Integrated Vector Management - Biological and Environmental Control of Disease Vectors - page 183

Such programmes need to consider the
sustainability of the intervention by supporting
initiatives to ensure continued use by
householders, maintenance of the intervention
and provision of sanitation for the safe disposal
of pit latrine contents (see Ensink, Chapter 8,
this volume). For example, when a traditional pit
latrine has fi lled, there is an increase in smells
produced by the pit and, consequently, an
increase in the number of fl ies and mosquitoes
in the latrine (Biran, 2010, 2011). In these
situations, people must have the pit emptied or
they may resort to open defecation, which then
leads to the spread of disease (Esrey et al ., 1991).
If a large number of pit latrines are built for
global IVM programmes, then methods of pit
emptying must be able to cope with the increased
number of pits being installed. There are
dif erent methods available for pit emptying
(Still, 2002), and several studies have been
performed to evaluate innovative technologies
for the safe treatment of pit latrine waste. Some
of these technologies use biological agents, and
will be discussed below.
Vermicomposting technology, using
earthworms, Eisenia fetida , to consume faeces
taken from non-fl ush, drop and store toilets,
may potentially reduce the fi ll rate of faeces in
latrines (Yadav et al ., 2010). However, one
limiting factor of this technology is the fact that
it takes up to 1 year for the faeces to be fully
composted and for all pathogens to be destroyed.
Larvae of M . domestica have also been shown to
reduce faeces in the chicken, bovine and porcine
industries (Miller, 1961; Miller and Shaw, 1969;
Muller, 1980). One drawback to using housefl ies
for the purpose of consuming human faeces is
that, if not properly managed, the larvae can
pupate and become adults capable of
mechanically transmitting human pathogens.
An alternative solution is black soldier fl y larvae
(BSFL), Hermetia illucens , because they readily
consume organic matter including dung,
carrion, decaying fruit, garbage, vegetables and
compost (Copello, 1926). BSFL have been used
to ef ectively reduce pig manure (Newton et al .,
1977) and chicken faeces (Sheppard et al .,
1994) in farms, and to reduce municipal organic
waste (Diener et al ., 2011). More importantly,
for present purposes, BSFL have been shown to
develop on fresh human faeces (Banks, 2010)

and on pure faecal sludge taken from septic
tanks (Diener et al ., 2011).
Unlike with M . domestica , there is no
published evidence supporting the involvement
of BSFL in the transmission of human
pathogens, making them far more suitable for
use in sanitation systems. The BSF adults do not
feed (Sheppard et al ., 2002), but survive on fat
stores from their larval stage (Furman et al .,
1959), so they are not attracted to human food
sources. This behaviour prevents them from
transmitting pathogens from waste to human
food. However, BSFL have been responsible for
seven cases of fortuitous enteric myiasis in the
USA between 1953 and 1961 (Scott, 1963).
More recent reports include a single incident of
furuncular cutaneous myiasis (Adler and
Brancato, 1995) and two cases of intestinal and
enteric myiasis (Calderon-Arguedas et al .,
2005; Fuentes Gonzalez and Risco Oliva, 2009).
Nevertheless, given that only a total of ten cases
of human myiasis involving BSFL have been
published, despite their ubiquitous distribution
(Leclercq, 1969), they present a negligible
public health risk. In fact, there are potential
added benefi ts to public health from using BSFL
to treat faeces. For example, BSFL have been
shown to reduce the pathogens Escherichia coli
O157:H7 and Salmonella enterica serotype
Enteritidis (ME18) in chicken manure (Erickson
et al ., 2004), and reduce E . coli dairy manure
(Liu et al ., 2008). Furthermore, BSFL may
inhibit the oviposition and the development of
M . domestica larvae in chicken manure (Furman
et al ., 1959, Sheppard, 1983) and in pit latrines
(Kilpatrick and Schoof, 1959). Another
advantage of BSFL is the potential value of
prepupae. Prepupae contain high protein and
fat contents, 42-45% and 31-35%, respectively
(Hale, 1973; Booram et al ., 1977), and can be
used as a suitable animal food source for
chickens (Hale, 1973), pigs (Newton et al .,
1977) and fi sh (Bondari and Sheppard, 1987;
St-Hilaire et al ., 2007).
BSFL technology has been incorporated in
some commercial ventures for managing
compost at the residential level and in large-
scale commercial bioconversion systems.
However, before BSFL can be used for large-scale
treatment of pit latrine waste, further research is
required. In particular, if prepupae, which have