Eucalyptus: A sustainable self-delivery molluscicide?

Abstract

Attention is drawn to the limitations of conventional methods of controlling important trematode infections such as schistosomosis and fasciolosis. Plant molluscicides could have a role in the future control of these infections. There are, however, major problems with most plant molluscicides in that their use is labour-intensive, in many cases relatively skilled workers are required, they must be applied regularly and arable land may be required for their cultivation. Thus, little progress is to be expected until plant species with sustainable self-delivery systems are identified. Eucalyptus is proposed as a likely candidate. The leaves of many species in this genus have molluscicidal properties and their intermittent fall could effect self-delivery if the trees were planted in appropriate places. Relatively little work has been carried out on this possibility and much more is necessary, especially field trials. Before field trials are started, more laboratory testing is also necessary to determine the LC50 values for different snail species and to study toxicity to non-target organisms.

Riparian eucalypts and willows and their significance for aquatic invertebrates in the River Murray, South Australia

“…In contrast, the sparse, open canopy of redgums favours a more diverse understorey of littoral macrophytes and terrestrial plants, and their propensity to drop limbs provides fallen wood as habitat for animals. Their leaves are lignified, however, and contain high levels of tannins (Campbell and Fuchshuber, 1995) that are toxic to some animals, including certain fish (Gehrke et al, 1993) and molluscs (Cheuiryot et al, 1981;Hammond et al, 1994). Thus, it was hypothesized that there would be corresponding differences in invertebrate assemblages.…”

Preliminary investigations of toxicity in the Georges Bay catchment, Tasmania, Australia

“…The most potent molluscicidal agents from Eucalyptus sp . appear to be present in the leaves [ 17 ].…”

Impact of Human Activities on Fasciolosis Transmission

“…One solution is the use of molluscicides, which was highly recommended during the 1970s but has been abandoned because most products are toxic for the macrofauna that inhabit the freshwater environment [31,53]. Only a few studies have been conducted to test natural molluscicides [54,55]. A recent study on a new biomolluscicide, Citrullus colocynthis, shows that it kills the snail vector of fasciolosis, G. truncatula and also the larvae of F. hepatica without affecting the associated fauna of the snail [56].…”