the GlobalChangeBiology blog

Tropical fruit flies are considered among the most economically important invasive species detected in temperate areas of the United States and the European Union. Detections often trigger quarantine and eradication programs that are conducted without a holistic understanding of the threat posed. Weather-driven physiologically-based demographic models are used to estimate the geographic range, relative abundance, and threat posed by four tropical tephritid fruit flies (Mediterranean fruit fly, melon fly, oriental fruit fly, and Mexican fruit fly) in North and Central America, and the European-Mediterranean region under extant and climate change weather (RCP8.5 and A1B scenarios). Most temperate areas under tropical fruit fly propagule pressure have not been suitable for establishment, but suitability is predicted to increase in some areas with climate change. To meet this ongoing challenge, investments are needed to collect sound biological data to develop mechanistic models to predict...

Before its eradication from North America, the subtropical‐tropical new world screwworm fly Cochliomyia hominivorax (Coquerel) invaded southwestern temperate areas of the U.S.A., where it caused myiasis in wildlife and livestock. Outbreaks of the fly occurred during years when adult migrants were carried northward on North American monsoon winds from the northern areas of Mexico and south Texas. We deconstruct, retrospectively, the biology and the effect of weather on the eradication of the fly in North America. Screwworm was found to be an ideal candidate for eradication using the sterile insect technique (SIT) because females mate only once, whereas males are polygynous, and, although it has a high reproductive potential, field population growth rates are low in tropical areas. In northern areas, eradication was enhanced by cool‐cold weather, whereas eradication in tropical Mexico and Central America is explained by the SIT. Despite low average efficacy of SIT releases (approximately...

The new world screwworm Cochliomyia hominivorax (Coquerel) was eradicated in North America, Libya and other locations using the sterile insect technique (SIT). To examine the role of weather in its eradication, a physiologically-based demographic model (PBDM) was developed and used to characterize its range of year-round persistence. Winter temperature and rainfall are shown to have a strong influence on screwworm outbreaks and in facilitating eradication in North America and Libya. Prospective analysis for the Mediterranean Basin suggests eastern areas are most favorable for screwworm establishment (e.g., the Nile River area of Egypt). The SIT eradication programme and its possible extension into South America are discussed. Expected +2°C climate warming is predicted to increase the potential year-round range of screwworm in the SE USA. Gutierrez A.P., Ponti L., 2014. The new world screwworm: prospective distribution and role of weather in eradication. Agricultural and Forest Entom...

Using published bi- and tri-trophic physiologically-based demographic system models having similar sub components, the geographic distributions and relative abundance (a measure of invasiveness) of six invasive herbivorous insect species is assessed prospectively across the United States and Mexico. The models used are mechanistic descriptions of the weather-driven biology of the species. The plant hosts and insect species included in the study are: (1) cotton/pink bollworm, (2) a fruit tree host/Mediterranean fruit fly, (3) olive/olive fly, (4) a perennial host/light brown apple moth; (5) grapevine/glassy-winged sharpshooter and its two egg parasitoids, (6) grapevine/European grapevine moth. All of these species are currently or have been targets for eradication. The goal of the analyses is to predict and explain prospectively the disparate distributions of the six species as a basis for examining eradication/containment efforts against them. The eradication of the new world screwworm...

Since being detected in California in 1975, the polyphagous tropical Mediterranean fruit fly ( Ceratitis capitata Weid. (medfly)) has been the subject of a large-scale eradication campaign in the absence of sound knowledge of its invasive potential. We use a weather-driven physiologically-based demographic system model ( CASAS ) embedded in a GIS based on GRASS to examine medfly's potential distribution across Arizona-California (AZ-CA), and Italy where its establishment is documented. AZ is unfavorable for medfly because of high summer temperatures, while much of CA, including many frost-free areas, is too cold during winter. Only the south near coastal region of CA is predicted to be potentially favorable for medfly, but in the absence of consistent measurable populations, we cannot say if medfly is established there. Medfly has been established in Italy for decades, and our model predicts a wide distribution in the southern and western regions of the country. Gutierrez A.P.,...

The highly polyphagous light brown apple moth (LBAM) ( Epiphyas postvittana (Walk.): Tortricidae) is indigenous to Australia and was first found in California in 2006. It is currently found in 15 coastal counties in California, but nowhere has it reached outbreak status. The USDA projects the geographic range of LBAM will include much of Arizona and California and the southern half of the U.S., which together with economic estimates of potential crop losses have been used as the rationale for an eradication program in California. We report a temperature-driven demographic model to predict the likely distribution and relative abundance of LBAM using the detailed biology reported by W. Danthanarayana and colleagues, and climate data from 151 locations in California and Arizona for the period 1995 to 2006. The predictions of our model suggest that the near coastal regions of California are most favorable for LBAM, the northern Central Valley of California being less favorable, and the de...