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Journal of the Lepidopterists Society 40(4), 1986, 298-303

TRAP PREFERENCES OF RETINIA METALLICA AND

SEASONAL FLIGHT BEHAVIOR OF RETINIA SPP.,

RHYACIONIA SPP. (TORTRICIDAE), AND

CHIONODES SPP. (GELECHIIDAE)

IN THE DAKOTAS

Mary Ellen Dix

Rocky Mountain Forest and Range Experiment Station,

Forestry Sciences Laboratory, East Campus, University of Nebraska,

Lincoln, Nebraska 68583

AND

Martin Jacobson

Biologically Active Natural Products Laboratory,

Agricultural Environmental Quality Institute, Agricultural Research Service,

Beltsville, Maryland 20705

ABSTRACT. At high population levels, white and green traps baited with (Z)-7-dodecenyl acetate caught more Retinia metallica than blue traps. Diamond-shaped traps were more effective than cup traps, but did not differ significantly in effectiveness from triangular-shaped traps. Rhyacionia fumosana and R. neomexicana responded throughout May to synthetically-baited traps. Rhyacionia bushnelli and Retinia metallica flew in late May or early June.

Tip mining lepidopterous larvae can cause extensive damage to pon-derosa pine (Pinus ponderosa Laws.) in the northern Great Plains (Stein & Kennedy 1972). Information on their distribution is limited; effective techniques for detecting and evaluating infestations are not available (Dix et al. 1984). Accurate determination of the flight period of Lepidoptera that are concealed for most of their life cycle is crucial to the effective timing of insecticide applications. Sex attractants are ideal for detecting and delineating the adult flight period of such Lepidoptera (Stevens et al. 1980). Jacobson and Jennings (1978) and Stevens et al. (1980) identified attractants of Rhyacionia fumosana Powell and Rhyacionia neomexicana (Dyer). Several possible lures of Retinia metallica (Busck) and Rhyacionia bushnelli (Busck), two of the more common species in the north central U.S., were identified by Dix et al. (1984). A trapping technique for Retinia metallica using these lures needs to be refined. This article describes trap design and trap color preferences of R. metallica, and delineates the flight period of Retinia spp., Rhyacionia spp. (Tortricidae: Olethreutinae), and Chionodes spp. (Gelechiidae) that infest ponderosa pine in North Dakota and South Dakota.

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Table 1. Description of sites used to determine flight periods of pine-feeding Lep-idoptera in North Dakota and South Dakota, 1973-76.

1975      Near Burning Coal Vein, Little

Missouri Grasslands, Custer National Forest, Slope Co., North Dakota

North Cave Hills, Custer National Forest, Harding Co., South Dakota

Slim Buttes, Custer National Forest, Harding Co., South Dakota

Big Sioux Conifer Nursery, Cod-dington, Co., South Dakota

1976      Near Burning Coal Vein, Little

Missouri Grasslands, Custer National Forest, Slope Co., South Dakota Big Sioux Conifer Nursery, Cod-dington Co., South Dakota

Native 0.5-20

Native 0.5-20

500 10 May-20 July

500 10 May-20 July

Native 0.5-20         500 10 May-

20 July

Planted         2-6 3,000 8 May-

15 June

Native 0.5-20         500 10 May-

3 Aug

Planted         2-6 3,000 27 May-

22 June

Methods and Materials

Trap design and trap color preferences of R. metallica. Trials were conducted in May and June at the Big Sioux Conifer Nursery, Cod-dington Co., South Dakota. Initially, a moderate population (5 pitch blisters/tree) was present in the 9-year-old ponderosa pine provenance planting, and a high population (36 pitch blisters/tree) was present in the 20-year-old ponderosa pine in the nursery's border planting.

A cardboard cup trap (0.24 liter), a triangular milk carton trap (9 cm high and 15 cm long), and a diamond-shaped milk carton trap (9 x 9 x 15 cm) were each lined with Stikem Special® and were baited with 10 mg of (Z)-7-dodecenyl acetate. All traps were open at both ends and were white. There were six blocks of three traps (one of each design). Traps in each block were hung in the border planting 20 m apart at a height of 1.5 m.

The effect of trap color on trap catch was determined with diamond-shaped traps painted white (2A1), pale blue (24A5), green (28D8), or fluorescent orange (7A8). Notations following colors refer to Kornerup and Wanscher's (1967) standard colors. All traps were baited with rubber septum dispensers containing 10 mg (Z)-7-dodecenyl acetate plus 10 mg trioctanoin and were deployed 20 m apart at a height of 1.5 m in perimeter ponderosa pines. There were six blocks of four traps (one of each color) in trial 1 and four blocks of four traps in trial 2.

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Journal of the Lepidopterists' Society

Table 2. Comparison of trap catch of male R. metallica with different sticky trap designs baited with 10 mg of (Z)-7-dodecenyl acetate plus 10 mg trioctanoin.

1 Means followed by the same letter are not significantly different (P < 0.05) according to Tukey's procedure for multiple comparisons.

Each week for three weeks, trap catches were counted and the traps were randomly reassigned to a new site within the block. Analysis of variance and Bartlett's test for homogeneous variance were performed on the total catch per trap. When necessary, the data were transformed by ln(x 4- 1) to stabilize the variance for analysis of variance. Tukey's honestly significant difference procedure at the 5% level was used to separate means (Sokal & Rohlf 1969).

Seasonal flight record. During spring and early summer of 1975 and 1976, known attractants of Rhyacionia spp. and Chionodes spp., and several related synthetic compounds were used to attract Rhy-acionia spp., Retinia spp., and Chionodes spp. that damaged ponderosa pine in native and planted stands (Table 1). Compounds used as lures included (E)-7-decenyl acetate, (Z)-7-decenyl acetate, (E)-7-dodecenyl acetate, (Z)-7-dodecenyl acetate, (Z)-7-dodecen-l-ol, (E)-8-dodecenyl acetate, (Z)-8-dodecenyl acetate, (Z)-9-dodecenyl acetate, (E)-9-dodecenyl acetate, (E)-9-dodecen-l-ol, (Z)-lO-dodecenyl acetate and (E)-lO-dodencenyl acetate. In 1975, each compound was replicated twice at a site, and traps and dispensers were changed three times during a trapping period. In 1976, each compound was replicated five times at a site, and traps were changed six times at two-week intervals during a trapping period.

Traps were cardboard cups (0.24 liter) with a 2.5 cm diameter opening at both ends. The inside was coated with Stikem Special®. In 1975, a cotton wick dispenser (12 x 10 mm) was impregnated with 20 mg of a test compound and placed in the bottom of each trap. In 1976, a rubber septum dispenser (5x9 mm) baited with 10 mg of test compound was used. In 1975 and 1976, compound activity was prolonged by adding 10 mg of the extender trioctanoin. Control dispensers also were baited with 10 mg of trioctanoin and were replicated twice per site in 1975 and five times per site in 1976. Traps baited with synthetic attractants or with control dispensers were hung on ponderosa pine branches at a height of 1.5 m and a spacing of at least 20 m.

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Table 3. Effect of trap color on catches of male Retinia metallica in diamond-shaped sticky traps baited with 10 mg of (Z)-7-dodecenyl acetate plus 10 mg trioctanoin.

1 Means followed by the same letter are not significantly different (P < 0.05) according to Tukey's procedure for multiple comparisons.

Captured moths were identified and counted when traps were changed. Moths were removed from traps with forceps or by carefully cutting the trap around the moth. Specimens were tentatively identified and numbers of moths per species were recorded. Representative samples of each presumed species were sent to specialists for identification.

Results and Discussion

Trap design and trap color preferences of R. metallica. Traps in several blocks were blown down during a spring storm; catches in traps from these blocks were not included in analyses. The second color preference trial was conducted the following spring, after the number of active R. metallica had abruptly decreased (less than 1 pitch blister/ tree). An unusually wet August and winter probably contributed to the high larval mortality and reduction in number of adults.

Effectiveness of the traps varied with design and color (Tables 2, 3). Diamond-shaped traps had the largest surface area and caught more moths than either triangular or cup traps. However, only mean catches per trap of the diamond-shaped traps and cup traps differed significantly. At high population levels, as exhibited in trial 1, white, green, and orange traps caught significantly more males than blue traps (Table 3). However, at low population levels (trial 2), trap color did not affect trap catch.

Seasonal flight behavior. The beginning and end of male flight for five species of Olethreutinae which infest the branch tips of ponderosa pine varied yearly with the onset of spring. For example, the spring of 1976 was warmer than in 1975, and moth flights of Retinia metallica, R. gemistrigulana and Rhyacionia fumosana were earlier (Fig. 1).

In southwestern North Dakota and northwestern South Dakota, male R. fumosana and K. neomexicana, the first species trapped in the

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Journal of the Lepidopterists' Society

Retina metallica Retina gemistrigulana

Rhyacionia bushnelli

Rhyacionia fumosana

Rhyacionia neomexicana

Chionodes spp.

ED 1975 Slope Co., N. Dak.

■I1975 North Cave Hill, Harding Co., S. Dak.

E3 1975 Slim Buttes, Harding Co.,S. Dak.

Q 1975 Coddington Co., S. Dak.

1=1 1976 Slope Co., IM.Dak.

12231976 Coddington Co.,S.Dak.

V////A

MINI I I I I I I I I I ID

ii 11 nun]

I i i i i i i i i rm

Ml II I I I MT-

Esnsszzsins

I I i l i i i I I I i I t I I iTT

MB»*MaHa«g«»tt«as»ff

-I___I___I__I         , I_____L_

5 15 25 4 14 24 | 4 14 May                  June             July

Fig. 1. Seasonal flight of Tortricidae: Olethreutinae and Gelechiidae that damage ponderosa pine in North Dakota and South Dakota.

spring, were usually caught in early May. Rhyacionia bushnelli, Re-tinia metallica, and R. gemistrigulana (Kearfott) were caught two to three weeks later, frequently in late May or early June. Large numbers of Chionodes spp. (Gelechiidae), which mine cones of ponderosa pine, were caught during June and July. Flight of Retinia metallica in northeastern South Dakota (Coddington Co.) was about two weeks earlier than in northwestern South Dakota.

In conclusion, white, green, or orange diamond- and triangular-shaped traps are effective in catching male R. metallica. However, diamond-shaped traps are preferred for future attractant trials and for detecting males because they provide a larger surface area. Time of moth flight varies annually. Additional research is needed to determine the effect of cumulative atmospheric and ground temperature on moth flight and to develop a method for accurately predicting moth flight.

Acknowledgments

William Miller, USDA Forest Service, North Central Experiment Station, St. Paul, Minnesota, and Jerry A. Powell, University of California, Berkeley, identified the Tor-

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tricidae; and R. W. Hodges, USDA, Agricultural Research Service, Northeastern Regional Agricultural Research Center, Beltsville, Maryland, identified the Gelechiidae.

Literature Cited

Dix, M. E., A. D. Tagestad, J. D. Stein & M. Jacobson. 1984. Detecting tip mining Olethreutinae (Tortricidae) moths in the northern and central Great Plains with synthetic attractants. USDA Forest Service Research Note RM-445. Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado. 5 pp.

Jacobson, M. & D. T. Jennings. 1978. Attraction of Rhyacionia neomexicana (Dyar) to synthetic pheromones. J. Environ. Sci. Health, Part A, 13:429-443.

KORNERUP, A. & J. H. Wanscher. 1967. Methuen handbook of colour. 2nd ed. Meth-uen and Co. Ltd., London. 243 pp.

Sokal, R. R. & F. J. Rohlf. 1969. Biometry: The principles and practice of statistics in biological research. W. H. Freeman and Co., San Francisco. 776 pp.

Stein, J. D. & P. C. Kennedy. 1972. Key to shelterbelt insects in the northern Great Plains. USDA Forest Service Research Paper RM-85. Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado. 153 pp.

Stevens, R. E., C. Sartwell, Jr., T. W. Koerber, G. Daterman, L. L. Sower & J. A. Powell. 1980. Western Rhyacionia (Lepidoptera: Tortricidae, Olethreutinae) pine tip moths trapped using synthetic sex attractants. Can. Entomol. 112:591-603.