Optimal Oviposition Theory Research Articles

Comparative demography, population projection, functional response and host age preference behavior of the parasitoid Goniozus legneri on two lepidopterous insect hosts

BackgroundThis study was conducted to investigate life table characteristics of the parasitoid species, Goniozus legneri Gordh (Hymenoptera: Bethylidae), a major gregarious larval ecto-parasitoids of the carob moth, Ectomyelois ceratoniae Zeller (Lep.: Pyralidae). Demographic parameters of G. legneri reared on two hosts, the carob moth and the flour moth, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae), were studied under laboratory conditions using age-stage, two-sex life table. Host stage preference and the functional response of this parasitoid were also determined.ResultsThe duration of the immature period, adult pre-ovipositional period and total pre-ovipositional period of G. legneri reared on E. kuehniella was significantly longer than that of those reared on E. ceratoniae, while fecundity and ovipositional days of the wasp were greater/longer in females reared on E. ceratoniae. There were also significant differences in intrinsic and finite rates of increase and mean generation time between wasp parasitoid reared on two hosts. Moreover, population projection indicated that the G. legneri population can grow swifter when reared on E. ceratoniae than on E. kuehniella. Based on the experiments conducted to determine the larval stage preferences of G. legneri, for both hosts, larger larvae were more preferred stages compared to smaller ones, thereby fulfilling the optimal oviposition theory. The functional responses of G. legneri to different population densities of E. kuehniella two last instar larvae were determined as type III at 25 °C and 60% RH.ConclusionThe results offer valuable information on some life history attributes of G. legneri. Although G. legneri performed better on E. ceratoniae larvae than on E. kuehniella, as the use of E. ceratoniae larvae as the main host in rearing of G. legneri might be a laborious process and can increase the production costs, E. kuehniella can be used as an alternative host. Further studies are required under greenhouse and field conditions for effective use of this biocontrol agent against the carob moth.

Effect of Temperature on Oviposition Behavior and Egg Load of Blow Flies (Diptera: Calliphoridae).

Making optimal oviposition decisions is especially important for female carrion colonizing insects whose larvae often depend on ephemeral resources. Optimal oviposition theory predicts that females should exhibit behaviors that will maximize the performance of their offspring. Oviposition can be influenced by a variety of factors, including temperature. The aim of this study was to investigate the effects of temperature on the oviposition behavior and egg load of two blow fly species native to southern Ontario: Phormia regina Meigen, and Lucilia sericata Meigen (Diptera: Calliphoridae). Using fetal pig carcasses as an oviposition substrate, we assessed the length of time until the first oviposition event, preferred oviposition sites, and the total number of eggs oviposited. For each of the two species, five different temperature treatments ranging from 15 to 35°C were used. Temperature influenced time to the first oviposition event, as well as the number of eggs deposited by L. sericata and P. regina. As temperature increased, oviposition occurred faster with more eggs deposited for these two species. Female P. regina, in particular, demonstrated a higher egg load with increasing temperature. Differences in optimal temperatures for reproduction, including egg load and oviposition, may be a mechanism driving seasonal temporal resource partitioning leading to species coexistence utilizing ephemeral resources.

Does host plant quality affect the oviposition decisions of an omnivore?

Optimal oviposition theory predicts a positive relationship between female preference for oviposition hosts and offspring performance. Interspecies effects on oviposition preference have been widely investigated, especially for herbivores. However, intraspecies variation, such as nitrogen content, might also influence female preference for oviposition hosts and subsequent offspring performance. To evaluate this possibility, we investigated the oviposition preference of a zoophytophagous omnivore and the development and survival of its nymphs on a single species of host plant that varied in nitrogen content. In choice and no-choice experiments without prey, female omnivores were allowed to oviposit on plants that had been fertilized using 4 rates of nitrogen fertilizer (39, 78, 156, and 311 mg/L nitrogen) for 72 h. After 72 h, the most females were found on tomato plants receiving high concentrations of nitrogen fertilizer and more eggs were laid on those plants. First instar nymphs developed more rapidly on high-nitrogen plants and third instar nymphs developed faster on low-nitrogen plants. Plant nitrogen did not affect nymph survival to the adult stage, or the probability of survival over time. Although female omnivores did discriminate between potential oviposition hosts based on plant nitrogen, their choices did not significantly impact nymph development or survival. This is the first study to show that intraspecies variation in nitrogen content between plants affects the oviposition preference of female omnivores, but not offspring performance.

Does insect mother know under what conditions it will make their offspring live?

According to the optimal oviposition theory, the larval success of insects depends on the oviposition site selection by females. Females are expected to choose a site with many resources and few competitors or predators to allow the best performance for their progeny, assuming that "mother knows best." However, this is not systematically observed. The Aphidoletes aphidimyza larvae are generalist aphid predators and females consequently lay their eggs near or inside aphid colonies. The goal of this study was to investigate the impact of intraspecific competition on oviposition behavior of A. aphidimyza females. First, we counted the number of eggs laid by a female on a leaf with 20 aphids, in the presence of 0, 2, 4, or 6 conspecific eggs or in the absence of eggs but in presence of 3 virgin females. The same experiment was also performed under choice condition with 2 oviposition sites. Our results show that the presence of low densities of conspecific eggs, or the presence of conspecific females, have no significant impact on the number of eggs laid by A. aphidimyza females. One of the hypotheses advanced to explain these results is the advantages of conspecifics presence. At low densities, the presence of eggs on an oviposition site can indicate the suitability of the site for the females. The conspecific presence can also insure a dilution effect against predator and increase the presence of potential mating partners for this monogenic species.

Spatial analysis ofListronotus maculicollisimmature stages demonstrates strong associations with conspecifics and turfgrass damage but not with optimal hosts on golf course fairways

For insects that develop on few hosts and/or have immobile immature stages, optimal oviposition theory suggests that females should seek high-quality hosts that maximize larval development and reduce competition from conspecifics. However, there is a growing amount of evidence that suggests female choice may often be at odds with their offspring's development. Listronotus maculicollis (Kirby) (Coleoptera: Curculionidae) is a serious pest of golf course turfgrass in eastern North America. The weevil develops on few hosts and demonstrates improved fitness traits when developing on Poa annua L. (Poaceae). However, previous population studies observed either weak or no correlations between the spatial dispersion of larval populations and P. annua in the field. In this study, populations on three golf course fairways were monitored over a 4-year period (2009–2012) to determine whether the lack of spatial associations between preferred hosts and immatures was a result of spatial scale or the density and distribution of conspecifics. Spatial Analysis by Distance IndicEs (SADIE) was used to characterize the spatial dispersion of populations of individual stages (larvae and pupae), P. annua, and turfgrass damage. Life stages were aggregated in each observation, independent of population density or the spatial dispersion of hosts. The distribution of consecutive and non-consecutive immature stages was found to be correlated in all years, suggesting that females do not avoid patches already occupied by conspecific eggs. Surprisingly, significant spatial associations were not found between larvae and P. annua when the host plant was relatively abundant. Hence, multiple mechanisms may drive L. maculicollis oviposition site-selection behavior, and a flexible strategy may allow the weevil to persist in areas where P. annua is not the dominant species. Future studies are required to determine what other factors (e.g., natural enemy-free space, egg or time limitations) influence oviposition behavior.

Specialist pollinating seed predator exhibits oviposition strategy consistent with optimal oviposition theory

Abstract The outcome of mutualistic interactions depends on the costs and benefits for each of the partners, which have been shown to be both context‐ and species‐dependent. This phenomenon is seen in the interactions between plants in the genus Silene and moths in the genus Hadena. In this study, the interaction between native North American species Silene stellata and Hadena ectypa is examined to understand the factors that influence female H. ectypa oviposition decisions, a behaviour that influences both herbivore and plant fitness. While most studies focus on oviposition preference between different host plant species, here it is shown that for a specialist pollinating seed predator, oviposition preference occurs within a host species (and even within a plant) based upon individual flower age and pollination status. Female H. ectypa preferentially visited and oviposited on young flowers and flowers that were unpollinated. Larvae also preferred to feed on young fruits. Female H. ectypa oviposition choice was consistent with optimal oviposition theory, as oviposition preference was correlated with larval feeding preference and not just adult visitation preference.

Host preference and nymph performance of B and Q putative species of Bemisia tabaci on three host plants

Host selection is central to understanding the evolution of the interaction between herbivorous insects and host plants. Most studies on host selection of herbivorous insects are focused on the optimal oviposition theory which posits that the herbivores preferentially oviposit on plants that provide optimal conditions for offspring development (preference–performance hypothesis). However, the positive correlation between female oviposition preference and offspring performance is not always observed. Here, we determined the relationship between whitefly settling and oviposition preference and nymph performance of B and Q putative species of Bemisia tabaci on three host plants, cotton Gossypium hirsutum L., tomato Lycopersicum esculentum Mill, and poinsettia Euphorbia pulcherrima Wild. We further investigated whether nutritional and defensive chemistry of the three host species shaped whitefly settling and oviposition preference of both putative species. Foliar chemistry differed significantly among the three host species. Compared to cotton and tomato foliage, poinsettia foliage was 8 % lower in nitrogen, 60 % higher in carbohydrate, and 90 % higher in phenolic compounds, respectively. When given a choice, B and Q putative species of B. tabaci preferred settling on nutritionally superior tomato, whereas both putative species preferentially oviposited on nutritionally inferior poinsettia. Nymph survivorship of B and Q putative species was substantially reduced and nymph developmental duration (egg-to-adult) was markedly prolonged on poinsettia relative to those reared on cotton and tomato. Therefore, our results are consistent with the optimal foraging theory, rather than the optimal oviposition theory. Females of B and Q putative species of B. tabaci preferentially ovipositing on poinsettia may be a trade-off between nymph performance and the avoidance of natural enemy.

Trade-offs of host use between generalist and specialist Helicoverpa sibling species: adult oviposition and larval performance

Much attention has been paid to the question of the relative importance of female behaviour versus larval feeding capacities in determining the host range of herbivorous insects. Host-use trade-offs displayed by generalist and specialist sister species of the genus Helicoverpa were evaluated to examine the relationship between maternal choice and offspring performance. The prediction of optimal oviposition theory, that females will choose to lay eggs on plants on which their offspring perform best as larvae, was tested by measuring oviposition preference and larval performance of Helicoverpa armigera and H. assulta on tobacco, sunflower, and hot pepper. These two measures were more highly correlated in the specialist H. assulta. Both species exhibited the same oviposition preference ranking: tobacco > sunflower > hot pepper. H. armigera larvae preferred sunflower, followed by tobacco and hot pepper; while H. assulta larvae preferred tobacco to sunflower and hot pepper, consistent with their mothers' oviposition preference. Duration of the total period from egg to adult emergence for each species was significantly shorter on the host plant preferred by the larvae. H. assulta had shorter larval duration and higher relative growth rate than H. armigera on tobacco and hot pepper, and vice versa for sunflower, indicating species differences in host utilization. Thus, while only the specialist H. assulta displayed the predicted optimal oviposition pattern, females of both species show the least preference for the plant on which their offspring perform worst. Selection for optimal oviposition may be stronger on the specialist, which has fewer choices and lower lifetime fecundity than the generalist.

Relationship Between Behavior and Physiology in an Invasive Pest Species: Oviposition Site Selection and Temperature-Dependent Development of the Oriental Fruit Moth (Lepidoptera: Tortricidae)

Oviposition site selection is crucial for the reproductive success of a herbivore insect species with relatively sedentary larvae. The optimal oviposition theory, i.e., the preference-performance hypothesis, has thus far mainly been tested with a focus on nutritional quality of the host. This study investigates whether female oriental fruit moth Grapholita (Cydia) molesta choose a microhabitat for oviposition characterized by a temperature range within which their offspring perform best. Thermal preferences of females during oviposition were assessed in a circular temperature gradient arena. Offspring performance and survival were assessed under different constant temperature conditions. Females preferred oviposition sites of approximately 30 degrees C over lower and higher temperatures. At this temperature, egg, larval, and pupal development was significantly faster than at 22 and 25 degrees C, and larval development was also faster than at 33 degrees C. At 30 degrees C and at the lower temperatures tested, survival of eggs and larvae was significantly higher than at 33 degrees C, whereas development was precluded at 35 degrees C. Furthermore, female pupal weight attained at 30 and 33 degrees C exceeded that reached at the lower temperatures tested. Considering the potentially reduced predation risk caused by the shorter developmental time of eggs and larvae, the laboratory data suggest that this species maximizes its fitness by selecting a thermally optimal environment for its offspring, supporting the optimal oviposition theory. Conversely, it is known that the codling moth (C. pomonella) lacks a mechanism to avoid temperatures lethal to progeny development, which may reflect the differences in geographic ranges of these tortricids.

Use of odours by Cycloneda sanguinea to assess patch quality

AbstractAdult ladybirds are likely to encounter various species of prey when foraging for oviposition sites. Optimal oviposition theory predicts that females should lay eggs in those sites that are the most suitable for offspring development. Therefore, factors that directly affect offspring mortality, such as the presence of predators and food, are expected to play an important role in the assessment of patch profitability by ladybird predators. Using a Y‐tube olfactometer, we tested whether the predatory ladybird Cycloneda sanguinea L. (Coleoptera: Coccinellidae) can use volatile cues to assess patch profitability and avoid predator‐rich patches. We assessed the foraging behaviour of C. sanguinea in response to odours associated with tomato plants infested with a superior prey, Macrosiphum euphorbiae Thomas (Homoptera: Aphididae), and with an inferior prey, Tetranychus evansi Baker and Pritchard (Acari: Tetranychidae), in the presence or absence of the heterospecific predator Eriopis connexa Mulsant (Coleoptera: Coccinellidae). Females of C. sanguinea significantly preferred plants infested by M. euphorbiae to plants infested by T. evansi and avoided odours emanating from plants on which E. connexa females were present. Our results show that C. sanguinea use volatile cues to assess patch profitability and to avoid patches with heterospecific competitors or intraguild predators.

Females and Larvae of a Geometrid Moth, <I>Cleorodes lichenaria</I>, Prefer a Lichen Host That Assures Shortest Larval Period

Optimal oviposition theory predicts that females prefer a host that assures the highest offspring Þtness. I compared the host preference of females and larvae of a lichenivorous moth, Cleorodes lichenaria, and subsequent larval performance on host lichens with laboratory experiments and Þeld observations. Both females and larvae preferred Ramalina fraxinea and Ramalina farinacea over Xanthoria parietina and Parmelia sulcata. Larvae reached the pupal stage faster on Ramalina species than on other lichens, whereas other Þtness parameters including larval survival and pupal size did not differ between the lichen species. Interestingly, growth rates before overwintering were higher on P. sulcata and X. parietina than on Ramalina species, whereas after overwintering, the situation was reversed. The results of this study support the preferenceÐperformance hypothesis. Females clearly preferred host lichens that ensure the shortest developmental period at the expense of higher growth rates at the beginning of the larval period. Moreover, ecological and/or evolutionary factors in addition to femalesO oviposition in host selection of C. lichenaria seem to be important. Because more larvae were found on Ramalina species than expected according to the oviposition pattern of females, Þnal host selection is at least partially determined by larval behavior. It is also suggested that the physical and chemical properties of the hosts may provide a basis for enemy-free space for larvae.

A tritrophic analysis of host preference and performance in a polyphagous leafminer

AbstractThe optimal oviposition theory predicts that oviposition preferences of phytophagous insects should correlate with host suitability for their offspring. As plant host suitability depends not only on its quality as food, but also on its provision of enemy‐free space, we examined the relationship between adult host preference and offspring performance for the leafminer Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) on various host plants, considering also the interaction with natural enemies. Preference and offspring performance were assessed through observational field data and laboratory experiments in central Argentina. Field data suggested a positive host preference – performance linkage, as the leafminer attained larger body size on the crops where it was more abundant. Laboratory trials supported these results: Vicia faba L. (Fabaceae) was the preferred host in the laboratory as well as in the field, performance of L. huidobrensis being also best on this host, with highest survival rates and shortest development time. The actively feeding larval stage showed the largest plant‐related effects. Higher overall parasitism rates were found on plants from which smaller leafminers were reared, reinforcing the preference–performance linkage. On the other hand, the main parasitoid Phaedrotoma scabriventris Nixon (Hymenoptera: Braconidae) reached larger body size, and caused higher mortality rates on crops where the leafminer was larger. Changes in abundance of particular parasitoid species could thus modify overall parasitism trends.

Should aphidophagous ladybirds be reluctant to lay eggs in the presence of unsuitable prey?

AbstractThe quality of different species of aphids as food for aphidiphagous ladybird beetles varies greatly. The optimal oviposition theory predicts that a female should lay eggs preferentially in patches of suitable prey and should be reluctant to oviposit in patches of less suitable prey. A no‐choice experiment was used to test whether aphids (Homoptera: Aphididae) of different suitability influence the oviposition behaviour of the two‐spot ladybird beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae). The results indicate that A. bipunctata females are not more reluctant to lay eggs in the presence of moderately suitable compared to highly suitable aphids. However, females laid fewer eggs in the presence of toxic aphids.

Optimal foraging shapes host preference of a polyphagous leafminer

Abstract. 1. Most research on host selection by arthropods is based on optimal oviposition theory. This theory, also called the oviposition preference–offspring performance hypothesis, predicts that a female will choose those hosts for oviposition on which larvae perform best. Recent studies suggested, however, that optimal foraging by adults, or the quality of the host for adult performance, might also influence host choice.2. This study investigated whether host preference of the polyphagous leafminer Liriomyza trifolii is determined by optimal foraging and/or optimal oviposition.3. Female realised fecundity correlated nearly perfectly with feeding and oviposition preference of L. trifolii. The relationships between host preference and the offspring performance measures were always weaker. Hosts optimal for adult nutrition were also optimal for offspring performance but not vice versa. Hence, it was concluded that optimal foraging shapes feeding and oviposition preference of L. trifolii as this is the best strategy in order to maximise female fitness.

Covariance of preference and performance on normal and novel hosts in a locally monophagous and locally polyphagous butterfly population.

Covariance between preference and performance was quantified for Papilio glaucus strains derived from a locally monophagous Florida population and a locally polyphagous Ohio population. I used two-choice assays to assess relative host preferences of mothers for plant species that represent reciprocal normal and novel hosts for each population (i.e., Liriodendron tulipifera and Magnolia virginiana) and a split-brood design to quantify relative performance of their progeny on each host. Covariance between preference and proxies of performance was detected independently within each population, which is a level of genetic structure at which such covariance has rarely been documented. These results support the hypothesis that preference-performance covariance can exist in populations that have no obvious internal host-associated structure. In the Ohio strain, all proxies of performance (larval duration, pupal mass, relative growth rate, and survival) were significantly correlated with relative preference for the normal host, L. tulipifera. In the Florida strain, however, only pupal mass was correlated with maternal preference, and this correlation was not in the direction expected. Progeny that attained the heaviest mass were derived from mothers that preferred L. tulipifera, the locally rare host. The nature of the preference-performance links was not in the manner predicted by conventional optimal oviposition theory, whereby host-associated tradeoffs have been considered an implicit element. Relative performance was congruent across hosts, regardless of whether mothers preferred L. tulipifera, M. virginiana, or neither host. After considering possible genetic and nongenetic explanations that could account for preference-performance covariance in P. glaucus, I conclude that this covariance has a genetic basis. Likely, multiple genetic control mechanisms (e.g., pleiotropy and co-adaptation) integrate at the level of different trait combinations and/or a particular trait combination to generate observed patterns.

Integrating optimal foraging and optimal oviposition theory in plant–insect research

The current approach for studying host selection by phytophagous insects is mainly based on optimal oviposition theory, i.e. the preference–performance hypothesis. Almost no attention has been given to optimal foraging theory. However, recent papers and additional evidence given in this work illustrate that also optimal foraging may shape host preference patterns of phytophagous insects. Therefore and because optimal foraging and optimal oviposition may oppose conflicting needs to phytophagous insects, we plea for an integration of optimal foraging and optimal oviposition in plant–insect research. We argue how this may improve our understanding of plant–insect interactions.

Optimal Oviposition by the Corn Earworm (Lepidoptera: Noctuidae) on Whorl-Stage Sweet Corn

Commercial fields of sweet corn in coastal southern California were sampled for corn earworm, Heliothis zea (Boddie), eggs in 1986 and 1987. Staggered planting schedules within each study site produced fields of varying maturity that overlapped in occurrence. Using stepwise regression, we quantified the dependence of egg density on field size, adult population level as estimated with pheromone traps, and field maturity as estimated by plastochron index. Also included were three variables associated with the probability of female moths finding a more suitable host: the hectares of older corn available, distance to the closest older cornfield, and the mean distance to all older cornfields. We found egg density to be significantly related to field maturity and the distance to the closest older cornfield. In 1987, when the average distance between fields was less than in 1986, egg density was more closely associated with field maturity and, therefore, host suitability. These results are discussed in relation to optimal oviposition theory.