Trapping Plum Curculio Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae) in the Southern United States

Abstract

A more practical method than limb jarring is needed to monitor the plum curculio, Conotrachelus nenuphar (Herbst), in peach trees. Of 223 orchard visits made in Arkansas, traps captured plum curculio adults on 114 visits, whereas limb jarring did so on only 29 visits. Pyramid traps and jarring tree limbs along the orchard edge began to capture plum curculio adults 1 wk before the start of fruit feeding damage and continued to capture plum curculio adults until after harvest. Pyramid traps located at the edge of the peach orchard caught significantly more adults than did traps placed >30 m into the orchard interior or traps placed along the edge of an adjacent woodlot. Pyramid traps and screen traps captured similar numbers of plum curculio adults in 14 of 17 samples. Only one orchard in Oklahoma and another in Arkansas had smaller circumference tree trunks (<38 cm) than the other orchards resulting in significantly more plum curculio adults captured in pyramid traps than in screen traps. The screen trap was less expensive and sustained environmental conditions better than did the pyramid trap and may be used on trees >38 cm in circumference. The derived economic threshold of 0.045 plum curculio adults per pyramid trap per day equated to 1% new fruit damage. This study suggested that combining trap counts with percentage of new fruit damage should be used to make insecticide application decisions against plum curculio.

Full text

PEST MANAGEMENT AND SAMPLING
Trapping Plum Curculio Conotrachelus nenuphar (Herbst)
(Coleoptera: Curculionidae) in the Southern United States
DONN T. JOHNSON,
1
PHILLIP G. MULDER, JR.,
2
B. DEAN MCCRAW,
3
BARBARA A. LEWIS,
BRIAN JERVIS, BECKY CARROLL,
3
AND PAUL J. MCLEOD
Department of Entomology. University of Arkansas, Fayetteville, AR 72701
Environ. Entomol. 31(6): 1259Ð1267 (2002)
ABSTRACT A more practical method than limb jarring is needed to monitor the plum curculio,
Conotrachelus nenuphar (Herbst), in peach trees. Of 223 orchard visits made in Arkansas, traps
captured plum curculio adults on 114 visits, whereas limb jarring did so on only 29 visits. Pyramid traps
and jarring tree limbs along the orchard edge began to capture plum curculio adults 1 wk before the
start of fruit feeding damage and continued to capture plum curculio adults until after harvest. Pyramid
traps located at the edge of the peach orchard caught signiÞcantly more adults than did traps placed
⬎30 m into the orchard interior or traps placed along the edge of an adjacent woodlot. Pyramid traps
and screen traps captured similar numbers of plum curculio adults in 14 of 17 samples. Only one
orchard in Oklahoma and another in Arkansas had smaller circumference tree trunks (⬍38 cm) than
the other orchards resulting in signiÞcantly more plum curculio adults captured in pyramid traps than
in screen traps. The screen trap was less expensive and sustained environmental conditions better than
did the pyramid trap and may be used on trees ⬎38 cm in circumference. The derived economic
threshold of 0.045 plum curculio adults per pyramid trap per day equated to 1% new fruit damage. This
study suggested that combining trap counts with percentage of new fruit damage should be used to
make insecticide application decisions against plum curculio.
KEY WORDS plum curculio, Conotrachelus, peach, apple, sampling, trap
THE PLUM CURCULIO, Conotrachelus nenuphar (Herbst),
causes yield loss and lowers fruit quality of pome and
stone fruits east of the Rocky Mountains (Chapman
1938). After mid-August, plum curculio adults over-
winter in weedy litter in Arkansas (Wylie 1954) or up
to 2 cm below the soil surface in Virginia (Bobb 1949).
Adults can overwinter in weedy orchards where suit-
able cover is available (Quaintance and Jenne 1912,
Snapp 1930, Chapman 1938). However, plum curculio
adults tend to move outside the orchard and enter
litter or soil in hedgerows or woodlots adjoining or-
chards. In spring, plum curculio adults begin to
emerge from the ground litter from full bloom to petal
fall (Wylie 1954). Once in fruit trees, they mate, then
feed on and lay eggs in fruit (Wylie 1954, Laßeur et al.
1987). Egg hatch prediction models have been de-
scribed by Reissig and Nyrop (1994), Johnson (1996),
Mulder et al. (1997), and Reissig et al. (1998).
Several methods have been used to detect damage
and monitor plum curculio activity in orchards. Grow-
ers inspect fruit for adult feeding damage, presence
of eggs under feeding scars, or larvae inside fruit
(LeRoux 1961). Jarring fruit limbs can be used to
determine the location and relative abundance of
adult weevils in a fruit orchard (Scott and Quaintance
1911, Wylie 1951). This technique dislodges plum cur-
culio adults from the limbs onto an underlying ground
cloth. A scout can quickly count the number of adult
weevils jarred onto the cloth because jarred weevils
remain motionless for several seconds. However, limb
jarring is labor intensive and dislodges blossoms or
fruit. In addition, it is difÞcult to achieve accurate
counts because of variations in tree shapes, height, and
weather conditions, and most importantly, because
plum curculio adults are most active in trees at night
(Wylie 1951; LeBlanc et al. 1984; Racette et al. 1991;
Chouinard et al. 1992, 1993). Other detection methods
include sticky-green thinning apples, sticky-green
balls, green painted sticky-coated ping pong balls, pit-
fall traps, sticky-trunk bands, inverted screen and win-
dow-pane traps (Scott and Quaintance 1911, Chap-
man 1938, Wylie 1951, Le Blanc et al. 1984, Jones and
Johnson 1988, Yonce et al. 1995, Maleckas 1996). A
more practical and reliable monitoring method than
jarring trees is needed, which will aid growers in
determining when plum curculio populations exceed
economic thresholds.
The pyramid trap and screen trap were both de-
veloped for monitoring pecan weevils, Curculio caryae
1
E-mail: dtjohnso@uark.edu.
2
Department of Entomology and Plant Pathology, Oklahoma State
University, Stillwater, OK 74078.
3
Department of Horticulture and Landscape Architecture, Okla-
homa State University, Stillwater, OK 74078.
0046-225X/02/1259Ð1267$02.00/0 䉷 2002 Entomological Society of America

(Horn). The pyramid trap was reported as an effective
monitoring tool that attracts pecan weevils and other
weevil species that walk up tree trunks. This trap
appears to mimic a tree trunk (Tedders and Wood
1994, Tedders et al. 1996). Pyramid traps placed be-
tween peach trees captured plum curculio adults in
Georgia (Yonce et al. 1995), Arkansas (Johnson 1996),
and Oklahoma (Mulder et al. 1997). Pyramid trap
captures coincided well with peach fruit damage by
plum curculio in Arkansas (Johnson 1996). Maleckas
(1996) found the pyramid trap worked well by itself
as a monitoring tool for plum curculio in Michigan
apples, whereas Prokopy et al. (1996) and Prokopy
and Wright (1998) found less relationship between
periods of pyramid trap capture of plum curculio
adults and damage in Massachusetts apples. Pyramid
traps have problems including warping of the Maso-
nite base and having the trap top or the pyramid trap
base dislodged by severe winds or livestock. The
screen trap was developed after the pyramid trap and
initially used to monitor pecan weevil, Curculio caryae
(Mulder et al. 1997). The screen trap can also capture
plum curculio adults in peaches (Johnson et al. 1998).
The economic threshold for plum curculio captures
in traps varies between processing and fresh market
peaches. In processing peaches, the economic thresh-
old was set at 0.2 plum curculio adults per pyramid trap
per day, which usually ensured ⬍2% fruit damage
(damage threshold set by processors). However, the
fresh market allowed ⬍1% fruit damage. Several years
of sampling experience indicated that to achieve ⬍1%
damage of fresh market peaches, the economic thresh-
old had to be reduced to ⬍0.2 plum curculio adults per
pyramid trap per day (DTJ, unpublished data).
In this study, we note the seasonal changes in the
number of plum curculio adults captured by pyramid
traps, jarring peach limbs, and percentage of new fruit
damage. Analyses were conducted to determine the
effects of trap locations in and around the orchard and
trap types on captures of plum curculio adults. Also, an
economic threshold was derived based on a linear
regression of pyramid trap captures to percentage fruit
damage assessed 1 wk after traps were sampled.
Materials and Methods
Pyramid traps were constructed from 6.35 mm Ma-
sonite and a boll weevil trap top (Technical Precision
Plastics, Mebane, NC) (Tedders and Wood 1994).
One side was painted with a medium gray paint (50:50
black/white), whereas the other side was painted with
dark gray paint (9:1 black/white). The paint was su-
perwhite #40-17 and black #40-11 ßat latex (Gabbard
Paint, Fayetteville, AR). From 1995 on, each trap was
kept visible by periodic hoeing or hand-removal of tall
weeds.
The screen trap was constructed by following step-
by-step construction directions (Mulder et al. 1997).
The initial rectangular piece of 21-gauge galvanized
hardware cloth was 30 ⫻ 38 cm. The 30-cm straight
edges were folded together to form a cone, and the
overlapping edges were stapled together onto a piece
of wood lath 2 cm wide ⫻ 10 cm long. Another piece
of lath 2 cm wide ⫻ 15 cm long was stapled to the
opposite side of the cone. The wood lath added sup-
port to the cone. A boll weevil trap top was trimmed
down to the center cone and top plastic ring. Hot glue
was used to attach the top ring and small screen cone
to the small open end of the larger screen cone. The
trap was inverted and a 38-cm section of the screen
base was secured to a tree trunk by wire or rubber
strapping (Fig. 1).
Weekly, biweekly, or monthly counts of plum cur-
culio adults were recorded by two techniques: jarring
fruit tree limbs and pyramid traps. Limb jarring was
done during daylight hours only because of the many
sites being sampled in any given day. Counts were
made at 2Ð 4 locations in and around commercial apple
or peach orchards from 1994 to 2001 in Arkansas and
Oklahoma. From 1997 to 2000, screen traps were
added to this study for comparison to counts obtained
in pyramid traps.
Peach orchards were sampled from 1994 to 2001 in
Arkansas. In 1994, mean counts of plum curculio adults
were recorded twice monthly from three pyramid
traps, each set between peach trees located at the
orchard edge, 10 m in from the edge (third row of
trees) and in the orchard center (⬎30 m in from edge)
of each peach block VB in Haynes. Concurrently,
plum curculio adults were jarred from one limb on
each of four trees adjacent to each trap. These two
estimates of population levels of plum curculio adults
around and in peach trees were compared with per-
centage new catfaced fruit (30 fruit from each of 10
trees).
In 1995, there were Þve pyramid traps at the orchard
edge and Þve in the orchard center, each 1 m from a
peach trunk, and Þve pyramid traps along the edge of
the adjacent woodlot in two peach blocks VL and VB
in Haynes. All traps were spaced at least 15 m apart at
each location.
In 1996, counts were made twice a month from Þve
pyramid traps, each at the orchard edge and in the
orchard center of 14 orchard blocks in and around
Haynes and Forrest City. In Forrest City orchard M,
a comparison was made of trap counts relative to
distance from adjacent woodlots. This orchard had a
narrow fencerow woodlot to the east of row 1, a
woodlot north of rows 1Ð30, a pasture north of rows
30Ð55, a fresh market peach orchard north of rows
55Ð105, and a soybean Þeld to the south (Fig. 2). Two
pyramid traps were placed in rows 5, 30, 55, and 94
along the north edge and in the orchard center, and
four traps were placed along the east edge of row 1. In
1997, peach orchard VB and M, each had four blocks
consisting of two screen traps and two pyramid traps
at the edge and center of each peach block. Each block
had traps either with no bait or baited with a lure of
grandisoic acid, the plum curculio aggregation pher-
omone (all lure effects reported elsewhere). In 1998,
orchard M had two screen traps and two pyramid traps
only at the orchard edge of rows 55, 30, and 1. In 1999,
peach orchard VL had traps arranged in a randomized
complete block design (3 replicates) each consisting
1260 E
NVIRONMENTAL ENTOMOLOGY Vol. 31, no. 6

of four screen traps and four pyramid traps. One of
each trap type in each block had no bait or was baited
with a lure of plum essence or grandisoic acid (IPM
Technologies, Portland, OR). In 2000, an abandoned
peach orchard L in Wynne had a randomized com-
plete block design (3 replicates) each with Þve screen
traps and Þve pyramid traps. One of each trap type in
each block had no bait or was baited with a lure of
grandisoic acid or essence of tart cherry, sweet cherry,
or plum (IPM Technologies).
Peach orchards were sampled from 1995 to 2000 in
Oklahoma. In 1995, weekly counts were made of plum
curculio adults captured in Þve pyramid traps (three
along the edge and two in the center) in a peach
orchard in Perkins (PK), and two in Stratford (ST). In
1996, the PK orchard and the Porter (P) orchard each
had Þve pyramid traps (three along the edge and two
in the center), whereas the two ST orchards had three
traps along the edge. In 1997, the ST and PK orchards
had two screen traps and two pyramid traps arranged
in a randomized complete design using eight repli-
cates. In 1999 and 2000 in the PK orchard, weekly
counts were made for 10 screen traps and 8 pyramid
traps. Each block had traps either with no bait or
baited with a lure of grandisoic acid. In 2000, the peach
orchard in Harrah (H) had eight screen traps and six
pyramid traps. The two ST orchards each had eight
screen traps and eight pyramid traps in the edge and
center.
Data were sorted by year (1994Ð2000), by state (AR
or OK), and orchard site. SigniÞcant differences were
determined between mean trap counts of plum cur-
culio adults for three sources of variation: trap location
(L), trap distance from woods (R ⫽ row), and trap
type (T). An analysis of variance (ANOVA), using
PROC GLM (General Linear Models) LSMEANS
(STDERR PDIFF) and MEANS (Tukey), was used to
identify signiÞcant main and interaction effects, to
calculate the standard error of the mean and the prob-
ability of differences between means for each source
Fig. 1. Screen trap attached to (A) large circumference peach trunk and to (B) small circumference peach trunk.
December 2002 JOHNSON ET AL.: TRAPPING PLUM CURCULIO 1261

of variation (SAS Institute 2000). The lure effect on
trap counts recorded in 1997, 1999, and 2000 in Ar-
kansas and 1997 in Oklahoma was removed from the
mean trap counts by incorporating lure effect into the
mean error value (see footnotes in Tables 3 and 4).
The economic threshold of the number of plum
curculio adults captured per trap per day for the pyr-
amid trap was derived by regression. The independent
variable of the number of plum curculio adults cap-
tured per pyramid trap per day (ranging from 0.01 to
0.4 adults) was regressed against the dependent vari-
able of the percentage of new fruit damage assessed 1
wk later (ranging from 0 to 8%) using the Fit Line
analysis in the JMP software (SAS Institute 1996). All
trap data and percentage damage data (1 wk later)
were collected from the following orchards in several
cities of Arkansas and sample dates: Forrest City (F)
on 15 and 29 April, 5 May, 6 June 1997, 26 May 1998;
Haynes (H) on 29 April, 4 and 11 June 1997, 2, 14, and
24 April, 26 May, 4 and 17 June, and 8 July 1998; Wynne
(B and KL) on 14, 24, and 30 April, 13 May, 29 June
1998, 28 April, 28 May, 4 and 18 June 1999; Colt (S) on
1 May 1998; Clarksville (MO) on 27 May and 6 July
1999, 3 April 2000; and Conway (G) on 11 April 2000.
Results and Discussion
Two sampling methods were used to detect pres-
ence of plum curculio adults in and around peach
orchards. In Arkansas from 1997 to 2001, 223 orchard
visits were made to record the number of plum cur-
culio adults captured in traps and jarred from peach
Table 1. The number of plum curculio adults captured per pyramid trap and per limb jarring (means ⴞ SE; n ⴝ 5) and percentage
new fruit damage in peach orchard VL in Haynes, AR (1995)
Date
Pyramid trap Limb jar % New damage
Woods Edge Center Edge Center Edge Center
20 March Set out
3 April 1.0 ⫾ 0.6a 4.6 ⫾ 1.7a 0.6 ⫾ 0.2a 1.8a 0.0b Ñ Ñ
10 April 0.4 ⫾ 0.2b 3.0 ⫾ 1.0a 0.6 ⫾ 0.2ab 0.4a 0.4a 9.0 3.3
26 April 0.8 ⫾ 0.2a 1.0 ⫾ 0.3a 0.0 ⫾ 0.0b 1.2a 0.0b 1.3 3.7
17 May 0.0 ⫾ 0.0a 0.8 ⫾ 0.6a 0.2 ⫾ 0.2a 0.2a 0.0a 1.3 0.3
2 June 0.6 ⫾ 0.4a 0.8 ⫾ 0.2a 0.8 ⫾ 0.4a Ñ Ñ 1.7 1.0
14 June 0.0 ⫾ 0.0a 1.6 ⫾ 1.0a 0.8 ⫾ 0.6a 0.4a 0.2a 2.0 0.3
29 June 0.0 ⫾ 0.0b 1.8 ⫾ 0.7a 0.2 ⫾ 0.2b 2.0a 0.2b 0.7 0.0
12 July 0.0 ⫾ 0.0a 0.4 ⫾ 0.2a 0.2 ⫾ 0.2a 1.0a 0.4b 0.3 0.7
26 July 0.0 ⫾ 0.0a 1.0 ⫾ 0.6a 0.0 ⫾ 0.0a Ñ Ñ Harvest
27 Sept. 0.6 ⫾ 0.4a 2.6 ⫾ 1.0a 0.4 ⫾ 0.4a Ñ Ñ Ñ Ñ
Column sums 3.4 16.6 4.8 7.0 1.2 16.3 9.3
Means trap values or mean limb jar values within a row followed by the same letter are not signiÞcantly different (P ⬎ 0.05, TukeyÕs
Studentized Range Test; SAS Institute 2000).
Fig. 2. Season mean catch of plum curculio adults (mean values followed by the same letter do not differ signiÞcantly
(P ⬎ 0.05, TukeyÕs Studentized Range Test; SAS Institute 2000) in pyramid traps positioned from the west in row 94 to the
east in row one along the orchard perimeter and in the center, where triangles denote trap locations and the oval-box symbol
represents woods on the northeast and east perimeters of commercial peach orchard M in Forrest City, AR, in 1996 and 1997.
1262 ENVIRONMENTAL ENTOMOLOGY Vol. 31, no. 6

tree limbs. Overall, traps captured plum curculio
adults on 114 visits, whereas limb jarring did so on only
29 visits. This low number of orchard sampling visits
with successful captures of a plum curculio adult by
limb jarring was attributed to jarring trees during the
day instead of at night. Racette et al. (1991) and
Chouinard et al. (1992) reported that plum curculio
adults are mainly active at night. Occasionally, grow-
ers do jar tree limbs, but it is usually during the day.
Our data indicated that growers would have more
success detecting plum curculio adults in orchards by
using traps than by limb jarring. In the rest of this
paper, we describe the effect of trap placement (lo-
cation) and trap type on monitoring plum curculio
adults and present an economic threshold based on
the number of plum curculio adults captured per trap
per day.
First capture of plum curculio adults in peach or-
chards in the spring 1995 varied signiÞcantly by sam-
pling location (Table 1). On 3 April, plum curculio
adults were Þrst captured by pyramid traps in the edge
and orchard center and by limb jarring peach trees
along the orchard edge. Traps and limb jarring cap-
tured adults along the orchard edge before Þrst fruit
damage was recorded on 10 April. However, plum
curculio adults were not jarred from limbs in the
orchard center until 10 April, when damage along the
peach orchard edge was 9 and 3% in the orchard
center. Pyramid traps set along the orchard edge cap-
tured signiÞcantly more plum curculio adults on 10
April (F ⫽ 5.81; df ⫽ 2,14; P ⫽ 0.03) than did traps
along the woods, but the numbers were similar to
counts from traps in the orchard center. On 26 April,
the traps along the edge and along the woods had
similar numbers of plum curculio adults but signiÞ-
cantly greater than that in the orchard center (F ⫽
9.33; df ⫽ 2,14; P ⫽ 0.008). On 29 June, traps placed in
the orchard edge had more plum curculio adult cap-
tures than at the center or along the edge of adjacent
woods (F ⫽ 5.62; df ⫽ 2,14; P ⫽ 0.003). Trap counts
along the edge of the woods were zero from 26 April
to 26 July. Concurrently, traps and limb jarring cap-
tured adults in the orchard edge and orchard center.
The only other dates when pyramid traps set along the
orchard edge captured signiÞcantly more plum cur-
culio adults than did traps set in the two other loca-
tions were 29 June (summer generation of adults
emerging from the soil) and 27 September (adults
dispersing to overwintering sites).
Pyramid traps and limb jarring peach trees had
larger cumulative captures of plum curculio adults for
the season when sampled along the orchard edge (16.6
adults/trap and 7.0 adults/jarring) than did sampling
in the orchard center or along the edge of the woods
Table 2. Number of plum curculio adults captured per pyra-
mid trap (means ⴞ SE; n ⴝ 3) when placed in three locations in
peach orchard VB in Haynes, AR (1994)
Date Edge 3rd Row (7 m) Center (⬎30 m)
8 April 1.3 ⫾ 0.3a 1.7 ⫾ 0.9a 2.0 ⫾ 1.0a
14 April 18.0 ⫾ 4.0a 7.7 ⫾ 2.6ab 3.0 ⫾ 1.0b
19 April 3.7 ⫾ 1.8a 0.3 ⫾ 0.3a 0.3 ⫾ 0.3a
28 April 3.7 ⫾ 0.3a 1.7 ⫾ 0.7a 1.0 ⫾ 0.6a
11 May 0.0 ⫾ 0.0a 0.3 ⫾ 0.0a 0.0 ⫾ 0.0a
26 May 0.0 ⫾ 0.0a 0.0 ⫾ 0.0a 0.3 ⫾ 0.3a
21 June 2.0 ⫾ 0.6a 2.0 ⫾ 1.2a 0.3 ⫾ 0.3a
8 July 0.7 ⫾ 0.3ab 2.0 ⫾ 0.6a 0.0 ⫾ 0.0a
20 July 0.0 ⫾ 0.0a 0.0 ⫾ 0.0a 0.0 ⫾ 0.0a
11 Aug. 2.3 ⫾ 2.3a 0.3 ⫾ 0.3a 0.0 ⫾ 0.0a
Means trap values or mean limb jar values within a row followed by
the same letter are not signiÞcantly different (P ⬎ 0.05, TukeyÕs
Studentized Range Test; SAS Institute 2000).
Table 3. Effects of trap location (L), row (R ⴝ trap distance
from woods), trap type (T), and interaction on counts of plum
curculio adults per trap in Arkansas
Yr (Site)-Source df F-value P
1994 (VB)-L 2, 4 6.31
a
0.058
1995 (VB)-L 2, 4 7.56
a
0.014
1995 (VL)-L 2, 8 13.79
a
0.0026
1996 (M)-L 1, 8 66.6
b
⬍0.0001
1996 (M)-R 3, 8 53.7
b
⬍0.0001
1996 (M)-L*R 3, 8 23.7
b
0.0002
1997 (M)-L 1, 3 606.9
c
0.0001
1997 (M)-T 1, 3 123.3
c
0.002
1997 (VB)-L 1, 3 19.6
c
0.02
1997 (VB)-T 1, 3 0.09
c
0.79
1998 (VB)-L 1, 4 1.82
d
0.25
1998 (VB)-T 1, 4 0.27
d
0.63
1998 (M)-T 1, 2 1.81
e
0.31
1999 (VL)-T 1, 2 0.21
c
0.70
2000 (L)-T 1, 2 3.72
c
0.19
a
Type III Mean Square with Location * Block as an error term.
b
Type III Mean Square with Replicate (Location * Row) an error
term.
c
Type III Mean Square with Lure * Block as an error.
d
Type III Mean Square with Block (Location * Trap) as an error
term.
e
Type III Mean Square with Trap * Block as an error term.
Table 4. Effect of trap location (L) and trap type (T) on counts
of plum curculio adults per trap in Oklahoma
Yr (Site)-Source df F-value P
1997 (P)-L 1, 2 0.0
a
1.0
1997 (P)-T 1, 2 4.0
a
0.18
1997 (PK)-L 1, 3 0.35
a
0.6
1997 (PK)-T 1, 3 13.74
a
0.03
1997 (S)-L 1, 3 11.4
a
0.04
1997 (S)-T 1, 3 6.15
a
0.09
1998 (P)-L 1, 8 0.0
b
1.0
1998 (P)-T 1, 8 3.75
b
0.09
1998 (PK)-L 1, 10 2.07
b
0.18
1998 (PK)-T 1, 10 0.0
b
1.0
1998 (S)-L 1, 12 0.05
b
0.83
1998 (S)-T 1, 12 4.04
b
0.07
1999 (PK)-L 1, 8 2.31
b
0.17
1999 (PK)-T 1, 8 2.61
b
0.15
1999 (S)-L 1, 10 4.45
b
0.06
1999 (S)-T 1, 10 0.08
b
0.78
2000 (PK)-L 1, 8 2.87
b
0.13
2000 (PK)-T 1, 8 24.6
b
0.001
2000 (S)-L 1, 10 0.05
b
0.82
2000 (S)-T 1, 10 0.49
b
0.50
2000 (H)-L 1, 9 12.3
b
0.0067
2000 (H)-T 1, 9 3.56
b
0.09
a
Type III Mean Square with Lure * Block as an error term.
b
Type III Mean Square with Block (Location * Trap) as an error
term.
December 2002 JOHNSON ET AL.: TRAPPING PLUM CURCULIO 1263

(trap only) where counts were ⬍5 adults/trap or 1.2
adults/limb jarring (Table 1). Similarly, the season
cumulative percentage new fruit damage was 16.3%
along the orchard edge and 9.3% in the orchard center.
The traps at the edge and in 3rd row of orchard had
similar counts all season, but counts in edge traps
differed signiÞcantly from those in center on 14 April
only (Table 2).
We expected that plum curculio adults exiting over-
wintering sites in the woodlot would be caught Þrst in
pyramid traps along the woodlot edge, rather than in
traps along the orchard edge and Þnally in the orchard
center. Trap location (L) did signiÞcantly affect the
number of plum curculio adults captured in traps in
Arkansas orchard sites VB, VL, and M from 1995 to
1997, whereas in Oklahoma only orchard sites S in 1997
and H in 2000 had signiÞcant differences due to lo-
cation (Tables 3Ð5). Edge and center trap counts were
similar in Arkansas only in the VB site in 1998. We
thought that plum curculio adults had overwintered
inside the orchard because the ground cover was al-
lowed to grow excessively high the previous season
during and after harvest.
In Oklahoma orchards, signiÞcant differences in
trap catch of adults at different locations were harder
to detect. This was attributed to low plum curculio
populations typically ⬍0.7 adults/trap in the orchard
edge, except in orchard PK in 1997 (1.44 adults/trap)
(Fig. 3A; Tables 4 and 5). In comparison, AR, popu-
lations in the orchard edge usually exceeded 0.9
adults/trap. It was as low as 0.76 adults/trap in orchard
VB in 1995.
Trap distance (R) noted as the number of tree rows
(7 m apart) from a woodlot signiÞcantly affected the
number of plum curculio adults captured in traps in
the Arkansas orchard site M in 1996 (Table 3). There
was also a signiÞcant interaction of trap location and
trap distance (L*R). Trap counts decreased signiÞ-
cantly the farther the traps were placed away from the
woods in the orchard edge and center (Fig. 3). These
Þndings agreed with those of Laßeur and Hill (1987)
and Laßeur et al. (1987), who used other sampling
methods to describe the edge effect that occurred
during the spring and late summer dispersal phases of
plum curculio adults.
Table 5. Number of plum curculio adults captured in traps (means ⴞ SE) at different locations in and around peach orchard sites
in Arkansas and Oklahoma
Yr (Site) No.
Trap location
Wood
edge
Orchard
edge
3rd-Row
(7 m inside)
Center
(⬎30 m inside)
Arkansas
1994 (VB) 30 Ñ 3.12 ⫾ 1.04a 1.6 ⫾ 0.5a 0.7 ⫾ 0.2a
1995 (VB) 50 0.1 ⫾ 0.05b 0.76 ⫾ 0.18a Ñ 0.34 ⫾ 0.1b
1995 (VL) 50 0.34 ⫾ 0.1b 1.76 ⫾ 0.3a Ñ 0.42 ⫾ 0.1b
1996 (M) 56 Ñ 0.93 ⫾ a Ñ 0.23 ⫾ b
1997 (VB) 304 Ñ 3.83 ⫾ 0.6a Ñ 1.38 ⫾ 0.2b
1997 (M) 304 Ñ 2.59 ⫾ 0.6a Ñ 0.25 ⫾ 0.05b
1998 (VB) 120 Ñ 1.43 ⫾ 0.21a Ñ 1.98 ⫾ 0.28a
Oklahoma
1997 (P) 24 Ñ 0.13 ⫾ 0.09a Ñ 0.13 ⫾ 0.07a
1997 (PK) 32 Ñ 1.44 ⫾ 0.37a Ñ 1.33 ⫾ 0.33a
1997 (S) 32 Ñ 0.69 ⫾ 0.17a Ñ 0.22 ⫾ 0.01b
1998 (P) 16 Ñ 0.06 ⫾ 0.06a Ñ 0.06 ⫾ 0.04a
1998 (PK) 24 Ñ 0.66 ⫾ 0.25a Ñ 0.17 ⫾ 0.1a
1998 (S) 24 Ñ 0.5 ⫾ 0.33a Ñ 0.42 ⫾ 0.22a
1999 (PK) 370 Ñ 0.08 ⫾ 0.017a Ñ 0.04 ⫾ 0.01a
1999 (S) 192 Ñ 0.04 ⫾ 0.01a Ñ 0.01 ⫾ 0.01a
2000 (PK) 370 Ñ 0.16 ⫾ 0.03a Ñ 0.1 ⫾ 0.02a
2000 (H) 140 Ñ 0.17 ⫾ 0.04a Ñ 0.04 ⫾ 0.01b
2000 (S) 198 Ñ 0.066 ⫾ 0.02a Ñ 0.057 ⫾ 0.02a
Means trap values or mean limb jar values within a row followed by the same letter are not signiÞcantly different (P ⬎ 0.05, TukeyÕs
Studentized Range Test; SAS Institute 2000).
Table 6. Number of plum curculio adults captured in either of
two trap types (means ⴞ SE) placed in peach orchard in Arkansas
and Oklahoma from 1997 to 2000
Yr (Site) No.
Trap type
Pyramid Screen
Arkansas
1997 (VB) 298 2.51 ⫾ 0.4a 2.7 ⫾ 0.5a
1997 (M) 306 1.94 ⫾ 0.6a 0.9 ⫾ 0.25b
1998 (VB) 120 1.81 ⫾ 0.26a 1.6 ⫾ 0.24a
1998 (M) 90 2.22 ⫾ 0.67a 1.07 ⫾ 0.3a
1999 (VL) 88 2.55 ⫾ 0.31a 2.78 ⫾ 0.5a
2000 (KL) 165 2.9 ⫾ 0.24a 2.02 ⫾ 0.23a
Oklahoma
1997 (P) 24 0.17 ⫾ 0.1a 0.08 ⫾ 0.06a
1997 (PK) 28 2.25 ⫾ 0.41a 0.54 ⫾ 0.17b
1997 (S) 32 0.63 ⫾ 0.17a 0.28 ⫾ 0.1a
1998 (P) 24 0.13 ⫾ 0.07a 0.0 ⫾ 0.0a
1998 (PK) 28 0.43 ⫾ 0.19a 0.46 ⫾ 0.24a
1998 (S) 16 0.75 ⫾ 0.35a 0.13 ⫾ 0.09a
1999 (PK) 518 0.08 ⫾ 0.01a 0.03 ⫾ 0.01a
1999 (S) 224 0.027 ⫾ 0.01a 0.022 ⫾ 0.01a
2000 (PK) 518 0.21 ⫾ 0.03a 0.046 ⫾ 0.01b
2000 (H) 245 0.03 ⫾ 0.01b 0.12 ⫾ 0.02a
2000 (S) 231 0.05 ⫾ 0.02a 0.07 ⫾ 0.02a
Means trap values or mean limb jar values within a row followed by
the same letter are not signiÞcantly different (P ⬎ 0.05, TukeyÕs
Studentized Range Test; SAS Institute 2000).
1264 ENVIRONMENTAL ENTOMOLOGY Vol. 31, no. 6

Pyramid traps captured signiÞcantly more plum
curculio adults than did screen trap types (T) only in
Arkansas orchard site M in 1997 and Oklahoma site PK
in 1997 and 2000 (Fig. 3C; Tables 3, 4, and 6). It was
observed that peach trees in sites M and PK had a
trunk circumference ⬍38 cm. All other sites had trees
with circumference ⬎38 cm (Fig. 1A and B). Likewise,
the length of the screen trap bottom is 38 cm, so the
bottom overlaps on these small circumference peach
trunks. Future studies are expected to show that as
trunk circumference decreases below 38 cm, so will
screen trap catch. In contrast, counts from pyramid
traps remain the same to that from limb jarring re-
gardless of peach trunk size.
Prokopy and Wright (1998) suggested that pyramid
traps placed closer to fruit tree trunks caught more
plum curculio adults than those further away. From
1994 to 1997 in Arkansas, pyramid traps were staked on
the ground at least 1 m from peach trunks. This place-
ment resulted in low trap captures of adults in samples
taken after mid-May (summer adults) in Arkansas
(Oklahoma populations were always low). From 1998
on, pyramid traps were set on the ground but were tied
to peach tree trunks and kept weed-free. This in-
creased the season mean trap captures of summer
adults from ⬍1 per trap before 1998 to between 1.5 and
3.3 adults per trap from 1998 to 2000 (Fig. 3B). Thus,
to maximize trap capture all season, the bottom edge
Fig. 3. Number of plum curculio adults caught per trap in Arkansas (bars to the left of vertical dotted line) or in Oklahoma
all sorted by year and orchard where (A) is the season catch, (B) is catch accumulated before (overwintered) or after 15
May (summer), and (C) is catch in pyramid traps or screen traps.
December 2002 JOHNSON ET AL.: TRAPPING PLUM CURCULIO 1265

of the pyramid trap should be in full contact with the
ground, placed next to and tied to the peach tree; and
the area around each trap should be maintained weed-
free. Screen traps should be used only on trees with a
circumference ⬎38 cm.
The economic threshold of 0.045 adults per pyramid
trap per day was derived from the following linear
equation (t ⫽ 5.37, df ⫽ 28, P ⬍ 0.0001, r
2
⫽ 0.51): D ⫽
0.33 ⫹ 14.49 * X; where X is the number of plum
curculio adults per pyramid trap per day (range, 0.01Ð
0.4 adults); and D is the assessed percentage of fruit
damaged 1 wk after recording the trap counts (range,
0Ð8% damage). Fruit damage was ⱖ1% in 19 out of 22
cases where the pyramid trap catch exceeded the
threshold of 0.045 plum curculio adults per trap per
day (Fig. 4).
In 1997Ð2001, several peach growers in Alabama,
Arkansas, and Oklahoma participated in an insect pest
management program (Johnson et al. 2002). Each or-
chard contained several pest-speciÞc traps. Three ori-
ental fruit moth, Grapholita molesta (Busck), phero-
mone traps were set at eye level in peach trees in the
center of the orchard (set 30 m apart). Four gray
pyramid traps for monitoring plum curculio were tied
to peach tree trunks along the orchard edge adjacent
to woods. Four yellow pyramid traps for monitoring
brown stink bug, Euschistus servus (Say), were staked
between peach trees along the orchard edge and
baited with rubber septa charged with 50(l methyl
(2E, 4Z)-decadienoate, the aggregation pheromone
of Nearctic Euschistus spp. (Aldrich et al. 1995). Tar-
nished plant bugs, Lygus lineolaris (Palisot de Beau-
vois), were monitored using four white sticky traps
tied to the lowest scaffold limb in trees along the
orchard edge (30 m apart). Growers or scouts made
weekly inspections for new pest damage on 30 fruit on
each of 10 trees along the orchard edge, scouted traps
for the presence of key pests, and accumulated
degree-days to predict hatch of oriental fruit moth.
Growers used this IPM program to assist in determin-
ing when plum curculio populations exceeded eco-
nomic thresholds.
The pyramid trap can be used in tree fruit orchards
with any size trunk circumference, whereas the screen
trap is restricted to orchards with trunks that exceed
a circumference of 38 cm. In these more mature or-
chards, the screen trap could replace the pyramid trap
for a number of reasons. First, a screen trap is only $15,
whereas a pyramid trap is more than $24. Also, screen
traps are more easily attached to tree trunks, are more
durable, have fewer maintenance problems, are
lighter than pyramid traps, and require less storage
space. Neither trap is a stand-alone decision-making
tool during the season, especially for the summer gen-
eration(s) of plum curculio. This study suggests that
combining weekly trap counts with percentage of fruit
damage should be used to make insecticide decisions
against plum curculio. Further research is needed to
increase plum curculio adult attraction toward either
the pyramid or screen trap.
Acknowledgments
We thank the peach producers who allowed us to evaluate
these traps in their orchards; Ron McNew and Ed Gbur
(University of Arkansas) and Mark Payton (Oklahoma State
University) for statistical analysis, and reviewers for their
comments. This work was partially funded by Gerber Prod-
ucts Company, USDA/CSREES Grant 99-04786 and
99-04785, and an Oklahoma Cooperative Extension Service
Internal IPM Grant.
References Cited
Aldrich, J. R., M. C. Rosi, and F. Bin. 1995. Behavioral cor-
relates for minor volatile compounds from stink bugs
(Heteroptera: Pentatomidae). J. Chem. Ecol. 21: 1907Ð
1920.
Bobb, M. L. 1949. Hibernation of the plum curculio in Vir-
ginia. J. Econ. Entomol. 42: 19 Ð22.
Chapman, P. J. 1938. The plum curculio as an apple pest.
N.Y. State Agric. Exp. Stn. Bull. 684: 1Ð75.
Chouinard, G., C. Vincent, S. B. Hill, and B. Panneton. 1992.
Cyclic activity of the plum curculio (Coleoptera: Curcu-
lionidae) on caged dwarf apple trees in spring. J. Insect
Behav. 5: 385Ð394.
Chouinard, G., S. B. Hill, and C. Vincent. 1993. Spring be-
havior of the plum curculio (Coleoptera: Curculionidae)
within caged dwarf apple trees. Ann. Entomol. Soc. Am.
86: 33Ð34.
Johnson, D. T. 1996. Development of a peach IPM program
in Arkansas. Gerber Integrated Pest Management News-
letter 1(fall): 3Ð4.
Johnson, D. T., B. A. Lewis, K. Striegler, P. Mulder, R. F.
Mizell, D. McCraw, B. Carroll, B. Jervis, B. Boozer, W. G.
Foshee, and J. McVay. 2002. Development and imple-
mentation of a peach integrated pest management pro-
gram in the southern USA. V Internat, Peach Symposium,
Davis, CA. Acta Hort. (in press).
Johnson, D. T., P. Mulder, and D. McCraw. 1998. Trap de-
sign for plum curculio monitoring and pest management
in peach. Proceedings of the Oklahoma and Arkansas
Horticultural Industry Show 17: 146Ð149.
Jones, B. F., and D. R. Johnson. 1988. Jarring peach trees to
check for insects. Publication EL 289, University of Ar-
kansas Cooperative Extension Service, Little Rock, AR.
Lafleur, G., and S. B. Hill. 1987. Spring migration, within-
orchard dispersal, and apple tree preference of plum
Fig. 4. Observed data points from Arkansas orchard sites
B, G, J, KL, M, MO, S, VB, VL from 1997 to 2001 and the
predicted line for the following linear equation: D ⫽ 0.33 ⫹
14.49 * X; where X is the number of plum curculio adults per
pyramid trap per day (range, 0.01Ð0.4 adults); and D is the
assessed percentage of fruit damaged 1 wk after recording the
trap counts (range, 0Ð8% damage) (t ⫽ 5.37, df ⫽ 28, P ⬍
0.0001, r
2
⫽ 0.51).
1266 ENVIRONMENTAL ENTOMOLOGY Vol. 31, no. 6

curculio (Coleoptera: Curculionidae) in southern Que-
bec. J. Econ. Entomol. 80: 1173Ð1187.
Lafleur, G., S. B. Hill, and C. Vincent. 1987. Fall migration,
hibernation site selection, and associated winter mortal-
ity of plum curculio (Coleoptera: Curculionidae) in a
Quebec apple orchard. J. Econ. Entomol. 80: 1152Ð1172.
Le Blanc, J.P.R., S. B. Hill, and R. O. Paradis. 1984. Ovipo-
sition in scout apples by plum curculio, Conotrachelus
nenuphar (Herbst) (Coleoptera: Curculionidae), and its
relationship to subsequent damage. Environ. Entomol. 13:
286Ð291.
LeRoux, E. J. 1961. Variation between samples of fruit, and
of fruit damages mainly from insect pests, on apple in
Quebec. Can. Entomol. 13: 680Ð 694.
Maleckas, C. L. 1996. Predicting and monitoring spring
emergence of the plum curculio, Conotrachelus nenuphar
(Herbst), (Coleoptera: Curculionidae), using Tedders
weevil traps, ßight barrier traps and environmental vari-
ables. M.S. thesis, Michigan State University, East Lan-
sing.
Mulder, P. G., B. D. McCraw, W. Reid, and R. A. Grantham.
1997. Monitoring adult weevil populations in pecan and
fruit trees in Oklahoma. Oklahoma State University Ex-
tension Facts F-7190, Stillwater.
Prokopy, R. J., K. Leahy, T. Leskey, and C. Bramlage. 1996.
Plum curculio responses to unbaited Tedders traps. Fruit
Notes, University of Massachusetts 61: 3Ð9.
Prokopy, R. J., and S. E. Wright. 1998. Plum curculio (Co-
leoptera: Curculionidae) responses to unbaited pyramid
and cone traps. J. Econ. Entomol. 91: 226 Ð234.
Quaintance, A. L., and E. L. Jenne. 1912. The plum curculio.
U.S. Dep. Agric. Bull. 103.
Racette, G., G. Chouinard, S. B. Hill, and C. Vincent. 1991.
Field activity of adult plum curculio (Coleoptera: Cur-
culionidae) in spring. J. Econ. Entomol. 84: 1827Ð1832.
Reissig, W. H., and J. P. Nyrop. 1994. Timing insecticide
applications for controlling plum curculio using a pre-
dictive model. N.Y. Fruit Q. 2: 3Ð5.
Reissig, W. H., J. P. Nyrop, and R. Straub. 1998. Pest man-
agement and samplingÑ oviposition model for timing in-
secticide sprays against plum curculio (Coleoptera: Cur-
culionidae) in New York State. Environ. Entomol. 27:
1053Ð1061.
SAS Institute. 1996. JMP start statistics a guide to statistics
and data analysis using JMP and JMP IN software. SAS
Institute, Cary, NC.
SAS Institute. 2000. SAS system for Windows release 8.01.
SAS Institute, Cary, NC.
Scott, W. M., and A. L. Quaintance. 1911. Spraying peaches
for the control of brown rot, scab and plum curculio. U.S.
Dep. Agric. Bull. 440.
Snapp, O. I. 1930. Life history and habits of the plum cur-
culio in the Georgia peach belt. U.S. Dep. Agric. Tech.
Bull. 188: 1Ð7.
Tedders, W. L., and B. W. Wood. 1994. A new technique for
monitoring pecan weevil emergence (Coleoptera: Cur-
culionidae). J. Entomol. Sci. 29: 18 Ð30.
Tedders, W. L., R. F. Mizell, and B. W. Wood. 1996. Inßu-
ence of trap color on pecan weevil monitoring. J. Ento-
mol. Sci. 31: 414 Ð 419.
Wylie, W. D. 1951. Technique in jarring for plum curculio.
J. Econ. Entomol. 44: 818Ð 819.
Wylie, W. D. 1954. The plum curculio on peaches in Ar-
kansas. Ark. Agric. Exp. Stn. Bull. 542.
Yonce, C. E., D. L. Horton, and W. R. Okie. 1995. Spring
migration, reproductive behavior, monitoring procedures
and host preference of plum curculio (Coleoptera: Cur-
culionidae) on Prunus species in central Georgia. J. En-
tomol. Sci. 30: 82Ð92.
Received for publication 29 June 2001; accepted 27 June
2002.
December 2002 JOHNSON ET AL.: TRAPPING PLUM CURCULIO 1267