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.

Abstract-- 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) resistor with aggregating nematodes 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. 1 - test arena
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. 2 - electronic thermometer 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.

Chemical Ecology