Washington Tree Fruit Research Commission

Research Reports

Optimizing Ammonia with Traps to Manage Apple Maggot in Washington (2004)

WTFRC Project #
YEAR 0/0
Organization Project #
Title:Optimizing Ammonia with Traps to Manage Apple Maggot in Washington
PI:Wee Yee
Organization:USDA-ARS, 5230 Konnowac Pass Rd Wapato, WA 98951 509-454-6558 / wlyee@yarl.ars.usda.gov
 PDF version of report


Pete Landolt, Research Entomologist



·Determine the effectiveness of ammonia release rates from yellow panel and red sphere traps
·Determine optimal ammonia concentrations and release rates
·Compare ammonium hydroxide with conventional, commercially available ammonia lures
·Test effects of different ammonia volumes on trap effectiveness.

·Further determine season-long effectiveness of ammonium hydroxide and commercial lures
·Determine effectiveness of ammonia together with apple volatile lures.
·Effectiveness of ammonia- and apple volatile-baited traps in large- and small-tree orchards.

Significant findings

2001-2002 Significant Findings:
·All rates of 29% ammonia release, based on release from vials with 0.05-, 0.16-, and 0.32-cm diameter holes, were equally effective in trapping apple maggots.  Baited traps usually captured more flies than unbaited traps. Baited spheres were better than baited yellow rectangles, especially for males.
·Effects of traps depended on the sites – in a site with small trees, spheres were better, whereas sites with larger trees, spheres and yellow panels were equally good.
·Females generally responded to higher ammonia concentrations, males to a wider range of concentrations.  Male responses were more variable. 
·The optimal ammonia release for females and males seemed to be about 1-4 mg ammonia/hour, as rates higher than this did not increase captures. 
·The 29% ammonium hydroxide lures significantly outlasted the commercial supercharger and Pherocon AM lures over 3-week tests.
·Increasing volumes (10-60 ml/trap) of ammonium hydroxide using multiple bottles did not increase attractiveness; only 10 ml was needed.

2003 Significant Findings:
· With yellow panels, the most effective lure based on the Washington State Department of Agriculture (WSDA) design had six 1-mm holes baited with 15 g ammonium carbonate.  This lure released a mean of 4.39 mg ammonium carbonate/hour over 121 days.  However, lures with 2 and 4 holes with both 10 and 15 g ammonium carbonate were nearly as good.
· With red spheres, lures with mean ammonium carbonate release rates of 2-6 mg/hour over 70-112 days were more effective than lures with butyl hexanoate and the 5-component fruit volatile blend that released 0.250-0.840 mg volatiles/hour.  There was no synergistic effect of combining ammonium carbonate and fruit volatiles.
· With both yellow panels and red spheres, lures with two 1-mm holes and 20 g ammonium carbonate were more effective than lures that released about 0.450-0.600 mg component blend/hour late in the year when flies apparently seek fruit for oviposition.   
· Similar results using ammonium carbonate and fruit volatiles with yellow panels were seen on large and small trees.


Methods for 2001-2002, summary:

1.    Different trap types, ammonia-dispensing systems, sugar-derived baits, and ammonia concentrations were used to trap apple maggots at two disparate sites in western Washington.

2.    Longevity of commercial and experimental lures was determined.

Methods for 2003
1.       The longevity of experimental ammonium hydroxide lures were compared with WSDA lures for 3 months from mid June through mid September 2003, using similar designs and same sites as in 2002.  WSDA lures were 3.7 x 2.6 cm yellow containers with 10 or 15 g ammonium carbonate and had two, four, or six 1-mm holes.   
2.       Ammonia lures were tested with apple volatiles to determine if there are synergistic effects by placing both on yellow panels and red spheres.  Apple volatiles that have been identified for apple maggot in the eastern U.S. were tested: these were butyl hexanoate or a 5-component blend that includes butyl hexanoate and 2 other hexanoates and 2 butanoates from apples.   For both trap types, treatments were 1) a control, 2) ammonia only, 3) butyl hexanoate only, 4) 5-component blend only, (5) ammonia-butyl hexanotae, and (6) ammonia-5-component blend.  Experiments were conducted in Puyallup and the Vancouver areas and lasted the entire 3 months of the season.   
3.       The effect of tree size on use of ammonia/apple volatile cues or visual cues was tested in lots in Puyallup.  Large and small trees within the same orchards or within the same general areas were trapped to determine how tree size and density affect the ability of flies to find traps.  (In large, dense tree stands, flies may need to rely more on smell to find traps.)  Yellow panels were baited with 20 g ammonium carbonate, the 5-component blend, or the two together, along with controls. 

Results and discussion

In 2001-2002, ammonia lures used were 15-ml polyethylene bottles filled with 10 ml of the 100% ammonium hydroxide solutions saturated in 0.75 g cotton.  Bottles with 0.025, 0.05, and 0.64 cm holes or different numbers of bottles with the 0.05 cm holes were used to regulate release rate from yellow panels and red spheres.   No consistent difference in female and male fly captures were seen using the three hole sizes from sticky yellow panels or sticky red spheres in Pierce and Cowlitz Counties (Fig. 1).  However, there were differences in the relative numbers caught on panels and spheres in the two sites.  In Pierce County, a site with small 1.5-2.5 m tall trees, significantly more flies were caught on spheres than panels, especially for males.  Differences between control and baited traps were small.  In Cowlitz County, a site with 5-7 m tall trees, spheres caught only slightly more flies than panels, and control versus baited trap differences were larger (Fig. 1).  Traps with more than one bottle did not increase responses within trap types in Pierce and Cowlitz Co. (Fig. 2).  However, as in the previous experiment, red spheres were superior for males and females in Pierce Co., whereas red spheres and yellow panels were equal in Cowlitz Co.  All baited traps were superior to controls for both sexes.  The combined results from these two experiments suggest that habitat type and perhaps tree size affect the numbers detected using spheres or panels by altering the visibility of the traps.
                In 2001, acetic acid, ethanol, and butyl compounds together with ammonia did not enhance apple maggot captures above that of using ammonia alone.  Flies appear not to use sugar fermentation cues to find sugar.    

In 2001-2002, flies were also trapped using yellow panels baited with experimental ammonium hydroxide lures containing 0 and 1.9 to 29% ammonia in apple orchards in Pierce, Clark, Cowlitz, and Skamania Counties, WA.  Ammonia was released from a 0.05 cm diameter hole in each bottle.  Females responded to 1.9% ammonia, but were most attracted to 20-29% ammonia (Fig. 3).  Males also responded to 1.9% ammonia, but were equally responsive to
to 7.3 to 29% ammonia and showed more variability in responses to ammonia than females (Fig. 4).  Site differences were also detected, indicating environmental factors influence responses.  The wide range of ammonia concentrations attracted females with similar egg loads. Based on these and previous results and those from laboratory determinations, flies responded maximally to ammonia released from traps at 1-4 mg/h.  Higher amounts had no positive or negative effect. 
                The experimental lure containing 10 ml of 100% ammonium hydroxide (AH) was compared with two commercial apple maggot lures, the Pherocon AM trap with ammonium acetate + protein hydrolysate mixed in adhesive, and the supercharger (SC), containing 2.14 g ammonium carbonate (AC).  All were equally effective over 4 days.  However, the AH lure was superior to both commercial lures over 3 weeks (Fig. 4).  A modified supercharger (MS) containing 8.46 g AC, 4 times the amount in SC, was also more effective than the Pherocon AM trap and SC, although less effective than the AH lure in one test.  As before, based on field and laboratory tests, an ammonia release rate of 1-4 mg/h was necessary to effectively attract AM to traps.  Ammonia was released more steadily from the AH and MS lures than from the Pherocon AM trap and SC, which lost most of their ammonia within one week (Fig. 5).  Laboratory ammonia release rates from AH, Pherocon AM, SC, and MS lures at 0 and 3 weeks post exposure were 5.24 and 1.14, 10.55 and 0, 36.75 and 0.52, and 49.05 and 7.36 mg/h, respectively.  Results indicate that the simple AH or MS lure used in this study are superior to some commercial lures for apple maggot detection under Washington conditions.  They also demonstrate the importance of maintaining ammonia release rates over time when trapping apple maggot in a detection and management program. 
               In 2003, experiments were conducted in the Puyallup and Vancouver areas using WSDA ammonia lures with two, four, and six 1-mm holes and 10 or 15 g AC with yellow panels.  The best lure in Puyallup was a lure with 6 holes containing 15 g AC (Table 1), which released a mean of 4.39 mg AC/hour over 121 days.  In the laboratory, release rates of the 10 g lures were sustained longest with 2 holes, and shortest with 6 holes (Fig. 6).  Experiments were also conducted at the two sites comparing ammonia and fruit volatile lures, butyl hexanoate and a 5-component blend of apple volatiles, with red spheres.  Spheres baited with 20 g AC that released 2-6 mg/h over 70-112 days were more effective than those baited with butyl hexanoate and the 5-component blend released at 0.250-0.840 mg/h (Table 2).  Because the fruit volatile release rate from these may have been inadequate, another test was conducted later in the year with yellow panels and red spheres.  Holes for fruit volatile lures were increased to 4.5 mm in diameter, resulting in release rates of 0.457-0.597 mg/hour over 81 days in the laboratory (rain prevented calculations of weight losses used to calculate release rates in the field).  The higher fruit volatile release rates did not increase attractiveness, and the 20 g AC lure was still more effective (Table 3).  The greater effectiveness of ammonia was also seen in another test on both large and small trees (Table 4).   
     Several conclusions can be drawn from this project.  Optimizing the use of ammonia is critical for effective apple maggot detection.  Ammonia release rates have not adequately documented in past studies. Lures that release high amounts initially but small amounts later are less useful than those that maintain a sustained release.  Results indicate the optimal ammonia release rate is 1-4 mg/hour.  These rates can be obtained by using 10 ml ammonium hydroxide (one 0.5 mm hole) or 10 g AC (two-six mm holes) in containers.  Combining these with red spheres may be more effective than with yellow panels.  Fruit volatiles do not enhance catches, but the effects of higher release rates need to be studied.   


Fig. 5.  Longevity of ammonium hydroxide and commercial lures as determined by pH of volatiles emitted from lures over 3 weeks in Pierce and Skamania Co., 2002.  Lines followed by the same letters are not significantly different (P > 0.05).
Table 1.  Seasonal trap captures (expressed as % of total flies within a block) + SE of apple maggot on yellow panels using ammonia lures of different designs in Puyallup and Vancouver areas, WA, in 2003.
                                                                                                                                                                                                                                                            Puyallup                                                                                                                                                                                                                                   Vancouver

Treatment                                                                                                                                                         %                                                                                             Total No.                                                                                                         %                                                                                             Total No.

Control                                                                                                                                     1.9 + 0.2a                                                                    45                                                                                                                    1.9 + 1.0a                                                                                                40
100% NH4OH                                                                         15.4 + 15.4bc                                      285                                                                                                      13.1 + 2.9b                                                                              291
2 h 10 g            AC                                                                                           16.1 + 4.1bc                                                    451                                                                                                      14.4 + 5.3b                                                                              283
4 h 10 g            AC                                                                                           11.2 + 1.5b                                                                  286                                                                                                      17.4 + 0.8b                                                                              357
6 h 10 g            AC                                                                                                       9.1 + 1.0b                                                                    233                                                                                                      12.6 + 0.6b                                                                              262
2 h 15 g            AC                                                                                                       9.8 + 1.0b                                                                    200                                                                                                      11.3 + 1.8b                                                                              237
4 h 15 g            AC                                                                                           14.8 + 4.6bc                                                    362                                                                                                      12.8 + 2.4b                                                                              258
6 h 15 g            AC                                                                                           21.6 + 5.6c                                                                  415                                                                                                      16.6 + 0.9b                                                                              349


h = Number of 1-mm holes; g = Amount of ammonium carbonate (AC).
Means followed by same letters within columns are not significantly different (P > 0.05).
Four replicates of each treatment in a randomized block design.


Fig. 6.  Ammonia release rates of lures with 10 g of ammonia carbonate and 10 ml of 100% NH4OH over time in the laboratory.



Table 2.  Seasonal trap captures (expressed as % of total flies within a block) + SE of apple maggot on red spheres using ammonia and fruit volatile lures in Puyallup and Vancouver areas in 2003.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
                                                                                                                                                                                                                                                            Puyallup                                                                                                                                                                                                                                                                       Vancouver

Treatment                                                                                                                                             %                                                                                                                     Total No.                                                                                                                                 %                                                                                                         Total No.

Control                                                                                                                         3.8 + 1.2c                                                                                            85                                                                                                                                            4.4 + 0.2f                                                                                             227
10 g AC                                                                                                                       13.2 + 2.6ab                                                                            266                                                                                                                  14.0 + 1.4bc                                                                           744
20 g AC                                                                                                                       13.4 + 2.9ab                                                                            226                                                                                                                  23.6 + 2.2a                                                                                                1,258
BH                                                                                                                                                       10.7 + 2.7abc                                                              219                                                                                                                              4.7 + 0.6f                                                                                             245
BH-10 g AC                                                                                        6.3 + 1.8bc                                                                              133                                                                                                                              9.7 + 1.3d                                                                                            478
BH-20 g AC                                                                            11.8 + 4.3abc                                                              216                                                                                                                                    9.6 + 2.0de                                                                              498
CB                                                                                                                                                       14.8 + 3.3ab                                                                            246                                                                                                                              5.8 + 0.8ef                                                                               288
CB-10 g AC                                                                                        8.0 + 1.9abc                                                                167                                                                                                                  10.4 + 0.6cd                                                                            540

CB-20 g AC                                                                            17.8 + 4.8a                                                                                          333                                                                                                                  17.7 + 1.3b                                                                                          903

AC= ammonium carbonate; BH = butyl hexanoate; CB = 5-component blend.
AC lures, Two 1-mm holes; g = amount of AC; BH, CB lures, 10 ml, one 0.5 mm hole.
Means followed by same letters within columns are not significantly different (P > 0.05).
Four (Puyallup) or three (Vancouver) replicates of each treatment in a randomized block design.


Table 3.  Seasonal trap captures (expressed as % of total flies within a block) of apple maggot on red spheres using ammonia and fruit volatile lures on tall and short trees in Puyallup, 2003.  5 replicates.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
                                                                                                                                                            Yellow Panels (29 Aug-2 Sep)                                                      Red Spheres (3 Sep-27 Oct)

Treatment                                                                                                                                 %                                                                                 Total  No.                                                                                                                                %                                                                                             Total No.

Control                                                                                                 4.1 + 1.7a                                                                                50                                                                                                                                6.0 + 1.4a                                                                                            116
20 g AC                                                                                               46.8 + 5.6b                                                                              534                                                                                                                  38.6 + 2.8d                                                                              733
BH                                                                                                                                           4.1 + 1.7          a                                                                                  49                                                                                                                                12.6 + 2.9ab                                                                228
CB                                                                                                                                           6.2 + 0.3          a                                                                                  72                                                                                                                                18.6 + 2.0bc                                                                360
CB-20 g AC                                                    38.8 + 4.2b                                                                              453                                                                                                                  24.1 + 3.4c                                                                              426
AC= ammonium carbonate; BH = butyl hexanoate; CB = 5-component blend.
AC lures, Two 1-mm holes; g = amount of AC; BH, CB lures, 10 ml, 0ne 4.5 mm hole.
Means followed by same letters within columns are not significantly different (P > 0.05).


Table 4.  Seasonal trap captures (expressed as % of total flies within a block) of apple maggot on yellow panels using ammonia and fruit volatile lures on tall and short trees in Puyallup, 2003.  5 replicates.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

                                                                                                                                                                                                Large Trees (5-6 m tall)                                                                                                                        Small Trees (2-3 m tall)      

Treatment                                                                                                                                 %                                                                                                         Total No.                                                                                                                     %                                                                                                         Total No.

Control                                                                                                             2.8 + 1.3a                                                                                            16                                                                                                                                5.3 + 1.2a                                                                                      94
20 g AC                                                                                                           42.9 + 2.2        b                                                                                  292                                                                                                                  42.6 + 3.8b                                                                                    731
20 g AC/CB                                                                 46.2 + 2.7        b                                                                                  286                                                                                                                  33.6 + 4.1b                                                                              572

CB                                                                                                                                                       8.1 + 1.1c                                                                                            55                                                                                                                    18.0 + 2.7c                                                                              303                                                                 

AC= ammonium carbonate; BH = butyl hexanoate; CB = 5-component blend.
Means followed by same letters within columns are not significantly different (P > 0.05).


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