2 METHODS AND MATERIALS

2.1 APPARATUS

A WALK-IN freezer unit was used for all low-temperature tests. The temperature was maintained at a constant −20�C. The relative humidity was monitored using a Lambrecht hygrometer and varied between 75% and 85%.

2.2 INSECT CULTURES

Stock cultures of Stegobium paniceum were obtained from the Stored Grain Research Laboratory, CSIRO Division of Entomology, Canberra, ACT. Laboratory stocks reared on a culture medium consisting of 90% cracked wheat and 10% brewers' yeast at 25�C and 70% RH were used for all experiments.

2.3 EGGS

One-to-three-day-old eggs were obtained by placing young adult insects on 10g of culture medium, which had been sieved through a 250-micron mesh. After three days the adults were removed, and the medium resieved. The eggs were then collected and counted under a binocular microscope.

2.4 LARVAE AND PUPAE

Larvae and pupae were obtained by allowing 100 young adults to oviposit on 200 g culture medium for 24–48 hours. The adults were then removed, and the cultures were incubated as described above for 32 and 42 days, respectively. The larvae and pupae were then separated from the medium by hand and counted.

2.5 ADULTS

One-to-five-day-old adults were obtained by placing 100 young adults on 200 g culture medium for 24–48 hours. The adults were then removed, and the culture was incubated as in the above until the emergences of the next generation of adult insects. Following the first emergence the adults were collected five days later and counted.