Emilio Hernández

Effects of Diet, Ginger Root Oil, and Elevation on the Mating Competitiveness of Male Mediterranean Fruit Flies (Diptera: Tephritidae) from a Mass-Reared, Genetic Sexing Strain in Guatemala

The release of sterile males is a key component of an areawide program to eradicate the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), from Guatemala and southern Mexico. The objective of our study was to assess the effects of adult diet, exposure to ginger root oil (Zingiber officinale Roscoe), and elevation on the mating competitiveness of the sterile males used in an areawide program. Sterile males were maintained on a protein-sugar (protein-fed) or a sugar-only (protein-deprived) diet and were exposed (for 4 h 1 d before testing) or not exposed to ginger root oil. In field-cage trials conducted at a high (1,500 m) and low (700 m) site, we monitored the influence of these treatments on the mating success of sterile males in competition with wild males (reared exclusively on the protein-sugar diet and without ginger root oil exposure) for wild females. Elevation and ginger root oil exposure had significant effects, with sterile males having higher mating success at the low-elevation site and ginger root oil-exposed males having greater success than ginger root oil-deprived males at both sites. Diet did not have a significant overall effect, and its influence varied with elevation (dietary protein seemed to provide an advantage at the high-elevation site but not at the low-elevation site). Possible implications of these findings for eradication programs against the Mediterranean fruit fly are discussed.

Demographic Changes in Anastrepha obliqua (Diptera: Tephritidae) Throughout the Laboratory Colonization Process

ABSTRACT The demographic changes in Anastrepha obliqua (Macquart) (Diptera: Tephritidae) throughout laboratory colonization were characterized over the course of 11 generations. Four significant changes were determined. The first change was a reduction in the preoviposition period from the Gp to G1. The second was that wild female flies had difficulty ovipositing in an artificial substrate, yielding the lowest fecundity rates observed throughout the experiment. The third significant change was a decrease in longevity and life expectancy from Gp to G1, which then continued to decrease with successive generations. This resulted in a lab strain with high fecundity limited to a short period of oviposition. The last significant change was a reduction in larval and pupal weight. In addition, larval recovery decreased from Gp to G1 but displayed rapid recovery over the course of generations. There was no change in adult emergences for all generations, and flight ability increased with successive generations. These changes were correlated with demographic parameters, indicating that the increased investment in early age reproduction incurs costs such as a reduction in life expectancy or fecundity later in life. This trend was also correlated with an increase in early fecundity and reduction in the oviposition period.

Mass rearing and sterile insect releases for the control of Anastrepha spp. pests in Mexico – a review

The sterile insect technique (SIT) requires the rearing, sterilization, and release of large numbers of insects to induce sterility within wild pest populations. In 1992, the Mexican government launched a national campaign against economically important fruit fly pests, with the aim of establishing free areas and strengthening fruit exports. To achieve these objectives, the Moscafrut facility began operations in 1993 with the mass rearing of Anastrepha ludens (Loew) (Diptera: Tephritidae: Toxotrypanini) and in 2002 with Anastrepha obliqua (McQuart). Field releases of sterile insects began in the north of the country, and currently 51% of the country is free of these pests. In this review, we describe the mass‐rearing process and the quality control tests used in the production of the above‐mentioned species. As a case study, we also describe the achievements of applying the SIT against A. ludens populations in the citrus‐growing zone of the state of San Luis Potosí, which has resulted in dramatic reductions in both wild fly populations and the use of chemical sprays. We discuss the implications, achievements, and perspectives regarding the use of this technology to control Anastrepha pests in Mexico.

Phytosanitary Treatments Against Bactrocera dorsalis (Diptera: Tephritidae): Current Situation and Future Prospects

Abstract Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is arguably the most important tephritid attacking fruits after Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). In 2003 it was found in Africa and quickly spread to most of the sub-Saharan part of the continent, destroying fruits and creating regulatory barriers to their export. The insect is causing new nutritional and economic losses across Africa, as well as the losses it has caused for decades in infested areas of Asia, New Guinea, and Hawaii. This new panorama represents a challenge for fruit exportation from Africa. Phytosanitary treatments are required to export quarantined commodities out of infested areas to areas where the pest does not exist and could become established. This paper describes current phytosanitary treatments against B. dorsalis and their use throughout the world, the development of new treatments based on existing research, and recommendations for further research to provide phytosanitary solutions to the problem.

Anastrepha obliqua (Diptera: Tephritidae) mass-rearing: effect of relaxed colony management

In this study, the effects of relaxed mass-rearing conditions on Anastrepha obliqua (Macquart) production and quality were determined. Relaxed rearing conditions were defined by a reduction in the density of adult flies, from 80,000 to 60,000 flies per mass-rearing cage, and a reduction in the density of larvae, from 6.18 to 3.70 eggs/g of diet. In the parental generation, flies reared under relaxed conditions exhibited significant and a few non-significant changes - increased daily fecundity from 37 to 42 eggs per female, larval recovery from 80 to 91%, larval weight from 18.5 to 19.5 mg, pupation at 24h from 92 to 96%, pupal weight from 13.5 to 14.3 mg, adult emergence from 92 to 94% and percentage of fliers from 89 to 90%. During the following 12 generations, non-significant differences were observed, but comparisons between relaxed and non-relaxed colonies were significant. The sexual competitiveness of males produced under relaxed conditions was similar to that of wild males.

Comparison of Anastrepha ludens (Diptera: Tephritidae) Bisexual and Genetic Sexing (Tapachula-7) Strains: Effect of Hypoxia, Fly Density, Chilling Period, and Food Type on Fly Quality

Abstract The use of genetic sexing strain (GSS) insects in the sterile insect technique (SIT) makes necessary the revision of quality parameters of some stressful steps used during the packing process for aerial release because of possible differences in tolerance between fly strains. Here, we determined the effect of three periods of hypoxia (12, 24, and 36 h at pupal stage), three cage densities (1.0, 1.3, and 1.5 flies/cm2), two different foods (protein/ sugar (1/24) and Mubarqui), and three chilling times (20 min [control], 90, and 180 min) on the quality parameters of flies of two Anastrepha ludens (Loew) strains (bisexual and GSS Tapachula-7). In general, the response to stressful conditions of both fly strains was qualitatively equivalent but quantitatively different, as flies of both strains responded equally to the stressful factors; however, flies of Tapachula-7 exhibited lower quality parameters than the control flies. Thus, hypoxia affected the flying ability but not the emergence or longevity of flies. The food type affected the adult weight; protein/sugar produced heavier flies that also survived longer and had a greater mating propensity. Flies under the lowest density were better fliers that those at the other two densities. Increasing chilling time reduced flight ability but not longevity or mating propensity. The implications of these findings for the use of A. ludens GSS in SIT programs are discussed herein.

Male irradiation affects female remating behavior in Anastrepha serpentina (Diptera: Tephritidae)

Female remating in target pest species can affect the efficacy of control methods such as the Sterile Insect Technique (SIT) but very little is known about the postcopulatory mating behavior of these pests. In this study, we investigated the remating behavior of female Anastrepha serpentina (Diptera: Tephritidae), an oligophagous pest of Sapotaceae. First, we tested how long the sexual refractory period of females lasted after an initial mating. Second, we tested the effect of male and female sterility, female ovipositing opportunities and male density on female propensity to remate. Lastly, we tested if the amount of sperm stored by females was correlated to the likelihood of females to remate. We found that receptivity of mass-reared A. serpentina females had a bimodal response, with up to 16% of mass-reared A. serpentina females remating five days after the initial copulation, decreasing to 2% at 10 and 15 days and increasing to 13% after 20 days. Compared to fertile males, sterile males were less likely to mate and less likely to inhibit females from remating. Copula duration of sterile males was shorter compared to fertile males. Remating females were less likely to mate with a sterile male as a second mate. Sterile females were less likely to mate or remate compared to fertile females. Opportunity to oviposit and male density had no effect on female remating probability. Sperm numbers were not correlated with female likelihood to remate. Information on the post-copulatory behavior of mass-reared A. serpentina will aid fruit fly managers in improving the quality of sterile males. We discuss our results in terms of the differences this species presents in female remating behavior compared to other tephritids.

Hot-Water Phytosanitary Treatment Against Ceratitis capitata (Diptera: Tephritidae) in ‘Ataulfo’ Mangoes

ABSTRACT We determined the thermal death rate constants and mortality curves for the eggs and different instars of Ceratitis capitata (Mediterranean fruit fly) (Wiedemann) submerged in isolation in water at 44, 46, and 48°C and submerged within fruits of Mangifera indica (mango) (L.) in water at 43.1, 44.1, 45.1, and 46.1°C. The first instar was the most tolerant to this treatment, with estimated times for achieving 99.9968% mortality of 103.28,92.73, and 92.49 min at temperatures of 43.1, 44.1, and 45.1°C, respectively. The results of the study indicate that ‘Ataulfo’ mangoes weighing <329 ±2.11 g and at risk immature Mediterranean fruit fly infestation should be immersed for 95 min at 46.1-47°C to ensure that the fruit pulp remains at this temperature for 10 min. An efficacy test was conducted that involved treating 730 mangoes, with an average weight of 326 ±2.11 g (mean ±SE) and infested with 84 ±1.15 first instars. In this test, none of the 61,720 larvae treated survived. The confirmatory test was performed using commercial equipment in which 1,112 infested mango fruit weighing an average of 329 ±2.11 g were treated. Each fruit was previously infested with an average of 59 ±0.61 first instars (=65,825 total larvae) of which none survived. The data collected on mango quality indicate that hot water immersion for 95 min at 46.1–47°C can produce a more uniform fruit-color and positively modify the pH (producing more palatable fruits), but can also produce a loss of firmness and weight (5%). Taking all factors into consideration, we conclude that this treatment is sufficient to meet quarantine restrictions against C. capitata while maintaining market quality at least for 15 d.

An Artificial Larval Diet for Rearing of Anastrepha striata (Diptera: Tephritidae)

ABSTRACT An artificial larval diet for Anastrepha striata (Schiner) was developed and the changes in the rearing and quality parameters through 6 generations during the adaptation were characterized. In the first experiment we tested diet formulations that had already been developed for the mass-rearing of Anastrepha ludens (Loew), A. obliqua (Macquart), A. serpentina (Wiedemann) and Ceratitis capitata (Wiedemann) by sowing A. striata eggs (20–40% hatched) in each diet. In those tested diets, the maximum larval recovery percentage was 4.82%. In the second experiment, in the AOII modified diet of A. obliqua, we substituted the protein source, torula yeast by Nutrifly™, torula yeast-casein and hydrolyzed protein. A formulated diet contained 4.83% Nutrifly™, 15% corn cob fractions, 8.0% corn flour, 8.33% sugar, 0.23% sodium benzoate, 0.11% nipagin, 0.13% citric acid, and 63.37% water allowed higher larval survival compared to diets with different protein sources. In the third experiment, we evaluated adaptation of the larvae to Nutrifly diet. Over 6 generations, the larval and pupal weights and pupation percentage decreased from parental to first generation and increased after the third generation, recovering the initial value. Larval recovery and adult emergence increased from parental generation to the next generations; and was maintained during the next 5 generations. Larval recovery only a light decreased in the third generation. The laboratory colonization of A. striata reared on this artificial diet required at least 5 generations for the larvae to adapt to the artificial diet and increase pupal weight and adult emergence.

Generic larval diet for mass-rearing three species of Anastrepha (Diptera: Tephritidae)

The objective of this study was to determine whether a generic diet could be developed for three species of Anastrepha: A. ludens, A. obliqua and A. serpentina. Laboratory and mass-rearing tests to assess the suitability of the A. ludens (Loew) (ALU) diet, normally used for rearing A. ludens, indicated that it was also suitable for rearing A. obliqua (Macquart) and A. serpentina (Wiedemann). Therefore, this diet appeared to be a suitable generic diet for the three species based on quality control parameters. In comparison with those observed when rearing larvae on the commonly used A. obliqua diet, the number of A. obliqua larvae recovered per g diet increased from 4.2 to 5.1, larval weight increased from 17 to 18.2 mg, pupation after 24 h from 89.3 to 96.9%, adult emergence from 91.5 to 93.7% and flight ability (% of fliers) from 86.1 to 90.4% when reared on the ALU diet. Usually, A. serpentina larvae are reared on the A. serpentina diet, but when reared on the ALU diet, larval recovery increased from 61.8 to 69.8%, number of larvae recovered per g diet from 3.7 to 4.4, larval weight from 21.7 to 23.8 mg and flight ability from 64.6 to 70.2%. These results show that the nutritional requirements of the three Anastrepha species are similar. The use of a generic diet for rearing the three species requires only one line to prepare the diet, reducing time and labour costs.