Destructive Fruit Research Articles

Naturally Abscised Fruitlets as a Potential Breeding Resource for Early Spring Buildup of Medfly Populations in Temperate Regions

The Mediterranean fruit fly (medfly), Ceratitis capitata, is considered one of the most destructive fruit pests worldwide. Female medflies prefer to lay eggs in ripening, ripe, or overripe fruits. In deciduous orchards of temperate regions, fruitlets (juvenile fruits) of early cultivars could represent the earliest spring resource with a potential host function for medflies. However, little is known about the medfly female’s ability to ovipositing and complete breeding in fruitlets. To clarify the possible role of fruitlets, the suitability of key-host fruitlets for the oviposition of medflies and the further development of immature stages were examined in laboratory conditions and an attempt was made to assess the degree of infection of fruitlets collected in the field. Additionally, the development of the overwintering medfly population and the putative use of fruitlets as a resource for early population growth were simulated using the PESTonFARM model optimized to reflect specific features of medfly biology and behavior. Our laboratory data demonstrate that nectarine and pear fruitlets can support the full development of medfly offspring. However, no medfly pupae were obtained from a sample of 14,000 fruitlets collected at the farm. The simulation showed that the sample number needed to detect with at least 95% certainty rare cases of medfly pupae or adults emerging from infected fruitlets is several tens of thousands, which is several times more than the actual number of fruitlets used in our study. Our research suggests that the fruitlets of some cultivated fruit species can potentially constitute a viable food resource for the development of the earliest generation of spring medflies, with implications for medfly Integrated Pest Management (IPM).

Olfactory receptors in Bactrocera species for sustainable fruit fly management: A review and future perspectives

AbstractMolecular studies on odorant receptors (ORs), odorant‐binding proteins (OBPs) and the functioning of the receptor and pheromone signal transduction in fruit fly Bactrocera species have expanded exponentially during the past few decades. OBPs contribute to the sensing of the olfactory system (OS) via the transduction of odorants through the sensillum lymph. However, ORs, a family of G‐protein‐coupled receptors in Bactrocera and various other species, exhibit heightened responsiveness to multiple chemical odours such as hormones, sensory stimuli and neurotransmitters. The apparent mechanism involves a combinatorial code encompassing both peripheral and antennal lobe processing, facilitating the reception of sexual pheromones and environmental cues. The OS is specifically designed to recognize and process information from volatile chemical signals, and these chemical signals play an important function in various flies. Insects rely on these chemicals to navigate and comprehend their surroundings. A mature insect OS is composed of two pairs of sensillae‐covered palps, antennae and two primary pairs of olfactory appendages on the anterior head. It has been shown that chemosensory gene families contribute in odour perception. These include various neuroreceptor families, such as OBPs, chemosensory proteins and sensory neuron membrane proteins. Additionally, there are three divergent chemoreceptors, namely ORs, ionotropic receptors and gustatory receptors. Methods based on systematic biology, molecular biology and bioinformatics tools have rapidly emerged to investigate the insect communication systems and provide new insights for the management of many agricultural pest. Several aromatic compounds, including semiochemicals and pheromones, have been employed to defend crops and animals from destructive fruit flies and other invasive and frugivorous species. To promote the expansion of the cropping system, the utilization of phytochemical lures can be convenient for sustainable agriculture production and enhance food security. Hence, this review examined the state of the art in chemical communication of insects with a focus on fruit fly pest species to identify OS and their semiochemical receptors, protein receptors and chemosensory receptors (CSRs), as well as their practical applications for biological control and integrated pest management are highlighted.

To Evaluate The Bioefficacy Of Several Insecticides Against The Brinjal Shoot AndFruit Borer (Leucinodes Orbonalis Guen.)

During Kharif 2022, an experiment was carried out in the brinjal field (Cultivar- Makra) at the Central Research Farm of Bidhan Chandra Krishi Viswavidyalaya, Gayeshpur, Nadia, West Bengal, to investigate the field efficiency of several pesticides against the brinjal shoot and fruit borer. Nine treatments (including control) i.e., Diflubenzuron+Deltamethrin 20% WP + 2% SC @ 2.25 ml/3L, Spinosad 45 SC @ 0.1ml/3L, Indoxacarb 14.5 SC @ 0.3 ml/3L, Diflubenzuron 25% WP @ 2.4 ml/3L, Deltamethrin 2.8% EC @ 2.13 ml/3L, Cypermethrin+Quinalphos 3%+20% EC @ 3.6 ml/3L, Deltamethrin+Triazophos 1% WP+35% EC @ 7.5 ml/3L, Emamectin Benzoate 5 SG @ 0.20 ml/3L were imposed with three replications in RBD. All the insecticidal treatments were significantly superior to the untreated control. Spinosad 45 SC was discovered to be the best-performing pesticide treatment against shoot and fruit borer with the lowest percentage of fruit loss (10.04%). Deltamethrin 2.8% EC was the poorest effective treatment when compared to the other treatments because it generated the highest fruit destruction (13.88%). In terms of yield Spinosad 45 SC performed well than all other treatments (227.05 q/ha) and Deltamethrin 2.8% EC was the lowest (176.10 q/ha).

Maturity, Ripening and Quality of ‘Donghong’ Kiwifruit Evaluated by the Kiwi-Meter™

Traditional destructive fruit assessment methodologies are currently being replaced by non-destructive alternatives. The Kiwi-Meter™ is promoted as a non-destructive device for assessment of kiwifruit maturation and ripening. In this study, three trials evaluated the feasibility of using the Kiwi-Meter and its IAD™ index data for monitoring maturation, ripening, and quality of Actinidia chinensis var. chinensis ‘Donghong’ kiwifruit. The findings from the trials suggest that the Kiwi-Meter provides a non-destructive tool for measuring the color or chlorophyll content of the outer tissues of ‘Donghong’ kiwifruit. Since the timing of harvest of kiwifruit is not determined solely by flesh color, the utility of the Kiwi-Meter in any wider evaluation of fruit maturation (or ripening or quality) is dependent on there being a strong association between other fruit characteristics of interest with flesh color. The ‘Donghong’ fruit used in this trial degreened fully before ripening and thus the Kiwi-Meter could not provide a measure of maturation, ripening, or fruit quality. It is concluded that the Kiwi-Meter can assess fruit for flesh color, although even for this purpose, it must be considered that the IAD measurement may be limited to only the outer area of the fruit flesh.

Evaluation of insecticidal activity of Lavandula coronopifolia essential oil against the Mediterranean fruit fly Ceratitis capitata Wiedemann (Diptera: Tephritidae)

The present investigation was aimed to assess the toxicity of Lavandula coronopifolia (Lamiaceae) essential oil (EO) against adult Mediterranean fruit fly. Ceratitis capitata (Wiedemann) (Diptera Tephritidae) is one of the most destructive fruit pests in Morocco.Essential oil was extracted from leaves of lavender (L. coronopifolia) by hydrodistillation and analyzed by GC and GC/MS. The main compound is carvacrol (48.9%) followed by E-caryophyllene (10.8%) and caryophyllene oxide (7.7%).The EO was examined in the laboratory for 7 days to assess their activity against Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) adults by ingestion toxicity. We also conducted oviposition bioassay in the laboratory, testing the oviposition deterrence of essential oils.The oil showed 75% mortality of adults at the concentration of 150 µl/g after 24 h of exposure. Great differences in insect mortality were observed depending on the sex of the insects, oil concentrations and exposure time.The ingestion toxicity potential of L. coronopifolia on adults was higher (LC 50 = 86.34 µl/g, LC 95 = 236.07 µl/g) and also, deterred significantly the oviposition by C. capitata, reducing the number of eggs laid by about 94% compared with the controls for the concentration of 55µl/g.Results suggested that L. coronopifolia EOs may have potential as a control agent against this major stored product insect.

Sublethal Dose of β-Cypermethrin Impairs the Olfaction of Bactrocera dorsalis by Suppressing the Expression of Chemosensory Genes.

Simple SummaryThe oriental fruit fly, Bactrocera dorsalis, is a pest that causes huge economic losses in the fruit and vegetable industry. β-cypermethrin has been widely used in the orchard to control this major pest. According to a previous study, the oriental fruit fly developed significant resistance against β-cypermethrin in fields, which indicated that the oriental fruit fly has been exposed to sublethal concentrations of β-cypermethrin in the field for a long time. However, the sublethal effect and its mechanism are still unclear. In our present study, after treatment with sublethal concentrations of β-cypermethrin, the olfaction was disrupted significantly and the chemosensory genes were suppressed obviously. Our data demonstrated that the sublethal dose of β-cypermethrin impairs the olfaction of the pest insects by suppressing the expression of chemosensory genes, which provided theoretical guidance for the rational use of pesticides in fields.The oriental fruit fly, Bactrocera dorsalis, is one of the most destructive fruit insect pests. β-cypermethrin has been widely used in the orchard to control this major insect. Based on the resistance monitoring in 2011, B. dorsalis developed significant resistance against β-cypermethrin in fields. This indicated that the B. dorsalis has been exposed to sublethal concentrations of β-cypermethrin in the field for a long time. Thus, it is urgent to understand the sublethal effects of β-cypermethrin on this fly to guide the rational use of an insecticide. According to the olfactory preference assays and electroantennogram (EAG) recording, the B. dorsalis after β-cypermethrin exposure (LD30 = 10 ng/fly) severely decreased the ability to perceive the tested odorants. Moreover, we then performed quantitative real-time PCR and found the chemosensory genes including odorant receptor co-receptor (BdorORco) and ionotropic receptor co-receptors (BdorIRcos) were obviously suppressed. Our results demonstrated that the sublethal dose of β-cypermethrin impairs the olfaction of the pest insects by suppressing the expression of chemosensory genes (BdorORco and BdorIRcos), which expanded our knowledge of the sublethal effects of the pesticide on insects.

Bacterial Symbionts in Ceratitis capitata.

Simple SummaryThe Mediterranean fly (Medfly), Ceratitis capitata, is considered one of the world’s most destructive fruit pests, as it can attack commercially important fruit, thus causing considerable economic damages, estimated to be more than 2 billion dollars annually. The yield reductions are mainly due to the damage incurred when larvae feed directly on the pulp, inducing the premature fruit drop. Additionally, oviposition holes facilitate secondary fungal and bacterial infections, further reducing the yields. Integrated pest management (IPM) strategies for medfly control are highly dependent on the use of insecticides, which, however, pose environmental concerns. Alternative strategies include the Sterile Insect Technique (SIT), which aims to eliminate or suppress pest insects without using pesticides. Lately, the medfly microbiota has been explored to develop new control strategies for insect pests and insect vectors. Here, we report the characterization of the microbial communities associated with selected organs of three different populations of C. capitata to identify possible candidates for a Symbiotic Control approach. Our findings provide new knowledge about the microbiota associated with C. capitata and stress the characterization of microbial symbionts as possible tools for a Symbiotic Control approach to implementing the pest management programs.Ceratitis capitata (Diptera: Tephritidae) is responsible for extensive damage in agriculture with important economic losses. Several strategies have been proposed to control this insect pest including insecticides and the Sterile Insect Technique. Traditional control methods should be implemented by innovative tools, among which those based on insect symbionts seem very promising. Our study aimed to investigate, through the 16S Miseq analysis, the microbial communities associated with selected organs in three different medfly populations to identify possible candidates to develop symbiont-based control approaches. Our results confirm that Klebsiella and Providencia are the dominant bacteria in guts, while a more diversified microbial community has been detected in reproductive organs. Concertedly, we revealed for the first time the presence of Chroococcidiopsis and Propionibacterium as stable components of the medfly’s microbiota. Additionally, in the reproductive organs, we detected Asaia, a bacterium already proposed as a tool in the Symbiotic Control of Vector-Borne Diseases. A strain of Asaia, genetically modified to produce a green fluorescent protein, was used to ascertain the ability of Asaia to colonize specific organs of C. capitata. Our study lays the foundation for the development of control methods for C. capitata based on the use of symbiont bacteria.

Fruit Fly Larval Survival in Picked and Unpicked Tomato Fruit of Differing Ripeness and Associated Gene Expression Patterns.

Simple SummaryTephritid fruit flies are major pests to a wide range of fruits and vegetables. Female flies lay their eggs into the fruit where the resultant larvae cause damage and yield loss. To replace pesticide-based controls with more sustainable management approaches, we need to develop new generation technologies. Enhancing fruit resistance is a promising alternative but it has received limited research attention. In this study, we examined larval survival and gene expression changes of B. tryoni larvae and tomato fruit while the fruits were in different picking statuses (unpicked vs. picked) and ripening stages (colour break vs. fully ripe). We assessed larval survival in two time points of 48 h and 120 h after inoculation. The fruit picking status and ripening stage had a significant effect on B. tryoni larval survival at 120 h. The gene expression patterns were not affected by picking status; however, insect detoxification genes and plant-induced defence genes were upregulated across the treatments. Overall, we anticipated the lack of conformity between larval survival and gene expression as a result of overlooked candidate genes or critical sampling time points.The larvae of frugivorous tephritid fruit flies feed within fruit and are global pests of horticulture. With the reduced use of pesticides, alternative control methods are needed, of which fruit resistance is one. In the current study, we explicitly tested for phenotypic evidence of induced fruit defences by running concurrent larval survival experiments with fruit on or off the plant, assuming that defence induction would be stopped or reduced by fruit picking. This was accompanied by RT-qPCR analysis of fruit defence and insect detoxification gene expression. Our fruit treatments were picking status (unpicked vs. picked) and ripening stage (colour break vs. fully ripe), our fruit fly was the polyphagous Bactrocera tryoni, and larval survival was assessed through destructive fruit sampling at 48 and 120 h, respectively. The gene expression study targeted larval and fruit tissue samples collected at 48 h and 120 h from picked and unpicked colour-break fruit. At 120 h in colour-break fruit, larval survival was significantly higher in the picked versus unpicked fruit. The gene expression patterns in larval and plant tissue were not affected by picking status, but many putative plant defence and insect detoxification genes were upregulated across the treatments. The larval survival results strongly infer an induced defence mechanism in colour-break tomato fruit that is stronger/faster in unpicked fruits; however, the gene expression patterns failed to provide the same clear-cut treatment effect. The lack of conformity between these results could be related to expression changes in unsampled candidate genes, or due to critical changes in gene expression that occurred during the unsampled periods.

Prediction of potential economic impact of Bactrocera zonata (Diptera: Tephritidae) in China: Peaches as the example hosts

• Bactrocera zonata is among the most destructive fruit fly species throughout the world. • @RISK and Monte Carlo simulation model were used to predict economic losses. • Under nil management, B. zonata would cause 0.82–3.07 billion dollars in China. The peach fruit fly (PFF), Bactrocera zonata (Diptera: Tephritidae), is among the most destructive Bactrocera fruit fly species in Asia and Africa. The peach fruit fly is currently absent from China but has high risk of invasion to China. This study primarily quantifies the direct potential economic impact of B. zonata in China using Monte Carlo simulation model, taking peaches as the example hosts. The results showed that under nil management scenario, the potential economic loss in China caused by B. zonata would be 0.82–3.07 billion dollars (90% confidence level), and potential savings after management will be 0.20–1.00 billion dollars (90% confidence level). Quarantine measures against B. zonata and field control should be strengthened to prevent its introduction and reduce the potential economic impact in China.

CRISPR/Cas9 mutagenesis abolishes odorant-binding protein BdorOBP56f-2 and impairs the perception of methyl eugenol in Bactrocera dorsalis (Hendel)

Olfaction underpins many insect behaviors, such as foraging, host location, mating, and predator avoidance. In the first step of insect olfaction, odorant-binding proteins (OBPs) bind hydrophobic odorants and transport them to odorant receptors. Methyl eugenol (ME) is a powerful attractant for mature males of the oriental fruit fly Bactrocera dorsalis (Hendel), one of the most destructive fruit pests. The underlying molecular mechanism is unclear, but there is in vitro evidence that BdorOBP56f-2 is involved in ME perception. We used microscale thermophoresis to confirm that BdorOBP56f-2 directly binds ME with strong affinity in vitro. We then used CRISPR/Cas9 to knock out the BdorOBP56f-2 gene, allowing us to establish a homozygous mutant B. dorsalis line. The electroantennogram response and behavioral attraction to ME were significantly reduced in the mutant, providing in vivo evidence that BdorOBP56f-2 is necessary for efficient ME perception. Our results offer insight into the molecular mechanism of ME perception in B. dorsalis and provide a theoretical basis for the functional analysis of other OBPs.

Phenazine-1-carboxylic Acid Produced by Pseudomonaschlororaphis YL-1 Is Effective against Acidovorax citrulli.

The bacterial pathogen Acidovorax citrulli causes the destructive fruit blotch (BFB) on cucurbit plants. Pseudomonas chlororaphis YL-1 is a bacterial strain isolated from Mississippi soil and its genome harbors some antimicrobial-related gene clusters, such as phenazine, pyrrolnitrin, and pyoverdine. Here, we evaluated the antimicrobial activity of strain YL-1 as compared with its deficient mutants of antimicrobial-related genes, which were obtained using a sacB-based site-specific mutagenesis strategy. We found that only phenazine-deficient mutants ΔphzE and ΔphzF almost lost the inhibitory effects against A. citrulli in LB plates compared with the wild-type strain YL-1, and that the main antibacterial compound produced by strain YL-1 in LB medium was phenazine-1-carboxylic acid (PCA) based on the liquid chromatography-mass spectrometry (LC-MS) analysis. Gene expression analyses revealed that PCA enhanced the accumulation of reactive oxygen species (ROS) and increased the activity of catalase (CAT) in A. citrulli. The inhibition effect of PCA against A. citrulli was lowered by adding exogenous CAT. PCA significantly upregulated the transcript level of katB from 6 to 10 h, which encodes CAT that helps to protect the bacteria against oxidative stress. Collectively, the findings of this research suggest PCA is one of the key antimicrobial metabolites of bacterial strain YL-1, a promising biocontrol agent for disease management of BFB of cucurbit plants.

Sterile Insect Technique Programme against Mediterranean Fruit Fly in the Valencian Community (Spain).

Simple SummaryThe Mediterranean fruit fly, Ceratitis capitata (Wied.), is one of the most destructive fruit pests in the world. In the Valencian Community, it has become a key pest affecting many fruits, but mainly citrus, the most important crop cultivated. Traditionally, control of C. capitata has been based on the use of insecticides. In line with the trend in recent years to minimize the use of insecticides and promote environment-friendly techniques, in 2007 the Department of Agriculture of Valencia implemented an area-wide integrated pest management (AW-IPM) programme for the suppression of C. capitata, in which the sterile insect technique (SIT) is the primary method of application integrated with other suppression methods. As a result, there has been a large reduction in the aerial spraying of insecticides as well as a growth trend in exports of citrus and fresh fruits from the Valencian Community in recent years.The Mediterranean fruit fly, Ceratitis capitata (Wied.), is an endemic pest in fruit-growing areas of the Spanish Mediterranean coast. In the Valencian Community, it represents a serious problem in the cultivation of citrus and numerous species of fruit, such as peach, cherry, apricot, persimmon, etc. For over 50 years, the Department of Agriculture of Valencia has led, promoted, and carried out a C. capitata control programme to protect crops, especially citrus fruits, because this community is the largest national producer and the leading region for fresh citrus exports in the world. Traditionally, pest control has been based on the use of insecticides. However, a reduction of more than 90% of a target wild population was achieved in the frame of a pilot integrated pest management (IPM) project based on the sterile insect technique (SIT), which was implemented from 2003 to 2006. Based on this successful result, in 2007 the Department of Agriculture of Valencia initiated an area-wide integrated pest management (AW-IPM) programme for the suppression of C. capitata, using the SIT as the primary control method. Complementary activities are implemented periodically in hotspots and during different time periods depending on the pest population dynamics. As a result, there has been a reduction of more than 90% in the use of insecticides by aerial means to control C. capitata, as well as a growth trend in exports of citrus and fresh fruits from the Valencian Community in recent years. This paper provides a historical review of the Valencian programme and briefly describes how technological innovations and decision-making tools have contributed to programme efficiency.

Long‐term automatic trap data reveal factors affecting diurnal flight patterns of the Mediterranean Fruit fly

AbstractMediterranean Fruit Fly (medfly), Ceratitis capitata (Wiedemann), is considered to be one of the most destructive fruit insect pests throughout the world. In recent years, the temporal dynamics of the medfly have been extensively studied by season, and, to a lesser extent, on a daily basis. We exploited, for the first time, a sequential automatic medfly male trapping system, in combination with climate data, to characterize diel flight patterns of male medflies trapped. The process was carried out in four commercial citrus fields over three growing seasons. Results showed that throughout the year, medfly flight activity began 4–6 hr after sunrise and peaked up to 2 to 3 hr before sunset. Generalized additive models (GAM) of the 934 days sampled revealed that in the fall, the diurnal flight activity was unimodal, that is, it began increasing at noon, peaking in the afternoon. By contrast, in the spring and summer, the diurnal flight activity exhibited a bimodal pattern, decreasing at midday. GAMs also revealed that hour after sunrise and temperature influenced medfly captures, with the former the more dominant factor. Thus, photophase significantly impacted the medfly's diurnal flight activity in each season. This study demonstrated that automatic traps that timestamp each capture are a primary research tool in insect flight activity studies that contributes to understanding diurnal insect activity within the growing season.

Artificial diet development for mass rearing and its effect on the reproduction of yellow peach moth, Conogethes punctiferalis (Guenée)

AbstractYellow peach moth, Conogethes punctiferalis (Guenée) (Lepidoptera: Crambidae), is a very destructive fruit borer in Eastern Asia and Australia. A successful artificial diet and rearing protocol are urgently needed for its biological control and research. In this study, we developed and assessed four artificial diets: AD‐1, AD‐2, AD‐3 and AD‐4, for rearing yellow peach moth larvae. AD‐1 is effective supplements, leading to the larval survival rate of 82.05%, percentage of pupation 79.48%, mean pupa weight of 76.53 mg, emergence rate of 95.25%, and an adult fecundity rate of 121 eggs/female. Using it to feed can shorten the whole generation developmental period to 33 days. Based on this diet AD‐1, we also develop a suitable mass rearing method. During the larval stages providing three‐ to four‐time fresh diet can keep a healthy larval colony.

Mediterranean Fruit Fly Ceratitis capitata (Diptera: Tephritidae) Eggs and Larvae Responses to a Low-Oxygen/High-Nitrogen Atmosphere.

Simple SummaryMany chemicals have been removed from registration for the postharvest treatment of insect pests due to consumer/environmental safety and phytotoxicity. There is very limited operation for international trade purposes, particularly for management of Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae) on harvested fruit. Therefore, the non-chemical method is being considered for postharvest treatment of fruit. This study explored and evaluated Medfly response to low-oxygen and high-nitrogen treatment. The results will guide the development of a novel postharvest strategy and the approach to controlling this destructive fruit fly and other pests.The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is one of the most damaging horticultural insect pests. This study used a low-oxygen/high-nitrogen bioassay to control C. capitata. Two low-oxygen treatments were applied (0.5% O2 + 99.5 N2 and 5% O2 + 95% N2) to C. capitata eggs and 1st, 2nd and 3rd instar larvae from 0 to nine days on a carrot diet at 25 °C; 70—75% RH. The pupariation, adult emergence, and sex ratios of survived flies were examined. The results demonstrate that increased mortality of all tested life stages correlated with increased exposure times at both levels of low-oxygen treatments. Complete control of eggs was achieved after eight days and nine days for larvae using 0.5% O2 at 25 °C; 70–75% RH. The 3rd instar was the most tolerant stage, while the egg was the most susceptible stage to the low-oxygen environment. There were no significant differences in sex ratios between emerged adults after low-oxygen and control treatments. The present work demonstrates and confirms the mortalities of C. capitata caused by low-oxygen treatment, which may help develop new postharvest strategies to control this destructive fruit fly pest.

Community responses to biosecurity regulations during a biosecurity outbreak: An Auckland, New Zealand Case Study

ABSTRACT The destructive Queensland fruit fly (QFF), known to attack export varieties of New Zealand grown primary horticultural produce was discovered in February 2015 in the suburb of Grey Lynn, Auckland, New Zealand, resulting in a biosecurity crisis. Invasion ecology theory was used to understand measures put in place by the authorities in the community to control its spread. Community members in the fruit fly affected area were invited to take part in research. Seven different questions related to the QFF and wider environmental issues were the focus during interviews. Results showed that although the community cooperated with the authorities by following strict guidelines such as restricting the movement of QFF host material. Loss of privacy, a lack of information about the QFF and unfamiliarity with the term biosecurity were some issues reported by the community. Education, coupled with effective marketing about biosecurity, may increase community involvement in the biosecurity cause.

Effect of tomato fruit cultivar and ripening stage on Bactrocera tryoni (Froggatt) egg and larval survival

AbstractIn studies of frugivorous tephritids, determining when offspring (i.e. egg and three larval instars) mortality occurs within the fruit can greatly improve the mechanistic understanding of the fly/host interaction. Previous research has demonstrated that the Queensland fruit fly, Bactrocera tryoni, has differential offspring performance in two tomato cultivars Cherry and Roma, but when juvenile mortality was occurring was not determined. We examined B. tryoni egg and larval survival in three different ripening stages (immature‐green (IG), colour‐break (CB) and fully‐ripe (FR)) of Cherry and Roma tomato cultivars through destructive fruit sampling at 72 and 120 hr for eggs, and 48 (1st instar), 96 (2nd instar) and 120 hr (3rd instar) after fruit inoculation with neonates for larvae. Cultivar and ripening stage had no significant effect on egg survival, nor larval survival at 48 hr: the overall percentage of egg survival was at least 80% across all treatments, while 1st‐instar larval was less than 52% across all treatments. In immature‐green tomatoes of both varieties, nearly all mortality occurred during the first and second instars, but at 96 and 120 hr, there were significant interaction effects between cultivar and ripening stage on larval survival. In both colour‐break Cherry and Roma tomatoes, there was significant larval mortality between 96 and 120 hr. However, in fully‐ripe Cherry, no further significant larval mortality happened after 48 hr, while in fully‐ripe Roma significant larval mortality occurred between the first and second larval instars but not thereafter. The difference in timing of larval mortality with ripening stage provides indirect evidence of active fruit defence which is strongest in immature‐green fruit, less in colour‐break fruit and absent in fully‐ripe fruit.

The general odorant receptor GmolOR9 from Grapholita molesta (Lepidoptera: Tortricidae) is mainly tuned to eight host-plant volatiles.

Grapholita molesta is one of the most destructive fruit pests distributed worldwide. Odorant receptors (ORs) located on the dendritic membrane of chemosensory neurons are deemed to be key molecules for sensing exogenous chemical signals. In this study, GmolOR9, a general OR from G. molesta, was functionally characterized. Quantitative real-time polymerase chain reaction revealed that GmolOR9 was more highly expressed in adults than in other stages, including eggs, larvae, and pupae. GmolOR9 expression was highly significantly more in the antennae of females than in those of males, and the highest level occurred in the antennae of 3-day-old female adults. GmolOR9 was broadly tuned to eight of 47 odorant components tested, including (Z)-3-hexenyl acetate, butyl propionate, ethyl hexanoate, ethyl heptanoate, 1-hexanol, (Z)-3-hexenol, 2-ethyl-1-hexanol, and linalool, by in vitro heterologous expression. Furthermore, electroantennogram responses indicated that the effects of dsOR9-injected females to (Z)-3-hexenyl acetate dramatically decreased. These results suggested that GmolOR9 might be involved in detecting host-plant volatiles. Moreover, (Z)-3-hexenyl acetate might serve as a potential attractant for the biological control of G. molesta.

New data on Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) from Bulgaria

The Mediterranean fruit fly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae) is considered to be one of the world’s most destructive fruit pests because of its global distribution, wide host range and rapid dispersal. In the period 1956–2006, transient populations of the pest have been reported regularly in Bulgaria. The Bulgarian Food Safety Agency (BFSA) initiated monitoring of C. capitata in 15 regions of the country. The surveys were conducted during the period 2013–2018, using Jackson traps with attractant trimedlure and Tephri traps with Biolure. The presence of adults of C. capitata was confirmed in peach, apple and mixed orchards, as well as in private yards at five locations in southern and south-eastern Bulgaria: Blagoevgrad, Kyustendil, Pazardzhik, Plovdiv and Sliven. The results from the five-year monitoring showed a variable abundance of C. capitata adults captured in different years and localities. The highest mean captures were recorded in 2014 (195) and 2018 (422), no specimen of the C. capitata was found in 2017. In 2018 the most abundant captures were from fruit gardens in Plovdiv (297♀;65♂) and Sliven (18♀; 22♂). Over the entire study period, the lowest rate of adult captures was in July and August (only a few individuals in traps in each region). The population abundance began to increase at the beginning of mid-September and a peak was observed at the beginning of mid-October. The results on the seasonal population fluctuations obtained are similar to data from neighbouring countries: northern Greece, Montenegro, Croatia, Romania, and Turkey.

Making males in a fruit fly pest

Sex Determination The Mediterranean fruit fly or Medfly ( Ceratitis capitata ) is a global and highly destructive fruit pest. Meccariello et al. identified the master gene for male sex determination on the Y chromosome of Medfly and named it Maleness-on-the-Y ( MoY ) (see the Perspective by Makki and Meller). Flies of each sex were transformed into the other sex by genetic manipulation, and crosses of transformed files generated male and female progeny. MoY is functionally conserved in the olive fruit fly and in the invasive oriental fruit fly. This discovery has potential for insect genetic control based on mass release of sterile males and future strategies based on gene drive. Science , this issue p. [1457][1]; see also p. [1380][2] [1]: /lookup/doi/10.1126/science.aax1318 [2]: /lookup/doi/10.1126/science.aaz0217