Two entomopathogenic nematodes, Steinernema riobravis and Steinernema carpocapsae, were compared for their ability to parasitize corn earworm, Helicoverpa zea (Boddie) prepupae and pupae in corn plots at the Lower Rio Grande Valley of Texas. The most effective S. riobravis concentration was 200,000 infective juveniles (IJ)/m(2) (95% parasitism), as compared with 100,000 IJ/m(2) (81%), 50,000 IJ...

Assuming the existence of tick parasitism in humans in the State of Pará, an aggregate observational study was developed along a transversal line in three cities of the State, during two years. Interviews and examinations of 2,160 townspeople and tourists were carried out, without discrimination of ethnic, sex, age, or social status, and classified for effects analyzed for four bands of age, si...

Parasitism of mammals is ubiquitous, but the processes driving parasite aggregation on hosts are poorly understood, as each system seems to show unique correlations between parasitism and host traits such as sex, age, size and body mass. Genetic diversity is also posited to influence susceptibility to parasitism, and provides a quantifiable measure of an intrinsic unchanging host property, but ...

Incidence of parasitism is often underestimated because ‘ghost’ parasitoids (dead unemerged or those that have emerged leaving the host carcasses) are difficult to detect and identify. This study demonstrates use melting curve analysis (MCA) carcasses can identify DNA ghost even a month after death. The coccinellid hosts Cycloneda sanguinea, Eriopis connexa, Harmonia axyridis Hippodamia converg...

Lygus lineolaris is a pest of many economically important crops. While the species comprising the Peristenus pallipes complex are native parasitoids of L. lineolaris, they do not provide adequate biological control of L. lineolaris. As a result, the European parasitoid, Peristenus digoneutis, was introduced in forage alfalfa. Peristenus digoneutis successfully dispersed from forage alfalfa to s...

Parasites can play an important role in biological invasions. While introduced species often lose parasites from their native range, they can also accumulate novel parasites in their new range. The accumulation of parasites by introduced species likely varies spatially, and more parasites may shift to new hosts where parasite diversity is high. Considering that parasitism and disease are genera...

Homogenates from 5 species of Trypanosomatids were screened for the presence of a series of acid hydrolases. The insect flagellae, Crithidia sp., contains 5 enzymes reminiscent of plant parasitism, which were absent from or of very low specific activity in parasites of the genera, Trypanosoma and Leishmania. The latter mammalian parasites, on the other hand, exhibited higher acid proteinase and...

—We studied the breeding biology of the Baywing (Agelaioides badius), a shared host of Screaming (Molothrus rufoaxillaris) and Shiny (M. bonariensis) cowbirds. We monitored 193 nests from December 2002 to March 2007 in the Province of Buenos Aires, Argentina. Baywings used a wide variety of nesting sites, mainly old nests of furnarids. Their breeding season lasted from late November to February...

Costs of parasitism are commonly measured by comparing the performance of infected groups of individuals to that of uninfected control groups. This measure potentially underestimates the cost of parasitism because it ignores indirect costs, which may result from the modification of the competitiveness of the hosts by the parasite. In this context, we used the host-parasite system consisting of ...

1. Previous studies have demonstrated that phenotypic traits of plants have the potential to affect interactions between herbivores and their natural enemies. Consequently, the impact of natural enemies on herbivore vital rates and population dynamics may vary among plant species. This study was designed to investigate the potential for density-dependent parasitism of an aphid herbivore feeding...