Since the industrial revolution large amounts of insecticides have been used in the control of insects with stronger chemical controls being needed to be developed as insects have caught up and become resistant to the insecticides. New Zealand has been a world leader in the use of bio-controls as a small isolated island nation with many pest species of insects and plants being introduced since humans arrived on NZ's shores. As a nation which relies on exports of dairy, meat and fruit as a major source of income, our boarders need to be effectively managed so the worst pests do no arrive here.


From the 1960's to the 1980's the light brown apple moth was an economically important pest within the fruit sector. After developing resistance to broad-spectrum insecticides, research began to focus on biological controls and native enemies were introduced from Australia in the late 1960's. By the 1990's this resulted in decreased damage to the fruit sector. and today the light brown apple moth is successfully managed by the use of IPM (integrated pest management).

In recent years the light brown apple moth has been found in California, USA and has effected trade and export of produce. In California the light brown apple moth is affecting the same products as it did in New Zealand (apples, pears and berry fruits). In NZ growers are able to use a combination of selective pesticides and natural controls to keep the damage under 2% and meet the export standards of 60 countries. Acomplex program of native and introduced species is used in NZ which attacks all life stages of the light brown apple moth. Californian growers could benefit greatly from the experience NZ growers have gained from this pest. As chemical uses are not the best solution as they can damage both pests and beneficial species.

Varela, L., Walker, J., Lo, P., Rogers, D. () New Zealand lessons may aid efforts to control light brown apple moth in California. California agriculture. 64: 6-12.

Painted in auckland.

I remember growing up in west Auckland when we were invaded by a low flying plane dropping a nasty smelling chemical spraying for the painted apple moth (Teia anartoides). As a teen being easily influenced by others opinions i was very definitely against the aerial spraying. I recall a conversation with my Dad where I was telling him how wrong i thought the spraying was because of the so called health effects of the spray (as a sufferer of asthma although the spraying had no effect on my asthma)  and my Dad telling me would I like to see the Waitakere ranges looking like a desert in a matter of years if the council did not do anything about the painted apple moth.  After that conversation i changed my perspective on the importance of aerial spraying.

In 1999 the painted apple moth Teia anartoides was found in Glendene, Auckland, New Zealand. As the moth is a pest of many commercially important plant species and endemic plant species the decision to eradicate it was made. The program to eradicate the moth was the largest eradication program New Zealands biosecurity agent MAF has undertaken to date and by March 2006 the moth was declared eradicated. Between 1999 and 2003 contractors and MAF staff visually searched for the moth in the areas where it was originally found and in schools, parks, gardens and road side. Where both alive and dead larvae, pupae and moths were found and destroyed once correctly identified.

As the females are apterous (wingless) and immobile the larvae are self dispersed by walking and ballooning. because of this the larvae represent a more accurate idea of spread than the finding of female moths. In the moths native Australia the main host is wattle species which is where the moth was most commonly found in New Zealand. But the moth was not only found on exotic species of plants but also native species such as mangrove (Avicennia marina) and karaka (Corynocarpus laevigatus). Also the number of larvae found on inanimate objects (clothing, walls, fences, plant pots and other objects in home gardens) was surprising and points to the larvae ability to  mobilize to find alternative food sources. This also suggests that inanimate objects provide a suitable site for pupation.

Stephens, A., Suckling, D., Burnip, G., Richmond,J., Flynn, A. (2007) Field records of painted apple moth (Teia artoidenas Walker: Lepidoptera: Lymantriidae) on plants and inanimate objects in Auckland, New Zealand. Australian Journal of Entomology. 46:152-159.

Success of biological controls

Weed species have a huge impact on native flora and fauna aswell as agricultural systems in many countries. In New Zealand there are 20, 000 non indigenous plants with about 240 of them being considered pests. Ideally plants that could potentially become weeds should not be allowed into NZ. But if they do make it into NZ the next best scenario is early detection. Often by the time plant pests are detected they are widespread and out of control. Chemical control of these pests can be costly, time consuming and risks the plant becoming immune or partially immune to chemicals. Many plant pests have highly specific insects that prey on them and can be highly effective in suppression of pest spescies.

This paper argues in favor for the advantages of bio-controls on plant pests. Initially research costs to find and test the effectiveness of insect controls can be high but the long term effects on the control of plant pests can outweigh the initial costs. Also the testing may go on for a number of years before the control agent is released into the environment as bio-controls are often non-reversible and may have an impact on native ecosystems.

An example of a bio-control program is the Heather, Calluna vulgaris (Ericaceae) which is a low growing perennial shrub.The heather beetle, Lochmaea suturalis (Coleoptera: Chrysomelidae) was researched for 5 years before being released as a control agent. From 1991 to 1993 choice feeding tests occurred. Larvae and adult beetles were exposed to a test plant in the presence of heather. 1993-97- tests on the ovipositor preferences and rates, larval and adult survival rates on plants from choice tests, quarantine and rearing in confinement to remove a parasitic microsporidian from the beetle cultures. 1996-1997 releases into Tongariro National Park. Following the release of the heather beetle ongoing monitoring of the spread and impact of the beetle on the heather plant. Ecological studies are needed following the release to show the impact of the beetle on the population of the plant.

Introductions of insects also causes huge environmental impacts as pest plants can. A well documented example of this is the accidental introduction of the Oak leafminer, Phyllonorycter messaniella (Zeller) which began to attack Nothofagus spp. The leafminer became so abundant that it damaged its natural hosts as well as Nothofagus spp. After introducing two species of parasitic wasps the leafminer was successfully controlled to a level where they have not been reported to attack Nothofagus since.