Diel patterns of reproductive activities in the tomato fruit fly, Neoceratitis cyanescens

We describe the diurnal temporal and spatial patterns of reproductive activities (mating and ovipositing) of adult tomato fruit flies, Neoceratitis cyanescens (Bezzi) (Diptera: Tephritidae), under laboratory, field‐cage and field conditions. The distribution pattern of flies in the different habitats (host and non‐host plants) showed temporal, physiological and sexual differences. Mature females were observed to frequent host plants preferentially, particularly in the late afternoon. By contrast, immature females preferred to rest on non‐host plants throughout the day. Males frequented mainly non‐host plants but some were observed on host fruits in the morning. Mating activity took place preferentially on non‐host plants, in the morning. In laboratory cages, females showed a strong daily propensity to engage in mating behaviour; the mean percentage of mating females was 88 ± 5%. Time allotted to this activity (4 h 52 min ± 1 h 23 min in laboratory cages and at least 3 h for the mating pairs observed in the field) appeared considerable compared to the time required to satisfy feeding or oviposition activities. Except for a few ovipositing females observed in the morning, oviposition activities occurred mainly in the late afternoon.     

Factors affecting behavioural responses to visual stimuli in the tomato fruit fly, Neoceratitis cyanescens

Responses of Neoceratitis cyanescens (Bezzi) (Diptera: Tephritidae) females to visual stimuli were studied in a laboratory flight chamber. A bright orange sphere was used to investigate the effects of age, mating status and time of day on their responses. In no-choice assays, four parameters were considered: mean time before leaving the release vial, percentage of flies that visited the sphere, mean number of flights and mean time before landing on the sphere. Naive mated females first became strongly responsive to the orange sphere 6 days post-adult emergence (> 40%). The percentage of females that visited the sphere increased significantly with egg load. There were no significant differences in behavioural responses between virgin and mated mature females. In a choice situation between a yellow and an orange sphere, starved females displayed a greater propensity than well-fed females to land on the yellow sphere. Mature females were more responsive to the orange sphere when tested in the afternoon than earlier in the day. In a no-choice situation, females visited the yellow sphere as often as the orange sphere. However, the mean delay before landing was significantly greater for the yellow sphere. The results emphasize the importance of physiological condition on responses of N. cyanescens females to host-simulating visual stimuli.     

Relationships between temperature, development and survival of different life stages of the tomato fruit fly, Neoceratitis cyanescens

The development and survival of female Neoceratitis cyanescens (Bezzi) (Diptera: Tephritidae) from egg to complete ovarian maturation were studied in the laboratory at five different constant temperatures: 15, 20, 25, 30, and 35 °C. The aim of this study was to get information on the influence of temperature on pre-mature stages, as a prerequisite to optimise rearing procedures and to understand temporal and geographical patterns of fruit fly occurrence. The developmental rate of the different life stages increased linearly with increasing temperatures up to 30 °C. The fastest development of pre-mature stages was recorded at 30 °C (22±1 days) and the slowest at 15 °C (98±3 days). The day-degrees requirements (K) to complete total development were 432.6 day-degrees. Lower temperature thresholds were 11.4, 11.9, 10.0, and 11.1 °C for egg, larval, pupal stages and ovarian maturation, respectively. The number of adults obtained from an initial batch of 100 eggs reached a maximum (64) at 25 °C. At 35 °C, no adults emerged. Larval developmental time was significantly shorter in green tomato fruits than in potato tubers at 15, 20, and 25 °C. Mortality rate of larvae was higher in green tomato fruits than in potato tubers at 25 and 30 °C.     

The influence of host fruit morphology on parasitization rates in the Caribbean fruit fly,Anastrepha suspensa

Among the host fruits of the Caribbean fruit fly there are a variety of sizes and shapes. These morphological differences may influence the vulnerability of the larvae to parasites. In the laboratory, Caribbean fruit fly larvae placed in the smaller of 2 different sizes of artificial ‘fruit’ (cloth spheres filled with a diet material) were parasitized at a higher rate by the braconid,Diachasmimorpha longicaudata (Ashmead) when spheres were presented separately. However, when parasites were simultaneously presented with 6 different sizes of ‘fruit’ there was no significant relationship between size and parasitization rate. This may be due to the parasites preference to search for larvae in larger ‘fruit’. In field collections of different species of host fruit, a significant inverse correlation exists between fruit radius and rate of parasitization. However, host fruit size accounts for only about 5% of the variance in yearly parasitization rates.      

Effects of fruit fly host, fruit species, and host egg to female parasitoid ratio on the laboratory rearing of Biosteres arisanus

The host suitability of the oriental fruit fly, Bactrocera dorsalis (Hendel), for development of Biosteres arisanus (Sonan), a braconid parasitoid, was compared with three other fruit fly species, namely, Mediterranean fruit fly, Ceratitis capitata Weidemann, melon fly, Bactrocera cucurbitae Coquilett, and Malaysian fruit fly, Bactrocera latifrons (Hendel). In addition, effects of five different fruit species, namely, Carica papaya L. (solo papaya), Musa sapientum (L.) O. Ktze. (apple banana), Mangifera indica (L.) (Haden mango), Terminalia catappa (L.) (false kamani), and Citrus aurantiifolia (Christman) Swingle (common lime), on the parasitization rate of B. dorsalis and sex ratio of parasitoid progenies were evaluated. Effects of host egg to female B. arisanus ratios on parasitoid progeny yields were likewise determined. The host suitability of fruit flies for development of B. arisanus was ranked as: B. dorsalis>C. capitata=B. latifrons=B. cucurbitae. Based on percent parasitization of B. dorsalis, preference of B. arisanus females for host eggs varied with fruit species, however, preferential oviposition displayed by female parasitoids did not influence sex ratios of subsequent parasitoid progenies. Increases in host egg to female parasitoid ratios of 5:1, 10:1, 20:1, 25:1, and 30:1 corresponded with increases in parasitoid progeny yield reaching a plateau at 20:1.     

Proteomic interactions between the parasitoid Diachasmimorpha longicaudata and the oriental fruit fly,Bactrocera dorsalis during host parasitism

The oriental fruit fly, Bactrocera dorsalis, is an important agricultural pest and biological control is one of the most effective control methodologies. We conducted an investigation on the molecular response of the fruit fly to parasitism by the larval parasitoid, Diachasmimorpha longicaudata using two-dimensional gel electrophoresis and mass spectroscopy. We identified 285 differentially expressed protein spots (109 proteins) during parasitism. The molecular processes affected by parasitism varied at different time point during development. Transferrin and muscle specific protein 20 are the only two proteins differentially expressed that play a role in host immunity 24 h after parasitism. Developmental and metabolic proteins from parasitoids (transferrin and enolase) were up-regulated to ensure establishment and early development of parasitoids 48 h post parasitism. 72 h after parasitism, larval cuticle proteins, transferrin and CREG1 were overexpressed to support the survival of parasitoids while host metabolism proteins and parasitoid regulatory proteins were down-regulated. Host development slowed down while parasitoid development went up at 96 h after parasitism. All developmental, regulatory, structural, and metabolic proteins were expressed at their optimum at 120 h post parasitism. Host development was reduced, metabolism and regulatory proteins were strongly involved in the activities. The development deteriorated further at 144 h after parasitism. Enolase and CREG1 were indicators of parasitoid survival. Hexamerin and transferrin from the parasitoid was peaked at 168–216 h after parasitism, strongly indicating that parasitoid would survive. This study represents the first report that reveals the molecular players involved in the interaction between the host and parasitoid.     

Effect of larval host on life history traits of the mediterranean fruit fly,Ceratitis capitata

Summary Demographic parameters for the Mediterranean fruit fly reared on each of twenty four different hosts from sixteen different plant families are reported. These include cohort parameters of development, survival, pupal sizc, and fecundity as well as population parameters such as intrinsic rate of population increase (r) and mean generation time. Major findings include the following: i) no consistent quantitative relationships existed between r and its chief demographic determinants such as preadult developmental time and adult fecundity; and ii) few correlations existed among the cohort life history parameters themselves. The principle conclusion is that the medfly is a successful generalist frugivore because of its developmental ability to offset the effect of the value for a host-specific trait that tends to lower r with one that tends to increase r, the net result of which is to maintain a relatively high r.     

Age and host effects on clutch size in the Mexican fruit fly, Anastrepha ludens

We document individual and age-specific variation in reproductive output and clutch size of Anastrepha ludens Loew. (Diptera: Tephritidae). The influence of host size, color, and density on clutch size are also examined. Individual and groups of flies were offered artificial hosts composed of agar spheres wrapped in Parafilm. The gross reproduction rate of individual flies was 1000 eggs/female and 165 clutches/female with a range of 1 to 40 eggs/clutch. Mean clutch sizes for these females ranged from 4.5 to 10.6 eggs/clutch. The number of eggs/clutch laid by females held in groups was highly correlated with host size, ranging from about 4.4 eggs/clutch in 2 cm diameter hosts to 12.7 eggs/clutch in 11 cm hosts. Host color, host density, fly density, and fly age did not affect clutch size. This study suggests that variation among females and host size are the principal determinants of clutch size in A. ludens.

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Résumé L'examen a porté sur l'influence du polymorphisme et des modifications dues à l'âge des mouches sur la fécondité et la taille des pontes de A. ludens Loew (Dipt. Tephritidae). L'étude a concerné aussi l'influence de la dimension, de la couleur et de la densité des hôtes sur la taille des pontes. Des mouches isolées ou par groupes ont reçu des hôtes artificiels formés de sphères d'agar enveloppées dans du parafilm. La fécondité brute de femelles isolées a été de 1000 oeufs/femelle et de 165 pontes/femelle, avec une variation de 1 à 40 oeufs/ponte. La taille moyenne des pontes des différentes femelles isolées s'étalait de 4,5 à 10,6 oeufs/ponte. Le nombre d'oeufs/ponte des femelles groupées était fortement liée à la dimension de l'hôte, s'étalant de 4,4 oeufs/ponte pour des hôtes de 2 cm de diamètre à 12,7 oeufs/ponte pour ceux de 11 cm de diamètre. Ni la couleur et la densité des hôtes, ni la densité et l'âge des mouches n'ont influé sur la taille des pontes. Ces résultats suggèrent que les variabilités du comportement des femelles et de la dimension des hôtes déterminent par priorité la taille des pontes de A. ludens.

     

Water relations of the tomato during fruit growth

Fruit and stem water potentials of tomato plants were measured continuously for several days using automated psychrometers. A linear voltage displacement transducer was used to simultaneously measure diameter changes on an adjacent fruit. A strong correlation was observed between the water potential gradient of the fruit and stem, and changes in fruit diameter. Fruit diameter increased when the apoplasmic water potential gradient favoured solution flow into the fruit and fruit shrinkage occurred only when the water potential gradient was inverted. Based on our data and other published data (Ehret & Ho 1986; Lee 1989a) on phloem transport in tomato, we have concluded that low stem water potentials have an immediate and direct effect on phloem turgor; reducing the driving force for sap flow into the fruit. Since fruit water potential remained relatively constant, the diurnal variation in stem water potential was sufficient to account for the correlation with changes in fruit diameter. There are consequences with respect to predicting the accumulation of dry matter in tomato fruit.     

The role of adult learning in the acceptance of host fruit for egglaying by the Queensland fruit fly, Dacus tryoni

Evidence presented indicates that exposure of wild Queensland fruit files, Dacus tryoni (Froggatt), to a given host fruit type (e.g. pear) for 3 days causes females to attempt oviposition to a greater degree in that fruit type than in other fruit types (e.g. tomato, grape). The effects of exposure to a particular fruit type proved reversible, suggesting that D. tryoni females were capable of learning. Females exposed to pear for 3 days appeared to retain the effect of such exposure on acceptance of tomato for up to 4 days but appeared to retain the effect on acceptance of grape for less than 2 days. The possible significance of prior experience of females with a particular fruit type on future ability to discriminate among varying-quality specimens of that type is discussed.

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Résumé Les éléments apportés montrent que l'exposition de D. tryoni Froggat à un type de fruit déterminé (par exemple, la poire) pendant 3 jours, conduit la femelle à tenter de pondre à une plus haute fréquence dans ce type de fruit que dans d'autres (par example; tomate ou raisin). Les effects de l'exposition à un type particulier de fruit étant réversibles, ceci suggère que les femelles de D. tryoni sont capables d'apprentissage. Des femelles exposées à des poires pendant 3 jours ont conservé l'effet d'une telle exposition pendant 4 jours en présence de tomates, mais moins de 2 jours en présence de raisin. La discussion porte sur la signification possible de la connaissance antérieure d'un type particulier de fruit sur l'aptitude ultérieure des femelles à distinguer parmi des spécimens de ce type, mais de qualités différentes.

     

Experimental analysis of the pattern of tethered flight in the Queensland fruit fly, Dacus tryoni

ABSTRACT. The tethered flight of the Queensland fruit fly, Dacus tryoni Frogg. (Diptera, Tephritidae), was investigated, and the duration of each flight during a 2-h experimental period was recorded. The pattern of flight was analysed, and related to the age, sex and origin of the specimens, and to the availability of host fruit during the rearing of the adults. The effect of adult crowding on the pattern of flight was also briefly examined. The results indicated that the origin of the flies had little effect on the pattern of flight; male and female flies showed different trends with respect to the proportion of short flights undertaken as the flies matured; and the availability of fruit had a marked effect on the pattern of flight in recently mature flies. These data are discussed with respect to the dispersive/non-dispersive movements of the flies postulated from previously documented field data. It is suggested that there is a characteristic pattern of tethered flight, which can be related to the absence of hosts in the immediate environment, and would be likely to lead to greater dispersal under natural conditions.     

Evolutionary pattern of protein architecture in mammal and fruit fly genomes

Mutations, which can alter amino acid constitution, contribute greatly to protein evolution. However, little is reported of their pattern during protein structural evolution. We investigated the distribution of non-synonymous single nucleotide polymorphisms (nsSNPs) and insertions/deletions (indels) along mammal and fruit fly proteins. We found the nsSNPs (and d(N)) and indels increased in protein boundary regions, and this pattern is inversely correlated with the distribution of protein domain density. Additionally, synonymous substitutions (and d(S)) are reduced in 5' and 3' regions, indicating more variable protein boundaries, compared with central interior. All evidence suggests that the inner part of coding sequences (CDSs) is comparatively conserved, whereas the 5' and 3' regions, with higher evolution rates, are more variable. We assumed that due to greater frequencies of nsSNPs and indels in adaptive regions of CDSs it could be easier to ultimately alter, gain, or lose amino acids, thus becoming the front line of protein evolution.     

Biochemical mechanism on GABA accumulation during fruit development in tomato

A large amount of gamma-aminobutyric acid (GABA) was found to accumulate in tomato (Solanum lycopersicum) fruits before the breaker stage. Shortly thereafter, GABA was rapidly catabolized after the breaker stage. We screened the GABA-rich tomato cultivar 'DG03-9' which did not show rapid GABA catabolism after the breaker stage. Although GABA hyperaccumulation and rapid catabolism in fruits is well known, the mechanisms are not clearly understood. In order to clarify these mechanisms, we performed comparative studies of 'Micro-Tom' and 'DG03-9' fruits for the analysis of gene expression levels, protein levels and enzymatic activity levels of GABA biosynthesis- and catabolism-related enzymes. During GABA accumulation, we found positive correlations among GABA contents and expression levels of SlGAD2 and SlGAD3. Both of these genes encode glutamate decarboxylase (GAD) which is a key enzyme of GABA biosynthesis. During GABA catabolism, we found a strong correlation between GABA contents and enzyme activity of alpha-ketoglutarate-dependent GABA transaminase (GABA-TK). The contents of glutamate and aspartate, which are synthesized from GABA and glutamate, respectively, increased with elevation of GABA-TK enzymatic activity. GABA-TK is the major GABA transaminase form in animals and appears to be a minor form in plants. In 'DG03-9' fruits, GAD enzymatic activity was prolonged until the ripening stage, and GABA-TK activity was significantly low. Taken together, our results suggest that GAD and GABA-TK play crucial roles in GABA accumulation and catabolism, respectively, in tomato fruits.     

A theory of the pattern induced flight orientation of the fly Musca domestica

The theory presented here describes the visual orientation behavior of fixed flying insects (the fly Musca domestica) in the presence of elementary patterns. The theory, which is based on a number of experimental results, Reichardt (1973), is a phenomenological one whose main purpose is to provide an organizational framework for treating a complex phenomenon without the need of detailed assumptions about the neural mechanisms actually involved.A simple hypothesis concerning the basic structure of the pattern fixation process leads to an equivalent stochastic equation of the Langevin type, which can be linearized for simple single-stripe panoramas. A critical experiment supports these theoretical assumptions. In addition, the effect on pattern fixation behavior of adding contrast noise to the background of the panorama, is quantitatively predicted by the theory.In the more general case of a panorama consisting of many vertical stripes, the Fokker-Planck equation associated with the Langevin equation, no longer linear, is solved. Making use of an experimentally proven superposition principle, the stationary pattern fixation behavior of the fly in an arbitrary panorama consisting of a collection of vertical stripes is predicted. In this context, concepts like pseudo-invariance and phase-transition can be applied to the insects orientation behavior. The theory presented here seems to contain rich classification properties, which might provide the foundations for an understanding of more complex pattern discrimination processes.Possible extensions of the theory, as well as some similarities to human eye fixation, are also discussed.     

Temperature,humidity and depth of habitat influencing host destruction and fecundity of muscoid fly parasites

Comparisons of various strains of hymenopterous parasites,Muscidifurax raptor Girault & Sanders,M. uniraptor Kogan & Legner,M. zaraptor K. & L.,Spalangia cameroni Perkins,S. endius Walker,S. longepetiolata Boucek,S. nigra Latreille andSphegigaster sp. attackingMusca domestica L., showed that theSpalangia species consistently penetrated to the greatest depth, 4 cm, in an experimental wheat flakes habitat. Moisture influenced penetration behaviour of some species. Host destruction wrought by host-feeding and parasitization was often proportionally greater than progeny production at the lower depth, indicating that parasites searched there without finding conditions suitable for oviposition. Progeny production by all species was greater at the higher of 2 temperatures, 29 vs 21°C., but RH influenced parasitization and ♀♀ production, apparently according to strain preferences. Superiorily competitiveMuscidifurax species may be favored by comparatively cooler temperatures; this characteristic would account for their predominace in nature during cooler seasons. However, the problem of characterizing different species as to preference for certain strata of the host habitat and temperature is confounded with strain type, RH, habitat moisture and behavioral and developmental elements.     

Effect of the Cnr mutation on carotenoid formation during tomato fruit ripening

The characteristic pigmentation of ripe tomato fruit is due to the deposition of carotenoid pigments. In tomato, numerous colour mutants exist. The Cnr tomato mutant has a colourless, non-ripening phenotype. In this work, carotenoid formation in the Cnr mutant has been studied at the biochemical level. The carotenoid composition of Ailsa Craig (AC) and Cnr leaves was qualitatively and quantitatively similar. However, Cnr fruits had low levels of total carotenoids and lacked detectable levels of phytoene and lycopene. The presence of normal tocopherols and ubiquinone-9 levels in the ripe Cnr fruits suggested that other biosynthetically related isoprenoids were unaffected by the alterations to carotenoid biosynthesis. In vitro assays confirmed the virtual absence of phytoene synthesis in the ripe Cnr fruit. Extracts from ripe fruit of the Cnr mutant also revealed a reduced ability to synthesise the carotenoid precursor geranylgeranyl diphosphate (GGPP). These results suggest that besides affecting the first committed step in carotenoid biosynthesis (phytoene synthase) the Cnr mutation also affects the formation of the isoprenoid precursor (GGPP).     

Microgeographic adaptation linked to forest fragmentation and habitat quality in the tropical fruit fly Drosophila birchii

Little is known about the evolutionary implications of habitat fragmentation, although altered selection regimes could influence the genetic constitution of fragmented populations. In particular, fragmentation might lead to selection for enhanced stress resistance and tolerance of unfavorable environmental conditions. We investigated the evolutionary consequences of habitat fragmentation in Drosophila birchii flies from small fragments and the interior of large forests of northern Queensland, Australia, in three consecutive years. Evolved differences were detected in a common garden design. Flies from fragments were larger and less desiccation resistant, particularly in the first year, when they also developed faster, and had higher preadult survival under fluctuating temperatures. Furthermore, juvenile survival and adult body size were linked to a measure of habitat quality, the abundance of D. birchii in nature. The results support the hypothesis that fragmentation and habitat quality impose divergent selection. The results also bolster the conservation strategy of maintaining genetic variation for ecologically relevant traits, because persistence in fragmented habitats seems to depend on genetic variation in multiple expressed traits.     

Cyanide-resistant, ATP-synthesis-sustained, and uncoupling-protein-sustained respiration during postharvest ripening of tomato fruit

Tomato (Lycopersicon esculentum) mitochondria contain both alternative oxidase (AOX) and uncoupling protein as energy-dissipating systems that can decrease the efficiency of oxidative phosphorylation. We followed the cyanide (CN)-resistant, ATP-synthesis-sustained, and uncoupling-protein-sustained respiration of isolated mitochondria, as well as the immunologically detectable levels of uncoupling protein and AOX, during tomato fruit ripening from the mature green stage to the red stage. The AOX protein level and CN-resistant respiration of isolated mitochondria decreased with ripening from the green to the red stage. The ATP-synthesis-sustained respiration followed the same behavior. In contrast, the level of uncoupling protein and the total uncoupling-protein-sustained respiration of isolated mitochondria decreased from only the yellow stage on. We observed an acute inhibition of the CN-resistant respiration by linoleic acid in the micromolar range. These results suggest that the two energy-dissipating systems could have different roles during the ripening process.     

Effect of insectary rearing on host preference and oviposition behavior of the fruit fly parasitoid Diachasmimorpha longicaudata

Diachasmimorpha longicaudata (Ashmead) has been produced in the laboratory for >160 generations on the larvae of oriental fruit fly, Bactrocera dorsalis (Hendel), the propagation hosts raised routinely on a semi-synthetic wheat diet formulation. Choice tests using modified stinging units were conducted in the laboratory to investigate whether insectary rearing had altered the host seeking and oviposition behavior of female parasitoids. Results showed that fruit fly larvae that developed in papaya, Carica papaya L. var. solo, were less preferred for oviposition than fruit fly larvae that developed on wheat diet when both were exposed concurrently to naive D. longicaudata females (= females without prior oviposition experience). The substrates (pureed papaya or wheat diet) in which treatment larvae were exposed to parasitoids did not affect oviposition preference of gravid D. longicaudata for wheat diet-reared fruit fly larvae. Our study demonstrated the possibility that rearing in an insectary system may have modified the parasitization behavior of female D. longicaudata.     

Gut bacterial communities in the Mediterranean fruit fly (Ceratitis capitata) and their impact on host longevity

Fruit flies (Diptera: Tephritidae) harbor stable bacterial communities in their digestive system, composed mainly of members of the Enterobacteriaceae. However, the Enterobacteriaceae are not the sole community in this habitat. We examined the hypothesis that Pseudomonas spp. form a cryptic community in the gut of Ceratitis capitata, the Mediterranean fruit fly (‘medfly’). Suicide polymerase restriction PCR (SuPER PCR), a novel culture-independent technique, revealed that Pseudomonas spp. form minor, common and stable communities within the medfly's gut. These include P. aeruginosa, a known pathogen of arthropods. Experimental inoculations with high levels of P. aeruginosa reduced the medfly's longevity while inoculations with members of the Enterobacteriaceae extended the fly's life.Accordingly, we suggest that in addition to their possible contribution to the fly's nitrogen and carbon metabolism, development and copulatory success (as shown in previous studies), the Enterobacteriaceae community within the medfly's gut may also have an indirect contribution to host fitness by preventing the establishment or proliferation of pathogenic bacteria.