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52
ne M a t o d e re l a t i o n s h i P s
BULLETIN OF THE UNIVERSITY OF NEBRASKA STATE MUSEUM
Richter (1993) reported that Rhabditis
stammeri (Völk), a carrion-dwelling
nematode, is specifically associated with
Nicrophorus vespilloides. Juveniles of the
nematode use the adult beetle for transport
to carrion where both adults and larvae of
beetles become infected. Inside the beetle
larvae, the juvenile nematodes are transported
to the pupal chamber via the larval
gut. After pupation, the juvenile nematodes
are found in the pupal chamber at protected
places such as the exuvium or beneath the
wings of the pupa. After emergence from
the pupa, the nematodes migrate to the gut
and genitalia of the adult beetles. Rhabditis
stammeri is also transmitted from one adult
beetle to another during copulation. Infection
by nematodes probably occurs in many
other species of Nicrophorus as well, and is
an area needing additional study.
st r i d u l a t i o n
All species of Nicrophorus have a stridulatory
structure in both males and females
(Fig. 2). Stridulation is used during burial of
the carcass, copulation, and the interaction
between the female and her brood (Niemitz
1972, Niemetz and Krampei 1972). Huerta
et al. (1992) conducted lab experiments
with N. mexicanus and found that a lack of
stridulation in the female resulted in poor
or no “bonding” between the female and her
offspring, which negatively affected larval
survival. Inhibition of stridulation in the
male affected and sometimes precluded
copulation. Lack of stridulation in both nest
partners may affect the coordination of nest
preparation (Halffter 1982, Huerta et al.
1992, Halffter et al. 1983).
Pr e d a t i o n
Most ground-feeding insectivorous
birds are probably familiar with burying
beetles, and these beetles have been recorded
as among the food items of several species,
especially crows that routinely visit carrion.
Jones (1932) conducted a number of experiments
using N. americanus, N. orbicollis,
and N. pustulatus to determine if a variety
of insectivorous birds would be deterred by
these aposematically colored beetles. Although
he tested only seven specimens, none
were eaten by the birds, while 42 out of 46
other beetles (representing seven species) of
comparable size were eaten by seven species
of birds during 93 feeding events. Jones
concluded that birds do avoid these brightly
colored beetles, at least when other food is
available.
so c i a l i t y
The activities of adult Nicrophorus
species in rearing their young is the highest
level of sociality attained in the Coleoptera
(Wilson 1971, Wilson and Fudge 1984). On a
large carcass, the mating system is variable.
Larger carcasses can support greater numbers
of larvae and support broods of greater
total mass than smaller carcasses (Trumbo
1992). Consexual adults often tolerate each
other and often feed each other’s young in
a quasisocial fashion (Scott and Traniello
1990a, Eggert and Müller 1992, Trumbo
1992, Scott and Williams 1993, Trumbo and
Wilson 1993). According to Trumbo and Wilson
(1993), females of smaller Nicrophorus
(N. defodiens, N. tomentosus) species were
much more likely to feed young cooperatively
than females of, for example, N. orbicollis.
They hypothesized that since adults cannot
discriminate between related and unrelated
young, they feed any larvae on the carcass
to ensure adequate care for their own young.
Larger carcasses were more difficult to exploit
because: (a) they took longer to conceal
beneath the leaf litter; (b) they were less
likely to be rounded into brood balls; (c) they
were more likely to be utilized by dipterans;
and (d) they were occupied by greater numbers
of congeners (Trumbo 1992).
Scott (1994b) suggested that competition
with flies promotes communal breeding
in N. tomentosus. She demonstrated that