Methodology to rear sterile flies of Cochliomyia hominivorax (Coquerel, 1858) (Diptera: Calliphoridae) in Brazil

Author(s)

Thiago de Araújo Mastrangelo

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB)
• Defense date: 2011-10-17

Examining board members

Julio Marcos Melges Walder; Helder Louvandini; Márcia Cristina de Sena Oliveira; José Roberto Postali Parra; Cecilia Jose Verissimo

• Advisor: Julio Marcos Melges Walder

Abstract

The New World Screwworm (NWS), Cochliomyia hominivorax (Coquerel, 1858) (Diptera: Calliphoridae), is a fly species that provokes myiasis and is currently distributed at some Caribbean islands and South American countries. As an obligate parasite, this fly is one of the most serious threats to livestock industry, causing economic losses of millions of dollars per year in many countries. The main control strategies in the integrated management of myiasis rely on the use of chemicals and the so called Sterile Insect Technique (SIT). This technique, in particular, allowed the eradication of the NWS from the entire North and Central America between 1957 and 2004, and a biological buffer zone was set at the Panama-Colombia border. The eradication efforts still continue in Jamaica and several Caribbean islands. Some South American countries also declared interest for the use of the SIT against the NWS. Aiming to support projects to control the NWS through the SIT in MERCOSUR countries, several studies on rearing, sterilization with X rays and reproductive compatibility between strains were performed. The NWS colony was successfully established at CENA/USP and the MOSCAMED Brazil facility. Between the generations F1 and F18, a volume of 30.9 L of pupae ( 257,200 pupae) was produced. The values of the quality control parameters from the rearing were similar to those from the screwworm mass-rearing facility in Mexico and the USDA-ARS laboratory. To evaluate the best oviposition substrate, four treatments made of raw meat, liver or wasted larval diet were tested, and the one made of wasted larval diet + citrated bovine blood and clot allowed the highest oviposition and egg hatch. The estimated basal temperature for the embryonic development was 13.1 ºC, with a thermal constant of 9.17 GD. Six different adult diets made of honey, rapadura, spray dried egg, molasses or spray dried blood were tested and all allowed high fecundity and fertility. For the bioassays with larval diets, two liquid diets (with sugarcane bagasse or coconut fiber as bulking agents), the standard meat diet and a gelled diet were tested. There was no significant difference among the quality control parameters from the diets and the use of the gelled diet proved to be feasible and cheaper. In order to estimate the sterilization doses, pupae 24 h before the adult emergence were irradiated at 0 (control), 10, 25 and 60 Gy of X rays. The doses that induce 99% sterility were 43.7 and 47.5 Gy for males and females, respectively. To assess the reproductive compatibility and competitiveness between strains, four tests with crosses between a Caribbean strain (Jamaica-06) and the Brazilian one were performed. As no reproductive incompatibility nor competitiveness problems were found, suppression campaigns against the NWS in MERCOSUR could use sterile flies either from the Caribbean basin as from Brazil (AU)

• FAPESP's process: 09/51354-1 - Methodology for Cochliomyia hominivorax (Coquerel, 1858) sterile flies (Diptera: Calliphoridae) production in Brazil
• Grantee: Thiago de Araújo Mastrangelo
• Support Opportunities: Scholarships in Brazil - Doctorate