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0 .............................................................. Light shade P=0,05 8 " _ Medium shade ............................... _ ..... [] Deep shade l _._Control E 6 ...................................................... ........ (_ .. P=0.08 P=0,19 --...... __ __ "-_ P=0.03 ± 0 -- 10/92 11/92 1/93 3/93 9/93 Sample Date Figure 6.ENumber of Phytolyma tata galls per Milicia excelsa plant grown under four levels of shade. Light shade = 33%, Medium shade = 57%, Deep shade = 82%. 60 .................. _1_Height 15 50 ..................... b l_ Diebacks ............ b 'I 09 &"4o ..... -_ o - v _O 03 O3 "O •_ 30 cc- O {..- E _ 520 5 _x 10 0 0 Control 15-15-15 10-4-22 8-3-3 Fertilizer Treatment Figure 7.mMilicia excelsa height (cm) and average number of Phytolyma lata induced diebacks as the result of four fertilizer treatments. i 269
very different from the Milicia/Phytolyma system we examined. There is very little consistency in the response of herbivores to fertilization of their hosts (Stark 1965, Schowalter et al. 1986). Insufficient evidence exists to postulate any general pattern in this regard. Hall and Swaine (1983) reported that Iroko is not abundant in the evergreen tropical forest because it requires high light for germination and establishment. However, as previously noted, plantations of this species planted in full sun have been heavily attacked by the odum gaUfly and have largely failed. In contrast to the report of Hall and Swaine (1983), we have been told by a tropical tree physiologist that the optimal photosynthesis for Iroko seedlings occurs at 8-10% of full sunlight, suggesting this is a shade tolerant species (E.M. Veenendaal, pers. comm.). The results we report in this paper indicate that the abundance and subsequent impact of this insect is greater in full sun than under shade. We recognize that there would be considerable utility in examining the relationship between Iroko and the odum gallfly under natural field conditions. However, naturally regenerating seedlings of this species are difficult to find. In a recent field excursion to the Tain II Forest Reserve, which is noted for its high density of Iroko in the overstory, we were able to locate only a single seedling in 12 person/hours of searching. The low incidence of Iroko seedlings has been confirmed anecdotally by several botanists and forestry field surveys. Growing stock as of 1987 was immature stock (1-7ft girth) 834,000m 3and mature stock (> 7ft girth) 5,269,000m 3 (Alder 1989). The results we report suggest that standard agroforestry practices such as mixed planting with nitrogen-fixing trees may have utility as part of a pest management program to control the odum gallfly. Other approaches including selection for genetic resistances have resulted in considerable success (Cobbinah and Wagner 1994). Cooperative effort between silviculturists, physiologists, and genetists is required to fully understand how to reduce the impact of this insect and provide for a continuing supply of one of Africa's most valuable timber species. SUMMARY Planting the nitrogen-fixing Gliricidia sepium in conjunction with the tropical timber species Milicia excelsa reduces the abundance and damage caused by the gall-forming pysUid, Phytolyma lata. This effect appears to be related to both the increased shading and enhanced nitrogen environment. Shading independently has a strong impact on gall abundance with the lowest gall abundance occurring under the highest level of shade (82%). Gall abundance is reduced under shade even though more leaves are available to the insect. Fertilization at the highest levels of nitrogen also reduces the abundance of galls. ACKNOWLEDGEMENT These studies were supported by the International Tropical Timber Organization through research grant No. PD75/90 to J.R. Cobbinah and M.R. Wagner. LITERATURE CITED ALDER, D. 1989. Naturalforest increment, growth and yield, p. 47-52. In Ghana Forest Inventory Proceedings. Overseas Dev. Agency/Ghana For. Dep., Accra. COBBINAH, J.R. t986. Factors affecting the distribution and abundance of Phytolyma lata (Homoptera:PsyUidae). Insect Sci. Appl. 7: 1111-115. COBBINAH, J.R. 1988. The biology, seasonal activity and control of Phytolyma lata. IUFRO Regional Workshop on Pests and Diseases of Forest Plantations, June 5-10, 1988, Bangkok, Thailand. COBBINAH, J.R. and WAGNER, W.R. 1994. Phenotypic variation in Milicia excelsa toattack by Phytolyma lata. Biotropica. (in review). 270
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DYNAMICS OF FOREST HERBIVORY: QUEST
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TABLE OF CONTENTS Seeking The Rules
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32. Companion planting of the nitro
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GRIMALSKY, ¥.I., Research Institut
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POUTTU, ANTTI, Finnish Forest Resea
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persist in mature leaves and affect
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THE SINK-SOURCE HYPOTHESIS: TYPE AN
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late season defoliation decreases t
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BLANCHE, C.A., LORIO, EL., Jr., SOM
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NIEMELA, R, TUOMI, J,, and LOJANDER
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induced reactions have been studied
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summer, but the other sawfly specie
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LARSSON, S., BJ(_RKMAN, C., and GRE
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STAND AND LANDSCAPE DIVERSITY AS A
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not related to resistance to the se
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In contrast to the situation in eas
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ROOT, R.B. 1973. Organization of a
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We tlhus neglect two potential sour
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c__ c__ 1T1 Ill a) a) 0 0 0 e 1 o e
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c_ >l.s S S S m N < DN DN < D c DN
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:hen k > 0 suggest that the cue or
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oth as protective weapons and as po
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DEFENSE THEORIES AND BIRCH RESISTAN
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P 45 A L 40 A T 35 A B 30 I L 25 I
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However, hares showed strong prefer
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DUGLE, J.A. 1966. A taxonomic study
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accommodate findings related to mic
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Table l.--Mean ±S.E. area eaten by
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Sulfhydryl-Disulfide Mechanisms In
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Iraa prior experimental analysis of
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FRAZIER, J.L. and HEITZ, J.R. 1975.
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REICHARD, R 1993. From RNA to DNA,
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; trees, and between and within ind
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Encapsulated objects are data struc
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_re3.--The Lignum model can be cont
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SEVERE DEFOLIATION Tree Fine Root +
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RUMBAUGH, J., BLAHA, M., PREMERLANI
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oo0 a b ol ¢' _achiman_i ()® 1,eA
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1000 Conspicuous Defo i at ion 100
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2.oo 2.oo o t 4 t ¢._ e'- 1.80 1.8
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Qualitative Changes in [,eaves and
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t00 2 Yr 1 Yr o_ 80 Treatment Treat
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Table 2.--Body size of Q. purzctate
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06 b AddedBSA < 04 _ 2rag -'=' i:3
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Severe Defol iat ion Site-A 1993 _
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KAMATA, N. and IGARASHI, M. 1995b.
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enclosure %r 20 post-diapausing sec
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2,500 F 000 F NF NF b _7 a _;_ a _7
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8O D 09 i 4,'.) F AS4L a Z___7 2o !
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2,500 _ st2-st4 El st5 0 st6 [_ pup
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96 SLANSKY, E, Jr. 1990. Insect nut
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later, we selected one more floweri
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Table 2.---Mean spruce budworm perf
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Table 3..--Mean spruce budworm perf
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FOLIVORE FEEDING ON MALE CONIFER FL
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Table 3.--Lymantria monacha prefere
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500- 400- i 300 v ¢ m a 200- I00 L
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From the point of view of trees, th
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THE BLACKMARGINED APHID AS A KEYSTO
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Wood et al. (1987) report that M. c
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MIZELL, R.E 1991. Pesticides and be
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METHODS Study Site The study took p
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the samples. Fertilization had subs
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Table 2.--Percent nutrient content
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Some tree responses to fertilizatio
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PHYTOCHEMICAL PROTECTION AND NATURA
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Indirect effects of abiotic factors
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HUNTER, M.D. and PRICE, P.W. 1992.
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A° ADDITIVE C. HYBRID SUSCEPTIBILI
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Galls, leaf miners, or leaf folds w
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Table 2.--Summary of the hypotheses
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the inheritance patterns of seconda
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FLOATE, K.D. and WHITHAM, T.G. 1993
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Elements of the Suitability/Defense
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Table l.--Comparing the mean number
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ACKNOWLEDGEMENTS The authors sincer
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SINGH, D.R 1986_ Breeding for resis
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The objectives of this presentation
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Table 1.--Average weevil attack on
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1977, Kline and Mitchell 1979, Wood
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Further research is underway to cla
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A SUGI CLONE HIGHLY PALATABLE TO HA
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RESULTS Seasonal Stability of Palat
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-
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OGAWA, A., NAGATA, Y., and SUKENO,
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MATERIALS AND METHODS Field Work In
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Laboratory Procedures The week afte
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E 120 Nogent-sur-Vernisson Remnings
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Interdependence Between Reaction Zo
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alance hypothesis (Lorio 1986) cann
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SOLHEIM, H., LANGSTROM, B., and HEL
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In a second experiment, three 30-ye
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Considering biochemical pathways, i
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- = 120 N /'_" =40 1/ _ j Days 0 _
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BIGGS, A.R. 1985. Suberized boundar
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DIFFERENTIAL SUSCEPTIBILITY OF WHIT
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Table 2.--Mortality of white fir pr
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Results from the geographic range p
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esulting seedlings were then rooted
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-0.2 0 5 82. _j -0,4 e a a a D4 E I
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1960, Kalkstein 1976). Increased su
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RYAN, B.F., JOtNER, B.L., and RYAN,
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It is seldom feasible to control wa
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15 15 u. 10 |O O N tal 5 5 g ao o 4
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Only recently have we conducted stu
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esistance to beetle attack. Another
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LORIO, EL., Jr'. and HODGES, J.D. 1
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EFFECTS OF ROOT INHABITING INSECT-F
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OCCURRENCE OF ROOT AND STEM SUBCORT
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]Predisposition of Root-infected Tr
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chemistry associated with root colo
Page 228 and 229: Implications to Natural Resource Ma
Page 230 and 231: KLEPZIG, K.D., RAFFA, K.F., and SMA
Page 232 and 233: RAFFA, K.F., PHILLIPS, T., and SALO
Page 234 and 235: METHODS The study was installed in
Page 236 and 237: FURNISS, M.M., LIVINGSTON, R.L., an
Page 238 and 239: METHODS In the spring and summer of
Page 240 and 241: The importance of a compound as a r
Page 242 and 243: WERNER, R.A. 1995. Toxicity and rep
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Page 246 and 247: Table 1.--Summary data for the 26 p
Page 248 and 249: One weakness of using data from gen
Page 250 and 251: Lower Peninsula (populations 14-26)
Page 252 and 253: AUCLAIR, A.ND., WORREST, R.C., LACH
Page 254 and 255: KELLOMAKI, S., HANNINEN, H., and KO
Page 256 and 257: WARGO, RM. and HAACK, R.A. 1991. Un
Page 258 and 259: investigation. Sampling was done on
Page 260 and 261: Figure 2.--Changes in protein preci
Page 262 and 263: q) J 400 T J ! i i i i o control tr
Page 264 and 265: attacked trees than in control tree
Page 266 and 267: ACIDIC DEPOSITION, DROUGHT, AND INS
Page 268 and 269: Table 1.--Impact of acidic fog upon
Page 270 and 271: MENGEL, K., BREININGER, T., and LUT
Page 272 and 273: THE RESISTANCE OF SCOTCH PINE TO DE
Page 274 and 275: EXPERIMENTAL METHODS Experiments we
Page 276 and 277: C w Q. 1,200 1,000 o 800 C_ --- 600
Page 280 and 281: FONTAtNE, R.G. 1985. Forty years of
Page 282 and 283: Host Defenses An important componen
Page 284 and 285: Functional Heterogeneity of Forest
Page 286 and 287: The Connectivity Index (CI). The CI
Page 288 and 289: FUNCTIONAL HETEROGENEITYANALYSIS :
Page 290 and 291: The Modified Hazard Map. The next l
Page 292 and 293: systems facilitate mapping of fores
Page 294 and 295: KOLASA, J. and ROLLO, C.D. 1991. In
Page 296: ) i,i_i)i_)i_i_ U.S. Departme_]t of
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