Field evaluation of commercial formulations of the codling moth granulovirus CpGV:

1
Field evaluation of commercial formulations of
the codling moth granulovirus (CpGV) persistence
of activity and success of repeated applications
against natural infestations L.A. Lacey1, S.P.
Arthurs1, H. Headrick1, R. Fritts, Jr.2, and D.
Thomson3 1 USDA-ARS, Yakima Agricultural Research
Laboratory, Wapato, WA 2 Certis USA, Clovis, CA3
Sumitomo USA, Seattle, WA
2. Grower assessments Methods. The impact of CydX
as a primary control measure for codling moth
within commercial organic orchards was monitored
at five locations (Table 2). Individual growers
applied Cyd-X treatments within label
recommendations i.e. 3-4 oz in 100-200 gal.
6-12 oz wetting agent per acre. Applications were
timed according to biofix information and sticky
pheromone trap data, according to normal
monitoring practices. Historically all sites had
suffered repeated codling moth attacks with CydX
treatments generally confined to known hotspots
from 2002 where mating disruptors (200-400/ac)
and some routine sanitation of infested fruit was
also employed. Trees were sampled to estimate
damage throughout the season. Damaged fruit was
removed to determine the proportion of deep
entries caused by larvae surviving treatment.
Selected trees were banded to monitor
overwintering generations. Results. The grower
assessments provide strong circumstantial
evidence for the effectiveness of well-timed CpGV
applications against codling moth outbreaks
(Table 2). In all cases where 1st generation
larvae were targeted and treated areas monitored,
fruit damage was reduced or eliminated in the 2nd
generation, with the majority of neonates killed
throughout the season as indicated by the high
proportion of failed entries or shallow stings.
Adult catches in pheromone traps were also
significantly reduced in the second and third
generation combined, while trap bands placed
around trees indicated the overwintering
generations remained low (data not shown). In one
case (Moxee), a severe infestation was reduced
(when compared to an oil check) but not
adequately controlled by late season applications
of the virus alone.
The codling moth, Cydia pomonella L. is the most
significant and widespread insect pest of apples
in Washington State and beyond. While chemical
control remains the mainstay for most
conventional growers, concerns over environmental
impact and insecticide resistance coupled with
anticipated loss of registered compounds such as
Guthion (azinphos methyl) has focused efforts to
find more integrated approaches. Among the
biological control options available, the
granulovirus of C. pomonella (CpGV) has offered
potential for selective control of this key pest
(Lacey et al. 2002 Jaques, 1990). Although CpGV
has received considerable attention as a
microbial insecticide, problems including a
perceived lack of persistence and speed of kill
in the orchard agroecosystem and previous quality
control issues have to date limited its
widespread commercial development and adoption by
orchardists (Cross et al. 1999).
Table 1. CpGV applications made to experimental
plots at Moxee, 2003

• Objectives
• Assess the persistence and efficacy of three CpGV
  products recently certified for use in organic
  production in an experimental orchard CydX
  (Certis), Virosoft (Biotepp), Carpovirusine
  (Sumitomo)
• Monitor the season-long performance of Cyd-X used
  by several commercial organic growers

Fig.2. Live codling moth larvae recovered from
apples previously treated with commercial CpGV
products. Fruit was challenged with 5-neonate
larvae at various intervals after spraying
1. Persistence of CpGV products Methods. This
study was conducted in a plot of 224 trees
(spur-reds) at the USDA experimental orchard near
Moxee, WA. Applications were made on 2 June and
14 July to seventy individual trees using a
motorized backpack airblast sprayer (Stihl).
Products were applied in a 32 factorial design
according to Table 1 with 10 randomly selected
trees per treatment. Trees were sprayed from
multiple angles providing realistic coverage and
a large tarp was used to confine treatments
(Fig.1). Immediately after spraying and at 1, 3,
7, 10 and 14-day intervals 50 apples per
treatment were removed and challenged with 5
neonate codling moth larvae using a standardized
laboratory bioassay. After 10 days, apples were
destructively sampled to quantify fruit damage
and larval mortality. Results. For the June
application residual activity of all products
(label rates) remained highly effective (gt80
larval mortality relative to controls) for 24
hours following application and moderately
effective (gt70) after 72 hours (Fig.2).
Significant activity in all treatments remained
after 14 days, suggesting prolonged survival of
the virus in UV-protected locations, such as the
calyx of fruit. Fruit damage was also reduced
while overall gt97 control larvae formed deep
entries, lt35 of CpGV-killed larvaes stings were
gt3mm. The second application showed similar
results (data not shown).
Table 2. Fruit injury and adult codling moth
activity monitored in commercial orchards
following various CpGV applications (2003 season)
1Accumulated degree days 1st generation
220-1020, 2nd3rd 1100-2300 2A minimum of 30
trees assessed per generation
Discussion Our results show that repeated
applications of commercial CpGV formulations
provide a valuable alternative for management of
codling moth in Washington State and
elsewhere. Weekly applications timed during peak
egg hatch integrated with other strategies such
as mating disruption or other soft pesticides
will likely provide effective population
suppression for many growers with moderate to low
codling moth pressure. Future work at YARL will
focus on optimizing the application rate and
frequency of CpGV applications as well as
improving the persistence and uptake through
formulation.
References Cross, J.V., Solomon, M.G. et al.
1999. Biocontrol of pests of apples and pears in
northern and central Europe 1. Microbial agents
and nematodes. Biocontr. Sci. Technol. 9,
125-149 Lacey, L.A., Vail P.V. and Hoffmann D.F.
2002. Comparative activity of baculoviruses
against the codling moth Cydia pomonella and
three other tortricid pests of tree fruit. J.
Invert. Pathol. 80, 64-68 Jaques, R.P. 1990.
Effectiveness of the granulosis virus of the
codling moth in orchard trials in Canada.
Proceedings of the Vth international colloquium
on invertebrate pathology and microbial control,
Adelaide, Australia, 20-24 August 1990