Correction: Suppression of cuelure attraction in male Queensland fruit flies provided raspberry ketone supplements as immature adults.

[This corrects the article DOI: 10.1371/journal.pone.0184086.].

Suppression of cuelure attraction in male Queensland fruit flies provided raspberry ketone supplements as immature adults.

Tephritid fruit flies are amongst the most damaging insect pests of horticulture globally. Some of the key fruit fly species are managed using the sterile insect technique (SIT), whereby millions of sterile males are released to suppress reproduction of pest populations. Male annihilation technique (MAT), whereby sex specific lures are used to attract and kill males, is often used to reduce wild male numbers before SIT programs commence, providing released sterile males an increased numerical advantage. Overall program efficacy might be improved if MAT could be deployed simultaneously with SIT, continuously depleting fertile males from pest populations and replacing them with sterile males. However, such 'male replacement' requires a means of suppressing attraction of released sterile males to lures used in MAT. Previous studies have found that exposure of some fruit flies to lure compounds as mature adults can suppress subsequent response to those lures, raising the possibility of pre-release treatments. However, this approach requires holding flies until after maturation for treatment and then release. The present study takes a novel approach of exposing immature adult male Queensland fruit flies (Bactrocera tryoni, or 'Qfly') to raspberry ketone (RK) mixed in food, forcing these flies to ingest RK at ages far younger than they would naturally. After feeding on RK-supplemented food for two days after emergence, male Qflies exhibited a reduction in attraction to cuelure traps that lasted more than 20 days. This approach to RK exposure is compatible with current practises, in which Qflies are released as immature adults, and also yields advantages of accelerated reproductive development and increased mating propensity at young ages.

Raspberry ketone supplement promotes early sexual maturation in male Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae).

BACKGROUND: Raspberry ketone (RK) is highly attractive to sexually mature, but not immature, males of many Bactrocera species, including Queensland fruit fly ('Qfly', Bactrocera tryoni), and acts as a metabolic enhancer in a wide diversity of animals. We considered the possibility that, as a metabolic enhancer, RK in adult diet might accelerate sexual maturation of male Qflies. RESULTS: Recently emerged adult Qfly males (0-24 h old) were exposed to RK-treated food for 48 h and were then provided only sugar and water. Four doses of RK (1.25, 2.5, 3.75 and 5%) along with control (0%) were tested with two types of food: sugar alone and sugar mixed with yeast hydrolysate (3:1). For flies tested when 4-10 days old all RK doses increased mating probability of flies fed sugar mixed with yeast hydrolysate but did not show any effect on mating probability of flies fed only sugar. No effects of RK were found for flies tested when 10-30 days old for either diet group. There was no evidence that RK affected longevity at any of the doses tested. CONCLUSION: Feeding of RK together with yeast hydrolysate to immature Qfly increases mating propensity at young ages and accordingly shows significant potential as a pre-release supplement that might increase the proportion of released flies that attain sexual maturation in Sterile Insect Technique programmes. © 2017 Society of Chemical Industry.

Effects of Self-Superparasitism and Temperature on Biological Traits of Two Neotropical Trichogramma (Hymenoptera: Trichogrammatidae) Species.

It is common for a female trichogrammatid to lay more than one egg per host, a phenomenon known as self-superparasitism, which exposes her offspring to intraspecific, intrinsic competition (IIC) with its own siblings. Information about how often self-superparasitism occurs and how IIC interacts with abiotic factors is rare, especially regarding the Neotropical Trichogramma species. Here we determined the frequency of self-superparasitism in Trichogramma atopovirilia Oatman & Platner (Ta) and T. pretiosum Riley (Tp), and the effects of IIC and temperature on the sex ratio, egg-to-adulthood period, and survivorship of both species' offspring. Individual females were offered eggs of Spodoptera frugiperda (J.E. Smith) for 30 min. A group of parasitized hosts was then dissected for determination of the self-superparasitism frequency, while another group was incubated at 15, 18, 21, 24, 27, 30, and 33°C. High rates of self-superparasitism were found in both Ta (0.55 ± 0.07) and Tp (0.62 ± 0.06). IIC interacted with temperature decreasing Ta and Tp's survivorship, lengthening the egg-to-adulthood period in Tp and shortening it in Ta, and balancing Ta's sex ratio. Based on survivorship rate, Ta and Tp could not be differentiated if their immatures develop in absence of IIC. However, in its presence, Tp was 3 × more likely to survive than Ta at 33°C, while at 15°C Ta survived 2× better than Tp These results show that self-superparasitism can be very common in both Ta and Tp, and that its effects on the species' biological traits and competitiveness strongly depend on the IIC-temperature interaction.

Raspberry Ketone Analogs: Vapour Pressure Measurements and Attractiveness to Queensland Fruit Fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae).

The Queensland fruit fly, Bactrocera tryoni (Froggatt) (Q-fly), is a major horticultural pest in Eastern Australia. Effective monitoring, male annihilation technique (MAT) and mass trapping (MT) are all important for control and require strong lures to attract flies to traps or toxicants. Lure strength is thought to be related in part to volatility, but little vapour pressure data are available for most Q-fly lures. Raspberry ketone (4-(4-hydroxyphenyl)-2-butanone) and analogs that had esters (acetyl, difluoroacetyl, trifluoroacetyl, formyl, propionyl) and ethers (methyl ether, trimethylsilyl ether) in replacement of the phenolic group, and in one case also had modification of the 2-butanone side chain, were measured for their vapour pressures by differential scanning calorimetry (DSC), and their attractiveness to Q-fly was assessed in small cage environmentally controlled laboratory bioassays. Maximum response of one category of compounds, containing both 2-butanone side chain and ester group was found to be higher than that of the other group of compounds, of which either of 2-butanone or ester functionality was modified. However, linear relationship between vapour pressure and maximum response was not significant. The results of this study indicate that, while volatility may be a factor in lure effectiveness, molecular structure is the dominating factor for the series of molecules investigated.

New protein sources in adults diet for mass-rearing of Anastrepha fraterculus (Diptera:Tephritidae)

The aim of this study was to find alternatives to reduce the cost of mass production of the South American fruit fly (A. fraterculus) by looking for locally available products as protein source in the diet of adults to replace the imported product without changing the quality parameters. Two yeast from a Brazilian company were evaluated. The quality parameters showed that the imported hydrolyzed yeast used in the adult diet could be perfectly replaced by the local products tested, with a reduction of over 80% of the cost of the diet. The quality of the produced insects remained the same and there were improvements in some quality parameters such as the volume of eggs produced, number of adults flying and longevity under the stress.

Field dispersal and survival of sterile medfly males aromatically treated with ginger root oil.

We studied the dispersal behavior and survival of sterile medfly males either treated or not with ginger root oil (GRO), in field conditions, in Petrolina-PE, northeast Brazil, from May 2006 to December 2007 in a sterile insect technique (SIT) program. The tsl strain Vienna 8 from the Ceratitis capitata Wied. (Diptera: Tephritidae), medfly, mass-rearing facility located in Juazeiro-BA, Brazil, was used. The results showed that sterile males either exposed or not to GRO exhibit similar dispersal behavior and postrelease survival. More than 60% of the sterile males, either treated or not treated with GRO, were recovered at a 25-m distance from the releasing point, approximately 20% at 50 m, and 5% in traps situated 100 m from the releasing point. Around 90% of the sterile males, exposed or not to GRO, were recovered 5 d after release of the sterile male individuals, whereas <1% were recovered after 11 d. Our results imply that ginger root oil can be used to treat sterile medfly males without interfering with their dispersal or survival in the field.