There are many types of parasitic larvae that feed on animal flesh in open wounds (causing a so-called myiasis), but the New World screwworm is particularly gruesome due to how common it is, and the fact that it feeds on living and healthy tissue (Hall 1991). Beginning in the 1950’s and ending about half a century later, the New World screwworm (Cochliomyia hominivorax) was eradicated using the Sterile Insect Technique from the southern half of the United States, all of Mexico, and virtually all of mainland Central America, but stopped short of South America and the Caribbean islands. This eradication was motivated by the damage it was causing to the economy primarily through effects on livestock, and likely also by the severe suffering it causes in affected humans and pets. The successful and large-scale use of the Sterile Insect Technique to control and eliminate a parasite for our own benefit, raises the question of whether past and future work in this area have had/will have similar benefits to the welfare of wild animals. Unfortunately, the effects that the New World screwworm has on wild animal welfare has to the most part been ignored, even though, as Scott et al. (2017) put it: “Screwworm myiasis is also devastating when one’s pet is affected and its impact on wildlife is incalculable yet likely significant”. An infection by the New World screwworm is seemingly very painful in humans (see here, here, and here), and it can take up to two weeks for an infected animal to die if it is not treated (OIE Technical Disease Card on New World and Old World screwworm). While it is still an open question whether the eradication of the New World screwworm improved aggregate wild animal welfare when taking all effects into account, the first-order direct effects on the affected wild animals certainly warrants further investigation of that question.
We have identified two particularly promising versions of a project aimed at investigating the wild animal welfare effects of the New World screwworm (see “Option 1” and “Option 2” below). However, it is possible that we have missed an even better opportunity, so we also welcome project proposals that address the issue from another angle and/or by using other methods than the ones we suggest (see “Option 3” below).
Option 1 - Retrospective focus
It seems to us that a retrospective study on the wild animal welfare effects of the eradication New World screwworm would likely be the most valuable. There have been previous retrospective studies (e.g., Gutierrez et al. 2019) of the effects of the eradication program, but they have not focused on the welfare effects on wild animals. A retrospective study on the wild animal welfare effects would involve modelling/estimating the scope of the direct effects in different ways, such as the number of animals affected per unit time, either in total or separately for each host species. This could entail trying to estimate the number of wounds needed to sustain a screwworm population of a particular size, and by collating/collecting data on infection rates in wild animals (see e.g., Lindquist 1937, Marburger and Thomas 1965, Teer et al. 1965, Altuna et al. 2021) and compensatory increases in survival of hosts. Such a project would ideally also incorporate a number of indirect effects, such as compensatory increases of competing parasites (Bermúdez et al. 2007). Crucially, such a retrospective study would ideally also attempt to estimate changes in the causes of death of the host species; avoiding one cause of death only to die soon after in an even more painful way, would likely not be considered an improvement from the perspective of the animal in question (cf. Allen et al. 2019).
Option 2 - Current or prospective focus
This type of project would aim to estimate the current or future wild animal welfare effects of the presence of the New World screwworm in South America, by (similar to in ‘Option 1’) collating information about incidence rates in the affected species for instance.
There have been prospective studies conducted on the New World screwworm, such as the study by Gutierrez and Ponti (2014) where they investigated the risk of the New World screwworm spreading further north aided by global warming (Fresia et al. 2013), or spreading east causing a repeated invasion of Mediterranean countries (Vargas-Terán et al. 1994).
Option 3 - Other
If neither the retrospective or the prospective lens seems useful, and you see the potential for a different research project that investigates the wild animal welfare effects of the New World screwworm, that address the impact on the affective states of animals (i.e. it is not sufficient to measure stress hormones and/or indicators health), you can submit it under the category “Other”.
See the Challenge Grants webpage for project guidelines and general selection criteria. If you are interested in submitting a proposing a project under this specification, please email us at grants@wildanimalinitiative.org to discuss.
Provides an overview of the project and how it is relevant for advancing the understanding of wild animal welfare.
Provides additional details on the key questions, as well as constraints on experimental design, study system, timeline, etc.
Details any specific requirements of the project, such as geographic location, qualifications required of candidates, and any other details that define suitable applicants.