Fly Quality Research Articles

Fruit Bagging: An Approach for Control of Fruit Fly Infestation and Quality Improvement in Guava

This study executed at experimental site of Horticultural Research Institute, Faisalabad (central Punjab) during March- July 2020-2021 to scrutinize the impact of fruit bagging to control fruit fly infestation and overall quality of guava fruit. Three bagging materials viz. butter paper, brown paper (Chinese), non-woven selected for the research purpose and unwrapped fruits were taken as control treatment (To). The research was planned according to randomized complete block design (RCBD) replicated thrice. All the treatments exhibited significant impact on different traits evaluated. Enhanced fruit firmness, fruit size, ascorbic acid contents and fruit weight noted in wrapped fruits in comparison to un-wrapped fruit. Fruits attained maximum size (3108.25mm2) and weight (133.25a g) under brown paper bag followed by non-woven bag (3091mm2) and (131g) respectively. Total soluble solid (TSS) contents of the fruit were observed maximum (10.18 Brix) in non-woven bag whereas highest titratable acidity (0.77%) was recorded under control treatment. Highest ascorbic acid contents (214.25mg /100g) were recorded in non-woven bag. Disease incidence (2.25%) and fruit fly infestation (2.13%) were found minimum in non-woven bag. Among all the treatments, non-woven material was observed to be the best to control fruit fly infestation as well as overall improvement in Guava fruit quality.

Modulation of the Irrigation Practices in Croatia for More Sustainable Olive Growing

Olive groves in the Mediterranean may lose production sustainability because of their vulnerability to climatic change. Irrigation is an important measure that could significantly affect fruit yield, olive fruit fly infestation, and oil characteristics. The aim of paper was to compare the regulated deficit irrigation with different water management practices, in consecutive years, in two locations in Zadar County (Croatia), affecting fruit morphology, olive fruit fly infestation, and quantity and quality of the extracted Coratina cultivar oil. Treatments, namely C—rainfed, T1—deficit irrigation (produce’s practice), T2—regulated deficit irrigation, and T3—full irrigation (100% ECTO), were established. Irrigated treatments had a positive effect on all morphological characteristics of the fruit. The pulp mass, independently of the year, increased in irrigated treatment (ranging from 1.04 to 1.65 in C to 2.25 and 2.30 in the irrigated treatments) and resulted in a higher oil content on a fresh weight basis (ranging from 16.39% to 17.85% in C to 19.48% to 23.26% in the irrigated treatments). However, fruit yield per tree was only location-dependent. When olive fruit fly presence was high, fruit infestation was greatest in the irrigated compared to the rainfed treatment. According to quality parameters, all oils were classified as EVOO. Individual phenols were influenced by irrigation, while the composition of fatty acids was more influenced by location than treatment. The sensory characteristics of the resulting oil were slightly reduced compared to rainfed treatment. The results indicate that regulated deficit irrigation benefits water use sustainability without compromising the quality of the oil.

Reduced quality parameters in adult Queensland fruit fly (Bactrocera tryoni) after pupal irradiation and transportation

AbstractSterile insect technique is an effective tool to manage a range of pest insects, including the true fruit flies (Diptera: Tephritidae). As part of the process, pupae are dispatched from a mass‐rearing facility for several hundred km to a rearing out centre typically located near the release sites. Transportation of Queensland fruit fly (Qfly), Bactrocera tryoni (Froggatt), pupae from mass production facilities to field release sites is known to negatively affect fly quality. To determine which quality parameters are affected, we assessed adult emergence, flight ability, and rate of fliers between irradiated and non‐irradiated flies that were or were not transported long distance. Pupal weight was not affected by irradiation or transport. We found that transportation and irradiation of pupae resulted in a decrease in percentage fly emergence, flight ability, and fliers. Transportation and irradiation both resulted in 8% reduction in emergence of flies. Additionally, we found that transportation resulted in an increase in the rate of deformity by 65% and irradiation could increase deformity by 75%. Compounding these losses, both transportation and irradiation resulted in the decline of number of fliers by approximately 23% each.

Determining the Sterilization Doses under Hypoxia for the Novel Black Pupae Genetic Sexing Strain of Anastrepha fraterculus (Diptera, Tephritidae).

Simple SummaryThe sterile insect technique is an environmentally-friendly method that can be used to manage populations of the South American fruit fly Anastrepha fraterculus, but its sterilizing doses have been determined only under normoxia. To maintain sterile male fly quality without jeopardizing sterility, a strategy of applying the radiation dose under an oxygen-reduced atmosphere is commonly used. Therefore, this study tested a range of gamma radiation doses under hypoxia on pupae from a bisexual strain and a novel genetic sexing strain (GSS) of A. fraterculus. Four types of crosses between irradiated flies under hypoxia and nonirradiated flies of the bisexual strain were set to assess sterility for each strain and radiation dose. For males from both strains, the effect of radiation dose on the percentage of egg hatch, egg-to-pupa recovery, and recovery of adults were determined. A dose of 74 Gy reduced egg hatch by 99% regardless of the male strain and was considered the sterilizing dose. The fertility of irradiated females and development of their offspring were severely affected, even at low doses under hypoxia, and no eggs were laid with doses above 50 Gy.A common strategy used to maintain sterile fly quality without sacrificing sterility is to irradiate the insects under an oxygen-reduced atmosphere. So far, sterilizing doses for the South American fruit fly Anastrepha fraterculus have only been determined under normoxia. Our study reports for the first time the dose-sterility response under hypoxia for two different A. fraterculus strains. The pupae were derived from a bisexual strain (a Brazilian-1 population) and a recently developed genetic sexing strain (GSS-89). Two hours prior to irradiation, pupae were transferred to sealed glass bottles and irradiated when oxygen concentration was below 3%. Four types of crosses with nonirradiated flies of the bisexual strain were set to assess sterility for each radiation dose. For males from both strains, Weibull dose–response curves between radiation doses and the proportion of egg hatch, egg-to-pupa recovery, and recovery of adults were determined. The GSS males revealed high sterility/mortality levels compared to males from the bisexual strain at doses < 40 Gy, but a dose of 74 Gy reduced egg hatch by 99% regardless of the male strain and was considered the sterilizing dose. The fertility of irradiated females was severely affected even at low doses under hypoxia.

Disruption of duplicated yellow genes in Bactrocera tryoni modifies pigmentation colouration and impacts behaviour

Irradiated Queensland fruit flies (Bactrocera tryoni) used in Sterile Insect Technique (SIT) programmes are marked with fluorescent dyes to distinguish them from wild flies when recaptured in monitoring traps. However, coating sterile pupae with powdered dyes can reduce emergence rates and fly quality and can sometimes produce insufficiently certain discrimination through inadequate coating or because the dye is transferred to wild flies through contact. Here we created a phenotypically distinct B. tryoni strain that lacks typical melanisation patterns through CRISPR/Cas9-mediated mutagenesis of tandemly duplicated yellow-y genes and then assessed effects of this visible trait on fly performance. Recessive mutations are only required in one of these copies to restrict melanisation and generate a phenotype clearly distinguished from wild type. The yellow strain showed significant declines in eclosion rates and in the percentage of fliers directly after emergence. Locomotor activity was greater in the yellow strain, and these mutations did not generally affect mating probability, copula latency, or copula duration. The longevity of yellow flies was approximately 10 days shorter than wild-type flies in both sexes. Overall, replacing dyes with yellow body marker for SIT can simplify production, eliminate a step that is known to reduce fly quality, remove potentially hazardous dyes from production, enable accurate discrimination from wild flies, and improve cost-effectiveness; however, direct comparisons of the decrements in performance associated with dyes on mass-reared wild-type flies and disruption of yellow-y genes are now required to determine the relative suitability of these marking methods for B. tryoni SIT.

Visibility and Persistence of Fluorescent Dyes, and Impacts on Emergence, Quality, and Survival of Sterile Queensland Fruit Fly Bactrocera tryoni (Diptera: Tephritidae).

Tephritid flies released in sterile insect technique pest management programs are usually marked with fluorescent dyes so that they can be distinguished from wild flies in monitoring traps. Dyes can have adverse effects on emergence, quality, and survival, which can impact sterile insect technique (SIT) success, and so it is important to identify dyes and doses that maximize marking efficacy while minimizing deleterious effects on fly quality. This study examines the effects of five fluorescent dye products, Fluoro Pink, Fluoro Orange, Stella Green, Arc Chrome, and Astral Pink applied at four dose levels (1, 2, 3, and 4 g/liter) on Queensland fruit fly. All dye products caused a similar dose-dependent reduction in percentage of adult emergence. Incidence of morphological deformity of emerged adults increased with dose, and this trend was similar for all dye products. No effects of dye product or dose were found on survival rates over the first 35 d of adulthood, although females tended to have higher survival than males. Visibility varied with dose and dye product; 1 g/liter dye was less visible than 2, 3, or 4 g/liter, and Stella green had lower visibility than other dyes. All of the tested dyes except for Stella green were similar in all assessed metrics of fly performance and are recommended for use in SIT programs.

Artificial Larval Diet Mediates the Microbiome of Queensland Fruit Fly.

Larval diets used for artificial rearing can have a significant effect on insect biology. The Queensland fruit fly (aka “Qfly”), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), is one of the greatest challenges for fruit growers in Australia. The sterile insect technique (SIT) is being developed to manage outbreaks in regions that remain free of Qfly and to reduce populations in regions where this species is endemic. Factory scale rearing is essential for SIT; however, artificial larval diets are known to affect the microbiome of Qfly, which may then affect fly performance. In this study, high-throughput Illumina sequencing was used to assess the Qfly microbiome in colonies reared, for five generations from nature, on two common artificial diets (carrot and gel). At generation five (G5), the microbiome was assessed in larvae, pupae, adult males and adult females and standard fly quality control parameters were assessed together with additional performance measures of mating propensity and survival under nutritional stress. At the genus level, bacterial communities were significantly different between the colonies reared on the two larval diets. However, communities converged at Phyla to family taxonomic levels. Bacterial genera of Morganella, Citrobacter, Providencia, and Burkholderia were highly abundant in all developmental stages of Qfly reared on the gel diet, when compared to the carrot diet. Despite abundance of these genera, a greater percentage of egg hatching, heavier pupal weight and a higher percentage of fliers were found in the Qfly reared on the gel diet. Mating propensity and survival under nutritional stress was similar for adult Qfly that had been reared on the two larval diets. Overall, our findings demonstrate that the artificial larval diet strongly influences the microbiome and quality control measures of Qfly, with likely downstream effects on performance of flies released in SIT programs.

Biochar and gypsum amendment of agro-industrial waste for enhanced black soldier fly larval biomass and quality frass fertilizer.

Black soldier fly (BSF) (Hermetia illucens L.) is one of the most efficient bio-waste recyclers. Although, waste substrate amendments with biochar or gypsum during composting process are known to enhance nutrient retention, their impact on agro-industrial waste have not been documented. Hence, this study focuses on a comparative effect of agro-industrial waste amended with biochar and gypsum on BSF larval performance, waste degradation, and nitrogen (N) and potassium retention in frass fertilizer. Brewery spent grain was amended with biochar or gypsum at 0, 5, 10, 15 and 20% to determine the most effective rates of inclusion. Amending feedstock with 20% biochar significantly increased wet (89%) and dried (86%) larval yields than the control (unamended feedstock). However, amendment with 15% gypsum caused decrease in wet (34%) and dried (30%) larval yields but conserved the highest amount of N in frass. Furthermore, the inclusion of 20% biochar recorded the highest frass fertilizer yield and gave a 21% increase in N retention in frass fertilizer, while biomass conversion rate was increased by 195% compared to the control. Feedstock amendment with 5% biochar had the highest waste degradation efficiency. Potassium content in frass fertilizer was also significantly enhanced with biochar amendment. At maturity, frass compost with more than 10% inclusion rate of biochar had the highest cabbage seed germination indices (>100%). The findings of this study revealed that initial composting of biochar amended feedstocks using BSF larvae can significantly shorten compost maturity time to 5 weeks with enhanced nutrient recycling compared to the conventional composting methods.

Reduced quality of sterile Queensland fruit fly following post-production stress from hypoxia, irradiation and vibration

The sterile insect technique (SIT), a benign pest control strategy, is currently undergoing a substantial renewal for controlling the Queensland fruit fly (Q-fly), a major horticultural pest in Australia. Production and delivery of high-quality flies is fundamental to effective SIT. While efforts are commonly made to improve production at a factory level (both quantity and quality), the methods and conditions during post-production operations also need to be tuned to minimize reductions in fly quality. Hypoxia, irradiation and vibration are important stressors that are experienced by pupae during production, packing and transportation. However, little is known about the impacts of such stressors on Q-fly quality. We conducted two laboratory experiments to investigate the response of Q-fly to such post-production stressors, with the aim of then developing guidelines that minimize quality reductions for SIT programs. In Experiment 1, Q-fly pupae of different ages (3, 6 or 9-day old) were exposed to vibrations for 5, 30, 60 and 300 s. Flight ability tests revealed that 6- and 9-day-old pupae were the most sensitive to vibration, with significant reduction in emergence and percentage of fliers. In Experiment 2, the effect of hypoxia, irradiation and vibration, in isolation or in combination, was evaluated on 9-day-old pupae. Irradiation and vibration exhibited a multiplicative negative effect on flight ability parameters. It is recommended not to subject pupae to intense or extensive vibration during the late pupal stage and to avoid prolonged periods of hypoxia.

Almond by-product composition impacts the rearing of black soldier fly larvae and quality of the spent substrate as a soil amendment.

BACKGROUNDInsect biomass is a sustainable alternative to traditional animal feeds, particularly when insects are produced on low‐value high‐volume agricultural by‐products. Seven samples of almond by‐product (hulls and shells) were obtained from processors in California and investigated for larvae production. Experiments were completed with and without larvae and spent substrate samples were assessed for their potential as soil amendments based on standard compost quality indicators.RESULTSOn average, specific larvae growth and average larval harvest weight were 158% and 109% higher, respectively, when larvae were reared on Monterey and pollinator hulls compared to nonpareil hulls and mixed shells. Larvae methionine and cystine contents were highest when larvae were reared on Monterey hulls and mixed shells, respectively. Available phytonutrients in spent substrate were affected by feedstock sample and larvae rearing. Spent nonpareil substrate without larvae had the highest NH4‐N levels and spent pollinator substrate incubated without larvae had the highest PO4‐P levels. Spent mixed shell substrate had the lowest availability of phytonutrients.CONCLUSIONThe findings demonstrate that by‐product composition has a significant impact on larvae growth and the properties of the spent substrate, and that spent substrate from larvae rearing requires further stabilization before application as a soil amendment. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Diet and irradiation effects on the bacterial community composition and structure in the gut of domesticated teneral and mature Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae)

BackgroundMass-rearing, domestication and gamma irradiation of tephritid fruit flies used in sterile insect technique (SIT) programmes can negatively impact fly quality and performance. Symbiotic bacteria supplied as probiotics to mass-reared fruit flies may help to overcome some of these issues. However, the effects of tephritid ontogeny, sex, diet and irradiation on their microbiota are not well known.ResultsWe have used next-generation sequencing to characterise the bacterial community composition and structure within Queensland fruit fly, Bactrocera tryoni (Froggatt), by generating 16S rRNA gene amplicon libraries derived from the guts of 58 individual teneral and mature, female and male, sterile and fertile adult flies reared on artificial larval diets in a laboratory or mass-rearing environment, and fed either a full adult diet (i.e. sugar and yeast hydrolysate) or a sugar only adult diet. Overall, the amplicon sequence read volume in tenerals was low and smaller than in mature adult flies. Operational taxonomic units (OTUs), belonging to the families Enterobacteriaceae (8 OTUs) and Acetobacteraceae (1 OTU) were most prevalent. Enterobacteriaceae dominated laboratory-reared tenerals from a colony fed a carrot-based larval diet, while Acetobacteraceae dominated mass-reared tenerals from a production facility colony fed a lucerne chaff based larval diet. As adult flies matured, Enterobacteriaceae became dominant irrespective of larval origin. The inclusion of yeast in the adult diet strengthened this shift away from Acetobacteraceae towards Enterobacteriaceae. Interestingly, irradiation increased 16S rRNA gene sequence read volume.ConclusionsOur findings suggest that bacterial populations in fruit flies experience significant bottlenecks during metamorphosis. Gut bacteria in teneral flies were less abundant and less diverse, and impacted by colony origin. In contrast, mature adult flies had selectively increased abundances for some gut bacteria, or acquired these bacteria from the adult diet and environment. Furthermore, irradiation augmented bacterial abundance in mature flies. This implies that either some gut bacteria were compensating for damage caused by irradiation or irradiated flies had lost their ability to regulate bacterial load. Our findings suggest that the adult stage prior to sexual maturity may be ideal to target for probiotic manipulation of fly microbiota to increase fly performance in SIT programmes.

Cool storage of Queensland fruit fly pupae for improved management of mass production schedules.

Cool storage is a valuable means of manipulating insect development time. The Queensland fruit fly (Q-fly) is Australia's most economically significant pest of fruit crops. The present study investigates cool storage of Q-fly pupae for increasing production flexibility for sterile insect technique programs. Development time, survival and fly quality were assessed following continuous storage of 1-day-old pupae at temperatures ranging from 13 to 25 °C. Survival was reduced almost to zero by pupal storage at 13 and 15 °C, was greatly reduced by storage at 17 °C, and was modestly reduced by storage at 19 °C. Pupal development time was extended by 16 days at 17 °C and by 9 days at 19 °C. Cool storage negatively affected flight ability and depleted lipid reserves. Cool storage at 19 °C enhanced the ability of 3-day-old adults to recover from chill-coma compared to control flies, indicating cold acclimation. There is potential for use of cool storage in Q-fly mass rearing, especially to improve alignment between production and field releases. For the purpose of delaying the development time of Q-fly pupae with minimal quality reduction, storage at 23 °C is recommended for 1-day-old pupae. © 2019 Society of Chemical Industry.

Near full-length 16S rRNA gene next-generation sequencing revealed Asaia as a common midgut bacterium of wild and domesticated Queensland fruit fly larvae

BackgroundGut microbiota affects tephritid (Diptera: Tephritidae) fruit fly development, physiology, behavior, and thus the quality of flies mass-reared for the sterile insect technique (SIT), a target-specific, sustainable, environmentally benign form of pest management. The Queensland fruit fly, Bactrocera tryoni (Tephritidae), is a significant horticultural pest in Australia and can be managed with SIT. Little is known about the impacts that laboratory-adaptation (domestication) and mass-rearing have on the tephritid larval gut microbiome. Read lengths of previous fruit fly next-generation sequencing (NGS) studies have limited the resolution of microbiome studies, and the diversity within populations is often overlooked. In this study, we used a new near full-length (> 1300 nt) 16S rRNA gene amplicon NGS approach to characterize gut bacterial communities of individual B. tryoni larvae from two field populations (developing in peaches) and three domesticated populations (mass- or laboratory-reared on artificial diets).ResultsNear full-length 16S rRNA gene sequences were obtained for 56 B. tryoni larvae. OTU clustering at 99% similarity revealed that gut bacterial diversity was low and significantly lower in domesticated larvae. Bacteria commonly associated with fruit (Acetobacteraceae, Enterobacteriaceae, and Leuconostocaceae) were detected in wild larvae, but were largely absent from domesticated larvae. However, Asaia, an acetic acid bacterium not frequently detected within adult tephritid species, was detected in larvae of both wild and domesticated populations (55 out of 56 larval gut samples). Larvae from the same single peach shared a similar gut bacterial profile, whereas larvae from different peaches collected from the same tree had different gut bacterial profiles. Clustering of the Asaia near full-length sequences at 100% similarity showed that the wild flies from different locations had different Asaia strains.ConclusionsVariation in the gut bacterial communities of B. tryoni larvae depends on diet, domestication, and horizontal acquisition. Bacterial variation in wild larvae suggests that more than one bacterial species can perform the same functional role; however, Asaia could be an important gut bacterium in larvae and warrants further study. A greater understanding of the functions of the bacteria detected in larvae could lead to increased fly quality and performance as part of the SIT.

Effects of Storage at Suboptimal Temperatures on the In Vitro-Reared Parasitoid Exorista larvarum (Diptera: Tachinidae).

Exorista larvarum (L.) is a tachinid parasitoid native to the Palearctic region, known as an antagonist of lepidopterous defoliators. This species is suitable to be cultured in vitro, and yields of fecund adults, approaching those usually attained in host larvae, have been previously achieved on artificial media. Direct oviposition by E. larvarum on media has not yet been obtained, and the eggs for the in vitro rearing are routinely removed from parasitized host larvae. However, many eggs are usually laid throughout the cage by captive females and can be retrieved by placing them on artificial media. Storage at low temperatures provides a method for prolonging the development of insects and stockpile them when not needed immediately. We studied the effects of storage at 20 °C (for 5 d or until pupation) or 15 °C (for 5 d or until egg hatching) on the in vitro development of E. larvarum. Lower temperatures were excluded, because previous studies showed a strong negative impact on hatching when the eggs were stored at 5 °C or 10 °C. For the experiments, eggs were removed from hosts and placed on an artificial medium. The results suggested that it is possible to delay the development of the in vitro-reared E. larvarum, which eventually reached the adult stage, although some negative effects on fly quality (i.e., longevity and fecundity) were also observed. Because quality is not an absolute concept, all the situations tested in this study could be appropriate according to the current requirements.

Optimising irradiation dose in mass‐produced Queensland fruit fly, Bactrocera tryoni, for sterile insect release: the incorporation of residual effects on F1 progeny

AbstractThe sterile insect technique (SIT) is a potential tool for the management and eradication of incursions of Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). Mass‐produced B. tryoni are irradiated during the pupal stage to induce reproductive sterility. As increasing irradiation dosage results in declining fly quality, determining the lowest possible dosage that induces sufficient reproductive sterility is of particular interest. However, in calculating reproductive sterility, previous research has not considered carryover irradiation effects to F1 progeny. To test for these effects, B. tryoni pupae were exposed to one of five target dose ranges: 0, 20–25, 40–45, 60–65, or 70–75 Gy. Upon adult eclosure, fly quality was assessed using standard quality control (QC) measures: adult eclosure rates, flight ability, sex ratio, and longevity under nutritional stress. No effect of irradiation dose on any of the QC measures was found. Residual fertility was assessed by measuring larval eclosure failure for all doses. For the 0–45 Gy doses, mortality was measured during development of F1 progeny and larval eclosure rates were measured in F2 progeny. For irradiated females, irradiation dose significantly affected egg production, as well as increasing mortality during pupation of F1 progeny. For irradiated males, irradiation dose strongly affected larval eclosure of F1 progeny and, similar to females, mortality increased during pupation with higher doses. Our results suggest that residual effects of irradiation dose decreases F1 progeny viability and current estimates of residual fertility for B. tryoni underestimate the actual residual fertility. We conclude by synthesising our results with the previous findings and we propose that the target irradiation dose for B. tryoni may be lowered to 55–60 Gy.

Quality of Sterile Male Tsetse after Long Distance Transport as Chilled, Irradiated Pupae.

BackgroundTsetse flies transmit trypanosomes that cause human and African animal trypanosomosis, a debilitating disease of humans (sleeping sickness) and livestock (nagana). An area-wide integrated pest management campaign against Glossina palpalis gambiensis has been implemented in Senegal since 2010 that includes a sterile insect technique (SIT) component. The SIT can only be successful when the sterile males that are destined for release have a flight ability, survival and competitiveness that are as close as possible to that of their wild male counterparts.Methodology/Principal FindingsTests were developed to assess the quality of G. p. gambiensis males that emerged from pupae that were produced and irradiated in Burkina Faso and Slovakia (irradiation done in Seibersdorf, Austria) and transported weekly under chilled conditions to Dakar, Senegal. For each consignment a sample of 50 pupae was used for a quality control test (QC group). To assess flight ability, the pupae were put in a cylinder filtering emerged flies that were able to escape the cylinder. The survival of these flyers was thereafter monitored under stress conditions (without feeding). Remaining pupae were emerged and released in the target area of the eradication programme (RF group). The following parameter values were obtained for the QC flies: average emergence rate more than 69%, median survival of 6 days, and average flight ability of more than 35%. The quality protocol was a good proxy of fly quality, explaining a large part of the variances of the examined parameters.Conclusions/SignificanceThe quality protocol described here will allow the accurate monitoring of the quality of shipped sterile male tsetse used in operational eradication programmes in the framework of the Pan-African Tsetse and Trypanosomosis Eradication Campaign.

Costly Nutritious Diets do not Necessarily Translate into Better Performance of Artificially Reared Fruit Flies (Diptera: Tephritidae)

Protein, lipid, carbohydrate, and energy contents of three artificial diets (Xal2, Met1, and Met2) used for laboratory-rearing and mass-rearing the Mexican fruit fly, Anastrepha ludens (Loew), for a sterile insect technique program were measured. The larval survival, pupation, pupal weight, adult emergence, sex ratio, and flight capacity of the flies reared on each of these diets were also quantified. The diet with the highest nutrient and energy content was Xal2 followed by Met2 and Met1, but larval recovery and percent pupation was significantly higher in flies reared on either the Met1 or Met2 diets. A. ludens reared on Xal2 exhibited the highest proportion of adults capable of flight. No other response variable differed significantly among the three diets tested. This suggests that a high content of nutrients and multiple sources of protein (dried yeast and wheat germ in the case of the Xal2 diet) do not necessarily improve overall performance or fly quality. We conclude that nutritious diets for A. ludens can be modified to reduce their cost without compromising the performance of artificially reared flies.

Optimizing methyl-eugenol aromatherapy to maximize posttreatment effects to enhance mating competitiveness of male Bactrocera carambolae (Diptera: Tephritidae).

Methyl-eugenol (ME) (1,2-dimethoxy-4-(2-propenyl)benzene), a natural phytochemical, did enhance male Bactrocera carambolae Drew & Hancock (Diptera: Tephritidae) mating competitiveness 3 d after ingestion. Enhanced male mating competitiveness can significantly increase the effectiveness of the sterile insect technique (SIT). ME application to mass reared sterile flies by feeding is infeasible. ME application by aromatherapy however, would be a very practical way of ME application in fly emergence and release facilities. This approach was shown to enhance mating competitiveness of B. carambolae 3 d posttreatment (DPT). Despite this added benefit, every additional day of delaying release will reduce sterile fly quality and will add cost to SIT application. The present study was planned to assess the effects of ME-aromatherapy on male B. carambolae mating competitiveness 1DPT and 2DPT. ME aromatherapy 1DPT or 2DPT did enhance mating competitiveness of B. carambolae males whereas ME feeding 1DPT and 2DPT did not. Male mating competitiveness was enhanced by the ME aromatherapy irrespective if they received 1DPT, 2DPT or 3DPT. ME aromatherapy, being a viable approach for its application, did enhance mating competitiveness of male B. carambolae 1 d posttreatment as ME feeding did 3 d after ingestion.

A review of 16 years of quality control parameters at a mass‐rearing facility producing Queensland fruit fly, Bactrocera tryoni

AbstractFrom 1996 to 2012, the mass‐rearing facility at Camden (NSW, Australia) has been producing Queensland fruit flies, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). During this time, the facility has regularly recorded fly quality parameters, creating a unique data set that provides an invaluable opportunity to evaluate the interrelationships among standard quality control (QC) parameters and test for redundant QC variables. Here, we conducted an exploratory data analysis to reveal relationships among the QC parameters. We found that pupal weight, adult lifespan, and longevity under nutritional stress (i.e., survival duration without food or water) had distinct monthly trends, suggesting that these QC parameters are sensitive to seasonal conditions. Furthermore, emergence percentage, flight ability, and adult lifespan were adversely affected by the dyeing/handling/irradiation process associated with sterile insect releases. Using a multivariate approach and controlling for monthly and yearly patterns, we showed that pupal weight and egg hatch are consistently negatively related and that percentage male and emergence rates are consistently negatively related. These results suggest that these correlation pairs measure similar quality information and hence one QC variable from each pair could be dropped. Flight ability was not strongly correlated with any of the QC variables, suggesting that this QC variable remains a useful QC metric. Finally, the longevity under nutritional stress QC appears to be fairly insensitive to QCs and we suggest that it should be replaced by the standard mortality under stress test.

Combined effects of dietary yeast supplementation and methoprene treatment on sexual maturation of Queensland fruit fly

Yeast hydrolysate supplements promote maturation of many tephritid flies targeted for control using the sterile insect technique (SIT), including Queensland fruit fly (Bactrocera tryoni; ‘Q-fly’). Recently, application of the juvenile hormone analogue methoprene has been demonstrated to further promote maturation in some species. We here investigate the separate and combined effects of yeast hydrolysate and methoprene treatment on sexual maturation of sterile male and female Q-flies. Two methods of applying methoprene solution were used; topical application to adults and dipping of pupae. Consistent with previous studies, access to yeast hydrolysate greatly increased maturation of both male and female Q-flies. Maturation was further promoted by methoprene treatment, with similar effects evident for males and females and for both application methods. For flies provided access to yeast hydrolysate supplements, methoprene treatment advanced maturation by approximately 2days. No effects of diet or methoprene treatment were found on timing of copulation or copula duration. Countering the positive effects on sexual maturation, dipping of pupae in methoprene/acetone solution did diminish emergence rates and flight ability indices, and increased rates of wing deformity. Promising results of the present study encourage further investigation of treatment methods that maximise maturation while minimising detrimental effects on other aspects of fly quality.