Biology Reference
In-Depth Information
attractants from
E. agglomerans
for Mexican fruit Þy.
Thus, these Ýndings stimulated others to
explore the attractive inÞuences of
E.
agglomerans
cells toward
R. pomonella
and other fruit Þy
species.
has been reported to be a mediate attraction of locusts (Dillon et al., 2000)
and brown treesnakes (Jojola-Elverum et al., 2001).
Initially, however, others did not Ýnd the consistent behavioral responses to
E. agglomerans
E. agglomerans
described by MacCollom et al. (1992, 1994) for other fruit Þy species. The contrary Ýndings of
Jang and Nishijima (1990) using Oriental fruit Þies stimulated a closer examination by Lauzon
of strains of
for potential differences in their ability to attract fruit Þies. Lauzon
et al. (1998) examined the attractive qualities of
E. agglomerans
isolated from a variety of sources
that were associated with fruit Þies, such as bird feces, foliar surfaces, and the gut of the Þy, in
an attempt to explain the contrary or inconsistent results of others. They found that
E. agglomerans
R. pomonella
were indeed preferentially attracted to certain strains of
and those strains that
Þies were attracted to contained catabolic capabilities, an enzyme, in their outer membranes not
seen in nonattractive strains (Lauzon et al., 2000) identiÝed as uricase. These Ýndings provided
an explanation for the inconsistent results reported by others (see Robacker and Lauzon, 2002,
for an example of this concept) and suggested another example of attraction between fruit Þies
and nutrition.
E. agglomerans
TEPHRITID-MICROBE-PLANT INTERACTIONS
While microbial odors assist or mediate foraging fruit Þies to Ýnd valuable sources of nitrogen
and bacteria provide nitrogen in nitrogen-poor host plants, Drew and Lloyd (1991) hypothesized
that odors from Ñfruit-Þy-typeÒ bacteria, namely,
, also played a role in
host-plant location. They suggested that as fruit Þies entered host plants, host plant structures
accumulated
E. cloacae
and
K. oxytoca
spp. They suggested that over time bacterial numbers
would increase on the phylloplane and thus an increase in bacterial odors in the host-plant area
would naturally follow. These odors would facilitate host location for nearby, migrating Þies. While
this phenomenon remains to be deÝnitively proven, Raghu et al. (2002) and Lauzon et al. (unpub-
lished data) have additional data that support this hypothesis.
Enterobacter
and
Klebsiella
Also, Epsky et al. (1997) and Robacker
and Lauzon (2002) have found that odors from
are considered typical fruit and
plant odors. Mediation of host-plant location by bacterial odors is known to occur for other insect
pests, such as the bark beetle (Brand et al., 1975), and thus it is feasible that bacteria inÞuence
fruit Þy behavior in host detection and location.
E. agglomerans
spp. populations on the phylloplane of tephritid host plants
may be doing more than attracting fruit Þies. They may be catabolizing plant allelochemicals
that are either toxic to fruit Þies or that may interfere with the nutritive quality of compounds
ingested by foraging fruit Þies. Jones (1984) and Dowd (1991) suggested that symbionts might
be important in the detoxiÝcation of toxic and noxious compounds that insects encounter in
nature. Howard et al. (1985) hypothesized that bacteria associated with
Enterobacter
and
Klebsiella
performed
these functions. DetoxiÝcation of plant allelocompounds has been studied extensively for
herbivorous insects (Appel, 1993a,b); however, information regarding detoxiÝcation strategies
of nonfolivorous insects is scant.
Rhagoletis
has been shown
to degrade and detoxify the organophosphate azinphosmethyl and phloridzin, a dihydroxychal-
cone found typically in
E. agglomerans
isolated from
R. pomonella
adults (Lauzon et al.,
1994). It is possible that this bacterium and other bacteria on or within host plants may be
abating or remediating the toxicity of plant defensive compounds. The same may be true for
bacteria that reside on the phylloplane within the host fruit or within the alimentary canal of
tephritids. Bacterial utilization of highly toxic compounds may be the reason why certain fruit
Þies can survive within certain hosts. This type of involvement of microorganisms in plant
allelochemistry and insect behavior is poignantly made by Berenbaum (1988) and expanded in
her chapter in Barbosa and Letourneau (1988).
Malus
spp., to sublethal levels for
R. pomonella
