Week 1

Week 1 - Day 4 - Pesticide Formulations

ESSENTIAL READING BEFORE COMMENCEMENT OF COURSE:

Urban Pest Management in Australia: 2004 Edition, UNSW Press, Sydney

by J Gerozisis and P Hadlington - Chapter 9 - Pages 68 to 73.

Chapter 9 – Insecticides – Formulations & Applications - insecticide formulations - active constituent - diluent - solvent - attractant - surfacant - synergist - types of formulations - oil concentrates - emulsifiable concentrates - wettable powders - suspension concentrates - micro-encapsulated concentrate - dusts - aerosols - pressure pack aerosols - high pressure, liquid carbon dioxide propelled - other formulations - insecticidal lacquer - smoke generators - baits - granules - ULV (ultra low volume) formulations - impregnated resin strips - choice of formulations - pests to be controlled - convenience of use - application equipment available - pest habits and habitats - price - hazard minimisation - regulatory obligations

Formulations

Many chemicals exist for the control of pests.  Often, these chemicals can be obtained in various formulations eg. wettable powder, emulsion concentrate, dusts, mist or fog.  These forms are not interchangeable and each type of chemical is used for a particular purpose.

liquid concentrates

emulsifiable concentrates

This is a solution combining an insecticidal active ingredient (measured in mls/Iitre or grams/litre), a solvent and emulsifying agents.  The emulsifiers make it possible to mix the concentrate with water to form an emulsion spray.  This type of formulation is not recommended for use on porous surfaces when it is required to leave an active residual deposit.

Suspension concentrates

A suspension concentrate is a formulation, which has the advantages of both an emulsifiable concentrate and a wettable powder.  More precisely it is a water-based, particulate suspension, which contains no solvent.  The microscopic particles of insecticide remain on the treated surface for easy pick-up by the insects and the lack of solvent means that there are no staining or odour problems. 

wettable powders

This is a solid powder formulation with an insecticide component (often a very high proportion of the total weight and measured in grams/kilogram) and a special dispersing agent that enables it to be mixed with water forming an insecticidal suspension.  Wettable powders most often use organophosphates, carbamates and synthetic pyrethroids as their active ingredients.  They are ideal for use on porous surfaces where the water soaks in leaving a fine film of insecticide powder on top.

Fumigants
Fumigants encompass a wide range of diverse chemical materials. The fumigation process entails introducing the fumigant material into an airtight space containing the material to be treated.  The fumigant gas kills all stages of the insect life cycle when sufficient amounts are used.  Some fumigants are stable at ordinary atmospheric temperatures while others eg. methyl bromide, must be held under pressure in cylinders.  Various kinds of fumigation eg. stack or ship, exist and personnel must have a fumigator's licence in order to carry out such treatments.

Aerosols
There is a wide variety of active ingredients viz. insecticides, molluscicides, disinfectants and deodorisers.  They come in two varieties: push button and total release.  Insecticide aerosols are of two types - non-residual space sprays and residual surface sprays.  The use of residual aerosols as an alternative to conventional insecticidal sprays or dusts should be avoided.

rodenticide baits

cockroach baits

other pest baits

Baits are formulations of an insecticide or rodenticide combined with a palatable food source.  Water baits are used for rodent control in dry areas and are made by combining a water bait concentrate with the required amount of water.  The active ingredient is kept to the minimum effective amount.  The maximum amount practical depends upon the palatability of the active ingredient and the susceptibility of the target species.