PROLINK® OVERVIEW

ProLink Brochure

The active ingredient in all PROLINK products is (S)-methoprene, an insect growth regulator (IGR). IGR's are classified as biorational control agents. IGR's control insects by interrupting normal development. (S)-methoprene interferes with normal metamorphosis, preventing the immature insect from emerging as an adult

(S)-methoprene is a true analogue of the mosquito's own juvenile hormone. During the fourth larval instar, juvenile hormone (JH) levels drop to very low levels. PROLINK, when applied into the larval habitat, releases (S)-methoprene which artificially maintains the JH levels at a higher than normal titer. The higher than normal level during the latter instar stages, prevents the insect from developing into normal pupa. Mortality occurs during the emergence of biting adult mosquitoes.

Unlike conventional pesticides, (S)-methoprene is not a direct toxin. It is target-specific and does not harm mammals, waterfowl, or even beneficial predatory insects. In fact, methoprene has been recommended by the World Health Organisation (WHO) for the use in drinking water supplies to control container-breeding mosquitoes in developing countries.

By working specifically on fourth instar mosquito larvae, PROLINK offers effective control without upsetting the food chain relationships between larvae and their natural predators, and, most importantly, without impacting non-target species.

Environmental Properties

General: (S)-methoprene insect growth regulator (IGR) is a biodegradable compound of very low environmental persistence. The (S)-methoprene molecule contains only carbon, hydrogen and oxygen.

Persistence in Soil: The half-life of methoprene when applied to soil at 1 Kg per Hectare is less than 10 days. This is a highly exaggerated application rate with regard to the intended use pattern.

Movement in Soil: In leaching studies, it has been shown that methoprene remains in the top 10 cm of the soil even after repeated washings with water.

Persistence in Water: Technical methoprene degrades rapidly when applied to water under normal conditions of sunlight and temperature. Methoprene is degraded by aquatic microorganisms and sunlight. Slow release and microencapsulated formulations allow its operational use for mosquito control.

Persistence in Plants: When applied at the rate of 1 Kg per Hectare to alfalfa, methoprene has a half-life of less than two days. In rice, the half-life is less than one day. Rapid biodegradation is evident even after treatment at exaggerated rates.

Uptake by Plants: Studies show that wheat grown in methoprene-treated soil does not contain residues of methoprene.

Fate in Animals: Laboratory and field experiments have shown that methoprene is rapidly degraded by mammalian metabolic systems. When mice, rats, guinea pigs, steers, or cows are treated orally with methoprene, the compound is metabolised quickly and eliminated via urine, faeces, and expired breath.

Fate in Fish: In model ecosystem experiments, methoprene is shown not to accumulate in fish and does not inhibit growth or development of fry.

Effects on Non-Target Organisms: Toxicity studies have been conducted both in the laboratory and as part of field research programs. The action of methoprene is selective. When applied at the recommended use rate, methoprene does not harm wild fowl, amphibians, crustaceans or beneficial insects.

Effects of PROLINK in the Field

PROLINK, an insect growth regulator (IGR), acts by inducing morphological changes which interfere with normal development. These effects, not immediately apparent, result in the failure of adult mosquitoes to emerge from pupae.

Because the effect of PROLINK is neither total larval death nor widespread mortality immediately following pupation, the number of emerged adults is the only criterion for accurately assessing control. Checks by dip counts during larval and pupal stages are valid only for subjective evaluation by trained inspectors familiar with the subtle effects of labelled rates of PROLINK on larva and pupa.

After application of PROLINK to 2nd, 3rd, or 4th instar larvae, direct toxic effects on larvae are not likely to be observed. They will continue to develop and will pupate. Pupae will also live for a short time but will eventually die. Adults will not emerge. Infrequently, a few adults may be seen at the water surface, but will have abnormalities preventing flight and will not survive.

Subjective evaluation of PROLINK treated areas is routinely practiced by many professional mosquito control experts using PROLINK operationally. Inspectors who have familiarised themselves with subtle changes in appearance and behaviour of treated larvae and pupae advise us that a general determination can be made on whether or not an effective level of PROLINK has been delivered to the breeding site. Some of the subtle changes to look for are:

  1. Abnormally light coloured larvae and /or pupae.
  2. Less than normal larval vigour or pupal mobility.
  3. Malformation of treated larvae or pupae.
  4. Pupae may tend to be straighter than their normal "comma" shape.
  5. Failure of treated larvae to advance to the next instar stage of their development or to pupate within a normal time frame.

Any one or all of these abnormalities may be found in a treated area. Close observation during the first few uses of PROLINK may allow the field operator to forecast results of a treatment.

Application Checklist

Do the following:

  1. Do treat 2nd, 3rd, and/or 4th instar larvae, not pupae or adults. (1st instar larvae are so small they are not readily detectable.)
  2. Do wait until treated larvae have pupated. Then collect pupae and transfer to laboratory to observe for emergence of adults.
  3. Do observe pupae for several days, since death of IGR treated mosquitoes occurs when pupae would normally emerge as adults. (Careful observation is necessary since dead pupae decompose rapidly and thus are not easy to see).
  4. Do monitor emerging adults at the treatment site. This absolutely requires that emergence traps be placed in treatment areas to capture adult mosquitoes as they emerge.

Do not do the following:

  1. Do not take dip counts of larvae after treatment for the purpose of performance evaluation. Normal looking larvae may be present.
  2. Do not take dip counts of pupae after treatment for the purpose of performance evaluation. Normal looking pupae will be seen but will not develop into normal adults.
  3. Do not think PROLINK has failed if some adult mosquitoes are flying in the treated areas; they probably have flown in from nearby untreated areas. Number 2 and 4 of the "Do" checklist are the only methods of accurately assessing effectiveness.
  4. Do not spray again, either with PROLINK or a conventional insecticide, because larvae and pupae are present after application. This is normal. The effectiveness of PROLINK can only be measured by lack of adult emergence.

PROLINK Products

PROLINK XR Briquets

ProLink XR Briquets (150 days residual) are the ideal treatment for chronic breeding sites where access is difficult or where regular re-treatment would be impractical. ProLink XR Briquets can be applied (at a rate of 1 Briquet/10-20 m2) prior to flooding when sites are dry.  They can be used in storm drains, ditches, ornamental ponds, septic tanks, waste water ponds, abandoned swimming pools, construction sites, salt-marshes, semi-permanent and permanent freshwater laval habitats etc.  ProLink XR Briquets can also be used in rain water tanks containing potable water.  ProLink XR Briquets are available in buckets of 100 and 200 briquets, or cartons of 220.

PROLINK Liquid 5%

With a 7-10 day residual activity and an effect in all larval stages, ProLink Liquid Larvicide can be used in a wide range of larval habitats.  ProLink Liquid Larvicide is ideal for control of single cohort hatches or for multiple cohorts when applied weekly.  ProLink Liquid Larvicide is a simple to store and apply liquid formulation, suited to all salt-marsh and fresh water larval habitats where regular application and access is not a problem.  Application rate is 220-360 ml/Ha in sufficient water (5 to 50 litres) to give good coverage.  ProLink Liquid Larvicide can be applied by backpack or truck mounted sprayer, or aerially by ULV equipment.  ProLink Liquid Larvicide is available in 3.8 litre jugs and 4 x 3.8 litre cartons.

Prolink Pellets

ProLink Pellets will give control for up to 30 days. Conventional pellet application equipment can be used, or pellets can be simply distributed by hand.  Applied at 3-4 kg/Ha (approx. 2-4 pellets/m2) pellets can be applied prior to flooding.  ProLink Pellets are ideal for spot applications to control larvae in plant potholders, birdbaths, gutters, old tyres etc in domestic or commercial areas.  Pellets are also ideal for use in large mosquito control programs in salt-marsh and freshwater larval habitats, particularly where application cost or access are limiting factors.  ProLink Pellets are available in 10Kg jugs, and cartons of 2 x 10Kg Jugs.

PROSAND

ProLink ProSand is designed for spot ground or broad-acre aerial larviciding using standard granular application equipment where canopy penetration is required or where a granular product is the preferred option.  ProLink ProSand is applied at 3-5 kg/Ha.  When use for aerial application, accurate calibration of rate, swath width & lane separation is essential.  A differential GPS navigation & positioning system is a desirable aid to accurate application.  Salt-marsh with mangrove canopy or freshwater with emergent vegetation are ideal areas for ProLink ProSand or where wind may cause too much drift with liquid formulations.  ProLink ProSand is available in 20 Kg buckets.