Efficacy of Isomate-CM/LR for management of leafrollers by mating disruption in organic apple orchards of western Canada

2008·8.8 MB·English

by  Gary J R Judd

J.Entomol. Soc.Brit.Columbia 105,December2008 45
Efficacy ofIsomate-CM/LR for management ofleafroUers
by mating disruption in organic apple orchards
ofwestern Canada
GARY J.R. JUDD^ ^ and MARK G.T. GARDINER^
ABSTRACT
Results ofa three-year study demonstrated that Isomate-CM/LR, a polyethylene, single
tube-type pheromone dispenser releasing an incomplete mixture of several species'
multi-component pheromones is an effective management tool that provides multiple-
species mating disruption for Choristoneura rosaceana (Harris) and Pandemis limitata
(Robinson). When applied at a rate of 500 dispensers / ha within the orchard and the
equivalent of2000 dispensers / ha to trees on the orchard perimeter, levels of control
were adequate for production of organic apples in British Columbia, Canada. Trap
catches with synthetic pheromone lureswere reducedby79 -99% andmating offemales
on mating tables was reduced by 87 - 98% in these species. At harvest, damage from
leafrollers in pheromone-treated organic orchards was below organically-acceptable
economic levels {5%) and similar to damage levels observed in insecticide-treated con-
ventional orchards {2%). Overthree years, total trap catches ofthese two leafrollers and
theirdamage decreased in fouroffive orchards treatedwithpheromone, but catches and
damage from leafrollers increased in one orchard. These indices remained relatively
unchanged in paired insecticide-treated conventional orchards over the same three-year
period. Inpheromone-treated orchards, levels ofdamage from leafrollers at harvestwere
positively correlated with total leafroller catches in pheromone monitoring traps. Use of
Isomate-CM/LR as a supplemental pest management tactic in organic orchards will help
to reduce damage and economic losses from leafrollers that have been increasing under
the area-wide codling moth sterile insect programme ongoing in this semi-desert, mon-
tane appleproduction region.
KeyWords: leafrollers, multiple-speciesmatingdisruption, organic apples
INTRODUCTION
Overthe last decade a newparadigm for Knight 1995, Gut and Brunner 1998). Con-
integrated pest management in pome fruits sistent with earlier prediction (Madsen and
has emerged in western North America. Morgan 1970), several species of leaf-
This transformation was driven by imple- rolling caterpillars (Lepidoptera: Tortrici-
mentation ofarea-wide programmes to con- dae) have become an increasing problem
trol codling moth, Cydia pomonella (L.), when broad-spectrum insecticides that tar-
using sterile insect technique (SIT) in Can- get codling moth, but which provide partial
ada (Dyck and Gardiner 1992) and phero- control ofleafrollers, are removed from the
mone-based mating disruption inthe United production system (Madsen and Proctor
States (Calkins 1998). Application ofthese 1985). Although the species complex varies
species-specific controls for codling moth across production regions, increasing dam-
has resulted in increasing damage from age from leafrollers in orchards using mat-
secondary pests (Brunner et al 1994, ing disruption for codling moth is a recur-
'AgricultureandAgri-food Canada, Pacific Agri-foodResearch Centre, Box 5000,4200 Hwy97, Summer-
land,BritishColumbia,CanadaVOH IZO
^Author to whom correspondence should be sent. Tel.: [phone]; fax.: [phone]; E-mail:
[email protected]
.
46 J.Entomol. Soc.Brit.Columbia 105,December2008
ring problem seen around the world communication). When Isomate-CM/LR
(Charmillot 1990, Wearing et al 1995, was used in conjunction with insecticides
Walkerand Welter2001). (Knight et al 1997, Knight et al 2001),
The British Columbia (BC) organic ap- apple orchards had41% less leafroller dam-
ple industry is concentrated in the Simil- age and received one less spray per season.
kameen Valley (Judd et al 1997, Mullinix These same orchards consistently had less
2005). Although orchards in this region codling moth damage than orchards receiv-
have been receiving sterile codling moth ing Isomate-C^ and supplemental insecti-
since 1994 as part ofan area-wide SIT con- cides. Whether leafrollers can be controlled
trol programme (Dyck and Gardiner 1992), effectively, or sufficiently, with Isomate-
producers of organic fruit found it neces- CM/LR when no supplemental insecticides
sary to supplement this programme with are usedremains untested.
codling moth mating-disruption technology Judd and Gardiner (2005) reported on
in spring (Judd and Gardiner 2005). Be- the use of mating disruption as a supple-
cause codling moth is presently under con- mentary tactic for spring control ofcodling
trol but profit margins are shrinking under moth in organic orchards that were part of
increased foreign competition, organic ap- the area-wide SIT programme. Herein we
ple producers in BC are seeking alternative report results using Isomate-CM/LRto con-
controls forleafroUers to improve quality of trol damage from leafrollers while at the
graded export fruit. Before 2005, Bacillus same time supplementing codling moth
thuringiensis Berliner (Bt) was the only control in those same organic apple or-
organic material available for controlling chards. The primary objective ofthis study
leafrollers in Canada. Although Bt is effec- was to conduct season-long assessments on
tive, its use is often limited by inclement disruption of pheromonal communication
spring weather in montane areas ofBC, and and mating in the leafrollers, Choristoneura
while fairly benign to beneficial species, it rosaceana (Harris) and Pandemis limitata
can have a significant effect on parasites of (Robinson) in commercial, organic apple
leafrollers if applied at the wrong time orchards where Isomate-CM/LR was used,
(Cossentine etal 2003). and to report on levels ofleafroller damage
Organic pome-fruit producers in BC inthe absence ofinsecticide inputs. Second,
have been interested in pheromonal control we wanted to collect data on the relation-
of leafrollers ever since pheromones were ship between different measures ofdisrup-
first applied to control codling moth (Judd tion and relative density ofadult leafrollers
et al. 1997). The idea ofusing one mating- as measured by pheromone traps, because
disruption system to simultaneously control questions about the efficacy ofmating dis-
codling moth and leafrollers has been ruption and population density are rarely
around for some time (van Deventer et al addressed experimentally. Third, we
1992) but few commercial products exist. wanted to determine ifpheromone trapping
Isomate-CM/LR, a multiple-species mat- ofC. rosaceana and P. limitata has the po-
ing-disruption product designed to control tential to be a predictive tool of potential
codling moth and leafroller species impor- damage in orchards under pheromone-
tant in western North America, was regis- based mating disruption (Walker and Wel-
tered in the United States in 1997 and in ter2001).
Canada in 2004 (Don Thomson, personal
MATERIALS AND METHODS
Test orchards. All apple orchards used m). The five organic orchards treated with
in this study are located at Cawston, BC, in Isomate-CM/LR and five paired conven-
the Similkameen Valley (latitude 49° 10.8' tional orchards treated with insecticides
N, longitude 119° 46.2' W, elevation 401 (Table 1) were described in detail by Judd
J.Entomol. Soc.Brit.Columbia 105,December2008 47
Table 1.
Management, monitoring and fruit sampling details for the leafrollers Choristoneura
rosaceana andPandemis limitata in each organic (01 - 05) andpaired conventional (CI - C5)
apple orchard studiedinCawston, BC, Canada, 1997 - 1999.
No. ofpheromone Yearly insecti- Yearly numberof Numberoffruit
dispensers/ha cidetreatments traps foreach sampled fordamage
applied each year^ forleafrollers^ leafrollerspecies'* at harvesteach year
Orchard* 1997 1998 1999 1997 1998 1999 1997 1998 1999 1997 1998 1999
01 500 500 500 0 0 0 4 4 4 3368 2145 2000
02 500 500 500 0 0 0 6 6 6 5006 1756 2000
03 500 500 500 0 0 0 4 4 4 4298 2100 2000
04 500 500 500 0 0 0 2 2 2 4300 2223 2000
05 500 500 500 0 0 0 4 4 4 3031 1939 2000
CI 0 0 0 0 1 1 2 2 2270 1698 2000
C2 0 0 0 3 3 4 2 2 2000 2000 2000
C3 0 0 0 2 2 3 2 2 2000 2000 2000
C4 0 0 0 1 1 0 2 2 2100 2000 2000
C5 0 0 0 2 3 4 2 2 2000 1883 2000
'Orchards 01 to 05 were cited by Judd and Gardiner (2005) as orchards Al - A4 and Bl, re-
spectively, and orchards CI - C5 remain the same across studies. Six untreated, organic, com-
parison orchards not listed were monitored but not sampled for damage (Cossentine et al.
2004).
^All trees on theperimeterofeach orchardreceivedthe equivalent of2000 dispensers/ha.
^Leafroller sprays consisted ofspring (April) sprays ofmethidathion in dormant oil and sum-
mer(July-August) sprays ofConfirm® (tebufenozide).
No leafroller monitoring was done in conventional comparison orchards in 1997 but they
were sampled for damage at harvest. Six untreated, organic, comparison orchards (Cossentine
etal. 2004)were eachmonitoredwithtwo traps in 1998 and 1999. Each species was monitored
with a septal lure loaded with 3 mg of a multi-component blend described by Deland et al.
(1994).
and Gardiner (2005). Six organic apple pyramid shape training system.
orchards that received no treatments for No synthetic insecticides were applied
control ofleafrollers were described in de- to any ofthe organic orchards examined in
tail by Cossentine et al. (2004) as part ofa this study (Table 1), but one orchard (03)
study on parasitism of leafrollers in 1998 received Bt sprays (Dipel 2X DF) in 1998
and 1999. The latter untreated orchards and this is noted in the Discussion. All but
were used to compare relative trap catches one conventional orchard also received at
ofleafrollers only, as no damage data were least one application of Guthion®
collected in the original study. Briefly, all (azinphosmethyl at 0.84 kg a.i./ha) for cod-
orchards ranged in size from 0.5 - 2 ha and ling moth control in 1997, but in later years
were composed of mixed apple varieties growers used Confirm® (tebufenozide) dur-
planted at densities of 267 - 938 trees/ha ing both spring and summer usually timed
with tree x row spacing of2.4 - 6.1 x 3.0 - for control of leafroller larvae. One caveat
6.1 m, respectively. Trees ranged in height is that conventional orchards did not neces-
m
from 2.5 - 3.5 and were pruned using a sarily receive similar or optimal insecticide
48 J.Entomol. Soc.Brit.Columbia 105,December2008
spray programmes because these orchards multi-component pheromone blend (Deland
were chosen by Judd and Gardiner (2005) et al 1994; described below) were de-
as local comparisons not controlled treat- ployed evenly throughout each orchard
ments. (Table 1). One trap for each species was
Pheromone disruption treatment. hung ca. 1.5 - 2.0 m above ground on dif-
Isomate-CM/LR is a brownish red, single- ferent sides ofthe same tree in 2 - 6 sepa-
tube, polyethylene dispenser, manufactured rate trees. Positions for all traps remained
by the Shin-etsu Chemical Company Ltd. fixed within and across years. In 1997 only
(Tokyo, Japan) and marketed by Pacific the five Isomate-CM/LR-treated organic
Biocontrol Corporation (Vancouver, Wash- orchards were monitored with pheromone
ington). Each Isomate-CM/LR dispenser traps. On 30 May 1997, wing traps were
contains a 285 mg blend of 36.9% {E,E)- deployed in each ofthese organic orchards
8,10-dodecadien-l-ol (codlemone), 1.8% and checked weekly fi-om 6 June until 18
isomers ofcodlemone, 6.0% dodecanol and September. In 1998, wing traps were de-
1.2% tetradecanol for disruption ofcodling ployed in these same five Isomate-CM/LR-
moth, and 43.5% (Z)-l1-tetradecenyl ace- treated organic orchards, five paired insecti-
tate (Zll-14:Ac) and 2.4% (£')-ll- cide-treated conventional orchards and six
tetradecenyl acetate (£'ll-14:Ac) for dis- untreated organic orchards on 8 May, and
ruption ofleairollers, plus 8.2% inert ingre- checked weekly from 15 May until 25 Sep-
dients and pheromone stabilizers (Don tember. In 1999, wing traps were deployed
Thomson, personal communication). in all orchards on 27 May and checked
Isomate-CM/LR dispensers were deployed weekly from 3 June until 30 September.
in five organic apple orchards at a rate of Moths were counted and removed weekly
500/ha, however each perimeter tree re- with trap bottoms replaced as needed and
ceived the equivalent of2000 dispensers/ha pheromone lures changed every three
(Table 1). Dispensers were attached to weeks.
branches in the upper third oftree canopies Synthetic multi-component pheromone
m
ca. 1 below the top ofthe central leader, lures for each leafroller species were pre-
or on the first lateral branch beneath the pared with chemical components (Aldrich
central leader. All pheromone dispensers Chemical Company Inc., Milwaukee, Wis-
were deployed a few days before codling consin) of known purity, as confirmed by
moths were expected to emerge and no later gas chromatographic analysis (Zll-14:Ac,
than 8 May each year (Judd and Gardiner 98% with 2% £'ll-14:Ac; (2)-ll-
2005). tetradecenal 96%; (Z)-l1-tetradecanol;
Monitoring seasonal flight activity of 97%, (Z)-9-tetradecenyl acetate, 96%) us-
moths. In all orchards, seasonal flight ac- ing published ratios (Roelofs et al 1976,
tivity and capture of adult leafrollers were Vakenti et al 1988). In making pheromone
assessed using traps baited with synthetic lures for each species, 200 fxl ofeach multi-
pheromones. Disruption of pheromone component pheromone blend was dissolved
communication in leafrollers was calculated in dichloromethane and 3 mg ofthe phero-
by expressing catches of moths in phero- mone blendwas loaded into eachredrubber
mone-treated organic orchards as a percent- septum (Aldrich Chemical Company Inc.,
age of catch in either insecticide-treated Milwaukee, Wisconsin). After loading,
conventional orchards or untreated organic septa were air-dried for ca. 18 h at 23 ''C in
orchards in 1998 and 1999. No comparisons a fume hood and stored at 0 °C until pinned
were made in 1997 as the latter sets ofor- to the innerside oftrap lids inthe field.
chards were not monitoredthat season. Assessment of mating in leafrollers.
Depending on orchard size and shape, 2 Mating was assessed using laboratory-
- 6 Pherocon 1-C style open (5-cm side reared, virgin, female moths placed in Tef-
spacers) wing traps (Pherotech Interna- lon®-lined mating tables described by
tional, Delta, BC) baited with each species' McBrien and Judd (1996). Both C.
J.Entomol. Soc.Brit. Columbia 105,December2008 49
rosaceana and P. limitata were reared on a where their mating status was assessed as
modified pinto bean-based diet (Shorey and before. This procedure was repeated for
T
Hale 1965) at 24 and 16:8 h L:D photo- several consecutive weeks.
regime. Female pupae ofeach species were Fruit damage sampling. Depending on
placed individually in 150-ml plastic cups year and orchard, we examined fruit from
provided with moist cotton wicks until 18 to 48 trees inthe paired, pheromone- and
eclosion. Female moths aged 24 - 72 hwere insecticide-treated orchards (Table 1) using
immobilized at 0.5 °C and one forewing a stratified, cluster sampling procedure,
and a tarsal tip were removed with fine for- where the outer row oftrees and all interior
ceps to prevent escape from mating tables. trees represent two strata, and each tree
Females were kept chilled and transported represents a cluster of fruit, respectively
to field sites in small ice chests. (Judd et al 1997). Sample trees were cho-
In 1998, mating activity ofboth leafrol- sen systematically by crossing each orchard
ler species was assessed weekly from 2 from comer to comer and edge to edge,
June until 3 September in each pheromone- ensuring that each variety and stratum was
and insecticide-treated orchard. During sampled. It was necessary to sample irregu-
each weekly assessment, one female of lar numbers oftrees and fruit from year to
each species was placed in 5 or 10 separate year because biennial bearing in organic
trees in each, insecticide- or pheromone- orchards resulted in large annual differ-
treated orchard, respectively, on Tuesdays, ences in fruit set. All orchards were sam-
Wednesdays and Thursdays = 15 or 30 pled during normal periods of harvest for
females/species/orchard/week). Two mating each variety as fmit maturity and growers
tables, each containing an individual female dictated. In most cases, a minimum of 100
of each species, were placed in opposite fmit were removed from each sample tree
sectors ofthe same tree, in the upper third by picking 50 low and 50 high fmit from
of the canopy, several rows and trees dis- south side branches. If there were fewer
tant from any pheromone traps. Females than 100 fmit on a tree, all fmit were re-
were placed in the field during the after- moved from the sample tree. Early- or late-
noon and removed the following morning season leafroller damage, caused by either
to minimize predation and escape. Females overwintering or summer larvae, respec-
recovered fromthe field <24 h after deploy- tively, canbe distinguishedby the degree of
ment were returned to the laboratory and surface tunneling and scarring offmit. Only
each was dissected and examined for the late-season damage caused by summer-
presence of a spermatophore in the bursa feeding larvae is scored in this study. All
copulatrix which indicates females have leafroller damage observed in this study
mated. Any females that were dead when was caused by either C. rosaceana or P.
collected from the field were omitted from limitata, as no other species were previ-
the data. ously found in this region (Madsen and
In 1999, we conducted an experiment Madsen 1980, Judd and Gardiner 2004).
during flight ofthe first summer generation Our damage comparisons were limited to
to determine if the probability of mating pheromone vs. insecticide-treated orchards
increasedwiththe length oftime (24 - 96 h) because no damage samples were taken in
females were exposed in the field in either the untreated organic orchards examined by
pheromone- or insecticide-treated orchards. Cossentine etal. (2004).
Starting onMonday, 21 June, 100 femaleP. Statistical analyses. For each species,
limitata were deployed in one pheromone- moth captures from all traps in the same
treated orchard and another 100 females orchard were pooled and transformed (logio
were placed in an insecticide-treated or- [x +1]) to normalize the data. Annual mean
chard. At 24-h intervals for four consecu- total number of moths caught per trap in
tive days, 25 females were recovered from untreated, Isomate-CM/LR-treated, and
each orchard and returned to the laboratory insecticide-treated orchards were compared
50 J.Entomol. Soc.Brit.Columbia 105,December2008
using an analysis of variance (ANOVA) a binomial Z-test (Zar 1984). Mean percent
followed by a Student Neuman Keuls' mul- leafroller damage at harvest forpheromone-
tiple comparisons test (Zar 1984), where and insecticide-treated orchards was com-
orchards are treated as replicates (n = 5 or pared annually using a two sample /-test
6). Mean weekly and seasonal total percent following an arcsine Vp transformation of
mating of each species in pheromone- and raw data. Linear regression analysis was
insecticide-treated orchards in 1998 were used to relate mean percent damage at har-
compared using two-sample ^tests (n = 5). vest in pheromone-treated orchards with
Linear regression analysis was used to re- mean seasonal cumulative moth catches
late mean weekly percent mating and mean using all three years of data (n = 15 data
weekly trap catches in 1998. The frequency pairs) and to examine changes in moth
ofmating among females placed inthe field catches and damage over time in organic
for varying lengths of time in either a orchards. All statistical tests were per-
pheromone-treated or insecticide-treated formed using SigmaStat® (Version 3.0.1,
orchard was compared weekly and season- SPSS Software Inc., San Jose, California)
ally using contingency tables and tests or and anexperimental errorrate ofa= 0.05.
RESULTS
Seasonal flight activity of leafroUers. tively, across years (Table 2). Catches ofP.
Mean weekly catches of C. rosaceana and limitata were always higher in insecticide-
P. limitata in orchards under different treat- treated conventional orchards compared
ment regimes in 1999 are shown in Fig. 1. withuntreated organic orchards (Table 2).
Similar weekly catches were seen in 1997 Mating in leafroUers. Duringthe entire
and 1998 but for brevity data are not 1998 season, 35.1% offemale C. rosaceana
shown. Catches ofboth species reflect two (n = 757 females recovered) and 57.4% of
adult flight periods representing the first female P. limitata (n = 702) mated on mat-
and second generations in this region, re- ing tables hung in the insecticide-treated
spectively. Weekly catches ofC. rosaceana orchards (Fig. 2). If 1 August is used as an
under all treatment regimes tended to be approximate starting point for second-
smallerduring second generationthan those generation flight activity in both species
during first generation, but this trend was (Fig. 2), then mating ofboth species tended
often reversed in P. limitata (Fig. 1). P. to increase during the second-generation
limitata appeared to be the most abundant flight period. In the insecticide-treated or-
leafroller species in conventional orchards, chards mating of C. rosaceana during the
but the relative species makeup reversed first (26.8%) and second generation
itselfannually in untreated and pheromone- (54.3%) was significantly different (x^ =
treated organic orchards (Table 2). 23.01, df= 1, P < 0.001). However, mating
Disruption of leafroller pheromone ofP. limitata during first (53.6 %) and sec-
trap catches. Weekly catches of C. ond generation (65.3%) was not signifi-
rosaceana were reduced 70 - 100% in the cantly different {y^ = 2.05, df = 1, P =
Isomate-CM/LR treatment relative to both 0.152).
untreated and insecticide-treated orchards During the entire 1998 season only
in 1999 (Fig. 1), and relative reductions 1.6% of female C. rosaceana (n = 1610)
averaged 90.4 and 92.1%, respectively, and 7.4% of female P. limitata (n = 1522)
across years in 1998 and 1999 (Table 2). mated on mating tables hung in the
Weekly catches ofP. limitata were reduced Isomate-CM/LR-treated orchards (Fig. 2).
67 - 100 % by treatment with Isomate-CM/ As seen in the absence of pheromone dis-
LR compared to untreated and insecticide- ruption (Fig. 2), significantly more C.
treated orchards (Fig. 1), and relative reduc- rosaceana mated during second generation
tions averaged 92.5 and 87.2 %, respec- (3.5%) than during first generation (0.75%)
1 1
J.Entomol. Soc.Brit. Columbia 105,December2008 51
—
-~
Q.
II May22 June 1! July 17 Aug 14 Sept 1
D)
COD
to Isomate-CM/LR 1/X /^ Untreated [ ] Insecticide
SI orchards orchards orchards
E
May22 June 19 July 17 Aug 14 Sept 1
Week
Figure 1. Mean weekly catches of two leafroller species in their species-specific synthetic
pheromone-baited traps hung in untreated organic apple orchards {n = 6), Isomate-CM/LR-
treated organic apple orchards (« = 5) and insecticide-treated conventional apple orchards {n =
5) in 1999.
= 14.14, d{= l,P< 0.001) and mating chards, weekly differences in mating of
ofP. limitata was also significantly greater female P. limitata were explained (see r^
in the second generation (15.4%) than in values) by differences in weekly catches of
the first generation (2.9%) in pheromone- males (Fig. 3), but both mating and catches
treated orchards (x^ = 65.14, df = 1, P < of C. rosaceana were too low in phero-
0.001). mone-treated orchards to ascribe any sig-
=
Regression analyses (Fig. 3) indicate nificant relationship to these variables {P
that weekly differences in mating of C. 0.06).
rosaceana andP. limitata inthe insecticide- Estimates of mating in P. limitata did
treated orchards were partially correlated not appear to increase with increasing time
with the differences in weekly catches of deployed in the orchard (Table 3). Compar-
males in pheromone-baited traps, respec- ing results in Table 3 (1999) and Fig. 2
tively. In the Isomate-CM/LR-treated or- (1998), it appears that percent mating of
.
52 J.Entomol. Soc.Brit. Columbia 105,December2008
Table 2.
Seasonal total number ofmale leafroller moths, Choristoneura rosaceana and Pandemis limi-
tata, caught in synthetic pheromone-baited traps placed in untreated organic orchards {n = 6),
insecticide-treated conventional orchards (n = 5) and Isomate-CM/LR-treated organic orchards
(n = 5) andrelativepercentdisruption oftrap catches.
Mean±SE total numberof Relative % trap
moths /trap/year/treatment^ catch reduction^
Year Species Untreated Insecticide Isomate- Untreated Insecticide
CM/LR
1997 C rosaceana - - 124.2±187.6
P. limitata - - 84.7 ± 103.7
1998 C. rosaceana 137.0±45.1a 56.3±21.6b 3.8±2.1c 93.3 97.2
P. limitata 282.6± 33.5b 460.3 ± 173.7a 66.2 ±35.3c 85.6 76.6
1999 C. rosaceana 211.7±37.1a 150.1± 73.1a 27.8 ± 11.3b 87.5 86.9
P. limitata 101.7±28.5b 386.8 ± 155.2a 2.3±0.8c 99.4 97.7
Mean C. rosaceana 174.4±37.4a 103.2±46.9a 51.9 ± 36.8b 90.4±4.6 92.1±5.1
1998-
P. limitata 192.2±90.5b 423.6±36.7a 51.1 ±24.9c 92.5 ±4.8 87.2 ± 10.6
1999
'Means within a row a followed by different letters are significantly different {P < 0.05) by
StudentNeumanKeuls' multiple comparisons test following significant(P< 0.05)ANOVA
^ Percenttrap catch reduction in Isomate-CM/LR-treated organic orchards relative to catches in
untreated organic orchards orinsecticide-treatedconventional orchards.
female P. limitata in the insecticide-treated age in pheromone-treated organic orchards
orchards was higher during the first genera- ranged from 1.7 - 24.8% in 1997, 0.4 -
tion in 1999 (82.9%) compared with 1998 4.2% in 1998, and0.4 - 13.7% in 1999 (Fig.
(53.6%), while percent mating (2.9%) dur- 4A). From 1997 - 1999 leafroller damage
ing the first generation in the Isomate-CM/ declined in 4 ofthe 5 organic orchards and
LR-treated orchards was identical in 1998 in 12 out of 15 orchard-years damage was
(Fig. 2) and 1999 (Table 3). less than 5% at harvest under Isomate-CM/
Disruption of mating in leafrollers. LR treatment. Downward trends in leafrol-
When the entire 1998 season is considered ler damage overthree years appeared corre-
(Fig. 2), Isomate-CM/LR significantly re- lated with downward trends in total catches
duced mating ofC. rosaceana by 95.4% (x^ of leafrollers in each orchard, respectively
= 378.47, df= 1, P < 0.001) and mating of (Fig. 4B). There was a significant correla-
P. limitata by 87.1% {%" = 376.78, df= 1, P tion (r = 0.65, P < 0.009) between total
< 0.001) relative to their mating in insecti- leafroller trap catches and damage at har-
cide-treated orchards, respectively. Disrup- vest, but catches of leafrollers only ex-
tion ofmating in both species tended to be plained 423% of the variation in harvest
lower during the second-generation flight damage (Fig. 4C). Comparison ofleafroller
period, dropping to 93.5% in C. rosaceana damage in five organic orchards under
and 76.4% inP. limitata, respectively. Even management with Isomate-CM/LR, and
though percent mating ofP. limitata in the five conventional orchards under various
insecticide-treated orchards was lower dur- insecticide programmes is shown in Fig. 5.
ing the first generation of1998 (Fig. 2) than Damage levels were not significantlydiffer-
1999 (Table 3), disruption of mating by ent between the two groups ofpheromone-
treatment with Isomate-CM/LR was similar and insecticide-treatedorchards in 1998 and
in 1998 (95.7%) and 1999 (96.4%). 1999 (Fig. 5).
Fruit damage. Summer leafroller dam-
J.Entomol. Soc.Brit.Columbia 105,December2008 53
Choristoneurarosaceana
100 7.5
Insecticide-treatedorchards Isomate-CM/LR-treatedorcliards
Seasonalmeanmating=38,8±5.7% Seasonalmeanmating=17±0.6%
0 I
May22 June19 July17 Aug. 14 Sept. 11 May22 June 19 July17 Aug.14 Sept.1
O)
_g
1 Mating '*-'
CO
E
Pandemis limitata
100 75
Insecticide-treatedorcl'iards Isomate-CM/LR-treated orchards
Seasonalmeanmating=51.6±5.6% Seasonalmeanmating=6.S±2.2%
03 45
0 -IT
May22 June19 July17 Aug.14 Sept. May22 June19 July17 Aug.14 Sept.
Week Week
Figure 2. Observed mean weeklypercent mating oftwo leafroller species on mating tables
hung in Isomate-CM/LR-treated organic apple orchards {n = 5) and insecticide-treated
conventional apple orchards (n = 5) and mean weekly catches ofmoths in synthetic phero-
mone traps inthe same orchards in 1998.
DISCUSSION
Previouslywe showedthat Isomate-CM/ scribed. This study has demonstrated that
LRwas a useful spring-time supplement for pheromone communication and mating in
the codling moth SIT programme in BC sympatric leafroller moths commonly found
(Judd and Gardiner 2005), but its additional infesting organic apples in the Similkameen
benefits as a supplement for control oflea- Valley ofBC can be effectively and simul-
frollers in organic orchards was not de- taneously disrupted by releasing a mixture
54 J.Entomol. Soc.Brit. Columbia 105,December2008
Choristoneura rosaceana
90 9
Insecticide-treated orchards Isomate-CM/LR-treated orcliards
60
%Mating=5.56+(7.06xcatch) %Mating=-0.02+(5.21xcatch)
r-=0.36, P=0.009 r-=0.31, P=0.06
T T T
I I I J L I I I I I I I I I
0.0 2.5 5.0 7.5 0.00 0.25 0.50 0.75
Pandemis limitata
30
Isomate-CM/LR-treatedorchards
%Mating= 12.53+(1.06'<catch) %Mating=0.076+(1.56xcatch)
r^=0.64. P=0.001 r-=0.85, P=0.001
0 25 50 75 0 5 10 15
Mean number of moths caught / trap / week
Figure 3. Regression analyses showing relationships between relative moth density (trap
catches) and mating in two leafrollerspecies in Isomate-CM/LR-treated organic apple orchards
(n = 5) and insecticide-treatedconventional appleorchards (n= 5) in 1998.
oftheir major pheromone components from and greater than levels observed in other
Isomate-CM/LR. Season-long reductions of studies (Lawson et al. 1996). There is no
pheromone trap catches of both C. generally accepted level for the reductions
rosaceana and P. limitata with Isomate- in pheromone trap catches often observed
CM/LR were comparable to levels seen in using mating disruption that correlate with
several studies examining each species indi- crop protection, but the observation has
vidually (Deland et al. 1994, Agnello et al. been made thatthis reduction is usually 97 -
1996, Knight et al. 1998, Knight and 100% in species where disruption appears
Turner 1999, Trimble and Appleby 2004) to be an effective crop-protection tool