Oviposition preference,larval performance and adaptation of Trichoplusia ni on cabbage and cotton

Most female herbivores ensure to lay eggs where their offspring can develop successfully. The oviposition preferences of females affect strategies in pest management. In this study, the performance of two cohorts of Trichoplusia ni larvae on cabbage and cotton (after they had been transferred from their original host plants) were investigated. The preferences of female moth ovipositing and larval feeding on these two host plants were observed. The results indicated that plants significantly affected oviposition preference of the female adults and development and survival of larvae of T. ni. All females preferred to lay eggs on cabbage than cotton regardless from which host they originated. The detrimental effects of cotton on the development and survival of T. ni larvae originated from cabbage (CaTn) increased with the increase of the larval age when they were transferred. In addition, the host plant change did not significantly affect the development and survival of larvae of T. ni originating from cotton (CoTn). Larvae of CaTn preferred cabbage plants as compared to cotton plants, whereas larvae of CoTn did not show a significant choice. Although the adult females preferred laying eggs on cabbage, they did not show preferences between cotton and cabbage in a Y‐tube olfactometer test. The hypothesis of oviposition preference and performance of larvae was supported by the results of CaTn, whereas they not supported by those from CoTn. Based on these results, the strategy to manage this serious pest was discussed.     

The Many Dimensions of Diet Breadth: Phytochemical,Genetic, Behavioral,and Physiological Perspectives on the Interaction between a Native Herbivore and an Exotic Host

From the perspective of an herbivorous insect, conspecific host plants are not identical, and intraspecific variation in host nutritional quality or defensive capacity might mediate spatially variable outcomes in plant-insect interactions. Here we explore this possibility in the context of an ongoing host breadth expansion of a native butterfly (the Melissa blue, Lycaeides melissa) onto an exotic host plant (alfalfa, Medicago sativa). We examine variation among seven alfalfa populations that differed in terms of colonization by L. melissa; specifically, we examined variation in phytochemistry, foliar protein, and plant population genetic structure, as well as responses of caterpillars and adult butterflies to foliage from the same populations. Regional patterns of alfalfa colonization by L. melissa were well predicted by phytochemical variation, and colonized patches of alfalfa showed a similar level of inter-individual phytochemical diversity. However, phytochemical variation was a poor predictor of larval performance, despite the fact that survival and weight gain differed dramatically among caterpillars reared on plants from different alfalfa populations. Moreover, we observed a mismatch between alfalfa supporting the best larval performance and alfalfa favored by ovipositing females. Thus, the axes of plant variation that mediate interactions with L. melissa depend upon herbivore life history stage, which raises important issues for our understanding of adaptation to novel resources by an organism with a complex life history.     

Host range evolution is not driven by the optimization of larval performance: the case of <Emphasis Type="Italic">Lycaeides melissa</Emphasis> (Lepidoptera: Lycaenidae) and the colonization of alfalfa

Herbivorous insects that have recently incorporated novel hosts into their diet provide unique opportunities for understanding factors that promote or constrain the evolution of niche breadth. Lycaeides melissa has colonized both cultivated and feral alfalfa (Medicago sativa) throughout much of North America within the past 200 years. We investigated the quality of the novel host as a resource for juvenile development, and asked if the novel host is a preferred host for oviposition relative to a native host (Astragalus canadensis). Larval-performance and oviposition-preference were examined using L. melissa individuals from a population associated with both M. sativa and A. canadensis, and oviposition-preference was also examined in another population associated exclusively with M. sativa. In addition, we investigated the effects of M. sativa and A. canadensis flowers on both preference and performance. Only one of the hosts, M. sativa, has flowers that are accessible to nectaring butterflies, and we hypothesized that the presence of flowers could affect female behavior. We find that the novel host is a relatively poor larval resource: adults that were reared as larvae on M. sativa were roughly one-third the size of adults that were reared on the native host, A. canadensis. The native host, Astragalus canadensis, is the preferred host in choice experiments involving only foliage. However, when flowers were included in preference assays, the native and novel hosts received similar numbers of eggs. Thus, the presence of flowers on hosts in the field might influence the utilization of a novel and inferior larval resource. These results are consistent with a model in which host shifts are driven by adult behavior that does not directly optimize larval performance.     

Does the periodical cicada,Magicicada septendecim,prefer to oviposit on native or exotic plant species?

Abstract 1. In 2004, Brood X of the periodical cicada (Magicicada spp.) emerged in Delaware. Extensive suburban development and concomitant planting of exotic species has occurred since the previous emergence of Brood X in 1987. 2. Exotic species could suffer extensive damage during years of cicada emergences if they are preferred for oviposition. Alternately, a shortage of suitable plant hosts may negatively affect remaining cicada populations. 3. We determined if the periodical cicada, Magicicada septendecim, preferred to oviposit on native or exotic woody plant species. Potential hosts were divided into three groups and planted in a randomised design near a likely source of cicadas. The first group, Natives, included 15 species native to Delaware. The second group, Non‐natives, included 15 exotic species that had a native congener represented in the Native group. The final group, Aliens, included 13 exotic species that did not have a native congener. 4. Based on observations of 428 plants, cicadas were more likely to oviposit on Natives or Non‐natives, which did not differ from each other in this measure, than on Aliens. Non‐natives had more oviposition holes per metre than Natives, which had more holes per metre than Aliens. The likelihood of stem flagging was lowest on Alien species; the percentage of the total plant that flagged was greatest for Natives. Plant morphology also influenced host preference and likelihood of flagging. 5. Taking plant morphology into consideration, we speculate that the evolutionary history between periodical cicadas and potential hosts is an important component of host preference.     

VARIATION IN PREFERENCE AND SPECIFICITY IN MONOPHAGOUS AND OLIGOPHAGOUS SWALLOWTAIL BUTTERFLIES

Although variation in oviposition preference and specificity for host plants has been demonstrated within populations of a variety of oligophagous insect species, it is unknown whether genetic variation in host choice is lost within populations of monophagous species. Analysis of a locally monophagous butterfly species, Papilio oregonius, and a locally oligophagous species, P. zelicaon, showed significant variation in oviposition preference within populations of both species. Females of both species chose primarily their native hosts. Nonetheless, the percentages of eggs laid by individual females among the plant species and the number of plant species on which individual females laid eggs differed significantly among isofemale strains within populations. Moreover, some females within all isofemale strains of both species laid a few eggs on Foeniculum vulgare, an umbelliferous species that does not occur in the native habitats of these populations but is a host for Papilio species in other geographic areas. The results suggest that local monophagy and oligophagy in these species reflect the relative ranking among potential plant species. Both populations harbor variation in oviposition choice that could allow for host shifts if these populations invaded new habitats.     

Cuckoo females preferentially use specific habitats when searching for host nests

Egg mimicry is an important adaptation of common cuckoos, Cuculus canorus, against rejection of eggs by their respective hosts. A precondition for the maintenance of egg mimicry is that female cuckoos find hosts with a matching egg type. Experimental evidence indicated that habitat imprinting may be important for host selection. We tested whether the spacing and laying patterns of female cuckoos in the field are compatible with the supposed habitat-imprinting mechanism. We observed 16 females, with the help of radiotelemetry; of seven females, we observed directly 26 egg layings and 27 nest visits without laying. As expected if females were imprinted on different vegetation types, (1) the distribution of vegetation types differed between female home ranges, (2) female habitat use differed from average habitat availability within the egg-laying area (habitat preference), (3) females visited nests and deposited their eggs in the habitat they preferred, and (4) females laid their eggs consistently in a particular habitat type, irrespective of the host species. These results indicate that cuckoo females show habitat preference when searching for suitable host nests. Hence our data are compatible with the habitat-imprinting hypothesis, but owing to the habitat specificity of hosts the data cannot disprove a potential role of host specificity in cuckoo females.Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Ability of a Generalist Seed Beetle to Colonize an Exotic Host: Effects of Host Plant Origin and Oviposition Host

The colonization of an exotic species by native herbivores is more likely to occur if that herbivore is a generalist. There is little information on the life-history mechanisms used by native generalist insects to colonize exotic hosts and how these mechanisms are affected by host properties. We examined the ability of the generalist seed beetle Stator limbatus Horn to colonize an exotic species. We compared its host preference, acceptability, performance, and egg size when ovipositing and developing on two native (Pithecellobium dulce (Roxb.) Benth and Senegalia riparia (Kunth)) and one exotic legume species (Leucaena leucocephala (Lam.)). We also analyzed the seed chemistry. We found that females recognize the exotic species as an unfavorable host for larval development and that they delayed oviposition and laid fewer and larger eggs on the exotic species than on the native species. Survivorship on the exotic host was 0%. Additionally, seeds of the native species contain five chemical compounds that are absent in the exotic species, and the exotic species contains three sterols, which are absent in the native legumes. Genetically based differences between beetles adapted to different hosts, plastic responses toward new hosts, and chemical differences among seeds are important in host colonization and recognition of the exotic host. In conclusion, the generalist nature of S. limbatus does not influence its ability to colonize L. leucocephala. Explanations for the colonization of exotic hosts by generalist native species and for the success of invasive species must be complemented with studies measuring local adaptation and plasticity.     

MATE CHOICE IN THE SAILFIN MOLLY,POECILIA LATIPINNA

We examined both female and male mate choice in the sailfín molly, Poecilia latipinna. Female mollies preferred larger males over smaller ones when comparing males from their own populations. Although the expression of this preference depends on a female's receptive state, the level of female preference does not appear to be associated with any other attribute of the female or of the males. When presented with males of the same size from different populations, females preferred native over foreign males in some but not all population combinations. These results cannot be explained by a bias for higher size-specific rates of courtship displays that is shared by all females. Males preferred larger over smaller females; larger males exhibited stronger preferences, and preference for the larger female also increased as the disparity in size between the two object females increased. We found no evidence that males preferred native over foreign females when encountered singly or in size-matched combinations. These results indicate that discrimination among populations arises because females exercise divergent directional preferences for size-specific trait values that are associated with differences among males in these values. This result implies an active role for sexual selection in contributing to the maintenance of the behavioral or morphological distinctions among males observed within and among populations.     

Escaping an evolutionary trap: preference and performance of a native insect on an exotic invasive host

Exotic plants may act as population sinks or evolutionary traps for native herbivores. The native butterfly Pieris oleracea lays eggs on garlic mustard, Alliaria petiolata, but larvae develop very poorly on this exotic invasive plant. We examined oviposition preference of individual females and larval performance of their offspring for individuals from one area where garlic mustard is well established and one where it is absent. These data were used to assess whether garlic mustard is being incorporated into or excluded from the diet. Females from the area without garlic mustard showed a wide range of preference, families had low larval survival on garlic mustard, and larval survivorship showed no correlation with mothers’ preferences. Females from the area with garlic mustard preferred it to the native host, and larval survivorship on garlic mustard was positively correlated with the mother’s preference. Individuals surviving on garlic mustard took longer to pupate and weighed >30% less compared to pupae reared on normal hosts. Our results suggest that where garlic mustard is well established P. oleracea may be adapting to this plant by both improved larval performance and increased adult female oviposition preference for it.     

Oviposition specificity in single vs. cluster egg-laying butterflies: a discrimination phase in Colias eurytheme?

Summary Oviposition preferences and rates of the pierid butterfly Colias eurytheme were examined in laboratory tests. Oviposition rates with only a non-preferred host plant present were not lower than rates observed when both preferred and non-preferred hosts were present. There was no correlation between strength of preference in simultaneous choice tests and the extent to which oviposition rate declined when the preferred host was absent. The results are consistent with the hypothesis that butterflies which lay their eggs singly will accept non-preferred hosts for oviposition more readily than cluster egg-layers.     

Biogeography and phenology of oviposition preference and larval performance of <Emphasis Type="Italic">Pieris virginiensis</Emphasis> butterflies on native and invasive host plants

In invaded environments, formerly reliable cues might no longer be associated with adaptive outcomes and organisms can become trapped by their evolved responses. The invasion of Alliaria petiolata (garlic mustard) into the native habitat of Pieris virginiensis (West Virginia White) is one such example. Female butterflies oviposit on the invasive plant because it is related to their preferred native host plant Cardamine diphylla (toothwort), but larvae are unable to complete development. We have studied the impact of the A. petiolata invasion on P. virginiensis butterflies in the Southeastern USA by comparing oviposition preference and larval survival on both plants in North Carolina (NC) populations without A. petiolata and West Virginia (WV) populations where A. petiolata is present. Larval survival to the 3rd instar was equally low in both populations when raised on A. petiolata. Mean oviposition preference on the two plants also did not differ between populations. However, we found a seasonal effect on preference between early and late season flights within WV populations. Late season females laid 99% of total eggs on A. petiolata while early season females utilized both host plants. Late season females were also less likely to lay eggs than early season females. This change in preference toward A. petiolata could be driven by the early senescence of C. diphylla and suggests a seasonal component to the impact of A. petiolata. Therefore, the already short flight season of P. virginiensis could become further constrained in invaded populations.     

Bayesian inference supports the host selection hypothesis in explaining adaptive host specificity by European bitterling

Generalist parasites have the capacity to infect multiple hosts. The temporal pattern of host specificity by generalist parasites is rarely studied, but is critical to understanding what variables underpin infection and thereby the impact of parasites on host species and the way they impose selection on hosts. Here, the temporal dynamics of infection of four species of freshwater mussel by European bitterling fish (Rhodeus amarus) was investigated over three spawning seasons. Bitterling lay their eggs in the gills of freshwater mussels, which suffer reduced growth, oxygen stress, gill damage and elevated mortality as a result of parasitism. The temporal pattern of infection of mussels by European bitterling in multiple populations was examined. Using a Bernoulli Generalized Additive Mixed Model with Bayesian inference it was demonstrated that one mussel species, Unio pictorum, was exploited over the entire bitterling spawning season. As the season progressed, bitterling showed a preference for other mussel species, which were inferior hosts. Temporal changes in host use reflected elevated density-dependent mortality in preferred hosts that were already infected. Plasticity in host specificity by bitterling conformed with the predictions of the host selection hypothesis. The relationship between bitterling and their host mussels differs qualitatively from that of avian brood parasites.     

Conserved oviposition preferences in alpine leaf beetle populations despite host shifts and isolation

Abstract.  1. Choosing the plant on which to lay their eggs is the last act of care that most female herbivorous insects bestow upon their offspring. These decisions play a pivotal role in insect–plant interactions, placing host preference under strong selection and contributing to the diversity of phytophagous insects as one of the first traits to adapt to new hosts.
2. This study presents a test of whether extreme isolation and exposure to different host plants can produce intra-specific divergence in oviposition preference in alpine insects. Geographic variation should impose selection to fine-tune host plant ranking and specificity to the plants normally encountered, to avoid wasting time during the very limited reproductive season experienced at high altitudes.
3. Beetles from five populations of Oreina elongata differing in host availability were offered three natural hosts: Cirsium spinosissimum , Adenostyles alliariae , and Adenostyles glabra . A novel application of a continuation ratio model (logistic regression) was made to sequential no-choice experiments, combined with quasi-likelihood analysis of multiple-choice experiments.
4. The results show little geographic variation in host plant choice: all populations strongly preferred Cirsium in multiple-choice trials, and in no-choice experiments laid around 47% of their remaining eggs during each stage, almost regardless of the host present.
5. Enemy-free space seems to explain the preference for Cirsium , but isolation and exposure to different plants has clearly not caused local adaptation in host plant ranking or specificity. Reasons for this conservatism despite divergence in other characteristics are discussed.     

Host species preferences by bitterling, Rhodeus sericeus, spawning in freshwater mussels and consequences for offspring survival

Two hypotheses have been advanced to explain the evolution of host responses to parasites: the arms race-evolutionary lag and equilibrium hypotheses. We investigated predictions from these hypotheses based on interspecies host preferences and adaptations in an obligate spawning relationship between a freshwater fish, the European bitterling (Cyprinidae) and four species of freshwater mussels (Unionidae), which the fish use as hosts for their eggs. We found a significant trend in preference by the fish for mussels in the following order: Unio pictorum, U. tumidus, Anodonta anatina and A. cygnea. Male and female bitterling both showed this ranking and the clutch sizes deposited into each species also followed this trend. These host preferences proved to be adaptive in terms of egg ejection, which was lowest in the most preferred species (U. pictorum). Furthermore, these hierarchical host preferences were flexible, as females switched species when individuals of the preferred species ejected a greater number of eggs. The similarity in mussel defences between the U.K. population and a European population of ancient sympatry suggests that the absence of a defence in some mussel species may not be due to evolutionary lag. Mussel ejection behaviour may have reached an evolutionary equilibrium in each host species, or alternatively the fish may have evolved adaptive preferences that coincide with generalized mussel responses to foreign objects in their gills. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Gene flow between alien and native races of the holoparasitic angiosperm Orobanche minor (Orobanchaceae)

The holoparasitic angiosperm Orobanche minor parasitizes a diverse range of flowering plants from at least 16 orders in both the monocots and eudicots. However, populations of O. minor show host specificity at a local level. Our previous work identified the potential for host specificity to act as a catalyst for genetic divergence among populations of O. minor. Here we have extended this investigation by sampling populations from multiple hosts, across a broad geographic range. Sequence characterised amplified region (SCAR) data identified an exotic host-generalist lineage and a native host-specialist lineage of O. minor, suggesting genetic structure in this species is defined by both host specificity and geography. In addition, host-range overlap, discordant tree topologies, and cryptic morphology indicate the presence of gene flow between alien races and endemic populations. Therefore, repeated introductions of alien races of O. minor from disparate sources leading to introgression with native populations, and cryptic race formation, seem to have contributed to the taxonomic confusion associated with this species. We speculate that radiations associated with broad host range and divergent host ecologies may have promoted the unusually wide geographic distribution and diversification of this species. Finally, evidence of multiple shifts to exotic hosts, coupled with the predicted northward shift in climatic suitability, identify the potential for range expansion in alien races of O. minor, which may threaten nationally scarce native taxa with genetic assimilation. Our phylogenetic analysis provides a framework for identifying host races in Orobanche with a view to setting conservation priorities.     

Population level correlation between pre-alighting and post-alighting host plant preference in the Glanville fritillary butterfly

1. In many populations of the Glanville fritillary butterfly Melitaea cinxia, ovipositing females exhibit a post‐alighting preference for one of the potential host plant species available. The work reported here aimed to establish whether females with different post‐alighting preferences can discriminate between their host plant species prior to alighting, and whether pre‐alighting and post‐alighting preferences are correlated at the population level. 2. Alighting and oviposition events were recorded for groups of females from six populations in greenhouse and field experiments. 3. Landing frequencies did not change with experience, indicating that M. cinxia females did not learn from previous encounters with host plants. 4. Females from populations exhibiting post‐alighting preference searched efficiently for their host plants in the sense that they landed mainly on the species on which they oviposited predominantly. Pre‐alighting and post‐alighting preferences were correlated at the population level. 5. The correlation between pre‐alighting and post‐alighting preferences helps to explain why in nature, where the host plants often occur in distinct patches, females are more likely to colonise habitat patches in which their preferred host plant is abundant.     

The roles of adult and larval specialisations in limiting the occurrence of five species of Dacus (Diptera: tephritidae) in cultivated fruits

Summary The relative importance of adult preferences or specialisations of larval physiology in restricting the host range of five species of Dacine fruit flies (Diptera: Tephritidae) was examined, with particular emphasis on their utilization of cultivated fruits. The species; D. tryoni, D. jarvisi, D. cucumis, D. musae and D. cacuminatus differ widely in host range with D. tryoni being highly polyphagous while D. cacuminatus is virtually monophagous. Laboratory experiments showed that larvae of all species survived and developed in many cultivated fruits in which the specialists never occur in the field. By contrast the oviposition preferences and specificity of adult females differed widely between species. Female D. tryoni oviposited in most species of fruit. The specialised species; D. cucumis, D. musae and D. cacuminatus strongly preferred their usual hosts and would not oviposit in novel fruits even in the absence of the preferred host. In contrast, D. jarvisi consistently preferred its main native host but when this was not offered readily accepted cultivated fruits. These differences in preference are consistent with the pattern of infestation displayed by each species in the field. The study indicate that, in general, the occurrence of these species of Dacus in cultivated fruits is constrained more by the behavioural preferences of adult females than by larval specialisations. A genetic change in some aspect of host recognition or acceptance would be necessary for the specialised species to regularly infest cultivated fruits though no change in larval characteristics may be needed. As the types and concentrations of defensive secondary compounds may differ between native and cultivated fruits this conclusion cannot be extended to host shifts among native fruits.     

Host-discrimination by <Emphasis Type="Italic">Phymastichus coffea</Emphasis>, a parasitoid of the coffee berry borer

Phymastichus coffea (LaSalle) (Hymenoptera: Eulophidae) is an African endoparasitoid of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) that has been introduced to several countries to control this important pest. In the present study we performed a series of laboratory experiments in order to determine if there was evidence of host discrimination and superparasitism in P. coffea. Our choice experiments demonstrate that P. coffea females showed significant preference to attack unparasitized hosts, rather than those parasitized conspecifically. No significant preferences were detected in self-specific attacks between parasitized hosts and the healthy ones. A further dissection of hosts sequentially attacked either self or conspecifically, revealed that there were no more than two eggs per host. As P. coffea is a species that normally allocates two eggs per host in a single attack, we assumed that females were able to attack already parasitized hosts, but they did not lay eggs in them. Based on this fact, we conclude that there is a host discrimination ability in P. coffea females. With respect to the superparasitism by P. coffea using non-choice experiments, there was no significant difference between self-specific or conspecific attacks with respect to the control after one or two successive attacks. Conspecific attacks yielded the largest numbers of eggs after 3rd, 4th and 5th attacks and significant differences were found between this treatment and the control. The maximum number of eggs found in a single host was six individuals (conspecific treatment). These results confirmed that P. coffea usually laid two eggs per host; however, when there are no hosts available, conspecific attacks can result in the superparasitism in this species.     

Choice versus no-choice test interpretation and the role of biology and behavior in parasitoid host specificity tests

The need to improve methods and interpretation of host specificity tests for arthropod natural enemies has been clearly identified, yet there remains a paucity of empirical evidence upon which to base recommendations. Factors influencing test outcomes and the mechanisms underlying them must be understood so they can be controlled, and test results can be interpreted correctly. In this study, an established exotic host/parasitoid system was used to assess the outcomes and predictive accuracy of no-choice compared to paired choice tests within small laboratory arenas. Host acceptance by two egg parasitoids, Enoggera nassaui and Neopolycystus insectifurax (Pteromalidae), was interpreted in light of percent parasitism, offspring sex ratios and observed parasitoid behavior. No-choice tests showed that the four host species, Paropsis charybdis, Dicranosterna semipunctata, Trachymela catenata and Trachymela sloanei (Coleoptera: Chrysomelidae) were within the physiological host ranges of both parasitoids. The results of paired choice tests with the first three species supported this interpretation, with two exceptions. Trachymela catenata eggs were not accepted by E. nassaui and were accepted significantly less often by N. insectifurax when compared to no-choice tests. Both test designs predicted that D. semipunctata is within the ecological host range of the two parasitoid species, whereas field evidence suggests this is a false positive result. Percent parasitism of all hosts was higher in no-choice compared to choice tests and was predictive of rank order of host preference in choice tests. Presence of the most preferred host did not increase attack on lower ranked hosts. Offspring sex ratios of E. nassaui were independent of host preference. In contrast, N. insectifurax allocated more females to P. charybdis and mostly males to D. semipunctata and T. catenata. The results support our assertion that both no-choice and choice tests along with detailed behavioral studies should be conducted for correct interpretation of pre-release host specificity tests. This will enable more accurate predictions of parasitoid host ranges and risks parasitoids may pose to non-target organisms in the field.     

寄主大小及寄生顺序对蝇蛹佣小蜂寄生策略的影响

寄主大小模型认为寄生蜂后代性比与寄主大小相关,寄生蜂倾向于在大寄主上产出更多雌性后代,在小寄主上产出更多雄性后代.探讨了以家蝇蛹为寄主时,蝇蛹佣小蜂后代产量和性比变化;单次寄生情况下,寄主大小及寄生顺序对寄生蜂后代性比等影响.结果表明,蝇蛹佣小蜂的产卵期为(8.93±3.34)d,单头雌蜂能产雌性后代(34.11±16.34)头和雄性后代(11.04±8.87)头,且雄性百分比为0.24±0.11.随成蜂日龄的增大,寄生蜂产生雄性后代的比率显著增加.蝇蛹佣小蜂在寄生家蝇蛹时,会优先选择寄生个体较大的蛹;在单次寄生的情况下,蝇蛹佣小蜂倾向于在较大的家蝇蛹内产出更多的雌性后代.