Oviposition Strategies Research Articles

Redescription and oviposition behavior of an orb-weaver spider parasitoid Hymenoepimecis cameroni Townes, 1966 (Hymenoptera: Ichneumonidae).

Strategies to invade and exploit hosts for survival are an essential part of the parasitic lifestyle. Species of the Polysphincta genus group (Hymenoptera: Ichneumonidae), which utilize spiders as hosts, are examples of parasitoids that present several behavioral strategies in host immobilization and egg laying. In this study, we characterized the oviposition behavior of the Darwin wasp Hymenoepimecis cameroni Townes, 1966 (Hymenoptera: Ichneumonidae) on their host spider, performed the taxonomic description of the female, and redescribed the male parasitoid. We observed eight H. cameroni females endeavoring to parasitize young Leucauge volupis (Keyserling, 1893) spiders. Each female made up to 12 successive attempts at oviposition, totaling 36 observed attacks, with only two successful attacks. The main oviposition behavior of H. cameroni individuals consists of flying close to the web and performing a direct attack on the spider, which often results in the spider escaping into the vegetation. We observed that in seven events where the spiders fled into the vegetation, the individuals of H. cameroni adopted a second strategy, which consisted of hanging from the hind legs in the web hub. This observation showed that the females of H. cameroni have the ability to modulate the oviposition strategy after a failure in the initial attack. The pattern observed for the attack of H. cameroni indicates that the ability to adjust the approach could be specific to the behavioral habits of L. volupis.

Warm-night temperature alters paternal allocation strategy in a North temperate-zone butterfly.

Warming temperatures are greatly impacting wild organisms across the globe. Some of the negative impacts of climate change can be mitigated behaviorally, for example, by changes in habitat and oviposition site choice. Temperatures are reportedly warming faster at night than during the day, yet studies assessing the impacts of increasing night temperature are rare. We used the Finnish Glanville fritillary butterfly (Melitaea cinxia) as study species and exposed adult butterflies of both sexes to warmer night conditions. Under a seminatural outdoor enclosure, we assessed whether females base their oviposition choices primarily on habitat site characteristics (open, suggestive of dry meadows, versus covered by a coarse canopy, suggestive of pastures) or on plant condition (dry vs. lush), and if their choice is altered by the thermal conditions experienced at night. As exposure to warmer environmental conditions is expected to increase resting metabolic rate and potentially reduce life expectancy, we further assessed the fitness implications of warm‐night temperatures. We found that females prefer open sites for oviposition and that females do not switch their oviposition strategy based on the thermal conditions they experienced at night prior to the reproductive event. Exposure to warm nights did not influence female lifespan, but the egg hatching success of their offspring was reduced. In addition, we found that males exposed to warm nights sired larger clutches with higher hatching rate. As warm‐night exposure reduced male lifespan, this may imply a switch in male resource allocation strategy toward increased offspring quality. The present work adds on to the complex implications of climate warming and highlights the importance of the often‐neglected role of males in shaping offspring performance.

Microorganisms Associated with Mosquito Oviposition Sites: Implications for Habitat Selection and Insect Life Histories.

Mosquitoes are considered one of the most important threats worldwide due to their ability to vector pathogens. They are responsible for the transmission of major pathogens such as malaria, dengue, zika, or chikungunya. Due to the lack of treatments or prophylaxis against many of the transmitted pathogens and an increasing prevalence of mosquito resistance to insecticides and drugs available, alternative strategies are now being explored. Some of these involve the use of microorganisms as promising agent to limit the fitness of mosquitoes, attract or repel them, and decrease the replication and transmission of pathogenic agents. In recent years, the importance of microorganisms colonizing the habitat of mosquitoes has particularly been investigated since they appeared to play major roles in their development and diseases transmission. In this issue, we will synthesize researches investigating how microorganisms present within water habitats may influence breeding site selection and oviposition strategies of gravid mosquito females. We will also highlight the impact of such microbes on the fate of females’ progeny during their immature stages with a specific focus on egg hatching, development rate, and larvae or pupae survival.

Larval habitat selection by females of two malaria vectors in response to predation risk

For species lacking parental care, selection of a suitable habitat for their offspring, with a limited predation risk, is important. The ability of two African malaria mosquito females to detect a predation threat for their larvae was assessed through an oviposition choice test design.Our results suggest that gravid females of both Anopheles gambiae s.s. and An. coluzzii (Diptera, Culicidae) were able to detect the presence of a predator (Anisops jaczewskii, Notonectidae, Hemiptera; backswimmer). However, An. coluzzii were more likely to choose the cups containing predation cues while An. gambiae tended to avoid them for oviposition. Anopheles coluzzii females might use either alarm cues or pre-digestive cues from the external prey digestion to gauge the threat level, while An. gambiae females might use predator cues (odor or vibrations) or digestive cues from the predator.Compared to An. gambiae, An. coluzzii females seemed to accept the predation threat for their larvae to some extent. These results are consistent with the observed larval distribution in the field. Anopheles coluzzii larvae are found in complex permanent reservoirs in which the predation pressure is high, while An. gambiae larvae are more frequently found in temporary reservoirs with a lower predation threat. To our knowledge, this is the first time such a divergence in oviposition strategies regarding predation risk management by females is shown between closely related mosquito species.

Extraordinary diversification of the “bristle flies” (Diptera: Tachinidae) and its underlying causes

AbstractThe family Tachinidae (“bristle flies”) is the most diverse and ecologically important group of insect parasitoids outside the parasitic wasps. It is among the most species rich families of flies (Diptera) and has experienced a recent adaptive radiation across the globe. We make use of a molecular phylogeny of the family to examine its rapid radiation and explore the traits of tachinid lineages that may have contributed to variation in their diversification. We apply a range of diversification analyses to assess the consistency and robustness of effects. We find that the Tachinidae are among the most rapidly diversifying families of animals. Six to eight clades of bristle flies, distributed across the phylogeny, exhibit strong evidence of accelerated diversification. Our results suggest that the use of holometabolous insect larvae, and specifically caterpillars (Lepidoptera), as hosts, is associated with increased diversification rates. However, these effects were inconsistent across analyses. We detected little influence of oviposition strategy (egg type) or host feeding habit, and we recovered evidence that unmeasured “hidden” traits may explain greater variance in diversification. We evaluated the strengths and weaknesses of different Maximum Likelihood and Bayesian approaches for analysing diversification and the potential for extrinsic factors, such as geography, to influence patterns of richness and diversification. In general, we conclude that although certain traits may provide opportunities for diversification, whether this is capitalized on may depend on additional traits and/or historical contingency.

Influence of the site of oviposition on the level of egg parasitism in the corn leafhopper, Dalbulus maidis (Hemiptera: Cicadellidae).

The corn leafhopper Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae), transmits three important plant pathogens that adversely affect corn crop and ranges from the USA to Argentina. The vector has a rich natural enemy complex that generates high levels of parasitism, but its populations are persistent and prevalent. We characterized the oviposition sites of D. maidis on young corn plants in order to verify the hypothesis that the vector has an oviposition strategy for mitigating parasitism. Oviposition locations on plants were assessed in the laboratory and eggs within corn plants were exposed to natural parasitism in a cornfield. Eggs were located mostly laid in the unfolded leaves and were attacked by five parasitoid species. Parasitism was significantly affected by the class of leaf and the position of the egg in the leaf. Anagrus virlai Triapitsyn was the most abundant parasitoid species, which emerged significantly higher in the basal blade than other species. Our results suggest that leafhoppers minimize egg parasitism by laying their eggs within concealed locations on the plant.

Enhancing the usefulness of artificial seeds in seed beetle model systems research

Abstract Seed beetles are among textbook examples of experimental model systems used to better understand nature's complexities. A potential seed beetle model systems' strength is the use of artificial seeds to remove experimental confounds. This is particularly relevant for scaling life histories to population dynamics but requires many artificial seeds. Current methods of producing seeds are laborious, limiting their application. Building on previous work, we developed efficient methods to produce artificial seeds and expand their use. We outline steps to produce artificial seeds and describe a new technique for transferring beetle eggs laid on natural seeds to artificial seeds. Our methods yielded a 100‐fold increase in artificial seed production that is 80% more efficient than current methods. Burrowing success of beetle larvae from eggs laid on natural seeds and transferred to artificial seeds (85.4%) was comparable to rates on natural seeds. Streamlining artificial seed production enables highly replicated life‐history and time‐series assays with large sample sizes. The ability to transfer eggs from natural to artificial seeds allows research on many phenomena including oviposition strategies, maternal provisioning and competitive strategies, broadening the usefulness of seed beetle model systems in ecological and evolutionary research.

Caterpillar-induced rice volatiles provide enemy-free space for the offspring of the brown planthopper.

Plants typically release large quantities of volatiles in response to herbivory by insects. This benefits the plants by, for instance, attracting the natural enemies of the herbivores. We show that the brown planthopper (BPH) has cleverly turned this around by exploiting herbivore-induced plant volatiles (HIPVs) that provide safe havens for its offspring. BPH females preferentially oviposit on rice plants already infested by the rice striped stem borer (SSB), which are avoided by the egg parasitoid Anagrus nilaparvatae, the most important natural enemy of BPH. Using synthetic versions of volatiles identified from plants infested by BPH and/or SSB, we demonstrate the role of HIPVs in these interactions. Moreover, greenhouse and field cage experiments confirm the adaptiveness of the BPH oviposition strategy, resulting in 80% lower parasitism rates of its eggs. Besides revealing a novel exploitation of HIPVs, these findings may lead to novel control strategies against an exceedingly important rice pest.

Multigene phylogeny uncovers oviposition-related evolutionary history of Cerambycinae (Coleoptera: Cerambycidae)

The correlated evolution of the morphology of reproduction-related organs and biological aspects of insects is intriguing yet poorly understood. As one of the largest subfamilies of phytophagous beetles, Cerambycinae provides a unique opportunity to study this topic because of the wide range of host plants, oviposition strategies, and various forms of ovipositors of its members. Nevertheless, the evolutionary pathway of these traits is unexplored and no robust phylogenetic study of the subfamily has been conducted. In this study, we reconstructed a first multi-locus phylogeny of Cerambycinae representing a wide range of oviposition strategies, host plants, and ovipositor lengths. Ancestral state reconstruction analyses showed that the shortened ovipositor in Cerambycinae evolved at least four times independently and that the use of host plant has evolved from stressed hosts to dead or living hosts and from broad-leaved trees to conifers. The correlated evolution test revealed the correlation between ovipositor length and oviposition strategy. Our study elucidates for the first time the complex evolutionary history of the ovipositor, oviposition strategy, and host plant usage, and their correlations within Cerambycinae.

Role of egg-laying behavior, virulence and local adaptation in a parasitoid’s chances of reproducing in a new host

Understanding the ability of parasitoid insects to succeed in new host populations is a relevant question for biological control and adaptive mechanisms. Cotesia typhae is an African parasitoid specialized on the moth Sesamiae nonagrioides, also called the Mediterranean corn borer. Two Kenyan strains of C. typhae differ in their virulence against a new host population from France. We explored behavioral and physiological hypotheses about this differentiation. Cotesia genus belongs to a group of Hymenoptera in which females inject a domesticated virus in their host to overcome its resistance. Since viral particles are injected along with eggs and since the strain with the higher virulence injects more eggs, we hypothesized that virulence could be explained by the quantity of virus injected. To test this assumption, we measured the injected quantities of eggs and viral particles (estimated by viral DNA segments) of each parasitoid strain along several ovipositions, to vary these quantities. Unexpectedly, results showed that virulence against the French host was not correlated to the injected quantities of eggs or viral segments, indicating that virulence differentiation is explained by other causes. The virulence against the respective natural hosts of the two C. typhae strains was also measured, and results suggest that local adaptation to a more resistant natural host may explain the pre-adaptation of one strain to the new host population. We also identified a differentiation of oviposition strategy and subsequent offspring number between the parasitoid strains, which is important in a biocontrol perspective.

Oviposition Substrate Selection, Egg Mass Characteristics, Host Preference, and Life History of the Spotted Lanternfly (Hemiptera: Fulgoridae) in North America.

Oviposition substrate selection, egg mass characteristics, host preference, and life history of Lycorma delicatula (White) (Hemiptera: Fulgoridae) were studied in Pennsylvania between 2016 and 2017. Twenty-four substrate types (trees, shrubs, and nonliving materials) were selected by females for oviposition. Tree-of-heaven, black cherry, black birch, and sweet cherry were favored at 62.5% of the types and accounted for 68.5% of the egg masses based on survey results 200 cm above ground. Egg mass density ranged between 0.2 and 75.2 egg masses/m2 with no significant difference among substrate types. Egg mass size ranged between 0 and 192 eggs/egg mass, with 91.8% containing <50 eggs. Significantly larger egg masses were found on sweet and black cherry compared with tree-of-heaven, with significantly higher hatch success on black locust. Eggs hatched between May 2 and June 5 and peaked on 18 May 2017. Tree-of-heaven and summer grape were preferred by nymphs and adults, while multiflora rose and black walnut were favored by the first, second, and the fourth instar nymphs, respectively. The first, second, third, fourth instars and adults lasted for 62 (2 May-3 July), 42 (8 June-20 July), 35 (26 June-31 July), 39 (10 July-18 Aug.), and 114 (24 July-15 Nov.) days, with peaks on 25 May, 22 June, 6 July, 31 July, and 22 Aug., respectively. Adult feed for 2 months before laying eggs in early October. Cumulative degree-days were 0-325, 153-652, 340-881, 567-1,020, 738-1,227, and 942-1,795 for the egg, first, second, third, fourth instar, and adult stage, respectively. Oviposition strategies and development patterns were discussed.

Viviparity and oviparity in termitophilous Rhiniidae (Diptera: Oestroidea) in the Western Ghats, India

ABSTRACTLife history observations are documented for two species of rhiniid flies from the Western Ghats in India: larviposition and termitophagy in Stomorhina procula (Walker), and oviposition and saprophagy in Borbororhinia bivittata (Walker). Oviposition and larviposition strategies in termitophilous Rhiniidae (Diptera: Oestroidea) are discussed based on these examples.

Different Oviposition Strategies of Closely Related Damselfly Species as an Effective Defense against Parasitoids.

Parasitoidism is one of the main causes of insect egg mortality. Parasitoids are often able to detect eggs using semiochemicals released from eggs and disturbed plants. In response, female insects adopt a wide variety of oviposition strategies to reduce the detectability of eggs and subsequent mortality. We evaluated the proportion of parasitized and undeveloped eggs of three common damselfly species from the family Lestidae, the most diverse group of European damselflies, in terms of oviposition strategies, notably clutch patterning and the ability to utilize oviposition substrates with different mechanical properties. We assumed that higher costs associated with some oviposition strategies will be balanced by lower egg mortality. We found that the ability of Chalcolestes viridis to oviposit into very stiff substrates brings benefit in the form of a significantly lower rate of parasitoidism and lower proportion of undeveloped eggs. The fundamentally different phenology of Sympecma fusca and/or their ability to utilize dead plants as oviposition substrate resulted in eggs that were completely free of parasitoids. Our results indicated that ovipositing into substrates that are unsuitable for most damselfly species significantly reduces egg mortality. Notably, none of these oviposition strategies would work unless combined with other adaptations, such as prolonging the duration of the prolarval life stage or the ability to oviposit into stiff tissue.

Tetranychus urticae changes its oviposition pattern in the presence of the predatory mites, Phytoseiulus persimilis and Typhlodromus bagdasarjani

Oviposition behaviors in herbivorous mites are affected by several factors i.e. food availability for juveniles and reduced predation risks. We used the twospotted spider mite, Tetranychus urticae Koch (Tetranychidae) to find out whether the previous presence of specialist/ generalist phytoseiid predator individuals, Phytoseiulus persimilis Athias-Henriot/ Typhlodromus bagdasarjani Wainstein & Arutunjan (here, direct effect) or their previous odour perception by prey (here, indirect effect) would affect T. urticae oviposition strategies. Tetranychus urticae female individuals were placed on a leaf disc in a plastic container with predators either on the same disc (direct presence of predator) or on the second disc (receiving odours related to a predator) in the same container. Getting experienced, the prey individuals transferred to the oviposition container to their oviposition pattern parameters get recorded. The ovipositing T. urticae were monitored in two experimental situations: 1. Receiving odours related to the predator- prey interaction from the second leaf disc in the same oviposition container during their oviposition period, and 2. Receiving no odour. Our results showed that when T. urticae females perceived the predator presence in their first container (with either predator species, both direct and indirect effect), they reduced their total egg distances, oviposition rates and oviposition periods significantly regardless of receiving odours related to prey-predator interactions during experiment. Receiving odours during oviposition, T. urticae females decreased their pairwise egg distances in at least 4 and at most 6 pairs of eggs, while when odours were absent during oviposition, the distances decreased in at least 2 and at most 3 pairs of eggs. The direct presence of P. persimilis reduced the prey oviposition period significantly more than that when T. bagdasarjani was present. The spider mites oviposition rate reduction was obviousely more than that in the presence of T. bagdasarjani. The different effects of predator species on T. urticae egg distances were discussed.

Evolution of Oviposition Techniques in Stick and Leaf Insects (Phasmatodea)

Stick and leaf insects (Phasmatodea) are large, tropical, predominantly nocturnal herbivores, which exhibit extreme masquerade crypsis, whereby they morphologically and behaviorally resemble twigs, bark, lichen, moss, and leaves. Females employ a wide range of egg-laying techniques, largely corresponding to their ecological niche, including dropping or flicking eggs to the forest floor, gluing eggs to plant substrate, skewering eggs through leaves, ovipositing directly into the soil, or even producing a complex ootheca. Phasmids are the only insects with highly species-specific egg morphology across the entire order, with specific egg forms that correspond to oviposition technique. We investigate the temporal, biogeographic and phylogenetic pattern of evolution of egg-laying strategies in Phasmatodea. Our results unequivocally demonstrate that the ancestral oviposition strategy for female stick and leaf insects is to remain in the foliage and drop or flick eggs to the ground, a strategy that maintains their masquerade. Other major key innovations in the evolution of Phasmatodea include the (1) hardening of the egg capsule in Euphasmatodea; (2) the repeated evolution of capitulate eggs (which induce ant-mediated dispersal, or myrmecochory); (3) adapting to a ground or bark dwelling microhabitat with a corresponding shift in adult and egg phenotype and egg deposition directly into the soil; and (4) adhesion of eggs in a clade of Necrosciinae that led to subsequent diversification in oviposition modes and egg types. We infer 16 independent origins of a burying/inserting eggs into soil/crevices oviposition strategy, 7 origins of gluing eggs to substrate, and a single origin each of skewering eggs through leaves and producing an ootheca. We additionally discuss the systematic implications of our phylogenetic results. Aschiphasmatinae is strongly supported as the earliest diverging extant lineage of Euphasmatodea. Phylliinae and Diapheromerinae are both relatively early diverging euphasmatodean taxa. We formally transfer Otocrania from Cladomorphinae to Diapheromerinae and recognize two tribes within Diapheromerinae: Diapheromerini sensu nov. and Oreophoetini sensu nov. We formally recognize the clade comprising Necrosciinae and Lonchodinae as Lonchodidae stat. rev. sensu nov.

Structure and function of the musculoskeletal ovipositor system of an ichneumonid wasp

BackgroundModifications of the ovipositor appear to have played a prominent role in defining the host range of parasitoid hymenopterans, highlighting an important contributing factor in shaping their oviposition strategies, life histories and diversification. Despite many comparative studies on the structure of the hymenopteran terebra, little is known about functional aspects of the musculoskeletal ovipositor system. Therefore, we examined all inherent cuticular elements and muscles of the ovipositor of the ichneumonid wasp Venturia canescens (Gravenhorst, 1829), investigated the mechanics of the ovipositor system and determined its mode of function.ResultsWe found that the movements of the ichneumonid ovipositor, which consists of the female T9 (9th abdominal tergum), two pairs of valvifers and three pairs of valvulae, are actuated by a set of six paired muscles. The posterior and the anterior 2nd valvifer-2nd valvula muscles flex and extend the terebra from its resting towards an active probing position and back. The dorsal T9-2nd valvifer muscle is modified in V. canescens and forms distinct bundles that, together with the antagonistically acting ventral T9-2nd valvifer muscle, change the relative position of the 2nd valvifer to the female T9. Thereby, they indirectly tilt the 1st valvifer because it is linked with both of them via intervalvifer and tergo-valvifer articulation, respectively. The 1st valvifer acts as a lever arm that transfers movements to the 1st valvula. The posterior T9-2nd valvifer muscle and the small 1st-valvifer-genital membrane muscle stabilize the system during oviposition.ConclusionsFrom our examination of the elements of the musculoskeletal ovipositor system of ichneumonids, we discussed leverages and muscle forces and developed a functional model of the underlying working mechanisms adding to our understanding of a key feature that has largely determined the evolutionary success of the megadiverse Ichneumonidae with more than 24,000 hitherto described species.

Facultative production of multiple-egg clutches in a quasi-gregarious parasitoid: fitness gains for offspring at low developmental temperature

In the quasi-gregarious parasitoid wasp Anastatus disparis, a mother may lay more than one egg in a host during a single host encounter. This is conventionally known as self-superparasitism and, since only one adult offspring can complete development on the host, it may represent a waste of eggs and time. However, this behavior may be better described as “multiple-egg clutches,” which differs fundamentally from self-superparasitism and has seldom been addressed. The potential benefits of laying multiple-egg clutches are currently unclear, and we therefore aimed to investigate them in A. disparis. First, our results showed that production of multiple-egg clutches by A. disparis is not due to a lack of discrimination between unparasitized and parasitized hosts, as females preferred to lay eggs in unparasitized hosts. It was also unrelated to the age of the female or her mating status, or to the presence of conspecific females. However, compared to the temperatures of 26 and 32 °C, we observed that the frequency of multiple-egg clutches increased at the temperature of 20 °C. In addition, low developmental temperatures significantly decreased the rate of successful wasp eclosion from hosts in which a single egg was deposited, and this rate was increased by laying multiple-egg clutches. These results suggest that female A. disparis adults produce multiple-egg clutches to increase the probability of obtaining offspring from the host, and may have the ability to regulate oviposition and reproduction strategy based on environmental temperature. Anastatus disparis exhibited an oviposition behavior of facultative production of multiple-egg clutches, which is not due to a lack of host discrimination, or due to the age of the female or her mating status nor the presence of conspecific females. However, our results suggest that A. disparis adults produce multiple-egg clutches when it increased the probability of obtaining offspring from the host, and may have the ability to regulate their oviposition strategy based on environmental temperature.

Oviposition Strategies of Tachinid Parasitoids: Two Exorista Species as Case Studies.

Oviposition strategies and mechanisms of host selection in parasitoids may be crucial for the success of parasitization and parasitoid production. These aspects are far less known in tachinid parasitoids than in hymenopteran parasitoids. Depending on the species, parasitoid flies may adopt direct or indirect oviposition strategies. The ‘direct type’ females lay eggs on or, in relatively a few species, inside the host body. This review describes cues involved in host selection by tachinid parasitoids and their oviposition strategies and presents 2 case studies in more detail, focusing on Exorista larvarum and Exorista japonica. These 2 polyphagous parasitoids of Lepidoptera lay macrotype eggs directly on the host cuticle. Both species have been used as biological control agents in inoculative release against the gypsy moth Lymantria dispar in the Northern United States. Improved knowledge of the mechanisms involved in host selection and oviposition strategies may increase the possibility of eliciting oviposition by these tachinids on target lepidopterous hosts (and even artificial substrates), thus facilitating their rearing and ultimately making their exploitation as regulators of target insect pests more feasible and efficient.

Comparison of the antennal sensilla of females of four fig-wasps associated with Ficus auriculata

A comparison was performed of the antennal sensilla of females of four chalcid wasp species Ceratosolen emarginatus Mayr, 1906, Sycophaga sp., Philotrypesis longicaudata Mayr, 1906, and Sycoscapter roxburghi Joseph, 1957, which are specific and obligatory associated with Ficus auriculata (Lour, 1790). The four species exhibit different oviposition strategies in the fig ovules where their offspring hatch and develop. Antennal sensilla morphology was evaluated using scanning electron microscopy. Females of the four species present 11 morphologically similar types of sensilla: trichoid sensilla, sensilla obscura, chaetica sensilla 1 and 2, which all have mechanosensory functions; uniporous basiconic sensilla, which are presumably contact chemosensilla; basiconic capitate peg sensilla, coeloconic sensilla 1, multiporous basiconic and placoid sensilla, which may be regarded as olfactory sensilla, and coeloconic sensilla 2 and 3, which are presumed to be proprioreceptors or pressure receptors. The four species have significant differences in the abundance and arrangement of trichoid sensilla and chaetica sensilla 1 on the flagellum. The coeloconic sensilla and sensilla obscura only occur on the antennae of C. emarginatus that enter figs. The chemosensilla which are presumably involved in host discrimination, i.e., basiconic sensilla, multiporous placoid sensilla and basiconic capitate peg sensilla, are similar in shape and configuration, although they present some differences in abundance. These findings provide practical information on the adaptations of fig wasps and the relationship between multisensory antennae and functions in fig wasp behaviour.

Tachinid Fly (Diptera: Tachinidae) Parasitoids of Danaus plexippus (Lepidoptera: Nymphalidae)

Extensive rearing of monarch larvae (Danaus plexippus L.) through the citizen science Monarch Larva Monitoring Project (MLMP) revealed that monarchs' primary parasitoids are flies in the family Tachinidae and that these parasitoids result in appreciable larval mortality. We document the tachinid community that attacks monarchs in the United States, evaluate their relative frequency, and examine variation in their specificity, oviposition strategy, and use of host stages. Based on results of rearing >20,000 monarchs by MLMP volunteers, overall parasitism by tachinids across life stages was 9.8% (17% for monarchs collected as fifth instars). We identified the flies that emerged from 466 monarch hosts, and found seven Tachinidae species. In decreasing order of frequency, these included Lespesia archippivora (Riley), Hyphantrophaga virilis (Aldrich & Webber), Compsilura concinnata (Meigen), Leschenaultia n. sp., Madremyia saundersii (Williston), Lespesia sp., and Nilea erecta (Coquillett). Lespesia sp., Leschenaultia n. sp., and N. erecta had not been previously reported as monarch parasitoids, and Leschenaultia n. sp. is apparently undescribed. We include new state records (Texas and Iowa) for C. concinnata. Lespesia archippivora and C. concinnata were overrepresented as parasitoids of later instars and were absent from monarchs collected as eggs, but H. virilis and Leschenaultia sp., which lay their eggs on foliage, were reared from caterpillars collected as eggs. To our knowledge, we include the first report of multiparasitism of monarchs, in which more than one parasitoid species emerged from a host. The biology of the tachinid parasitoids we identified and their relationship with monarchs is examined.