Female Oviposition Preference Research Articles

Effects of soil on the development, survival, and oviposition of Culex quinquefasciatus (Diptera: Culicidae) mosquitoes

BackgroundWater quality is known to influence the development and survival of larval mosquitoes, which affects mosquito-borne pathogen transmission as a function of the number of mosquitoes that reach adulthood and blood feed. Although water properties are known to affect mosquito development, few studies have investigated the link among soil properties, water quality, and mosquito development. Given the large number of ground-breeding mosquito species, this linkage is a potentially important factor to consider in mosquito ecology. In this study, we explored the effects of different soils on multiple life history parameters of the ground-breeding mosquito species Culex quinquefasciatus (Diptera: Culicidae).MethodsCx. quinquefasciatus larvae were reared in water combined with different soil substrates (sandy, silt, or clay loam textures) at increasing soil to water volume ratios, with and without the addition of organic matter (fish food). Gravid mosquitoes were offered different soil–water extracts to investigate soil effects on oviposition preference.ResultsWithout the addition of organic matter, larval survival and development differed significantly among waters with different soil textures and volumes of substrate. Mosquitoes in water with clay loam soil survived longer and developed further than mosquitoes in other soil waters. Larvae survived for longer periods of time with increased volumes of soil substrate. Adding organic matter reduced the differences in larval survival time, development, and pupation among soil–water extracts. Adult female mosquitoes oviposited more frequently in water with clay loam soil, but the addition of organic matter reduced the soil effects on oviposition preference.ConclusionsThis study suggests soil composition affects larval mosquito survival and development, as well as the oviposition preference of gravid females. Future studies could differentiate abiotic and biotic soil features that affect mosquitoes and incorporate soil variation at the landscape scale into models to predict mosquito population dynamics and mosquito-borne pathogen transmission.Graphical

An Odorant Receptor Expressed in Both Antennae and Ovipositors Regulates Benzothiazole-Induced Oviposition Behavior in Bactrocera dorsalis.

The oriental fruit fly,Bactrocera dorsalis (Hendel), is a notorious pest of fruit crops, causing severe damage to fleshy fruits during oviposition and larval feeding. Gravid females locate suitable oviposition sites by detecting the host volatiles. Here, the oviposition preference of antenna-removed females and the electrophysiological response of ovipositors to benzothiazole indicated that both antennae and ovipositors are involved in perceiving benzothiazole. Subsequently, odorant receptors (ORs) expressed in both antennae and ovipositors were screened, and BdorOR43a-1 was further identified to respond to benzothiazole using voltage-clamp recording. Furthermore, BdorOR43a-1-/- mutants were obtained using the CRISPR/Cas9 system and their oviposition preference to benzothiazole was found to be significantly altered compared to WT females, suggesting that BdorOR43a-1 is one of the important ORs for benzothiazole perception. Our results not only demonstrate the important role of antennae and ovipositors in benzothiazole-induced oviposition but also elucidate on the OR responsible for benzothiazole perception in B. dorsalis.

Spoilt for choice: Do female mosquitoes experience choice overload when deciding where to lay eggs?

Animals live in complex natural environments. Based on the effects of natural selection, theory on animal information use says that it is optimal for animals to make "rational" decisions, i.e., to choose alternatives which maximize fitness gains, irrespective of the number of alternatives presented to them. Yet, animals commonly make seemingly “irrational” choices in the face of complex and variable stimuli that challenge their cognitive machinery. Here, we test the choice overload hypothesis – decision-making is negatively affected when animals experience an overload of choice. Using simultaneous-choice trials that varied in choice repertoire size, we examined oviposition site selection behaviour in Aedes aegypti towards larval predators, the nymphs of Bradinopyga geminata. Based on the underlying fitness trade-offs of oviposition decision-making, we predicted that female oviposition preference would be weaker and variation in this response would be higher in complex, multiple-choice trials than in binary-choice trials. In partial support of our hypothesis, oviposition preference was weaker in the complex, multiple-choice trials, but the variation in response depended on predator density, and did not depend on choice repertoire size. We suggest that information overload can negatively affect certain aspects of animal decision-making, resulting in choices appearing as “irrational” if the complexity of the decision-making context is not incorporated. Information overload can potentially lead to alternative strategies, such as bet-hedging or decision-making with reduced discrimination.

Effect of various odour attractants on egg-laying activity of black soldier flies (Hermetia illucens)

Abstract The black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), is a cosmopolitan fly. Its feeding behaviour, high productivity and the high value of its larvae in macronutrients (mainly lipids and proteins) makes this species one of the promising candidates for large scale insect farming and organic waste management. The reproductive rate, female oviposition preference and oviposition attractants of H. illucens are understudied. A better knowledge of the attractants involved in oviposition site choice would help maximising black soldier fly reproductive success. The current study aims to compare the efficacy of four food attractants on the oviposition activity of H. illucens females. The trial was conducted in a cage (11 × 1.25 × 0.9 m) with a volume of 12.38 m3 and containing 83,610 adults (6750 adults/m3). The cages were placed in a rearing room where the conditions were: T = 28 ± 1 °C, RH = 70 ± 5%, photoperiod of 16 h light: 8 h dark and light intensity = 8140 Lux). The tested feeds included a rabbit feed, fish waste (sardine, sardinella, and anchovy waste), a mixture of tropical fruits (pineapple, banana, papaya and mango), and fresh cattle manure. The performance of each feed attractant was evaluated in terms of the mass of eggs laid on the laying medium. This study showed that fruit mixture is the most efficient attractant, followed by fresh cattle manure and fish waste while the rabbit feed was the least efficient. The results of this study can be used to optimise the reproduction of the black soldier fly.

A green leaf volatile, (Z)-3-hexenyl-acetate, mediates differential oviposition by Spodoptera frugiperda on maize and rice

BackgroundInsects rely on chemosensory perception, mainly olfaction, for the location of mates, food sources, and oviposition sites. Plant-released volatile compounds guide herbivorous insects to search for and locate their host plants, further helping them to identify suitable positions for oviposition. The fall armyworm Spodoptera frugiperda (S. frugiperda) was found to invade China in 2019 and has since seriously threatened multiple crops, particularly maize and rice. However, the chemical and molecular mechanisms underlying oviposition preference in this pest are not fully understood. Here, the oviposition preference of S. frugiperda on maize and rice plants was investigated.ResultsGC-EAD and GC–MS/MS techniques were used to identify the antennally active volatiles from maize and rice plants. The attraction and oviposition stimulation of identified components to female adults were tested in both laboratory and field settings. The odorant receptors (ORs) on female antennae were expressed in Xenopus oocytes, and their functions evaluated by RNAi. Ten and eleven compounds of maize and rice plants, respectively, were identified to possess electrophysiological activity from headspace volatiles. Among these compounds, (Z)-3-hexenyl-acetate specifically presented in maize volatiles was found to play a critical role in attracting females and stimulating oviposition compared to rice volatiles. Among the cloned ORs on the antennae of both sexes, SfruOR23 with highly female-biased expression mediated the responses of females to (Z)-3-hexenyl-acetate. Knockdown of SfruOR23 using RNAi markedly reduced the electrophysiological response of female antennae and oviposition preference to the compound.Conclusions(Z)-3-Hexenyl-acetate is a key volatile mediating the host and oviposition preference of S. frugiperda on maize. The olfactory receptor of (Z)-3-hexenyl-acetate was identified to be SfruOR23, which is mainly expressed in the antennae of S. frugiperda.

Hyphantria cunea (Drury) Showed a Stronger Oviposition Preference for Native Plants after Invading the Subtropical Region of China

Hyphantria cunea (Drury) (Lepidoptera: Erebidae) is an invasive alien species that is widely distributed in northern China. H. cunea now occurs for the first time in the subtropical areas of China. Despite the importance of identifying oviposition host plants to control the spread of H. cunea, it is not clear whether H. cunea has a new oviposition preference for plant hosts in the new habitat after invading the subtropical region. At the same time, whether the presence of new plant volatiles of new hosts in new habitats influences the oviposition host preference of H. cunea has not been studied. In this study, we investigated the oviposition host plant preferences of H. cunea in the subtropical region of China. In the presence of multiple potential host plants, we found, for the first time, that H. cunea preferred Carya illinoinensis, Morus alba, and Carya cathayensis for oviposition. Through the effects on plant volatiles and on the oviposition, ten volatile compounds with significant differences in relative abundance between five plants with different fitness levels were significantly correlated with the oviposition preference of females. Cis-Hex-3-en-1-ol, (E)-3-Hexen-1-ol, cis-3-Hexenyl acetate 1, and 3-Pentadiene,4-methyl, had a significant positive correlation with the adult oviposition preference. Our results provide an important research basis for the study of green prevention and control strategies of subtropical H. cunea in China.

Oviposition Preference of the American Hoverfly, Eupeodes americanus, between Banker Plants and Target Crops.

Assessing the oviposition preferences of predatory hoverflies is a key factor in the prediction of the success of these biological control agents against aphids in greenhouses, especially when using banker plant systems or in mixed-crop contexts. In this study, two aspects of the oviposition preferences of the American hoverfly, Eupeodes americanus (Wiedemann, 1830) (Diptera: Syrphidae), were evaluated. Firstly, the preference between the banker plant and the target crop was evaluated for three banker plant species (barley, finger millet, or corn) and two target crops (cucumber or pepper). Secondly, the preference between the same two target crops was assessed. Female oviposition preferences were evaluated via two-choice experiments using different plant/aphid systems. The results showed that, for the cucumber crops, the species of banker plant used drastically influenced the oviposition preference of the hoverfly, with a preference for barley over cucumber, cucumber over finger millet, and no preference between corn and cucumber. Unlike cucumber, when used with pepper, barley engendered a preference for the target crop. We conclude that the barley banker plant could be adequate for aphid control in pepper but not in cucumber crops. In a mixed-crop context, the American hoverfly had no preference between cucumber and pepper, which means it has the potential to protect both crops in a mixed-crop greenhouse context. This study shows that the banker plant system should be carefully chosen according to the crops/aphids present in the greenhouse to optimize the impact of the hoverfly as a biocontrol agent. Further work is required to confirm this choice of banker plant in semifield or field testing.

Simulating effects of agricultural intensification and climate change: Nitrogen fertilisation and drought stress decrease insect herbivore performance

Abstract Biodiversity is globally under pressure, and the current decline in insect biomass and diversity is likely caused by human activities. Key drivers of biodiversity loss include agricultural intensification and anthropogenic climate change. Nevertheless, a thorough understanding of potential interactions between both factors and the mechanisms underlying insect declines, in general, is still lacking. Here, the authors investigate the combined effects of nitrogen fertilisation and drought, as applied to host plants, on the preference and performance of the butterfly Lycaena tityrus. Individuals performed best on plants having received medium nitrogen levels, while performance was reduced by either a lack of or strong fertilisation, the former potentially caused by nitrogen limitation and the latter by increased concentrations of toxic allelochemicals. Female oviposition preference though was positively related to nitrogen fertilisation, resulting in a mismatch between preference and offspring performance at high nitrogen levels. Plant drought stress additionally reduced herbivore performance, and females appeared to suffer more from low‐quality food than males. Our results indicate that increasing nitrogen fertilisation, as applied in intensive agriculture, may substantially reduce host‐plant quality for insect herbivores, which may be exaggerated in the course of climate change due to the more frequent occurrence of droughts. Our study thus contributes to a better understanding of the mechanisms underlying human‐driven insect declines in agricultural landscapes and beyond.

Poleward increase in feeding efficiency of leafminer Stigmella lapponica (Lepidoptera: Nepticulidae) in a latitudinal gradient crossing a boreal forest zone.

Damage to plant communities imposed by insect herbivores generally decreases from low to high latitudes. This decrease is routinely attributed to declines in herbivore abundance and/or diversity, whereas latitudinal changes in per capita food consumption remain virtually unknown. Here, we tested the hypothesis that the lifetime food consumption by a herbivore individual decreases from low to high latitudes due to a temperature-driven decrease in metabolic expenses. From 2016 to 2019, we explored latitudinal changes in multiple characteristics of linear (gallery) mines made by larvae of the pygmy moth, Stigmella lapponica, in leaves of downy birch, Betula pubescens. The mined leaves were larger than intact leaves at the southern end of our latitudinal gradient (at 60°N) but smaller than intact leaves at its northern end (at 69°N), suggesting that female oviposition preference changes with latitude. No latitudinal changes were observed in larval size, mine length or area, and in per capita food consumption, but the larval feeding efficiency (quantified as the ratio between larval size and mine size) increased with latitude. Consequently, S. lapponica larvae consumed less foliar biomass at higher latitudes than at lower latitudes to reach the same size. Based on space-for-time substitution, we suggest that climate warming will increase metabolic expenses of insect herbivores with uncertain consequences for plant-herbivore interactions.

The Goldilocks principle: Finding the balance between water volume and nutrients for ovipositing Culex mosquitoes (Diptera: Culicidae).

Females of container-breeding mosquito species use visual and chemical cues to determine suitable habitats to oviposit their eggs. Female Culex mosquitoes oviposit single egg rafts containing hundreds of eggs on the surface of water in container habitats. In this project, the effects of water volume and nutrient concentration were studied using three semi-controlled field assays to determine the role these parameters play on female Culex mosquito oviposition preference. The results of this study suggest female Culex prefer to oviposit in larger volumes of water and higher concentrations of nutrients separately, but chose intermediate conditions when presented with a combination of these two variables, which follows the Goldilocks principle. This choice may provide their offspring with optimal conditions for development by reducing intraspecific competition, thereby maximizing the biological fitness of the ovipositing Culex females.

‘Mother knows best’: Maternal oviposition effects of a range‐expanding insect herbivore degrade coastal wetlands by targeting juvenile foundation plant species

AbstractSpecies range expansion induced by climate change and human activities threaten native populations and communities across the biosphere. Insect herbivores, important consumers of plants, are known to expand or contract their range under global change, with potential consequences to the newly reached environment. The selection of oviposition sites by herbivorous insects could notably impact offspring performance. However, the role of such effects in impacting the receiving ecosystem has been rarely explored. Here, we provide the first evidence showing that a terrestrial range‐expanding phytophagous wood‐borer moth (Zeuzera leuconotum Butler) heavily attacked the saplings of a foundation plant species tamarisk (Tamarix chinensis) in salt marshes. Long‐term field surveys and laboratory behaviour experiments revealed that the oviposition preference of adult females was beneficial to their larval performance. The preference to oviposit on young branches of the new host plants, which were often softer and contained enough nutrients for larval development, indicates that females could still make the right choice on novel host‐plants. This finding supports the ‘mother knows best’ hypothesis that female insects will evolve to oviposit on hosts on which their offspring fare best. Consequently, the survival of host‐plant saplings decreased dramatically under this top‐down control, revealing that herbivory of this range‐expanding insect has a profound negative impact on the recruitment and succession of coastal foundation species, thereby potentially leading to saltmarsh degradation. These findings highlight the importance of the maternal oviposition effects in range‐expanding insects and how these populations can establish using novel host‐plants and threaten coastal wetlands.

Mutualism between Gut-Borne Yeasts and Their Host, Thaumatotibia leucotreta, and Potential Usefulness in Pest Management

Simple SummaryThe false codling moth is an indigenous pest of the citrus industry in southern Africa. It is a major threat as it can cause substantial fruit damage through larval feeding. The microorganisms associated with insects are often studied for their potential to kill their host instead of how they could aid them. However, in recent years, this aspect of their interaction has received much attention. The codling moth has been shown to have a close relationship with the naturally occurring yeast found within their digestive tract. These beneficial yeasts help the adult female moths locate a suitable host for egg laying. During their larval phase, these yeasts help them develop faster and increase their chance of survival. These interactions could be manipulated for the purposes of biological control, as one might be able to combine these yeasts with existing biological control agents to improve their effectiveness. These yeasts may also provide additional methods for monitoring field populations of insect pests. In this study, we identified yeasts that occur naturally in the guts of false codling moth larvae and investigated whether any of them are beneficial to their host.Thaumatotibia leucotreta is endemic to southern Africa and is highly significant for various fruit industries, including the South African citrus industry, due to its classification as a phytosanitary pest. Mutualistic associations between C. pomonella, closely related to T. leucotreta, and yeasts have previously been described and reported to reduce larval mortality and enhance larval development. Here, we determined which yeast species occur naturally in the gut of T. leucotreta larvae and investigated whether any of the isolated yeast species affect their behaviour and development. Navel oranges infested with T. leucotreta larvae were collected from geographically distinct provinces in South Africa, and the larvae were processed for analysis of naturally occurring associated yeasts. Six yeast species were isolated and identified from the guts of these T. leucotreta larvae via PCR amplification and sequencing of the ITS region of rDNA and D1/D2 domain of large ribosomal subunit. Larval development and attraction assays were conducted, and T. leucotreta larvae that fed on Navel oranges inoculated with yeast had accelerated developmental periods and reduced mortality rates. Neonate T. leucotreta were also attracted to YPD broth cultures inoculated with yeast for feeding. Oviposition preference assays were conducted with adult T. leucotreta females. Navel oranges inoculated with yeast were shown to influence the oviposition preference of adult females. Yeasts harbour the potential for use in biocontrol, especially when combined with other well-established control methods. This study provides a platform for future research into incorporating yeast with current biological control agents as a novel option for controlling T. leucotreta in the field.

Leaf Induction Impacts Behavior and Performance of a Pollinating Herbivore

Flowering plants use volatiles to attract pollinators while deterring herbivores. Vegetative and floral traits may interact to affect insect behavior. Pollinator behavior is most likely influenced by leaf traits when larval stages interact with plants in different ways than adult stages, such as when larvae are leaf herbivores but adult moths visit flowers as pollinators. Here, we determine how leaf induction and corresponding volatile differences in induced plants influence behavior in adult moths and whether these preferences align with larval performance. We manipulated vegetative induction in four Nicotiana species. Using paired induced and control plants of the same species with standardized artificial flowers, we measured foraging and oviposition choices by their ecologically and economically important herbivore/pollinator, Manduca sexta. In parallel, we measured growth rates of M. sexta larvae fed leaves from control or induced plants to determine if this was consistent with female oviposition preference. Lastly, we used plant headspace collections and gas chromatography to quantify volatile compounds from both induced and control leaves to link changes in plant chemistry with moth behavior. In the absence of floral chemical cues, vegetative defensive status influenced adult moth foraging preference from artificial flowers in one species (N. excelsior), where females nectared from induced plants more often than control plants. Plant vegetative resistance consistently influenced oviposition choice such that moths deposited more eggs on control plants than on induced plants of all four species. This oviposition preference for control plants aligned with higher larval growth rates on control leaves compared with induced leaves. Control and induced plants of each species had similar leaf volatile profiles, but induced plants had higher emission levels. Leaves of N. excelsior produced the most volatile compounds, including some inducible compounds typically associated with floral scent. We demonstrate that vegetative plant defensive volatiles play a role in host plant selection and that insects assess information from leaves differently when choosing between nectaring and oviposition locations. These results underscore the complex interactions between plants, their pollinators, and herbivores.

Host-mediated, cross-generational intraspecific competition in a herbivore species

Conspecific insect herbivores co-occurring on the same host plant interact both directly through interference competition and indirectly through exploitative competition, plant-mediated interactions and enemy-mediated interactions. However, the situation is less clear when the interactions between conspecific insect herbivores are separated in time within the same growing season, as it is the case for multivoltine species. We hypothesized that early season herbivory would result in reduced egg laying and reduced performance of the next generation of herbivores on previously attacked plants. We tested this hypothesis in a choice experiment with box tree moth females (Cydalima perspectalis Walker, Lepidoptera: Crambidae). These females were exposed to box trees (Buxus sempervirens L., Buxaceae) that were either undamaged or attacked by conspecific larvae earlier in the season. We then compared the performance of the next generation larvae on previously damaged vs undamaged plants. Previous herbivory had no effect on oviposition behaviour, but the weight of next generation larvae was significantly lower in previously damaged plants. There was a negative correlation between the number of egg clutches laid on plants by the first generation and the performance of the next generation larvae. Overall, our findings reveal that early season herbivory reduces the performance of conspecific individuals on the same host plant later in the growing season, and that this time-lagged intraspecific competition results from a mismatch between the oviposition preference of females and the performance of its offspring.

How the seed coat affects the mother\u2019s oviposition preference and larval performance in the bean beetle (Acanthoscelides obtectus, Coleoptera: Chrysomelidae, Bruchinae) in leguminous species

BackgroundThe host specificity and host range of the dry bean beetle, Acanthoscelides obtectus (Coleoptera: Chrysomelidae, Bruchinae), a seed predator of beans, is poorly known. In addition, the female oviposition preference and larval performance relationship is complicated by the respective importance of seed coat and cotyledon, because, paradoxically, females lay eggs on the basis of stimuli of the seed coat alone, without directly being able to assess the quality of the cotyledon’s suitability for larval development. Conversely, the thickness of seed coat may prevent first instar larvae from entering the seeds, even if cotyledons are suitable for development.MethodsThe seeds of 62 leguminous species and 75 cultivars and accessions occurring in Hungary were evaluated for preference-performance relations. The preference of female bean beetles for seeds was measured in no-choice egg-laying tests. The ability of first instar larvae to overcome the seed coat as a physical barrier was tested with intact seed coat, while pre-drilled seed coats allowed the larvae to assess the suitability of cotyledon for development. The number of emerging adults was recorded. The thickness of seed coats and the weight of seeds were measured. Nonparametric tests and logistic regression were used for the statistical analyses of data and effect sizes were also calculated.ResultsSeeds of 18 leguminous species (35% of them Lathyrus) supported larval development to adults if the seed coat was pre-drilled; however, only nine leguminous species supported development to adults if the seed coat was intact. Seed coat thickness beyond a critical threshold of 0.1 mm strongly influenced survival of first instar larvae. There was no overall positive correlation between oviposition preference and larval performance, except for 16 so-called acceptable non-hosts (Kendall’s τ = 0.3088). A. obtectus females also showed an ovipositional hierarchy of legume species even in no-choice tests.ConclusionsThe results suggest that whereas the use of some acceptable non-host species by the A. obtectus is possible in seed stores, the same is unlikely under outdoor conditions, where the recognition of a diverse set of seed pod-related compounds would be necessary to induce egg-laying.

Challenging the Preference-Performance Hypothesis in an above-belowground insect.

The relationship between female oviposition preference and offspring performance has been a question of special interest in the study of host plant selection by phytophagous insects. The Preference-Performance Hypothesis (PPH) is one of the main hypotheses proposed to explain this relationship, stating that females should preferentially lay eggs on plants providing the best larval development. The PPH has been extensively tested on aboveground insects but its application to species with belowground larvae is still mostly unknown. In this study, the PPH was quantitatively tested in an above-belowground insect, the cabbage root fly Delia radicum. Female oviposition preference and larval performance were estimated on three brassicaceous species (Brassica oleracea, Brassica rapa, and Sinapis alba) as well as between four cultivars of B. rapa and four cultivars of S. alba. Larval performance was estimated through their survival and through three life-history traits (LHT) of emerging adults. The PPH was supported at the intraspecific scale but only in B. rapa and for some, but not all, of the life-history traits. No support for the PPH was found in S. alba as well as at the interspecific scale. This study pleads for the integration of insects with both above- and belowground life stages in the preference-performance debate. Moreover, it raises the importance of measuring several variables to estimate larval performance and to test the PPH quantitatively, both at the plant intraspecific and interspecific scales, before drawing general conclusions.

Fijian swallowtail butterfly Papilio schmeltzi (Papilionidae: Lepidoptera) shows clear preference–performance relationships on both native and exotic host plants

AbstractThe swallowtail butterfly Papilio schmeltzi is endemic to the Fiji Islands. To date, P. schmeltzi larvae and eggs have been found exclusively on a native Fijian shrub, Micromelum minutum, even though numerous other seemingly suitable native and exotic species of Rutaceae now occur in its Fijian forest habitat. This study used outdoor cages and laboratory studies to examine oviposition preferences and larval development of P. schmeltzi on four species of Rutaceae: the native species Micromelum minutum and Euodia hortensis and the introduced species Murraya koenigii and Citrus reticulata. The female oviposition preference sequence was the same as that for larval feeding preference, which ran, from most preferred, as Micromelum minutum > C. reticulata > Murraya koenigii > E. hortensis. The survival of the first and fifth instar larvae was highest (≥80%) when maintained on leaves of M. minutum and C. reticulata and lowest when reared on Murraya koenigii (≤20%) and E. hortensis (≤4%). Of the two preferred host plants, P. schmeltzi larvae gained weight more quickly, consumed a larger area of leaf and pupated earlier when reared on the natural host Micromelum minutum compared with the exotic C. reticulata. In quantitative nutritional studies, the consumption rate of leaf material, and the relative growth rate of the P. schmeltzi larvae, was highest when reared on Micromelum minutum compared with C. reticulata, although the efficiency of converting leaf biomass into larval biomass was highest when reared on C. reticulata, especially in the later instars. Overall, the results of our study indicate the plants on which P. schmeltzi females choose to lay eggs are not restricted to native Fijian plant species but are appropriate when viewed in terms of subsequent larval preferences, survival and growth rate.

Comparison of larval performance and oviposition preference of Spodoptera frugiperda among three host plants: Potential risks to potato and tobacco crops.

Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is a major polyphagous pest with the potential to seriously damage various crops. A better understanding of FAW's performance on different hosts may help to predict which plants will be attacked when the preferred host is absent, and facilitate the development of effective pest management practices. We compared the larval performance of FAW fed on maize with that of FAW fed on potato and tobacco, which are important crops in China, using an age-stage two-sex life table and adult female oviposition preference experiments. In cage experiments with potato, tobacco, or maize as the host, FAW reared on maize exhibited the strongest performance with shorter developmental time in the larval stage, longer longevity, and a higher reproductive rate in adults. Females oviposited on maize in preference to potato or tobacco. Compared with larvae fed on maize, those fed on potato and tobacco exhibited significantly lower survival, with only 31.61% and 8.13% developing to the adult stage, respectively. Several life table parameters, including the mean generation time (T), net reproductive rate (R0 ), finite rate of increase (λ), and intrinsic rate of natural increase (r) were negatively affected in FAW fed on potato and tobacco. Our results support the preference-performance hypothesis, that is, that herbivore females maximize fitness by choosing host plants associated with strong larval performance. Although larvae and adults performed poorly on potato and tobacco, their offspring will be capable of establishing populations on them, posing a potential threat to these crops in China.

Evaluation of plant quality by Corythucha marmorata (Hemiptera: Tingidae) mothers: relationship between oviposition preference and nymphal performance on four sweet potato cultivars and goldenrod

In novel plant–insect relationships, oviposition preference and nymphal performance determine host range evolution. Corythucha marmorata, native to North America and specialist on asteraceous plants, has been reported to exploit sweet potato (Convolvulaceae) in Japan. Here we examined the capability of females to oviposit and of nymphs to grow on both a conventional host (goldenrod, Solidago altissima) and novel hosts (four sweet potato cultivars), of which the test insects had virtually no experience of contact at the population level. We then tested whether female preference and offspring performance were correlated. Nymphal survival and development time were always significantly greater on goldenrod, followed by sweet potato cultivars Caroline Lea, Benisengan, Narutokintoki, and Beniazuma in that order. Female oviposition preferences showed a similar order. On higher-ranked plants, the females accepted the plant faster and had higher fecundity. When goldenrod was included in the analysis, nymphal development time and survival rate were significantly related to preoviposition period. When goldenrod was excluded, nymphal survival rate was still significantly related to preoviposition period. These results support the theory that females lay their eggs on the most suitable host to maximize offspring fitness, even though C. marmorata had no experience with sweet potato cultivars. As C. marmorata is a hemimetabolous insect, in which adults and nymphs have a similar feeding habit and exploit the same habitat, this relationship seems plausible.

Narrow oviposition preference of an insect herbivore risks survival under conditions of severe drought

Abstract Understanding species' habitat preferences are crucial to predict organisms' responses to the current climate crisis. In many insects, maternal habitat selection for oviposition essentially determines offspring performance. Whether future changes in climatic conditions may generate mismatches between oviposition preference and offspring performance, when mothers continue to prefer microhabitats that might threaten offspring survival, is an open question. To address this gap, we tested if oviposition preferences of the Glanville fritillary butterfly Melitaea cinxia females put offspring at risk when plants are under drought stress conditions. Mainly, we focus on identifying the microhabitat determinants for oviposition and the variation of conditions experienced by the sessile offspring, using field observations from 12 populations collected over 2015–2018. These data are combined with 10 years of larval nest and precipitation data to understand within‐population patterns of habitat selection. We tested whether the preferred microhabitats maximized the extended larval performance (i.e. overwinter survival). We found that females preferentially oviposited in microhabitats with higher host plant abundance and higher proportion of host plants with signs of drought stress. In most years, larval nests had higher survival in these drought‐stressed microhabitats. However, in an extremely dry year, only two nests survived over the summer. Our results highlight that a failure to shift habitat preference under extreme climate conditions may have drastic consequences for the survival of natural populations under changing climatic conditions. A free Plain Language Summary can be found within the Supporting Information of this article.