Biology Reference
In-Depth Information
ATTRACTION OF TEPHRITIDS TO ODORS OF BACTERIA
OR ODORS PRODUCED BY BACTERIA
The idea that bacteria are important to tephritids and either serve as food or make the host fruit
an environment for eggs and larvae more nutritious was emphasized when the
E. agglomerans
isolated from oviposition sites of
Þies in
Ýeld studies (MacCollom et al., 1992). Gravid females appeared particularly attracted to the bacteria
(MacCollom et al., 1994). The simultaneous deposition of speciÝc bacteria during oviposition
coupled to the attraction to these speciÝc bacteria by
R. pomonella
was found to be attractive to
R. pomonella
makes for an intriguing
possibility. The attraction to speciÝc bacteria by fruit Þies suggests that females that routinely feed
on nitrogen-poor food are directed to additional nitrogen by bacteria. This navigation of females
by bacteria to more nitrogen, including the nitrogen contained in bacteria themselves, may also
beneÝt eggs and larvae for nutritional and developmental purposes while within the nutrient-
insufÝcient host fruit.
Hodson (1943) and Gow (1954) were the Ýrst to describe the use of bacterial odors as attractants
for fruit Þies, with observations that certain tephritids were highly attracted to proteinaceous baits
containing actively growing bacteria. The odors that emanated from baits contained ammonia, a
known attractant to many insect species (e.g., Hribar et al., 1992; Taneja and Guerin, 1997). Though
ammonia is considered a common attractant for fruit Þies (Hodson, 1943; Drew and Fay, 1988;
Hendrichs et al., 1990, 1993), in later studies, researchers examined the attraction of
R. pomonella
R. pomonella
and other fruit Þies to odors emitted from bacteria other than ammonia (i.e., Bateman and Morton,
1981; Drew and Fay, 1988; Robacker and WarÝeld, 1993; Martinez et al., 1994; Robacker et al.,
1998; Epsky et al., 1998). Robacker and Moreno (1995) isolated attractive compounds from
Sta-
phylococcus aureus
(Robacker and Bartelt, 1997)
growing in nutrient broth. They methodically tested individual and combinations of the compounds
for their attraction to
,
and
K. pneumoniae
and
Citrobacter freundii
Anastrepha ludens
and
examined volatiles from numerous other bacteria
(Robacker et al., 1991, 1993, 1998). Although
S.
aureus
is not known to be closely associated with
A. ludens
, odors produced by the bacterium were found to be particularly attractive to the Þies.
The attractive odors from
are also those commonly emitted from rotting carrion and from
the degradation of other substrates containing proteins and lipids. Attractive odors from the deg-
radation of organic material by bacteria is related to documented attraction of fruit Þies to bird and
other animal feces by Prokopy et al. (1993)
S. aureus
and chemical proÝles identiÝed from bird feces by
Epsky et al. (1997).
Undoubtedly, natural odors serve as important cues and indicators of food for foraging fruit
Þies in nature. Microbial action appears to contribute substantially to the ability of tephritid Þies
to locate organic compounds in nature. Prokopy et al. (1993) found that feces lost their initial ability
to attract
R. pomonella
adults after treatment with antibiotics.
E. agglomerans
was isolated from
the bird feces used in ProkopyÔs study, and, unlike the
S. aureus
used in RobackerÔs work,
E.
agglomerans
has been found in close association with many fruit Þies. As mentioned earlier,
MacCollom et al. (1992) found that
R. pomonella
Þies were attracted to traps containing washed
cells of
. In particular, gravid females appeared to home in on the bacterial odors
(MacCollom et al., 1994). This is particularly interesting because the attraction behavior of the Þies
was strong to cells of bacteria that were free of a medium. All previous and subsequent studies on
fruit-Þy attraction involved compounds produced by bacteria while the bacteria were catabolizing
an organic substrate, for example, a protein bait (Gow, 1954), microbiological media (Robacker
and Flath, 1995; Robacker and Bartlett, 1997; Robacker et al., 1998), or chicken (Epsky et al.,
1997) or duck (Robacker et al., 2000) feces. The isolation, identiÝcation, and screening of chemicals
emitted from the cells alone would presumably narrow down the numerous chemical candidates
that may be serving as potent speciÝc attractants. This was indeed the case when Epsky et al. (1998)
isolated ammonia and 3-methyl-1-butanol as the primary attractive compounds for
E. agglomerans
A. suspensa
from medium-free cells of
E. agglomerans
.
Robacker and Lauzon (2002) also isolated candidate
