Trypanosomes and Leishmania are vector-borne parasites associated with high morbidity and mortality. Trypanosoma lewisi, putatively introduced with black rats and fleas, has been implicated in the extinction of two native rodents on Christmas Island (CI) and native trypanosomes are hypothesized to have caused decline in Australian marsupial populations on the mainland. This study investigated the distribution and prevalence of Trypanosoma spp. and Leishmania spp. in two introduced pests (cats and black rats) for three Australian locations. Molecular screening (PCR) on spleen tissue was performed on cats from CI (n = 35), Dirk Hartog Island (DHI; n = 23) and southwest Western Australia (swWA) (n = 58), and black rats from CI only (n = 46). Despite the continued presence of the intermediate and mechanical hosts of T. lewisi, there was no evidence of trypanosome or Leishmania infection in cats or rats from CI. Trypanosomes were not identified in cats from DHI or swWA. These findings suggest T. lewisi is no longer present on CI and endemic Trypanosoma spp. do not infect cats or rats in these locations.

Foliar application of herbicides, plant regulators, and nutrients is a well established practice. Yet, the many contradictory reports in the literature (7) indicate that the routes of entry into and movement within leaves are not clearly known. This situation has probably arisen because presently available techniques do not precisely establish the location of the penetrant on the cellular level.

Systemic herbicides applied to leaves must move from the leaf surface into uninjured phloem in sufficient quantity to be translocated throughout the plant. Contact herbicides must at least enter the leaf. Leaves of terrestrial plants are adapted to exchange of gases —water vapor, CO2, O2—but are not adapted to absorb foreign solutes in applied solutions and to translocate them systemically; insectivorous species and some water plants may be exceptions. Failure of herbicidal effectiveness often may be due to lack of penetration. However, selectivity towards herbicides is not clearly related to differential absorption (5, 82, 172, 176).