Availability of non-host food can determine the success of biological control through its effects on parasitoid survivorship. Here, importance of adult food in determining the longevity of Hemiptarsenus varicornis (Girault), a biological control agent of the pest leafminers Liriomyza trifolii (Burgess) and L. sativae Blanchard, was examined by means of laboratory experiments. Male and female H. varicornis lived less than 2 days with only water available. Provision of diluted honey improved the longevity of adult H. varicornis. Females benefited more by feeding on diluted honey than did males, extending their lifetime to around 2 weeks. In another experiment, newly emerged females were fed diluted honey for their first 5 days and with water only for their remaining lifetime. The result showed that both male and female H. varicornis lived no longer than 2 days after diluted honey was withheld, indicating that nutritional reserves that they could store were highly limited. Thus food sources should be continuously available in the environment for their reproduction. The implications of the results are discussed in the context of biocontrol of leafminers in greenhouses.

The reservoir capacity of domestic cats and dogs for Trypanosoma cruzi infection and the host-feeding patterns of domestic Triatoma infestans were assessed longitudinally in 2 infested rural villages in north-western Argentina. A total of 86 dogs and 38 cats was repeatedly examined for T. cruzi infection by serology and/or xenodiagnosis. The composite prevalence of infection in dogs (60%), but not in cats, increased significantly with age and with the domiciliary density of infected T. infestans. Dogs and cats had similarly high forces of infection, prevalence of infectious hosts (41–42%), and infectiousness to bugs at a wide range of infected bug densities. The infectiousness to bugs of seropositive dogs declined significantly with increasing dog age and was highly aggregated. Individual dog infectiousness to bugs was significantly autocorrelated over time. Domestic T. infestans fed on dogs showed higher infection prevalence (49%) than those fed on cats (39%), humans (38%) or chickens (29%) among 1085 bugs examined. The basic reproduction number of T. cruzi in dogs was at least 8·2. Both cats and dogs are epidemiologically important sources of infection for bugs and householders, dogs nearly 3 times more than cats.