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The relationship between humans, wildlife and disease transmission can be complex and context-dependent, and disease dynamics may be determined by idiosyncratic species. Therefore, an outstanding question is how general is the finding that species with faster life histories are more probable hosts of zoonoses. Ecological knowledge on species, jointly with public health data, can provide relevant information on species that should be targeted for epidemiological surveillance or management. We investigated whether mammal species traits can be good indicators of zoonotic reservoir status in an intensified agricultural region of Argentina. We find support for a relationship between reservoir status and the pace of life syndrome, confirming that fast life histories can be a factor of zoonotic risk. Nonetheless, we observed that for certain zoonosis, reservoirs may display a slow pace of life, suggesting that idiosyncratic interactions can occur. We conclude that applying knowledge from the life history-disease relationship can contribute significantly to disease risk assessment. Such an approach may be especially valuable in the current context of environmental change and agricultural intensification.

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The host status of sweet granadilla (Passifflora ligularis Juss.) to Ceratitis capitata (Wiedemann) and Anastrepha fraterculus (Wiedemann) in Peru was determined. Experiments were conducted in Pasco (Peru) in four different orchards, over 2 yr (2016 and 2017), two orchards per year. Choice (granadilla plus natural host) and no-choice foraging behavior trials were conducted using sleeves under field conditions, and forced infestation was examined in laboratory cages, with five females per fruit. The development time of C. capitata was determined, and the oviposition behavior of C. capitata and A. fraterculus was examined. Three fruit maturity stages of intact (n = 1,320) and punctured (n = 1,320) granadilla fruits were examined. Adult C. capitata (n = 4,418) and A. fraterculus (n = 2,484) were trapped in the orchards, and commercial granadilla fruits (n = 1,940) sampled and dissected. Fruit fly infestation was not found in any intact granadilla fruits. Larvae and pupae were found inside punctured granadilla only in fruits broken after 20 d, and adults only emerged when those pupae were removed from the fruit. Ceratitis capitata development time was longer in punctured granadilla than that in host fruit. In the oviposition test, A. fraterculus and C. capitata did not lay eggs in intact granadilla, and C. capitata laid eggs in punctured fruits but larvae were not found. Because of the resistance mechanisms of the pericarp, commercial fruits of Passiflora ligularis are not a natural host of C. capitata and A. fraterculus in Peru.

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Scientifically-based, tephritid fly host status determination lies at the heart of strategic regulatory decisions impinging on international fruit trade. Here we conducted intensive field and laboratory studies with peaches as controls, to determine the host status of Physalis peruviana for the Medfly-Ceratitis capitata, as this fruit is experiencing a consumption boom worldwide. A total of 98,132 Uchuvas (local name), collected in Colombia from the plant or the ground over a three-year period (2016-2018) did not yield a single C. capitata larva or pupa, thus reaching a Probit 9 level with 99.9968% efficacy and 96% confidence level. Field-cage studies with enclosed fruit-bearing Uchuva plants, exposing fruit with an intact, damaged or totally removed husk to the attack of C. capitata, also failed to yield infestations. Highly artificial choice experiments, exposing gravid females to unripe and fully ripe fruit, resulted in an absence of infestations, even when overripe Uchuvas were artificially damaged. The husk and surface resins/waxes inhibit fly landings on fruit and oviposition activity. Considering our results and the fact that the foliage, husk and fruit of P. peruviana are repellent/toxic to insects, we conclude that this plant should be treated as a non-natural and non-conditional host of C. capitata.

RESUMO

Anastepha ludens (Diptera: Tephritidae) is a highly polyphagous fruit fly that is able to develop in a wide range of hosts. Understanding the limits of this pest's host range could provide valuable information for pest management and plant breeding for pest resistance. Previous studies have shown that guavas (Psidium guajava (Myrtaceae) L.), are not attacked under natural conditions by A. ludens. To understand this phenomenon, guavas were exposed to natural infestation by A. ludens and to other fruit fly species that infest guavas in nature (Anastrepha striata Schiner, Anastepha fraterculus (Wiedemann), Anastepha obliqua (Macquart)). Once the susceptible phenological stage of guavas was determined, fruit infestation levels were compared between A. ludens and A. striata. Choice and non-choice tests were performed under field-cage conditions. Under field conditions, guavas were susceptible to A. striata and A. fraterculus attack all the way from when fruit was undeveloped to when fruit began to ripen. No infestation by A. ludens was recorded under natural conditions. Similar results were obtained when forced exposures were performed, indicating that unripe guavas were preferred by A. striata over ripe fruit, and that infestation rates were higher at early fruit maturity stages. Under forced oviposition conditions, A. ludens larvae were unable to develop in unripe guavas but did so in fully ripe fruit. However, A. ludens fitness parameters were dramatically affected, exhibiting reduced survival and reduced pupal weight compared to conspecifics that developed in a natural host, grapefruit. We confirm that P. guajava should not be treated as a natural host of this pestiferous species, and suggest that both behavioral aspects and the fact that larvae are unable to adequately develop in this fruit, indeed represent clear limits to A. ludens's broad host range.

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The toxicity of essential oils from the citrus peel has been proposed as the major resistance mechanism offered by citrus to fruit fly infestation. We evaluated the insecticidal activity of the ether extracts from the lemon (Citrus limon [L.] Burm.) and grapefruit (C. paradisi Macfadyen) peel as well as from limonene and citral against Anastrepha fraterculus (Wiedemann) and Ceratitis capitata (Wiedemann) immature stages. We also evaluated the toxicity of the extracts at two ripening stages. Extracts proved toxic to A. fraterculus egg and larvae. The lemon and grapefruit extracts showed the same toxicity in both fruit fly species. For A. fraterculus eggs, citral was more toxic than limonene; for larvae, they showed equal toxicity. Anastrepha fraterculus eggs were more sensitive than C. capitata eggs. In conclusion, we provide evidence of chemical resistance mechanisms that could account for the nonhost condition of lemon for A. fraterculus.

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