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Additional file 1: Text S1. Structure of the database on tsetse and animal African trypanosomiasis in Zimbabwe.

Background: The success of sterile insect technique (SIT) programs against many tephritid fruit flies, including Ceratitis capitata (Wiedemann), relies on the mating success of released sterile males in the field. Since its´ development in an area-wide concept, this control program is evaluated by the recapture ratio of sterile versus wild flies. This measure neither takes into account the real target of the SIT that is the wild female, nor does it give any clue about the success of released sterile males. Thus, the contribution of released sterile males to reduce the wild population still remains as a key issue. In this work we review recent findings on how sterile males contribute to reduce wild populations by means of analyzing the sperm content of wild females, as the real target of the SIT program. Methods: A mating competition test was initially performed in laboratory and then under semi-natural conditions, with different Ceratitis capitata Vienna-8 tsl release ratios. The efficacy of the SIT and its contribution to reduce wild population was assessed by determining the percentage of females mated with sterile male, with a sperm ID molecular test, and by linking to offspring production on sentinel hosts. Results: Statistical methods have been developed with the obtained data of sperm ID in the spermathecae of captured females and with data of viable offspring produced in sentinel fruits, revealing that both can be predicted using release ratio and mean temperature. Moreover, humidity arose also as a factor influencing the female capture in lured traps. A strong negative relationship was established between the proportion of Vienna-8 mated females and Ceratitis capitata offspring production, being a key point for a model to predict the SIT program success. Conclusions: The statistical models developed should contribute to enhance the efficacy of SIT programs against Ceratitis capitata by means of modulation of release ratios by season temperature and by checking wild female’s sterile sperm content.

Autocidal control of the Mediterranean fruit fly Ceratitis capitata (Wiedemann) is an environmentally friendly and safe practice employed successfully worldwide. A key component in the Sterile Insect Technique (SIT) is to release sterile males that can compete with wild males in nature. Exposure of sterile males to ginger root oil (GRO) in the form of aromatherapy prior to release has been shown to significantly improve male competitiveness and performance. However, alternatives to GRO exposure are desired to (i) reduce personnel costs and handling-time requirements and (ii) find new aromatherapeutic compounds. In this study, alternatives to GRO aromatherapy were investigated, such as incorporating GRO into the post-teneral diet, or employing other molecules (limonene and linalool) occurring naturally in citrus release areas. Our results reveal that both the GRO-supplemented diet and linalool aromatherapy were equal to the GRO aromatherapy control in improving mating performance in sterile males. In contrast, exposure to limonene did not afford a mating advantage to sterile mates when compared to the control. In addition, sterile male survival was not affected by any of the treatments tested. Implications for how both new approaches could be implemented in SIT programmes in citrus production areas are discussed.

Vienna-8 sterile males are currently released in Spain to reduce wild populations of the medfly. Because pesticides are required to maintain populations of some citrus key pests below economic thresholds, there is a need to evaluate the effects of pesticides commonly used in citrus on Vienna-8 males. Males were exposed to differently aged residues of eight pesticides. Abamectin, etofenprox, etoxazole, petroleum spray oil, pymetrozine, and pyriproxyfen resulted harmless to Vienna-8 males. However, fresh residues of chlorpyrifos and spinosad caused high mortalities and had residual effects until 21 and 28 d after treatment, respectively. Following the same method, the lethal effects of chlorpyrifos and spinosad on Ceratitis capitata (Wiedemann) wild-type (wt) males were determined. Surprisingly, these pesticides resulted more toxic for wt than for Vienna-8 males. To determine whether these results could be attributed to intrinsic characteristics of the pesticides or to behavioral differences among Vienna-8 and wt males, a topical application trial was conducted. Vienna-8 males were twice as susceptible to chlorpyrifos as wt males, whereas their susceptibility to spinosad was slightly lower. These results in intrinsic toxicity did not directly explain the differences observed in the extended-laboratory tests with these pesticides. We hypothesize that the lower flight activity of Vienna-8 males relative to wt conspecifics can explain the lower risk observed for Vienna-8 males in the residual tests. Our results should be taken into account when planning area-wide Sterile Insect Technique programs against C. capitata especially in those areas where treatments with chlorpyrifos are approved.

Background The success of an area-wide sterile insect technique (SIT) programme against Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) relies on the mating success of sterile males in the field. Limited information is available about the effectiveness of sterile males in achieving mates with wild females and how these matings contribute to reducing wild populations. To this end, firstly a mating competition test was performed in the laboratory with different release ratios (1:1:0, 1:1:1, 1:1:5, 1:1:10 and 1:1:20 for wild females:wild males:sterile VIENNA-8 males respectively) and different host fruit. Secondly, the same release ratios were evaluated under semi-natural conditions on caged trees and on sentinel host. Results By means of molecular markers, VIENNA-8 male sperm was positively detected in those females exposed to the male ratios 1:5, 1:10 and 1:20 in the laboratory. In the field test, sterile VIENNA-8 male matings and the C. capitata progeny on apples were positively correlated with the ratio of sterile males released and with the percentage of sterile matings respectively. Conclusions These results confirm the validity of using the molecular detection of VIENNA-8 male sperm to predict the C. capitata population under semi-natural conditions. Implications of these results in measuring the efficacy of an SIT programme are discussed. (c) 2012 Society of Chemical Industry

BACKGROUND: The success of an area-wide sterile insect technique (SIT) programme against Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) relies on the mating success of sterile males in the field. Limited information is available about the effectiveness of sterile males in achieving mates with wild females and how these matings contribute to reducing wild populations. To this end, firstly a mating competition test was performed in the laboratory with different release ratios (1:1:0, 1:1:1, 1:1:5, 1:1:10 and 1:1:20 for wild females:wild males:sterile VIENNA-8 males respectively) and different host fruit. Secondly, the same release ratios were evaluated under semi-natural conditions on caged trees and on sentinel host. RESULTS: By means of molecular markers, VIENNA-8 male sperm was positively detected in those females exposed to the male ratios 1:5, 1:10 and 1:20 in the laboratory. In the field test, sterile VIENNA-8 male matings and theC. capitataprogeny on apples were positively correlated with the ratio of sterile males released and with the percentage of sterile matings respectively. CONCLUSIONS: These results confirm the validity of using the molecular detection of VIENNA-8 male sperm to predict the C. capitatapopulation under semi-natural conditions. Implications of these results in measuring the efficacy of an SIT programme are discussed.

BACKGROUND: The sterile insect technique (SIT) is acknowledged around the world as an effective method for biological pest control of Ceratitis capitata (Wiedemann). Sterile insects are produced in biofactories where one key issue is the selection of the progenitors that have to transmit specific genetic characteristics. Recombinant individuals must be removed as this colony is renewed. Nowadays, this task is performed manually, in a process that is extremely slow, painstaking and labour intensive, in which the sex of individuals must be identified. The paper explores the possibility of using vision sensors and pattern recognition algorithms for automated detection of recombinants. RESULTS: An automatic system is proposed and tested to inspect individual specimens of C. capitata using machine vision. It includes a backlighting system and image processing algorithms for determining the sex of live flies in five high-resolution images of each insect. The system is capable of identifying the sex of the flies by means of a program that analyses the contour of the abdomen, using fast Fourier transform features, to detect the presence of the ovipositor. Moreover, it can find the characteristic spatulate setae of males. Simulation tests with 1000 insects (5000 images) had 100% success in identifying male flies, with an error rate of 0.6% for female flies. CONCLUSION: This work establishes the basis for building a machine for the automatic detection and removal of recombinant individuals in the selection of progenitors for biofactories, which would have huge benefits for SIT around the globe. (C) 2008 Society of Chemical Industry

El Centro de Agroingeniería del IVIA ha desarrollado máquinas para la liberación de machos estériles de Ceratitis capitata. Las máquinas son capaces de almacenar de uno a diez millones de individuos y de conservarlos en condiciones de temperatura y humedad relativa adecuadas. Los prototipos se diseñaron para ser económicamente factibles y autónomos y pueden ser transportados por una pequeña furgoneta o pick-up, para la liberación terrestre, o en avionetas, para la liberación aérea. Un sistema de control electrónico se encarga de mantener la temperatura y la humedad óptimas. Las pruebas de campo, realizadas en colaboración con la Unidad Asociada de Entomología del IVIA-CIB CSIC, han demostrado la eficacia del sistema. Máquinas similares pueden emplearse en otros sistemas de control autocida.

Un proceso fundamental dentro de la biofábrica de insectos estériles es la selección de los progenitores, que forman la denominada colonia. La colonia inicial está formada por individuos seleccionados con unas determinadas características genéticas, pero su descendencia puede sufrir mutaciones espontáneas que no expresen determinados caracteres deseados (individuos recombinantes). Entre los caracteres expresados que deben permanecer entre los individuos de la biofábrica están el que permite eliminar las larvas hembras a temperaturas de 37ºC y el de que las hembras formen puparios de color crema-blanquecino y los machos de marrón oscuro. De esta manera, se pueden distinguir fácil y rápidamente las hembras de los machos.

El Centro de Agroingeniería del IVIA ha desarrollado un prototipo de una máquina para la liberación de machos estériles de Ceratitis capitata desde tierra. La máquina es capaz de almacenar 1,8 millones de insectos y de conservarlos en condiciones de temperatura y humedad relativa adecuadas. El prototipo se diseñó para ser económicamente factible y autónomo. Puede ser transportado por una pequeña furgoneta o pick-up. El cuerpo central es de polietileno y permite un aislamiento completo para preservar la temperatura de los insectos. Las adultos se mantienen en compartimentos en forma de paralelepípedo, de manera que no se amontonan los individuos en grandes cantidades. El sistema de enfriamiento del aire se basa en paneles eutécticos, ya que de este modo no se requiere un aporte de energía externa. Dentro de cada compartimento, el aire circula por medio de ventiladores eléctricos que evitan la condensación de agua y permiten el mantenimiento de una temperatura uniforme dentro de los mismos. Un sistema de control electrónico se encarga de mantener la temperatura en el rango que define el usuario. Las moscas se dosifican usando un tornillo sinfín y son lanzadas por el flujo de aire generado por un ventilador centrífugo que requiere 1,9 kilovatios de una fuente externa. Las moscas se dirigen hacia las copas de los árboles objetivo usando dos tubos flexibles. Las pruebas de campo, realizadas en colaboración con la Unidad Asociada de Entomología del [VIA-CIB CSIC, demostraron que su eficacia es equivalente al sistema de liberación manual.