Fungal isolates involved in biodeterioration of book-paper and their effects on substrate selection by Liposcelis bostrychophila (Badonnel) (Psocoptera: Liposcelididae)

The effects of fungi on the distribution of groups of Liposcelis bostrychophila were investigated. Two strains of Ulocladium botrytis were obtained from biodeteriorated book-paper and Eurotium amstelodami was isolated from the food used to culture L. bostrychophila. Isolated fungi were cultured on either paper sterilised with ethanol (paper) or on a malt-agar medium (medium). One strain or species was presented to groups of L. bostrychophila on a glass-fibre disc, with a blank disc as the other choice, and the number of insects on each disc and those free in the Petri dish was recorded after 12 h. In general a lower proportion of insects selected when one of the choices was either a 10,000 ppm extract of extract of U. botrytis cultured on malt-agar or one of the more dilute extracts of U. botrytis cultured on either medium. In contrast, extracts of both strains of U. botrytis (paper, 10,000 ppm) and E. amstelodami (malt-agar medium; 10,000; 1000 and 100 ppm) did not affect the proportion of insects that selected. With the exception of an extract of one of the strains of U. botrytis (paper; 10,000 ppm) significantly more selecting insects were found on the blank disc. A second set of experiments, in which extracts were applied to both discs, showed that L. bostrychophila did differentiate between the same fungus grown on paper or malt-agar medium and also between extracts of U. botrytis and E. amstelodami. It would appear that fungi grown on malt-agar medium are more repellent than fungi grown on paper and that E. amstelodami is preferred to U. botrytis. However, the selection of a substrate by L. bostrychophila very much depends on the context in which it is provided, i.e. the other choice.