Dorsalis Eggs Research Articles

Toxicity of Beauveria bassiana to Bactrocera dorsalis and effects on its natural predators.

Entomopathogenic fungi (EPF) are economical and environmentally friendly, forming an essential part of integrated pest management strategies. We screened six strains of Beauveria bassiana (B1-B6) (Hypocreales: Cordycipitaceae), of which B4 was the most virulent to Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). We further assessed the biological characteristics of strain B4 and the environmental factors influencing its ability to infect B. dorsalis. We also evaluated the effects of B4 on two of the natural predators of B. dorsalis. We found that strain B4 was the most virulent to 3rd instar larvae, pupae, and adult B. dorsalis, causing mortality rates of 52.67, 61.33, and 90.67%, respectively. B4 was not toxic to B. dorsalis eggs. The optimum B4 effects on B. dorsalis were achieved at a relative humidity of 91-100% and a temperature of 25°C. Among the six insecticides commonly used for B. dorsalis control, 1.8% abamectin emulsifiable concentrate had the strongest inhibitory effect on B4 strain germination. B4 spraying affected both natural enemies (Amblyseius cucumeris and Anastatus japonicus), reducing the number of A. cucumeris and killing A. japonicus adults. We found a valuable strain of EPF (B4) that is virulent against many life stages of B. dorsalis and has great potential for the biological control of B. dorsalis. We also provide an important theoretical and practical base for developing a potential fungicide to control B. dorsalis.

Is phosphine an ideal candidate for fruit fly disinfestation in Java apple, Syzygium samarangense?

Java apple, Syzygium samarangense, a nutritionally rich fruit species cultivated in Southeast Asia is prone to fruit fly infestation. Since no commercial management protocols currently exist for disinfesting java apple against fruit flies, the present study investigated the suitability of phosphine fumigation for post-harvest disinfestation of java apple fruit. Fruit exposed to gravid female Bactrocera dorsalis overnight were subjected to phosphine fumigation at concentrations ranging from 0.14 to 2.78 mg/L for 24, 48 and 72 h at ambient conditions. Gas chromatographic analysis of the PH3 concentration revealed that approximately 65% of phosphine gas was lost in treatment chambers fumigated with highest concentration of 2.78 mg/L for 72 h. B. dorsalis eggs could be mitigated by exposing java apple fruit to a concentration × time product of 16.67 mg/L-h of PH3 or more. Fumigating fruit at PH3 concentrations below 0.69 mg/L for 24 h and 48 h did not significantly change the color of treated fruit. Furthermore, the texture of the fruit post PH3 fumigation remained unaffected. Phosphine treated java apple fruit showed no trace of phosphine residues at exposures shorter than 72 h. In conclusion, phosphine can be a viable treatment for the management of B. dorsalis eggs in S. samarangense fruit at lower concentrations and shorter durations without affecting the fruit quality.

Potential of a fly gut microbiota incorporated gel-based larval diet for rearing Bactrocera dorsalis (Hendel)

BackgroundThe Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is an important polyphagous pest of horticultural produce. The sterile insect technique (SIT) is a proven control method against many insect pests, including fruit flies, under area-wide pest management programs. High quality mass-rearing process and the cost-effective production of sterile target species are important for SIT. Irradiation is reported to cause severe damage to the symbiotic community structure in the mid gut of fruit fly species, impairing SIT success. However, studies have found that target-specific manipulation of insect gut bacteria can positively impact the overall fitness of SIT-specific insects.ResultsTwelve bacterial genera were isolated and identified from B. dorsalis eggs, third instars larval gut and adults gut. The bacterial genera were Acinetobacter, Alcaligenes, Citrobacter, Pseudomonas, Proteus, and Stenotrophomonas, belonging to the Enterobacteriaceae family. Larval diet enrichment with the selected bacterial isolate, Proteus sp. was found to improve adult emergence, percentage of male, and survival under stress. However, no significant changes were recorded in B. dorsalis egg hatching, pupal yield, pupal weight, duration of the larval stage, or flight ability.ConclusionsThese findings support the hypothesis that gut bacterial isolates can be used in conjunction with SIT. The newly developed gel-based larval diet incorporated with Proteus sp. isolates can be used for large-scale mass rearing of B. dorsalis in the SIT program.

Radiation of Bactrocera dorsalis (Diptera: Tephritidae) Eggs to Improve the Mass Rearing of Diachasmimorpha longicaudata (Hymenoptera: Braconidae).

This study explored the potential for Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) larvae hatched from irradiated eggs as hosts for Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). B. dorsalis eggs of three different ages (12-, 24-, and 36-h old) were analyzed for hatchability, pupation rate, pupal weight, emergence rate, and sex ratio after exposure to different doses of radiation (5 and 10 Gy) at different dose rates (1 and 6 Gy/min). For the eggs of different ages exposed to radiation, only the hatchability and pupal weight of 36-h-old eggs exposed to the dose rate of 1 Gy/min were not affected; therefore, 6 Gy/min was not suitable for irradiating eggs. The viability of the parents and progenies of D. longicaudata when the parents were reared from 36-h-old eggs irradiated at nine different doses (0, 5, 10, 15, 20, 25, 30, 35, and 40 Gy) under laboratory conditions were investigated. The emergence percentage, sex ratio, and longevity of parasitoids developed from irradiated eggs were similar to those reared from nonirradiated hosts. A significant increase in larva mortality was observed for the eggs irradiated at doses above 25 Gy, and no redundant adult flies emerged at doses above 15 Gy. Hence, for B. dorsalis eggs to be applied in the mass rearing of D. longicaudata, the age of 36 h and a dose of 20-25 Gy are the optimal parameters. The results reveal that hosts and parasitoids need not be separated, enabling a reduction in cost, labor, and time and resulting in an improved mass rearing procedure for D. longicaudata.

Demography and Mass-Rearing Harmonia dimidiata (Coleoptera: Coccinellidae) Using Aphis gossypii (Hemiptera: Aphididae) and Eggs of Bactrocera dorsalis (Diptera: Tephritidae)

We compared rearing Harmonia dimidiata (F.) (Coleoptera: Coccinellidae) on four combinations of Aphis gossypii Glover (Hemiptera: Aphididae), and eggs of Bactrocera dorsalis Hendel (Diptera: Tephritidae), using the age-stage, two-sex life table. The four combinations were: both larvae and adults were reared on aphids; larvae were reared on aphids and adults were reared on fresh fruit fly eggs; larvae were reared on lyophilized fruit fly eggs and adults were reared on aphids; and larvae were reared on lyophilized eggs and adults were reared on fresh eggs. The highest intrinsic rate of increase (r = 0.1125 d-1) and net reproductive rate (R0 = 260.7 offspring) were observed when both larval and adult stages of H. dimidiata were reared on A. gossypii. When B. dorsalis eggs were used as rearing media for larvae, adults, or both, the values of r and R0 were significantly decreased. The lowest values (r = 0.0615 d-1 and R0 = 38.6 offspring) were observed when both larvae and adults were reared entirely on B. dorsalis eggs. Despite the lower r and R0 values, our results showed that B. dorsalis eggs could be considered as an adequate, less expensive alternative diet for rearing H. dimidiata because of the time and labor savings resulting from the ease of preparation and the ability to store the eggs for timely usage. The mass-rearing analysis showed that the most economical rearing system was to rear larvae on A. gossypii and adults on B. dorsalis eggs.

Effects of Co-60 radiation on the activities of three main antioxidant enzymes in Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Co-60 radiation has been broadly used for pest management because it results in male sterility and a lack of emergence of unparasitized hosts due to oxidative damage. Insect life is significantly affected by abiotic stress factors, including Co-60 radiation. In the present study, we determined the influence of Co-60 radiation on an important pest in southern China, the oriental fruit fly Bactrocera dorsalis (Diptera: Tephritidae). We exposed 30-h-old B. dorsalis eggs to Co-60 radiation at doses of (0, 5, 10, 15, 20, 25, 30, 35, and 40 Gy) and determined the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). CAT and POX activity significantly increased in B. dorsalis in the 1st larvae instar after high-intensity radiation doses (25–40 Gy) and played an important role in the antioxidant response to intensive radiation. The activity of POX in B. dorsalis at the 2nd larval instar sharply decreased after different doses of radiation, except for 10 and 40 Gy. Our results demonstrated that Co-60 radiation affected the activity of antioxidant enzymes and disturbed the physiology of B. dorsalis, especially at early stages (the 1st, 2nd larvae instar). These three antioxidant defense enzymes cooperatively play an important role in protecting B. dorsalis from oxidative damage.

The optimal age and radiation dose for Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) eggs as hosts for mass-reared Fopius arisanus (Sonan) (Hymenoptera: Braconidae)

Fopius arisanus (Sonan) is a dominant egg-pupal parasitoid of many fruit fly pests. Bactrocera dorsalis (Hendel) is one of F. arisanus’ hosts and is the usual host used for mass rearing F. arisanus. To obtain parasitoids without hosts suitable for the release of F. arisanus in the field—skipping the need to separate parasitoids and unparasitized hosts—radiation (15, 20, 25 and 30Gy) was applied to B. dorsalis eggs of five different ages (24, 27, 30, 33, and 36h). Hatch rates, pupation rates, pupae weights, emergence rates, sex ratios, flight abilities, mortality rates and fertilities were analyzed during parasitoid development from irradiated eggs to adults. Irradiation of eggs aged 30–36h at 20Gy might be the optimal age and dosage when using B. dorsalis as hosts for mass rearing of F. arisanus. Furthermore, we investigated the viability of the parents and offspring of F. arisanus when the parents were raised from irradiated eggs under both laboratory and field cage conditions. The parasitism percentage, emergence rate, sex ratio (female: male) and longevity of parasitoids reared with irradiated hosts were similar to those of parasitoids obtained from non-irradiated host eggs. Significantly, the results revealed that unparasitized B. dorsalis previously irradiated with an appropriate dose at appropriate ages do not emerge: a finding that solves the problem of separating unparasitized emerging flies during mass rearing. This experiment also demonstrates that F. arisanus reared on irradiated hosts can find, identify, and parasitize hosts normally—both indoors and outdoors—and that the resulting parasitoids can be directly applied to control pest populations in the field.

Adenosine triphosphate assay of Bactrocera dorsalis (Diptera: Tephritidae) eggs treated with low or high temperatures

A bioluminescent adenosine triphosphate (ATP) assay using a luciferin-luciferase reagent was conducted as a viability test for Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) eggs treated with low or high temperatures to evaluate the potential into use for quarantine operations. ATP concentrations in B. dorsalis eggs treated with different temperatures, including freezing, cold treatment, and rapid and slow heating, simulating a hot water immersion treatment and vapor heat treatment, respectively, were measured. Mean ATP concentrations in untreated eggs decreased as egg age increased. For freezing and rapid heating, the mean ATP concentrations in treated eggs significantly decreased 24 h after the treatments, and the maximum ATP concentrations were lower than the minimum ones for untreated eggs. Most ATP concentrations in the cold treatment group exceeded the minimum ones in untreated eggs. Mean ATP concentrations in eggs treated with slow heating decreased less than those in eggs treated with rapid heating. There is potential to use ATP assays in plant quarantine operations for the rapid determination of the viability of fruit fly eggs treated with hot water immersion, although more validation research is first required. Verification tests should be performed by applying ATP assays during quarantine, by using flies and host fruit subjected to different temperature treatments.

Response of egg-pupal parasitoid Fopius arisanus (Sonan) to infochemicals from the host eggs' surface of Bactrocera dorsalis (Hendel)

To determine host-related infochemicals that facilitate contact between the egg-pupal parasitoid, Fopius arisanus (Sonan), and its host, Bactrocera dorsalis (Hendel), we analyzed the volatiles on the surface of B. dorsalis eggs by hydrocarbon profiling of the hexane extracts using Gas Chromatography–Mass Spectrometry (GC–MS). These analyses resulted in the identification of 12 components from the egg surface. Among these 6 were alkanes (Dodecane, Heneicosane, Docosane, Tricosane, Tetracosane and Pentacosane) and the proportion was 42.79%, 1 was a fatty acid (Palmitic acid) and the proportion was 3.88%, 3 were fatty acid derivatives (Dodecanoic acid methylester, Lauric acid ethyl ester and Ethyl tetradecanoate) and the proportion was 45.92%, and 2 were alcohols (Tetradecanol and Hexadecanol) and the proportion was 7.41%. 9 chemicals were chosen from the above 12 components to study the EAG and behavioral responses of male and female F. arisanus. The results showed that the EAG and behavioral responses of F. arisanus to same chemical had similar trends, and both EAG relative values and lure rates of females were higher than males' generally. However, for Dodecane and Tetracosane the EAG relative values and lure rates showed extremely significant differences between males and females respectively, for Tricosane there was significant difference, for Ethyl tetradecanoate there was no significant difference between males and females of the relative EAG values but of the lure rates there was significant difference. The results maybe provide new insights from the chemical relationship between parasitoid and host to biocontrol B. dorsalis using F. arisanus.

Implications of host mortality on the economics of Fopius arisanus (Hymenoptera: Braconidae) mass rearing

Fopius (= Biosteres) arisanus (Sonan) (= Opius oophilus Fullaway) is an egg-pupal parasitoid of tephritid fruit flies. Our breakthrough in the development of a laboratory-adapted strain of F. arisanus facilitated insectary rearing of parasitoids in large numbers. First colonized in captivity in 1989, F. arisanus has been reared routinely on the oriental fruit fly, Bactrocera (= Dacus) dorsalis (Hendel), its natural host. Parasitization by F. arisanus results in the latent death of developing hosts. Host mortality data are presented in a life table to estimate cost of parasitization on the economics of F. arisanus mass rearing. Percent kills of 10, 32, and 76% exerted by F. arisanus on the egg, larval, and pupal stages of the rearing hosts, respectively, resulted in a mean parasitoid recovery of 23.6%. The production cost was estimated by integrating life table data with the costs of rearing supplies and materials and personnel-hours requirements. Production of 1 million parasitoid adults requires the exposure of 4.2 million B. dorsalis eggs (= propagation hosts). We estimated the cost of producing 1 million parasitoids to be $2,363.30 and identified the most expensive aspects of F. arisanus rearing. Recommendations for streamlining the rearing process to reduce costs are provided.

Effect of Fruit Substrates on Parasitization of Tephritid Fruit Flies (Diptera) by the Parasitoid Biosteres arisanus (Hymenoptera: Braconidae)

The effect of fruit substrates on the parasitization of tephritid fruit flies by Biosteres arisanus (Sonan) was demonstrated in the laboratory. Naive female parasitoids (15-20-d old after emergence) discriminated among fruit varieties in which eggs of the oriental fruit fly, Bactrocera dorsalis (Hendel), and the Mediterranean fruit fly, Ceratitis capitata (Weidemann), occurred. The preference (in descending order) of B. arisanus for B. dorsalis eggs was apple banana, Musa paradisiaca ssp. sapientum (L.) O. Ktze ; false kamani, Terminalia catappa L. ; solo papaya, Carica papaya L. ; Haden mango, Mangifera indica L. ; and, common lime, Citrus aurantiifolia (Christmann) Swingle. Where C. capitata was the target host, eggs inoculated in common guava, Psidium guajava L., and solo papaya were parasitized more heavily than those in citrus fruits, namely, common lime ; tangerine, Citrus nobilis Lour. ; and, tangelo, a cross between Citrus nobilis and Citrus paradisi Macf. B. dorsalis or C. capitata eggs exposed to B. arisanus concurrently in a pair of fruits of the same variety showed that parasitoids did not discriminate between these 2 fruit flies when eggs occurred in arabian coffee, Coffea arabica L. However, eggs of B. dorsalis were more heavily parasitized than those of C. capitata in common guava or solo papaya.

Fruit trap: A detection and collection tool for opiine parasitoids (Hym.: Braconidae) of the oriental fruit fly,Bactrocera dorsalis (Dipt.: Tephritidae)

A fruit trap was developed for detection and collection of the opiine parasitoids of the oriental fruit fly,Bactrocera (=Dacus)dorsalis (Hendel). Gravid females ofBiosteres arisanus (Sonan), an egg-larval parasitoid, orDiachasmimorpha longicaudata (Ashmead) andPsytallia incisi (Silvestri), both larval parasitoids, were lured to parasitize the eggs or larvae ofB. dorsalis inoculated in ripe papaya fruits,Carica papaya L. Progenies ofB. arisanus were consistently recovered from papaya fruits inoculated withB. dorsalis eggs (subsequently referred to as egg fruit traps). Except in Moloaa on Kauai (6%), higher percentage ofB. dorsalis parasitization (range=38–43%) was recorded in Hilo, island of Hawaii and Waimanalo and Poamoho, island of Oahu. Progenies ofD. longicaudata and a fewP. incisi were recovered from papaya fruits artificially infested withB. dorsalis larvae (subsequently referred to as larval fruit traps). The recovery of parasitoid progenies from larval fruit traps suspended from papaya trees did not differ significantly from larval fruit traps placed on the ground. In both methods of trap placement, percent parasitization ofB. dorsalis byD. longicaudata (predominant species) ranged from 58–60%. On the other hand, significantly moreB. arisanus thanD. longicaudata andP. incisi adults (larval parasitoids) were recovered from fully ripened to highly deteriorated papaya fruits collected from papaya trees or ground (fallen fruits).

Evaluation of Oviposition Stimulants for Mass Production of Melon Fly, Oriental Fruit Fly, and Mediterranean Fruit Fly (Diptera: Tephritidae)

Responses of Melon fly, Dacus cucurbitae Coquillett, oriental fruit fly, Dacus dorsalis Hendel, and Mediterranean fruit fly, Ceratitis capitata (Wiedemann), to artificial oviposition bottles treated with various liquids derived from host juices or extracts and water was tested in a choice test device. Harvest of D. cucurbitae eggs was 89.4% higher from oviposition bottles that contained the juice of pumpkin, Cucurbita maxima Duchesne, than from bottles with the juice of tomato, Lycopersicon esculentum Miller, the standard oviposition stimulant. Harvest of D. dorsalis eggs was 55.2% higher from oviposition bottles that contained juice of orange, Citrus sinensis (L.) Osbeck, than from bottles with juice of guava, Psidium guajava L., the standard oviposition stimulant. Harvest of C. capitata eggs from oviposition bottles that contained an extract of coffee, Coffea arabica L., was equal to those with the standard oviposition stimulant (water). Results indicate that host fruit juices with minimal commercial processing and without additives were the best oviposition stimulants. Findings are discussed in the context of oviposition stimulant evaluation procedures and mass production of tephritid fruit flies.

Hawaiian Fruit Flies (Diptera: Tephritidae): Toxicity of Benzyl Isothiocyanate against Eggs or 1st Instars of Three Species1

The natural mortality of the eggs and 1st instars of Dacus dorsalis Hendel, Ceratitis capitata (Wiedemann), and D. cucurbitae Coquillett, in green papaya, Carica papaya L., was partly due to the toxicity of benzyl isothiocyanatc (BITC) which was produced naturally when the tissues were physically damaged during oviposition and larval feeding. The order of increasing susceptibility of the insects to BITC was 1st instars and then egg, and with respect to species, D. dorsalis, C. capitata , and D. cucurbitae . A BITC concentration of 847.0 ppm in artificial latex eliminated 50.0 or 99.9% of D. dorsalis eggs in 10.4 or 37.0 min, respectively, at 25°C. About 140.0 ppm produced similar effects with C. capitata , but D. cucurbitae did not survive at concentrations more than 9.3 ppm. Also, BITC enriched papaya puree prevented hatch of D. dorsalis eggs by 50.0 and 99.0% at 20.4 and 43.5 ppm, respectively. The mortality of the 1st instars was similarly affected at 19.3 and 33.8 ppm. C. capitata eggs required 9.3 and 24.0 ppm, but the larvae did not survive at either concentration. The BITC concentration produced by mature-green or color-turning papaya was more than 52 ppm, which was sufficient to prevent the development of an infestation after partial deterrence of oviposition.