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282 than were conspccifics with lower egg loads (van Randen & Roilberg. 1996). Once encountered, a given host is of higher value to a female with high egg load (because the female is more time-limited) and consequently (he female is less likely lo be deterred by MP. There are other contexts in which avoidance of utilized hosts is dynamic in nature. conte.xts well-studied in parasitoids. Under conditions where the survival of ihe second progeny or clutch is greater than zero, parasitism of an already-parasitized host (a phenomenon termed 'superparasitism') may be functional if unparositized hosts are scarce, if search or handling time is high, if females are time limited or if multiple females are exploiting a patch simultaneously ivan Lenteren. 1981; van Alphen et al.. 1992: van Alphen & Visser. 1990; Speirs et al.. 1991). .All of these factors influence the value of the host resource to a female and thus influence response to MP. Dynamics in the value of the resource The extent to which MP deters host use ought to depend on the relative value of the host resource from (he perspective of an ovipositing female. In medfly. for example, (he extent to which females avoid marked fruit relates both to the size and the ripeness of those fruit. On ripe fruit, females generally prefer (o lay eggs in unmarked, uninfested fruit (Prokopy et al.. 1978). However, degree of avoidance also depends on fruit size: large egg-infested hosts are avoided less than small infested hosts (Papaj & Messing. 1996). The difference in level of avoidance is probably functional, since the cost of larval competition is greater when that fruit is small (Averill & Prokopy. 1987a). •A more dramatic shift in medfly behavior accompanies changes in fruit ripeness. Whereas females prefer unmarked (o marked hosts when fruit are ripe, (he preference is actually reversed when fruit are unripe. with females preferring to lay eggs in marked hosts and. in fact, depositing eggs in existing oviposition punctures (Papaj el al.. 1992: Papaj & Messing. 1996). The preference for marked, infested fruit when fruit are unripe is also believed to be functional. Females have a difficult time penetrating unripe fruit with their ovipositors: re-use of an existing oviposition puncture saves time and increases the chances of successfully depositing a clutch. Re-use may also reduce ovipositor wear. Evidently, when fruit are unripe, such direct fetnale benettts ore relatively great and offset the cost of additional competition experienced by a 31 female's clutch; when fruit are ripe, in contrast, the cost of competition offsets the relatively small benefits and marked fruit are avoided. In ca.ses where responses to brood presence change with changes in the quality of (he host resource, it is not a given (hat (here is a change in (he response (o MP per se. In medfly. the response to MP itself does not appear to change at all with changes in fruit quality. A given quantity of MP is consistently deterrent, independent of other fruit quality traits (Papaj et al.. 1992). Moreover, the quantity of MP deposited does not seem to depend on fruit size or ripeness. Instead, degree of avoidance of marked fruit is governed by a balance between the deterrent properties of MP. on one hand, and stimulatory properties of the frui( surface, on (he other (Papaj et al.. 1992). Temporal patlerns in responses lo marked hosts Types of patterns and stimuli involved Sometimes the pattern of response to a marked, occupied host remains stable over time. More commonly, responses change markedly over the time since the host was previously utilized (revs, van Lenteren. 1976; Strand. 1986; Hofsvang. 1990). These changes in response run the gamut of possible forms. Sometimes females show increased levels of host rejection with time: some(imes females initially show high levels of rejection but accept hosts more readily with time. Responses can also be complex; for example, levels of rejection may be high at first, then decline to some asymptote and remain stable (Holler et al.. 1991). .Mtematively. levels of rejection may be high, then decline and then increase again (Chow & Mackauer. 1986). In any of these cases, the temporal dynamics may reflect changes in MP communication, changes in cues emitted by the host or brood, or cues generated by an interaction between host and brood (see Hubbard et al.. 1987: Ueno. 1994; and Gauthier et al.. 1996 for discussion of complex patterns). Female behavioral responses to a larval host that has been occupied for a given length of time may also not be a hxed species-speciflc pattern, but may be a condition-dependent one that varies with a female's experience level (Bosque & Rabinovich. 1979: Hubbard et al., 1999: Chow & Mackauer. 1986). rearing density (\1sser, 1996). age and egg load (Vblkl & Mackauer. 1990). and whether the mark encountered was produced by the female herself or by conspecifics
(Hubbard et ul.. 1987; Holler el al.. 1991; Gauthier et al.. 1996). Where L-OSLS and bcnetil.s of host re- UNC vary under the above conditions, female rejection patterns are expected to vary accordingly. Incri'tiM's in reiecluin levels over rune A pattern in which t'einales show increased level.": of host rejection with time may not retiect a pattern in MP communication at all. The patterns may simply retiect use of cues a.ssociated with the development of brood and consumption of the host (Strand, 1986). It is rea.sonable to suppose that such cues require extended periods of time before they are produced in enough quantity to be detected. However, increasing levels of reiection with time. ;i.s observed in certain para.sitoids. IS at least sometimes due to changes in .VIP activity. In some cases, changcs m activity probably reflect a constraint on the amount of time required for a MP to be produced, activated, or circulated within a host (van Lenteren. 1976; Cloutier et al.. 1984; Gauthier & Monge. 1999). In other ca.ses. such a pattern may have titnes.s value, as when second clutches are associated with a high rttness gam. but only for some hnite period of time after the tirst clutch is laid (Gauthier el al.. 1996). Where females commit ovicide, for example, there is likely to be a high payoff for second clutches until such time as the tirst eggs hatch, after which the payoff may decline precipitously i Strand & Godfray. 1989; Mayhew. 1997V Decreases in rejectum levels nver tune \ pattern in which females initially show high levels of rejection which then decline with time is often indicative of a breakdown of MP over time. While it is likely that degradation of MP sometimes reflects a constraint on an in.sect's ability to produce a more persistent signal, it is at least conceivable that the "half-life" of MP is functional. Roitberg &. Mangel (1988) addres.sed this possibility in theoretical model.s. In these models, they assumed that longer-lasting MPs are costlier to produce. The MP persisLs initially bccause both the marker and the recipient of the •MP benefit if the recipient avoids laying eggs in an already-utilized host. However, as time goes on and the marker's offspring grow, the probability that her offspring will be out-compcted by the offspring of a second female declines. .At some point in time, the benetii of additional persistence of the MP in terms of reducing the marker's competitive losses will equal the cost of the additional persistence. Tliis is the point in time at which the MP should, by design, break down. The half-life of MP may retiect not ju.st temporal changes in the relative payoffs for rirst and second clutches (Quiring
Page 1: INFORMATION TO USERS This manuscrip
Page 4 and 5: UMI Number: 3053915 Copyright 2002
Page 6 and 7: STATEMENT BY AUTHOR This dissertati
Page 8 and 9: DEDICATION This work is dedicated t
Page 10 and 11: ABSTRACT Choosing where offspring w
Page 12 and 13: An explanation of tiie problem CHAP
Page 14 and 15: euse occurs in the field, the impac
Page 16 and 17: Appendix D, "Aggregative behavior i
Page 18 and 19: offspring performance. Counter to t
Page 20 and 21: Lalonde RG, Mangel M, 1994. Seasona
Page 22 and 23: APPENDIX A HOST MARKING BEHAVIOR IN
Page 24 and 25: kluwer the language of science Dr.
Page 26 and 27: 174 belter categorized as cues than
Page 28 and 29: fubfe 2. Kinds ot cvicknce used lo
Page 30 and 31: 278 defend themselves and because i
Page 32 and 33: 280 lion of a signal. Costs associa
Page 36 and 37: 284 thai (he marker was a mutant fo
Page 38 and 39: 286 dropping on ihe MP communicatio
Page 40 and 41: 28S inac>. 3 larval partsiloiil of
Page 42 and 43: 290 Hol'svang. T. 1988. Mechanisms
Page 44 and 45: 29Z Roitbcfg. B- D it R- G- Laionde
Page 46 and 47: APPENDIX B HOST UTILIZATION BY THE
Page 48 and 49: Dispersal by Larvae of the Stem Bor
Page 50 and 51: POPULATION ECOUXTY Host Utilization
Page 52 and 53: October 2000 NUFIO ET AL.; HOST UTI
Page 54 and 55: October 2000 Nufio et au: Hoct Unuz
Page 56 and 57: October 2000 NUFIO ET AL4 HOST UIHI
Page 58 and 59: Reuse of larval hosts by the walnut
Page 60 and 61: KEYWORDS Life history" marking pher
Page 62 and 63: Alternatively, a weak correlation b
Page 64 and 65: previously attacked hosts early in
Page 66 and 67: walnut fly oviposition punctures. T
Page 68 and 69: Effects of offspring weight on adul
Page 70 and 71: she deposited over a lifetime and t
Page 72 and 73: RESULTS Levels of host reuse in the
Page 74 and 75: Survival from egg to egg hatch Of t
Page 76 and 77: significantly correlated with pupal
Page 78 and 79: DISCUSSION While the femaie-prefere
Page 80 and 81: discriminate between hosts that hav
Page 82 and 83: will consume fewer resources and th
Page 84 and 85:
females gain not by simply reusing
Page 86 and 87:
of her offspring but also of the nu
Page 88 and 89:
ACKNOWLEDGEMENTS We thank Henar Alo
Page 90 and 91:
Bjorkman C, Larsson S, Bommarco R,
Page 92 and 93:
Fujiyama N, Katakura H, 2001. Varia
Page 94 and 95:
Mayhew PJ, 1997. Adaptive patterns
Page 96 and 97:
Robertson IC, Roitberg BD, 1998. Du
Page 98 and 99:
Wiklund C, 1981. Generalist vs. spe
Page 100 and 101:
Table 2. The influence of various f
Page 102 and 103:
Table 4. Analysis of variance compa
Page 104 and 105:
nCURE CAPTIONS - Continued Figure 5
Page 106 and 107:
Figure 1. Fruit Cohorts (Number of
Page 108 and 109:
Figure 3. A. B. A > on •m e « 50
Page 110 and 111:
Figure 5. B. es & 1 1 0.8 • 0.6 -
Page 112 and 113:
Figure 7. B. > 09 "S s e s o •Ml
Page 114 and 115:
Figure 9. 400 9t W s 1 t 300 « Of)
Page 116 and 117:
Aggregative behavior is not explain
Page 118 and 119:
that the larval aggregations that f
Page 120 and 121:
2001). The shifting benefits and co
Page 122 and 123:
spatial patterning of clutches depo
Page 124 and 125:
16-fl oz (473-ml) plastic Solo cups
Page 126 and 127:
percentage of hatchlings that emerg
Page 128 and 129:
previously created oviposition punc
Page 130 and 131:
RESULTS Experiment 1. Effect of off
Page 132 and 133:
deposited) again improved the model
Page 134 and 135:
median pupal weight in the lone two
Page 136 and 137:
survival, using two-clutch and thre
Page 138 and 139:
DISCUSSION Absence of an AUee efTec
Page 140 and 141:
simultaneously. It would seem that
Page 142 and 143:
Spatial distribution of clutches In
Page 144 and 145:
If reuse of larval hosts negatively
Page 146 and 147:
Page 148 and 149:
Hausmann SM, Miller JR, 1989. Ovipo
Page 150 and 151:
Papaj DR, Alonso-Pimentel H, 1997.
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
FIGURE CAPTIONS continued Figure 4.
Page 158 and 159:
Figure 2 MD E DC n Om 3 Qi S V DA E
Page 160 and 161:
Figure 4. B. c. -g 60 S a. a 40 - S
Page 162 and 163:
Host marking beiiavior as a quantit
Page 164 and 165:
encountered either control fruit th
Page 166 and 167:
unparasitized and parasitized hosts
Page 168 and 169:
Finally, it is conceivable that the
Page 170 and 171:
Experiment 1. Relationship between
Page 172 and 173:
or 30 minutes). Fruit were then hun
Page 174 and 175:
After two replicates of the four tr
Page 176 and 177:
Experiment 3. Female responses to h
Page 178 and 179:
RESULTS Experiment 1. Effects of cl
Page 180 and 181:
Experiment 3. Female responses to f
Page 182 and 183:
example, the possibility that ovipo
Page 184 and 185:
field cage assays. What remains to
Page 186 and 187:
Page 188 and 189:
Bauer G, 1986. Life-history strateg
Page 190 and 191:
Landolt PJ, Averill AL, 1999. Fruit
Page 192 and 193:
Quiring DT, McNeil JN, 1984. Intras
Page 194 and 195:
FIGURE CAPTIONS Figure 1. The relat
Page 196 and 197:
Figure 2. w OA 8 k 98 s o a. QH s 8
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