Intrepid (methoxyfenozide) - Intrepid (and Confirm) acts to initiate a premature lethal molt in caterpillars. It is lethal because the insect is not able to complete the molt and dies within the old skin that it cannot shed. In some cases Intrepid will not kill the larva but the subsequent adult will not be able to reproduce. Intrepid has little or no contact activity and must be ingested by larvae to have a toxic effect. Intrepid has strong ovicidal activity whether applied topically or if eggs are laid on residues. Intrepid is very specific to lepidopteran pests and has the advantage over some older insecticides in having a short REI (4 hours) and PHI (14 days).
Lepidopteran pests
Codling moth – Intrepid controls codling moth in two ways, first
as an ovicide and then as a larvicide. This product cannot be considered
a simple replacement for Guthion. Intrepid is highly toxic to both eggs
and larvae in laboratory studies, but does not provide the same amount
of crop protection as Guthion or Imidan under the same use pattern. The
reduced efficacy in field applications relative to organophosphates is
probably due to reduced residual control. We expect only about 14 days
of activity against susceptible populations. Our data also suggests that
an earlier ovicide timing (100DD) is at least equivalent to the traditional
larvicide timing (250DD). If the ovicidal timing of Intrepid is as good
or better than the egg hatch timing it opens a new strategy for using this
product. Because Intrepid also has good activity against leafrollers its
use in the petal fall period could simultaneously control codling moth
and leafroller. Intrepid should not be considered a “stand alone” control
for codling moth except where very low pressures are present. It has its
best fit as a component of a pheromone-based IPM program where it is integrated
with the use of codling moth mating disruption. There is concern that codling
moth populations resistant to organophosphates may also be tolerant or
resistant to Intrepid due to OP mediated cross-resistance.
Leafrollers – Intrepid has good efficacy against leafrollers. Intrepid has primarily been evaluated at its full field rate against leafrollers; however, it is likely that reduced rates will also be effective. Intrepid is effective against leafrollers in the spring from bloom to about 14 days after petal fall. One application of Intrepid can be effective against low leafroller densities but a second application might prove necessary against high populations. In the spring Intrepid should be used when weather forecasts predict warm conditions, 65°F or better for at least 3 days, in order to ensure active feeding by larvae. Intrepid has a longer residual activity against leafrollers so it should not be subject to the vagaries of weather on efficacy as are Bt products. Intrepid is also effective against leafroller larvae in the summer and the best timing is when larvae are young. When applied at 20% egg hatch of leafroller Intrepid provided excellent control, comparable to Success in most tests. Intrepid has a long residual activity but has no contact activity. Therefore, Intrepid must be applied with good coverage but it is not necessary to use dilute sprays. We have some concern that leafroller populations show a highly variability degree of susceptibility to Intrepid, and this variability seems directly related to the OP resistance in the same populations. This could mean that the genetic basis for resistance to Intrepid exists in some leafroller populations in WA. Good product stewardship should be used including switching between products with different modes-of-action as part of a resistance management program.
Lacanobia fruitworm – Intrepid is very effective against Lacanobia. The best timing of Intrepid against this insect is when about 80% of eggs have hatched, prior to the presence of large larvae (700DD). A single application seems adequate to control this pest and it is very likely that reduced rates will be as effective as the full field rate. Experience in the Areawide II project showed that Lacanobia densities were suppressed in orchards that used Intrepid in multiple applications against codling moth. These timings overlapped with the optimal timing for Lacanobia providing control of both pests at the same time.
Indirect/secondary pests
Intrepid has no known effects on campylomma, leafhoppers, aphids, mites
(either phytophagous or predatory). Suppression of leafminer depends
on timing; better success has been achieved where it has been used in
codling moth programs than in single-application leafminer timings (although
suppression may be sufficient in some cases).
Pear pests
Intrepid has been tested against codling moth in pear, and appears to work
effectively against low to moderate populations. At low densities, Intrepid
was comparable with Guthion treatments. However, when challenged with
very high codling moth populations, Intrepid treatments sustained significant
damage. Intrepid does not affect pear psylla or grape mealybug.
Beneficial arthropods
Intrepid has no known negative impacts on beneficial arthropods.