Byers, J.A., & Poinar, G.O., Jr. 1982. Location of insect
hosts by the nematode, Neoaplectana carpocapsae, in
response to temperature. Behaviour 79:1-10.
The infective stage juveniles of N. carpocapsae, a parasitic nematode
of insects, aggregated at point sources heated to temperatures of only
0.3 degree C or less above ambient in either light or dark
conditions. The nematode also aggregated in response to heat
conducted from a wax moth larva (about 0.3 degree C above ambient)
in the absence of CO2 or chemical gradients. The responses to heat
sources (1 degree above ambient) occurred over a wide range of
ambient temperatures. The apparent response of the nematode to light
is at least in part caused by effects of heat from light absorption
by the agar medium and nematode. The response to temperature appears
to function in host location especially at close range from (within a
few mm) of the insect.
Fig. 1. Nematodes at center of photo are aggregating on the surface of the agar
next to a resistor that is being heated about 1 degree above ambient by 12 V batteries (see below).
Fig. 2. Diagram of test arena showing the three types of experiments. From 1000 to 2000
nematodes were placed in a 0.5 cm diam. area at the center of an 8.5 cm plastic petri dish
filled 1.5 mm deep with ion agar. The IR-LED (1) and 1000-Ohm resistor (3) were placed parallel
to the agar surface on the outside of the wall while the wax moth larva (2) was taped to the
underside of the dish.
Fig. 3. Schematic diagram of electronic thermometer sensitive to 0.01° from 0-20° C and 0.1° above
20° C. Temperature probe IC1 provides a voltage dependant on temperature to difference amplifier IC2.
R1 is adjusted so the voltage is 0 at 0° C. The voltage output of IC3 amplifier is adjusted
via R2 to give 100 mV/°C so that the voltage reading on a 3.5 digit voltmeter (DMM) is
the same as the temperature.