Salvador Flores

Horizontal Transmission of Beauveria bassiana in Anastrepha ludens (Diptera: Tephritidae) Under Laboratory and Field Cage Conditions

Abstract The virulence of two products of the fungus Beauveria bassiana (LCPP and Bassianil) on adult Anastrepha ludens (Loew) (Diptera: Tephritidae) and their effect on the mating performance of infected males was evaluated in laboratory and field cage tests. The horizontal transmission capacity of the fungus during copulation or attempted copulation also was quantified using inoculated males as well as the impact of infection on female fecundity and longevity. Both fungal products were found to be highly virulent (LCPP, mortality = 98.7% at 1 × 108 conidia per ml, LT50 = 4.20 d, LC50 = 9.35 × 105 conidia per ml; Bassianil, mortality = 99.3% at 1 × 108 conidia per ml, LT50 = 4.04 d, LC50 = 2.69 × 107conidia per ml). Mating success of inoculated males was not affected compared with the control group during the 3 d postinoculation. Horizontal transmission to females during the first day was 80.6 and 84.3% through mating and 15.4 and 21.6% through attempts to mate and contact during courtship for the LCPP and Bassianil products, respectively. The fertility of infected females was notably reduced, and longevity did not extend beyond 15 d. Our results suggest the possibility of using sterile flies as fungus vectors in sterile insect technique programs, but the potential benefits and shortcomings of this approach require further investigation.

There Is No Magic Fruit Fly Trap: Multiple Biological Factors Influence the Response of Adult Anastrepha ludens and Anastrepha obliqua (Diptera: Tephritidae) Individuals to MultiLure Traps Baited With BioLure or NuLure

ABSTRACT Field-cage experiments were performed to determine the effectiveness of MultiLure traps (Better World MFG Inc., Fresno, CA) baited with NuLure (Miller Chemical and Fertilizer Corp., Hanover, PA) or BioLure (Suterra LLC, Inc., Bend, OR) in capturing individually marked Mexican fruit fly, Anastrepha ludens (Loew), and West Indian fruit fly, Anastrepha obliqua (Macquart) (Diptera: Tephritidae), of both sexes. Experimental treatments involved wild and laboratory-reared flies of varying ages (2–4 and 15–18 d) and dietary histories (sugar only, open fruit, open fruit plus chicken feces, and hydrolyzed protein mixed with sugar). Data were divided into two parts: total captures over a 24-h period and trap visits/landings, entrances into interior of trap ,and effective captures (i.e., drowning in liquid bait or water) over a 5-h detailed observation period (0600–1100 hours). The response to the two baits varied by fly species, gender, physiological state, age, and strain. Importantly, there were several highly significant interactions among these factors, underlining the complex nature of the response. The two baits differed in attractiveness for A. obliqua but not A. ludens. The effect of strain (wild versus laboratory flies) was significant for A. ludens but not A. obliqua. For effect of dietary history, adults of both species, irrespective of sex, were significantly less responsive to both baits when fed on a mixture of protein and sugar when compared with adults fed the other diets. Finally, we confirmed previous observations indicating that McPhail-type traps are quite inefficient. Considering the total 24-h fly tenure in the cage, and independent of bait treatment and fly type (i.e., strain, adult diet, gender and age), of a total of 2,880 A. obliqua and 2,880 A. ludens adults released into the field cages over the entire study (15 replicates), only 564 (19.6%) and 174 (6%) individuals, respectively, were effectively caught. When only considering the 5-h detailed observation period and independent of bait treatment and fly type, of a total of 785 marked flies that landed on traps (519 females and 266 males, respectively), only 10.3% (144 females and 59 males) and 20.8% (25 females and 18 males) A. obliqua and A. ludens individuals, respectively, ended up being effectively captured. We discuss the practical implications of these findings with respect to developing new baits and designing new traps and to the interpretation of capture results in the field.

Effect of Rainfall and Soil Moisture on Survival of Adults and Immature Stages of Anastrepha ludens and A. obliqua (Diptera: Tephritidae) under Semi-field Conditions

Abstract In this work we report the effect of rainfall on survival of pupae and adults of Anastrepha ludens (Loew) and A. obliqua (Macquart) under semi-field conditions. The influence of 2 soil textures and soil moisture on depth of pupation and pupal survival of both species was studied. There was no statistical difference on depth of pupation between larvae of A. ludens and A. obliqua in both types of soils. Adult emergence of A. ludens was higher than A. obliqua from soils with low moisture, while no significant difference was observed in soils at field capacity and saturation point. In the farm “Alianza” locality (760 masl, 1219 mm of rainfall), adult emergence decreased in direct relation to rainfall (r = 0.956 for A. ludens; r = 0.952 for A. obliqua), but this was not observed in Metapa de Dominguez (120 masl, 1114 mm of rainfall). Rainfall did not have any significant effect on adult mortality (r = 0.038 for A. ludens; r = 0.051 for A. obliqua), even under intense precipitation (120-160 mm/day), which indicates that fruit fly adults are able to find adequate refuge during heavy rain. These results are evidence that rainfall does not exert a significant impact on emergence and survival of adults of these species, and that the yearly fluctuations of their populations are mainly correlated to other factors such as host fruiting phenology.

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.

Evaluation of lufenuron as a chemosterilant against fruit flies of the genus Anastrepha (Diptera: Tephritidae)

BACKGROUND Chemosterilisation with lufenuron bait stations is a recently developed technique that is being implemented for Ceratitis capitata Wiedemann control. The aim of this work was to evaluate the chemosterilising effect of lufenuron against four economically important Latin American fruit flies species: Anastrepha ludens (Loew.), A. obliqua Macquart, A. serpentina Wiedemann and A. striata Schiner (Diptera: Tephritidae) in order to design a similar strategy for their control. RESULTS Sexually mature adults were treated by ingestion with concentrations ranging from 0.1 to 30.0 mg g(-1) of lufenuron in the diet. In addition, conspecific crosses with only one of the sexes being treated (30.0 mg g(-1)) were performed in order to appraise the contribution of each sex to the sterilising effect. In all cases, fecundity was not affected by the treatments, as opposed to fertility where all Anastrepha species studied were significantly affected, although to different extents. The conspecific crosses showed that treated males of A. ludens, A. obliqua and A. serpentina were not able to transmit the sterility to their respective untreated females. Only in the case of A. striata did crossing treated males with untreated females significantly reduced egg hatch. CONCLUSION Although further investigations are required, the present results demonstrate that the use of lufenuron for controlling A. striata could be potentially viable.

Residual Control and Lethal Concentrations of GF-120 (spinosad) for Anastrepha spp. (Diptera: Tephritidae)

ABSTRACT The objective of this study was to determine the relationship between residual time of GF-120 (spinosad) treatment and mortality in three species of Anastrepha Schiner. Concentrations of 96, 72, 48, and 24 ppm were aged on mango leaves under field conditions for 0, 3, 7, 10, 14, 17, and 21 d after application. We found that Anastrepha ludens, A. obliqua, and A. serpentina were highly sensitive to spinosad. The effects of spinosad were not reduced over the 4 d after the initial application, even at a concentration of 24 ppm. Mortality at 14 d after the application of 72 and 96 ppm of spinosad was similar in each of the three fruit fly species. In addition, we found that 24 ppm of spinosad was consumed the most by each species even though no direct relationship between the rate of consumption per female and the dose of the product was observed, in this test, higher consumption of active ingredient was observed at a concentration of 72 ppm, for A. ludens, 48 ppm for A. obliqua, and 96 ppm for A. serpentina. Our results suggest that a spinosad concentration of 72 ppm may effectively control these pests for at least 10 d under field conditions.

Sterile males of Ceratitis capitata (Diptera: Tephritidae) as disseminators of Beauveria bassiana conidia for IPM strategies

Sterile Mediterranean fruit fly, Ceratitis capitata (Wied.), males were evaluated as vectors to spread Beauveria bassiana (Bals) conidia to wild C. capitata populations under field conditions. The inoculated sterile males were released by air, using the chilled adult technique over 7000 ha of coffee growing in Chimaltenango, Guatemala, Central America. The impact of releases was determined using dry traps baited with a food attractant. The effects of these releases on Apis mellifera, Linnaeus (honey bee), Hypothenemus hampei, Ferrari (coffee berry borer) and the parasitic mite Varroa destructor (Oudeman) were also evaluated. Inoculated sterile males were able to transmit fungal spores to 44% of the wild C. capitata flies captured in traps, which likely were infected through intra- and intersexual interactions during leks, mating or mating attempts. There was no transmission of the fungal spores to non-target insect species such as coffee berry borer, honey bees or varroa. We conclude that sterile males of Mediterranean fruit fly inoculated with B. bassiana can act as effective vectors of conidia to wild populations, constituting a safe, environmentally friendly and selective alternative for suppressing the medfly under a Sterile Insect Technique-based IPM approach.

Evaluation of field dispersal and survival capacity of the genetic sexing strain Tapachula-7 of Anastrepha ludens (Diptera: Tephritidae)

Abstract The sterile insect technique (SIT) is an ecologically oriented strategy for pest control and a very important tool for establishing low pest prevalence and/or areas free of fruit flies (Diptera: Tephritidae). This technique involves releasing highly competitive sterile adults into an area with the aim to induce sterility in the wild population. Because genetic sexing strains are an economical and efficient improvement for SIT, the Moscafrut Program in Mexico developed the Tapachula-7 (Tap-7) strain of Anastrepha ludens (Loew) from which the female flies emerge from black pupae and can be separated mechanically allowing release of predominantly male flies. This study compared the field dispersal and survival of Tap-7 adult males with those of standard mass-reared adult males (SMR strain) after irradiation, packaging, and an aerial release of chilled adults. The Tap-7 strain exhibited a statistically larger dispersal pattern and slightly lower, although not statistically significant, survival compared with the SMR strain. These results show that both strains should perform similarly in the field and suggest that the Tap-7 strain could replace the standard one for field release of sterile flies against A. ludens wild populations in the near future, reducing costs in the use of the SIT.

Effect of Multiple Endogenous Biological Factors on the Response of the Tephritids Anastrepha ludens and Anastrepha obliqua (Diptera: Tephritidae) to MultiLure Traps Baited With BioLure or NuLure in Mango Orchards

ABSTRACT The physiological state of an insect is likely the most important endogenous factor influencing resource-oriented behavior, and it varies considerably among individuals. Trials were conducted in mango orchards to study the effect of multiple endogenous biological factors on the response of two fly species, Anastrepha ludens (Loew) and Anastrepha obliqua Maquart (Diptera: Tephritidae), to BioLure and NuLure baits. The biological factors of the two fly species that were tested were the following: 1) fertility status—sterile (irradiated) and fertile flies; 2) two types of diets (only sugar and a 3:1 mixture of sugar and hydrolyzed yeast protein; 3) sex, and 4) two sexual maturity conditions (2–4- and 15–18-d-old flies, representing immature and sexually mature flies, respectively, and 2–4-d-old flies treated with methoprene as an artificially induced sexually state male condition). The laboratory-treated flies were released into three different mango orchards. The trials were conducted in four blocks per orchard using eight traps in each block (50:50 BioLure: NuLure). The traps were replaced every 2 d during the 12-d period and the flies per trap per day values were calculated. More protein-fed, fertile, female, immature, and A. obliqua flies were caught compared with the other flies tested. In addition, the traps baited with NuLure attracted more flies than those baited with BioLure. Interaction analyses indicated that the type of bait and the sexual maturity status were the most important factors affecting the responses of the flies. Our study demonstrated that lures attract only a small segment of the fly population, those that have a specific hunger for amino acids—immature flies—and those that were protein-starved. The implications for improved trapping system designs are discussed.

Estimation of Populations and Sterility Induction in Anastrepha ludens (Diptera: Tephritidae) Fruit Flies

ABSTRACT The relationship between different release densities of sterile flies and fly trap captures, expressed as flies per trap per day, in the monitoring of Anastrepha ludens (Loew) populations was evaluated in mango orchards. The induction of sterility in fertile females was evaluated using different ratios of sterile: fertile males under field cage conditions. A direct relationship between recaptured flies and densities of release sterile flies was found. However, trap efficiency, expressed as percentage of recaptured flies, decreased as the density of released flies increased. Sterility induction was positively correlated to the ratio of sterile: fertile flies. A significant difference in egg fertility among treatments was observed. The trajectory of sterility induction slowed down after a sterile: wild ratio of 30:1, which suggests that this ratio could be appropriate in an sterile insect technique program with A. ludens. Sterility induction was greater when only sterile males were released than when releasing both sterile males and females, but the differences were not significant. Our findings contribute to a better interpretation of fly captures obtained from the field trapping networks, and to an improvement in the efficiency of sterile insect technique against A. ludens fruit flies, through the implementation of more rational sterile fly release densities.