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CRISPR-based genetic engineering tools aimed to bias sex ratios, or drive effector genes into animal populations, often integrate the transgenes into autosomal chromosomes. However, in species with heterogametic sex chromsomes (e.g. XY, ZW), sex linkage of endonucleases could be beneficial to drive the expression in a sex-specific manner to produce genetic sexing systems, sex ratio distorters, or even sex-specific gene drives, for example. To explore this possibility, here we develop a transgenic line of Drosophila melanogaster expressing Cas9 from the Y chromosome. We functionally characterize the utility of this strain for both sex selection and gene drive finding it to be quite effective. To explore its utility for population control, we built mathematical models illustrating its dynamics as compared to other state-of-the-art systems designed for both population modification and suppression. Taken together, our results contribute to the development of current CRISPR genetic control tools and demonstrate the utility of using sex-linked Cas9 strains for genetic control of animals.

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Introduction: this study aims to investigate the eco-epidemiological factors associated with Leishmania spp. infection in dogs from the Metropolitan Area of Bucaramanga (MAB)‚ Santander‚ eastern Colombia‚ which is a region at risk of VL. Methods: we conducted molecular and serological surveillance of Leishmania spp. in 207 dogs from MAB to determine the epidemiological factors associated with infection. Subsequently‚ we carried out a molecular and serological analysis of phlebotomine and humans in the area to describe the main features associated with the transmission cycle. Results: out of the 207 dogs tested‚ 37 (17.8 %‚ 95 % CI=12.6 - 23.1 %) were positive for Leishmania spp. by the IFAT test‚ and only 9 (4.3 %‚ 95 % CI=1.55 - 7.15 %) were positive for L. infantum in the molecular analysis. Multivariate analyses indicated that canine shelters had a higher prevalence of infection (p < 0.05). In the entomological survey‚ 69 blood-fed female phlebotomine of the genus Lutzomyia were captured in canine shelters‚ among them‚ 55 % were identified as Lutzomyia camposi‚ 29 % as Lu. ovallesi‚ 7 % as Lu. dubitans‚ 6 % as Lu. torvida‚ and 3 % as Lu. cayennensis. The identified meal sources of the phlebotomine included human‚ pig‚ avian‚ cattle‚ and porcupine (Coendou quichua) blood. However‚ no phlebotomine positive for Leishmania spp. were detected by molecular analyses. Finally‚ 14 humans who had frequent contact with L. infantum-positive dogs were analyzed through rK39 test‚ but none was positive for IgG/IgM antibodies. Conclusion: the molecular and serological analyses indicate a low prevalence of L. infantum in dogs from MAB‚ with canine shelters having the highest prevalence of infection. The entomological survey of canine shelters showed a significant diversity of phlebotomine without potential vectors of L. infantum‚ suggesting that the infection in dogs from these areas could take place in other locations or through other transmission routes. The circulation of L. infantum in multiple dogs from MAB suggests a latent risk of zoonotic transmission of VL in these cities. [ABSTRACT FROM AUTHOR]

The abundance and aggregation of eggs of Aedes aegypti L. and Aedes albopictus Skuse was evaluated in the municipalities of Cambé, Ibiporã, Jacarezinho, Maringá and Paranavaí, in the State of Paraná, Brazil by means of oviposition traps. Of the 225 installed traps, 100 were registered as positive for eggs; 4140 eggs were collected, thus demonstrating an highly aggregate distribution. Both species were registered in Cambé, Jacarezinho, Maringá and Paranavaí. Ae. albopictus was generally less abundant and was not present in Ibiporã nor in the oviposition traps of a second collection of Maringá. The relation between sexes for Ae. aegypti was approximately 1:1. In the comparison of the number of adults collected between the two species, a negative correlation was obtained in the samples of Maringá and Cambé, what was attributed the seasonality of these populations. The coexistence of these species indicates that both are under pressure by the control programs, therefore specific evaluations are necessary.

Objective: A simulation model is presented to show the predation dynamics of Mesocyclops spp. over Aedes aegypti., Methods: The system is represented through four differential equations. H'(t), quantity of eggs; L'(t), quantity of larvae; A'(t), quantity of adults and C'(t), quantity of copepods. Initially the equations are of the classic predator-prey type, according to Lotka (1924) and Volterra (1926). Then it is modified into a system with functional response for invertebrates, according to Holling., Results: The first system effectively controls and stabilizes the mosquito population, while the second suggests that copepods may be ineffective as mosquito controllers., Conclusions: The need to study predator-prey systems (copepodos-mosquitos) with projects that integrate laboratory and of field tests is recognized. Only then will it be possible to establish the validity of predators as effective biological controllers of mosquitoes.