Maldison as a chemical for phasmatid control in Victoria.  J. A. Harris.  September 1980.  13 pp. (unpubl.)

SUMMARY

Maldison, a short-persistence organophosphorus insecticide of low mammalian toxicity, is the only insecticide used for phasmatid control and Victoria. In insect, bird and mammalian bodies maldison is converted to its oxygen analogue malaoxon, which inhibits the action of cholinesterase and thereby disrupts nerve activity by causing an accumulation of acetylcholine (the substance generated during transmission of nerve impulses) at nerve endings. In the mammalian liver, malaoxon is degraded rapidly by carboxyesterase enzyme activity, whereas in insect tissue the balance of enzymes present does not usually favour such degradation. Selectivity of maldison action is due to rapid degradation of malaoxon in non-susceptible species; these include birds, mammals, and some insects. Resistance is usually achieved by an increase in the level of degrading enzymes (β – napthylacetate, ali-esterase-a and carboxyesterases) and not by decreased absorption. In most cases maldison readily penetrates both the integument of insects and the skin of mammals. The effects of maldison on air, soil, water, man and other mammals, birds, fish, insects, soil, arthropods and plants are discussed. Studies of applications of maldison at up to four times the concentrations used in mountain ash forests indicate that phasmatid control operations are unlikely to cause changes in the environment.

Also published:

Harris, J.A. (1980)  Maldison as a chemical for phasmatid control in Victoria.  For. Comm. Vic., For. Tech. Pap. 28: 41-50.

Harris, J.A. (1981)  The effect of the insecticide maldison on Didymuria violescens (Leach) (Phasmatodea : Phasmatidae) on the sub-canopy insect fauna in mountain ash forests of the Central Highlands of Victoria.  M.Sc. Thesis, Univ. of Melbourne, 237 pp.