neotropical‐native Anastrepha fraterculus (Wiedemann) (both Diptera: Tephritidae), in northwestern Argentina. The Neotropical‐native parasitoid Ganaspis pelleranoi (Brèthes) (Hymenoptera: Figitidae) is frequently found in non‐crop fruit infested by those frugivorous dipterans. The northwestern Argentinian region is known for producing and exporting berries and citrus, which are affected by those pests. Thus, eco‐friendly control strategies are under assessment. This study mainly assessed the potential of the G. pelleranoi population lineage from Tucumán (GpTuc) as a D. suzukii biocontrol agent. First, both the host‐killing effectiveness and the reproductive success of GpTuc on larvae of D. suzukii, C. capitata, A. fraterculus, and Drosophila melanogaster Meigen were compared in no‐choice tests under laboratory conditions. Then, the GpTuc host preference was evaluated in dual‐choice tests (D. suzukii vs. C. capitata or A. fraterculus) under laboratory and field conditions. Naive parasitoid females were allowed to forage for 8 h on screen‐covered Petri dishes filled with host larvae under laboratory conditions and for 48 h on peaches inoculated with host larvae under field conditions. Host puparia dissections were performed to determine the number and condition of parasitoid eggs, first and second instars, such as alive/dead, without/with melanization process, and proportions of parasitized, superparasitized, and dead puparia. Drosophila suzukii was not a suitable host for the successful development of GpTuc immature stages as they did not overcome the host's immune system. However, GpTuc performed efficiently regarding D. suzukii mortality, but parasitoid specificity was restricted to both tephritid species as only thriving offspring were achieved from them. Interestingly, the effectiveness of GpTuc on D. suzukii increased when it co‐occurred with C. capitata instead of A. fraterculus, the preferred host.

Projecting the Global Potential Geographical Distribution of Ceratitis capitata (Diptera: Tephritidae) under Current and Future Climates.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), which is native to tropical Africa, has invaded more than 100 countries and constitutes a risk to the citrus sector. Studying its potential geographical distribution (PGD) in the context of global climate change is important for prevention and control efforts worldwide. Therefore, we used the CLIMEX model to project and assess the risk of global invasion by C. capitata under current (1981-2010) and future (2040-2059) climates. In the prevailing climatic conditions, the area of PGD for C. capitata was approximately 664.8 × 105 km2 and was concentrated in South America, southern Africa, southern North America, eastern Asia, and southern Europe. Under future climate conditions, the area of PGD for C. capitata is projected to decrease to approximately 544.1 × 105 km2 and shift to higher latitudes. Cold stress was shown to affect distribution at high latitudes, and heat stress was the main factor affecting distribution under current and future climates. According to the predicted results, countries with highly suitable habitats for C. capitata that have not yet been invaded, such as China, Myanmar, and Vietnam, must strengthen quarantine measures to prevent the introduction of this pest.

Virulence and biochemical activities of Heterorhabditis indica (Nematoda: Heterorhabditidae) against Bactrocera zonata and Ceratitis capitata (Diptera: Tephritidae)

This study examines the impact of Heterorhabditis indica entomopathogenic nematodes on mature larvae of the peach fruit fly, Bactrocera zonata (Saunders), and the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), both of which are highly detrimental species in the Tephritidae family. The investigation is conducted in a laboratory setting using two types of soil: sandy loam and sand. The research focuses on the virulence and biochemical effects of the nematodes. The results indicate that H. indica is more effective in sandy loam soil than sandy soil. This is supported by the LC50 values (the lethal concentration that kills 50% of the tested organisms) of 566.656 Infective Juveniles/ml for B. zonata and 250.53 Infective Juveniles/ml for C. capitata in sandy loam soil, whereas the corresponding values in sandy soil were 1149.051 and 701.839 Infective Juveniles/ml, respectively. Consequently, C. capitata larvae are more susceptible to entomopathogenic nematodes than B. zonata larvae. The infection by the nematodes also leads to changes in specific enzymatic activities of the larvae. This includes significant reductions in amylase, trehalase, and acetylcholine esterase, alongside an increase in invertase activity. Moreover, varying decreases are observed in chitinase, acid phosphatase, and alkaline phosphatase activities. In conclusion, the nematodes effectively reduce the emergence of adult flies by targeting the final stages of insect development. Furthermore, they offer an eco-friendly alternative to chemical pesticides.

A spatio-temporal modelling approach to understand the effect of urban fruit fly outbreaks on peri-urban orchards

Urban areas are well-known sources of fruit fly introduction and unmanaged populations pose a high risk of dispersal to surrounding agricultural areas. Although management of urban fruit fly populations is recognised as being important for area-wide control programmes, its relative importance is rarely quantified. Identifying possible sources of fruit fly populations is important to the success of area-wide programs, as well as to on-farm management. We developed a modelling approach to analyse the spatio-temporal connectivity of fruit fly across urban-agriculture boundaries. For a case study, we examine Mediterranean fruit fly, Ceratitis capitata, outbreaks in two fruit growing regions in south-west Western Australia. Connectivity between population sources was defined using a dispersal kernel and routinely collected surveillance data from traps located across urban and agricultural areas. Spatio-temporal Bayesian models were then developed to quantify the extent to which unmanaged urban populations contribute to commercial orchards across each region. Our model results from two fruit growing regions indicate that population connectivity is a strong predictor of urban and commercial orchard Mediterranean fruit fly density. Models demonstrate that unmanaged urban outbreaks can contribute to increased pest pressure in surrounding orchards up to 2 km, but the urban contribution quickly declines over this distance. We also demonstrated that our models provide a means of predicting changes in Mediterranean fruit fly density across a region. Regional scale inference from our models may be particularly useful for sites where surveillance trapping data is unavailable. With an increasing risk of fruit fly incursions from expanding urban areas into agricultural regions, it is important to understand the processes driving population connectivity to target pest management strategies. By modelling surveillance trapping data and population connectivity, we can quantify how unmanaged urban pest infestations can contribute to pest pressure in nearby commercial orchards. Such information can help pest managers quantify the risk posed by unmanaged urban infestations when designing and implementing area-wide management.

Species Composition of Fruit Flies (Diptera: Tephritidae) on Selected Fruit Crops in Northeastern Ethiopia

A study was conducted to characterize the species composition of fruit flies in South Wollo and North Wollo administrative zones of northeastern Ethiopia. Fruit flies were collected using two methods: rearing from infested mango, guava, and sweet orange fruits and trapping the adults with male lures and food-based attractants. Three fruit fly species were recovered from the fruits collected: Bactrocera dorsalis, Ceratitis cosyra, and Ceratitis capitata; in addition to these species, Ceratitis fasciventris was trapped. Bactrocera dorsalis was the most abundant species and accounted for 97.9 and 78.89% of the total trapped and emerged adults, respectively. The number of B. dorsalis and C. capitata showed a significant difference among trapping locations and attractants. The highest number of B. dorsalis was trapped with methyl eugenol at Kalu (722.2 flies per trap per week). Among the indigenous fruit fly species, C. capitata was higher at Habru which was guava and coffee-dominated habitat, whereas C. cosyra was relatively higher at Kobo which is mango dominated. More adults were trapped in male lure traps (97.03%) than in food-based attractants (2.97%). Hence, fruit fly management should focus on guava and mango crops which host all the fruit fly species, including the dominant B. dorsalis.

Direct and indirect host‐related volatile compounds attract a fruit fly parasitoid, Diachasmimorpha longicaudata

AbstractFruit fly pests (Diptera: Tephritidae) are a serious problem for fruit production and for local and international trade. Biological control is increasingly included as a pest control tool within integrated pest management (IPM) programmes, seeking to reduce pesticides and improve fruit quality. Ceratitis capitata Wiedemann, the Mediterranean fruit fly (medfly), is probably the most damaging fruit fly pest, with a global distribution and more than 200 host species. The solitary larval endoparasitoid Diachasmimorpha longicaudata Ashmead (Hymenoptera: Braconidae) is a biocontrol agent widely used against Tephritidae fruit fly pests. Previous studies showed that female wasps locate host larvae using visual, mechanical, and chemical cues. Here, we investigated the chemical basis of female parasitoid attraction to cues that guide D. longicaudata to the host, and thus unveil volatile organic compounds that might be used in IPM programmes. Female orientation to chemical cues was tested in a Y‐tube olfactometer, where attraction to C. capitata‐infested oranges, oranges with residues of larval activity, oranges infected with a green mould, and overripe oranges was confirmed. Volatiles from all these types of fruit were collected and used in gas chromatography‐electroantennographic detection (GC‐EAD) and GC‐mass spectrometry (MS) analyses. These studies allowed us to identify six candidate compounds that were present in all treated oranges but not in the control fruit (ripe and uninfested oranges): D‐limonene, acetophenone, linalool, nonanal, decanal, and eugenol. Electroantennography (EAG) showed that acetophenone, nonanal, and decanal triggered dose‐dependent responses, suggesting a relevant role in the process of host finding. Although responses to D‐limonene, linalool, and eugenol were independent of the dose, they could be involved in host location in areas with high probability of host presence. The fact that these six compounds are shared by the four behaviourally attractive sources opens new possibilities for the development of novel tools to improve biocontrol programmes.

Deep orange gene editing triggers temperature-sensitive lethal phenotypes in Ceratitis capitata

BackgroundThe Mediterranean fruit fly, Ceratitis capitata, is a significant agricultural pest managed through area-wide integrated pest management (AW-IPM) including a sterile insect technique (SIT) component. Male-only releases increase the efficiency and cost-effectiveness of SIT programs, which can be achieved through the development of genetic sexing strains (GSS). The most successful GSS developed to date is the C. capitata VIENNA 8 GSS, constructed using classical genetic approaches and an irradiation-induced translocation with two selectable markers: the white pupae (wp) and temperature-sensitive lethal (tsl) genes. However, currently used methods for selecting suitable markers and inducing translocations are stochastic and non-specific, resulting in a laborious and time-consuming process. Recent efforts have focused on identifying the gene(s) and the causal mutation(s) for suitable phenotypes, such as wp and tsl, which could be used as selectable markers for developing a generic approach for constructing GSS. The wp gene was recently identified, and efforts have been initiated to identify the tsl gene. This study investigates Ceratitis capitata deep orange (Ccdor) as a tsl candidate gene and its potential to induce tsl phenotypes.ResultsAn integrated approach based on cytogenetics, genomics, bioinformatics, and gene editing was used to characterize the Ccdor. Its location was confirmed on the right arm of chromosome 5 in the putative tsl genomic region. Knock-out of Ccdor using CRISPR/Cas9-NHEJ and targeting the fourth exon resulted in lethality at mid- and late-pupal stage, while the successful application of CRISPR HDR introducing a point mutation on the sixth exon resulted in the establishment of the desired strain and two additional strains (dor 12del and dor 51dup), all of them expressing tsl phenotypes and presenting no (or minimal) fitness cost when reared at 25 °C. One of the strains exhibited complete lethality when embryos were exposed at 36 °C.ConclusionsGene editing of the deep orange gene in Ceratitis capitata resulted in the establishment of temperature-sensitive lethal mutant strains. The induced mutations did not significantly affect the rearing efficiency of the strains. As deep orange is a highly conserved gene, these data suggest that it can be considered a target for the development of tsl mutations which could potentially be used to develop novel genetic sexing strains in insect pests and disease vectors.

Evidence that recent climatic changes have expanded the potential geographical range of the Mediterranean fruit fly

The species distributions migration poleward and into higher altitudes in a warming climate is especially concerning for economically important insect pest species, as their introduction can potentially occur in places previously considered unsuitable for year-round survival. We explore the expansion of the climatically suitable areas for a horticultural pest, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera, Tephritidae), with an emphasis on Europe and California. We reviewed and refined a published CLIMEX model for C. capitata, taking into consideration new records in marginal locations, with a particular focus on Europe. To assess the model fit and to aid in interpreting the meaning of the new European distribution records, we used a time series climate dataset to explore the temporal patterns of climate suitability for C. capitata from 1970 to 2019. At selected bellwether sites in Europe, we found statistically significant trends in increasing climate suitability, as well as a substantial northward expansion in the modelled potential range. In California, we also found a significant trend of northward and altitudinal expansion of areas suitable for C. capitata establishment. These results provide further evidence of climate change impacts on species distributions and the need for innovative responses to increased invasion threats.

Daily activity profiles over the lifespan of female medflies as biomarkers of aging and longevity.

The relationship between the early-age activity of Mediterranean fruit flies (medflies) or other fruit flies and their lifespan has not been much studied, in contrast to the connections between lifespan and diet, sexual signaling, and reproduction. The objective of this study is to assess intra-day and day-to-day activity profiles of female Mediterranean fruit flies and their role as biomarker of longevity as well as to explore the relationships between these activity profiles, diet, and age-at-death throughout the lifespan. We use advanced statistical methods from functional data analysis (FDA). Three distinct patterns of activity variations in early-age activity profiles can be distinguished. A low-caloric diet is associated with a delayed activity peak, while a high-caloric diet is linked with an earlier activity peak. We find that age-at-death of individual medflies is connected to their activity profiles in early life. An increased risk of mortality is associated with increased activity in early age, as well as with a higher contrast between daytime and nighttime activity. Conversely, medflies are more likely to have a longer lifespan when they are fed a medium-caloric diet and when their daily activity is more evenly distributed across the early-age span and between daytime and nighttime. The before-death activity profile of medflies displays two characteristic before-death patterns, where one pattern is characterized by slowly declining daily activity and the other by a sudden decline in activity that is followed by death.

An 18-day, 3 °C cold treatment effectively kills Ceratitis capitata (Diptera: Tephritidae) in kiwifruit (Actinidia spp.).

A series of experiments were carried out to develop a phytosanitary disinfestation protocol to kill Ceratitis capitata (Weidemann) (Mediterranean fruit fly, Diptera: Tephritidae) in 'Hayward' kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang and A.R. Ferguson) and 'Zesy002' kiwifruit (Actinidia chinensis Planch.). Experiments on 4 immature life stages (eggs and 3 larval instars) with treatment durations of between 5 and 18 days showed that third instars were the most tolerant to temperatures around 3 °C, with the lethal time to 99.9968% (probit 9) mortality (LT99.9968) estimated to be 17.3 days (95% confidence interval (CI) 16.4-18.2). Larvae reared and treated in 'Zesy002' were significantly more susceptible to cold treatment than those reared in 'Hayward'. A large-scale trial testing a disinfestation protocol of 3 ± 0.5 °C for 18 days treated over 500,000 third-instar C. capitata with no survivors. These results demonstrate that a cold treatment of 3.5 °C or below for 18 days induces C. capitata mortality in kiwifruit at a rate that exceeds 99.9968% with a degree of confidence greater than 99%.

Evaluation of the efficacy of X-ray irradiation on male testes of Mediterranean fruit fly using light and transmission electron microscopy

ABSTRACT The present study evaluated the efficacy of X-ray irradiation for the sterilization of Ceratitis capitata. Pupae were exposed to doses of 0 (control), 60.7, 137, 156.9, 237.7, 300.59 and 344.46 Gy to determine which dose would not affect viability of irradiated fruit flies but would result in their sterilization. Doses of 60.7 and 137 Gy were suitable as males emerging from irradiated 7-day-old pupae were 100% sterile but were otherwise viable. Light and transmission electron microscopy were used to examine the structure of normal and treated male C. capitata testes. The testes of males originating from non-irradiated pupae of C. capitata consist of a single long follicle that looks like a sac and is full of germ cells at different stages of development. In testes of males originating from irradiated pupae, the presence of lysosomes, many vacuoles, and irregular distribution of spermatogonia and spermatocytes, led to an overall slowed rate of spermatogenesis. Apparent degeneration and abnormalities of the sperms resulted in the production of non-functional sperm or to a reduction in sperm production. This study concluded that X-ray is an alternative irradiation method for the sterile insect technique used to control Mediterranean fruit fly populations.