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Aminergic signaling is known to play a critical role in regulating female reproductive processes in both mammals and insects. In Drosophila, the ortholog of noradrenaline, octopamine, is required for ovulation as well as several other female reproductive processes. Two octopamine receptors have already been shown to be expressed in the Drosophila reproductive tract and to be required for egg-laying: OAMB and Octβ2R. The Drosophila genome contains 4 additional octopamine receptors-Octα2R, Octβ1R, Octβ3R, and Oct-TyrR-but their cellular patterns of expression in the reproductive tract and potential contribution(s) to egg-laying are not known. In addition, the mechanisms by which OAMB and Octβ2R regulate reproduction are incompletely understood. Using a panel of MiMIC Gal4 lines, we show that Octα2R, Octβ1R, Octβ3R, and Oct-TyrR receptors are not detectable in either epithelium or muscle but are clearly expressed in neurons within the female fly reproductive tract. Optogenetic activation of neurons that express at least 3 types of octopamine receptors stimulates contractions in the lateral oviduct. We also find that octopamine stimulates calcium transients in the sperm storage organs and that its effects in spermathecal, secretory cells, can be blocked by knock-down of OAMB. These data extend our understanding of the pathways by which octopamine regulates egg-laying in Drosophila and raise the possibility that multiple octopamine receptor subtypes could play a role in this process.

Aminergic nuclei in mammals are generally composed of relatively small numbers of cells with broad projection patterns. Despite the gross similarity of many individual neurons, recent transcriptomic, anatomic and behavioral studies suggest previously unsuspected diversity. Smaller clusters of aminergic neurons in the model organism Drosophila melanogaster provide an opportunity to explore the ramifications of neuronal diversity at the level of individual cells. A group of approximately 10 tyraminergic/octopaminergic neurons innervates the female reproductive tract in flies and has been proposed to regulate multiple activities required for fertility. The projection patterns of individual neurons within the cluster are not known and it remains unclear whether they are functionally heterogenous. Using a single cell labeling technique, we show that each region of the reproductive tract is innervated by a distinct subset of tyraminergic/octopaminergic cells. Optogenetic activation of one subset stimulates oviduct contractions, indicating that the cluster as a whole is not required for this activity, and underscoring the potential for functional diversity across individual cells. Using whole cell patch clamp, we show that two adjacent and morphologically similar cells are tonically inhibited, but each responds differently to injection of current or activation of the inhibitory GluCl receptor. GluCl appears to be expressed at relatively low levels in tyraminergic/octopaminergic neurons within the cluster, suggesting that it may regulate their excitability via indirect pathways. Together, our data indicate that specific tyraminergic/octopaminergic cells within a relatively homogenous cluster have heterogenous properties and provide a platform for further studies to determine the function of each cell.

Understanding the circumstances under which insect herbivores will adopt a novel host plant is a longstanding question in basic and applied ecology. While geographic variation in host use can arise through differences in both herbivore preference and plant characteristics, there is a tendency to attribute geographic variation in host use to regional differences in herbivore preference alone. This is especially true for herbivores specialized to one or a few plant species. We compared how geographic variation in herbivore preference and host plant origin shape regional differences in host plant use by the specialized herbivore, Euphydryas phaeton. In parts of its range, E. phaeton uses only a native host, Chelone glabra, while in others, it also uses an introduced host, Plantago lanceolata. We offered female butterflies from each region the non-native host plant sourced from both regions and compared their oviposition behavior. The non-native host was almost universally rejected by butterflies in the region where only the native plant is used. In the region where butterflies use both hosts, females accepted non-native plants from their natal region twice as often as non-native plants from the other region where they are not used. Acceptance differed substantially among individual butterflies within regions but not among plants within regions. Thus, both individual preference and regional differences in both the insect and non-native host contributed to the geographic variation in different ways. These results highlight that, in addition to herbivore preference, regional differences in perceived plant suitability may be an important driver of diet breadth.

Oviposition preferences of plant‐feeding predators remain a complex topic, as such omnivores choose oviposition sites by assessing both plant characteristics and the quality and quantity of nearby animal food sources. Orius predators are omnivores that oviposit endophytically, thus plant characteristics play an important role in their oviposition choices. In this study, we assessed the oviposition and foraging preferences of O. laevigatus and O. majusculus on vegetative and flowering chrysanthemum plants, and assessed the survival of their offspring on differently aged tissues. Our results show a preference of O. laevigatus for young and tender chrysanthemum tissues, where the survival of the nymphs was longer on a plant diet. In contrast, O. majusculus selected older plant parts when laying its eggs, and nymphs did not survive long on any of the plant tissues offered. The foraging activity of Orius females for animal prey (Ephestia kuehniella eggs) did not reveal any specific pattern for either of the two predators. Furthermore, we tested the plasticity of the within‐plant oviposition preferences of O. laevigatus, by offering sentinel prey (E. kuehniella eggs) on distinct plant parts. We found that more eggs were laid in older plant tissue when animal prey was offered lower on the plant. Overall, our findings show that oviposition choices of Orius predators are based on a dynamic interplay between plant characteristics, presence of animal and/or floral food sources among other factors, and that differences may well occur between closely related species based on the importance of plant resources in their diet. [ABSTRACT FROM AUTHOR]

Conservation breeding programs (CBPs) are often the lifeline between extinction and survival for many imperilled amphibian species. With the goal of recovering wild populations, CBP success is reliant on their ability to successfully manage ex situ populations over time, breed viable offspring, and maintain genetic diversity and adaptive potential. Reproductive technologies have emerged as an important tool in the conservation toolkit to allow managers to improve reproductive output and genetic management, and their use in amphibian conservation is expanding. To date, studies investigating the efficacy of hormone therapies in amphibians typically only report spawning and fertility rates and do not monitor offspring to later stages of development. For the first time, here we assess the effect of hormone therapies on captive breeding outcomes beyond oviposition, to the point of metamorphosis, in the critically endangered Baw Baw frog, Philoria frosti. To determine the effect of hormone therapy on spawning success and offspring viability, male-female pairs were administered either 0 µg/g gonadotropin-releasing hormone agonist (GnRHa), 0.5 µg/g GnRHa, or 0.5 µg/g GnRHa + 10 µg/g metoclopramide (MET) (n = 12 pairs/treatment), and the number of pairs ovipositing, time to oviposition, clutch size, metamorph mass, and the proportion and number (mean and total) of offspring to metamorphosis were quantified. Overall, the percentage of pairs that oviposited was high across all treatment groups (92-100%). The percentage of fertile clutches was highest in the GnRHa group (92%) and lowest in the GnRHa + MET group (82%), though differences were not statistically significant. Both hormone treatment groups took significantly less time to oviposit than the control pairs. Notably, the proportion of eggs developing to metamorphosis was significantly higher in the GnRHa group, resulting in 74% (total eggs=539) metamorphosing compared to approximately 50% in the control and GnRHa +MET treatments (total eggs= 273 and 264, respectively). Interestingly, weight at metamorphosis was statistically similar across all groups, and results are consistent with previous studies in this species that show a narrow range in size at metamorphosis. The continued application of GnRHa is recommended to improve conservation outcomes for the critically endangered Baw Baw frog. The outcomes of this research advance our understanding of the impact of hormone therapies on reproductive outcomes and will inform amphibian conservation breeding programs globally. [ABSTRACT FROM AUTHOR]

Agricultural pests can develop behavioral resistance to insecticides by choosing to feed or oviposit on insecticide‐free hosts. As young larvae have relatively low mobility, oviposition preferences from female adults may play a critical role in shaping the evolutionary trajectory of pest populations. While oviposition avoidance of insecticide‐treated hosts was found in different agriculture pests, it remains unclear whether female adults actively choose to occupy insecticide‐free hosts. To address this question, we investigated feeding and oviposition preferences between imidacloprid‐treated and imidacloprid‐free plants in the Colorado potato beetle, Leptinotarsa decemlineata Say, a major potato pest. We performed behavioral choice assays on two strains that differed in both fecundity and insecticide resistance. We found that one strain preferred to feed on the insecticide‐free plants and that this preference is not innate. Meanwhile, the other strain chose plants for feeding and oviposition randomly. Further analyses of the moving patterns of the beetles suggested that the oviposition preference in the first strain is likely due to active learning. [ABSTRACT FROM AUTHOR]

The reproductive strategy of the European bitterling (Rhodeus amarus) involves an obligatory parasitic relationship with freshwater mussels from the family Unionidae. This study sets out to assess the possible threat that the invasive unionid species Sinanodonta woodiana poses to bitterling. The objective was accomplished by analysing the bitterling's reproductive preferences for S. woodiana and four native species of unionid mussels (Anodonta anatina, Unio crassus, U. pictorum and U. tumidus). We performed three experiments in a sand bottom tank. Experiments A and B lasted 20 for days and experiment C lasted 10 days. The highest numbers of eggs and embryos of bitterling in the experiment A were found in A. anatina. On the other hand, U. tumidus had the greatest number of embryos in the most developed embryonic stage (stage VI), followed by U. crassus, U. pictorum and lastly A. anatina, whereas U. crassus had the largest densities of eggs and embryos per unit gill area in cm2. As hypothesized, S. woodiana did not contain a single egg or embryo which was also confirmed in the experiments B and C. Results of the experiment C had shown that the first few days bitterlings laid eggs in Unio spp. and only after that in A. anatina. Furthermore, it is evident that bitterlings favour mussels without glochidia. In conclusion, European bitterling will be threatened if an invasive species S. woodiana outcompetes the native unionid species. [ABSTRACT FROM AUTHOR]

Adult female desert locusts (Schistocerca gregaria) dig underground to lay their eggs, ensuring optimal conditions for successful hatching. Digging is performed using the two pairs of oviposition valves at the tip of the female's abdomen. These valves are subjected to considerable shear forces during the repeated digging cycles, potentially leading to wear over time. The resilience of the valves is investigated by analyzing the relationship between digging experience and valve damage and wear throughout the female locust's life. The findings reveal the ability of the valves to withstand the significant shear forces encountered during digging. Despite this resilience, however, perceptible limitations in the valves’ mechanical durability against wear are observed. Toward the end of the female locust's life, the valves show substantial signs of wear, indicating effective performance but with limited longevity, i.e., a designated life span that enables successful oviposition for ca. four oviposition cycles. A comparison of the valve material with that of the animals’ mandibles, which are used continuously throughout their life and show remarkable wear‐resistance, further highlights the evolutionary adaptation of the valve materials to their specific function, suggesting a trade‐off between energetic investment and the sufficient, or “good‐enough”, performance that is required for survival. [ABSTRACT FROM AUTHOR]

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an important insect pest of maize (Zea mays L., Poaceae). The use of synthetic insecticides to control this pest remains the most popular option amongst growers. Natural insecticides offer a safer alternative to synthetic insecticides for controlling FAW. This study aimed to investigate the lethal and sublethal effects of a calcium carbonate formulation against this invasive insect pest. The tested formulation was a mixture of calcium carbonate (five concentrations), wetting agent and dispersant agent. Four experiments were conducted including a direct contact test, a no‐choice feeding test, a choice feeding test and an oviposition test. The application of the calcium carbonate formulation on maize leaves had a strong anti‐oviposition effect for adult female FAW, but a low‐to‐moderate antifeedant effect on FAW larvae. The growth and development of FAW larvae were only slightly affected by the calcium carbonate formulation in the feeding and the direct contact tests. The lethal effects of the calcium carbonate formulation against FAW larvae were low in direct contact and feeding tests. These results indicate that a calcium carbonate formulation has the potential to be used as the push component in a push–pull strategy for FAW control. Considering its low toxicity, both through direct contact and feeding, calcium carbonate can be an environmentally friendly alternative for the management of FAW. [ABSTRACT FROM AUTHOR]

Viral diseases like yellow fever, dengue, and Zika have an alarming impact on public health. These diseases can be transmitted by Aedes mosquito species, such as Ae. albopictus, which is now found in many countries outside its original range. Xenorhabdus and Photorhabdus spp. are enteric bacterial symbionts of insect-preying nematodes and are known to produce an array of natural products with various activities including larvicidal activity. In this study, the effects of natural products produced by four Xenorhabdus and one Photorhabdus bacteria on the ovipositional behavior of Ae. albopictus mosquitoes were assessed. Utilizing a binary choice assay in insect cages, gravid female mosquitoes were presented with two oviposition cups containing water supplemented with varying concentrations of bacterial supernatants (50–1% concentrations) versus control medium. After 72 h, the eggs deposited on filter papers were counted. The oviposition attractant index (OAI) feature of the bacterial supernatant was evaluated using the number of eggs laid in the cups. Notably, all tested supernatants exhibited concentration-dependent deterrence of oviposition. Xenorhabdus cabanillasii displayed the strongest deterrent effect, inhibiting egg-laying at 50–5% concentrations (OAI: − 0.87 to − 0.35), followed by X. nematophila (50–10%, OAI: − 0.82 to − 0.52). Xenorhabdus szentirmaii, X. doucetiae, and P. kayaii showed significant deterrence at ≥ 20% concentrations. Using promoter exchange mutants generated by the easyPACId approach, fabclavine from X. szentirmaii was identified as the bioactive compound with evident deterrent effects. Such deterrents targeting egg-laying could be valuable for controlling populations by disrupting their breeding in suitable habitats. [ABSTRACT FROM AUTHOR]

The red-necked longhorn beetle, Aromia bungii (Coleoptera: Cerambycidae), is a wood-boring pest of ornamental cherry trees in the Rosaceae family. This study evaluates the effectiveness of a preventive measure using fine-mesh netting in preventing A. bungii from oviposition on host cherry trees. Aromia bungii typically oviposits in cracks and crevices of host tree bark using its elongated ovipositor, leading to higher infestations on the lower trunk where there are abundant rough barks suitable for the beetle oviposition. Therefore, we assessed the effectiveness of netting with a gap that exceeded the reach of the A. bungii ovipositor from the tree surface. This evaluation involved laboratory experiments using cut branches and field experiments using lower trunks from standing trees. In the field, we determined the distribution of A. bungii body sizes and estimated the maximum ovipositor length based on their proportional relationship. This led to the establishment of a 10 mm gap for the test net, featuring a 0.4 mm mesh. Both laboratory and field experiments confirmed that the 0.4 mm mesh net with the specified gap effectively prevented A. bungii oviposition in netted areas. Field experiments also suggested a potential shift in oviposition sites from netted (lower) to un-netted (upper) areas in trees with nets, considering results from trees without nets. Although various measures, such as insecticide spraying, are necessary to safeguard areas without nets, our netting method can serve as a fundamental component of integrated pest management against A. bungii. [ABSTRACT FROM AUTHOR]

Sextonia rubra is an Amazonian tree known for the larvicide activity of its wood extracts against Aedes aegypti. However, the lipophilic character of this extract presents an obstacle to the development of vector management products. The purpose of this study was to assess the feasibility, efficacy, and selectivity of a water-soluble formulation based on a S. rubra wood extract characterized by its larvicidal compounds rubrenolide and rubrynolide. Using reference and wild strains, larval mortality, oviposition behavior, hatching response, and fitness of mosquitoes exposed to the extract were evaluated. Laboratory eco- and cytotoxicity bioassays were performed concurrently. The extract showed larvicidal efficacy and no repulsive effect on oviposition, thus supporting its use in the treatment of breeding sites. The formulation exhibited strong acute toxicity, leading to 100% larval mortality in 2–4 days in either the dry or rainy season at a test dose of 102 µg/ml under semi-operational conditions, with residual activity maintained during the 5 weeks of testing. The formulation allowed for a noticeable gain in selectivity compared with the extract, with lower immobilization rates for Daphnia magna and Chironomus riparius, and no significant toxicity towards human cell lines (IC50 > 100 µg/ml). These results highlight the potential of the S. rubra-based formulation for the management of Ae. aegypti larvae, including strains showing resistance to conventional insecticides. [ABSTRACT FROM AUTHOR]

Fifteen commonly grown potato varieties in Meghalaya, consisting of nine local and six commercial varieties, were screened for their susceptibility against potato tuber moth, Phthorimaea operculella. Based on four parameters, oviposition preference, feeding preference, percentage of survival and number of mines, the varieties were categorised into highly susceptible (HS), moderately susceptible (MS), slightly susceptible (SS), and slightly resistant (SR). Among the 15 varieties, two varieties, Kufri Jyoti and Kufri Megha, were highly susceptible (HS) and only one variety, Lah Ksain, was slightly resistant (SR) based on all the tested parameters. Number of eggs laid had a significantly positive correlation with number of eyes and number of mines. The varieties preferred for feeding had more mines compared to the less preferred ones as indicated by the high positive value of the correlation coefficient between penetrating larvae percentage and number of mines. Overall, the results indicated that the local varieties performed comparatively better than the commercial varieties in terms of the parameters studied. [ABSTRACT FROM AUTHOR]

Schistosomiasis is a disease affecting >200 million people worldwide, but its treatment relies on a single agent, praziquantel. To investigate new avenues for schistosomiasis control, we have conducted the first systematic analysis of bromodomain-containing proteins (BCPs) in a causative species, Schistosoma mansoni. Having identified 29 putative bromodomains (BRDs) in 22 S. mansoni proteins, we selected SmBRD3, a tandem BRD-containing BCP that shows high similarity to the human bromodomain and extra terminal domain (BET) family, for further studies. Screening 697 small molecules identified the human BET BRD inhibitor I-BET726 as a ligand for SmBRD3. An X-ray crystal structure of I-BET726 bound to the second BRD of SmBRD3 [SmBRD3(2)] enabled rational design of a quinoline-based ligand (15) with an ITC Kd = 364 ± 26.3 nM for SmBRD3(2). The ethyl ester pro-drug of compound 15 (compound 22) shows substantial effects on sexually immature larval schistosomula, sexually mature adult worms, and snail-infective miracidia in ex vivo assays.

Land cover is recognized as an important determinant of mosquito community assemblages and pathogen transmission, but few studies have investigated the role of land cover in populations of La Crosse virus (LACV) vectors. La Crosse virus is a zoonotic disease primarily maintained by native Aedes triseriatus, with accessory transmission by invasive vectors Ae. albopictus and Ae. japonicus. The objective of this study was to investigate the association between land cover composition and the egg abundances of LACV vectors in a city with endemic LACV transmission. Oviposition cups were deployed at sites ranging from recreational forests to urban areas. Mixed-effects regression models were used to test the relationships between land cover composition and species abundances. Sites characterized by large percentages of impervious and built surfaces were dominated by Ae. albopictus, but Ae. triseriatus was the most abundant species in forested areas. Aedes japonicus was rare at all sites, but its presence was associated with higher percentages of forested land. These results indicate that forested areas may allow Ae. triseriatus to maintain large populations near urban areas that are dominated by Ae. albopictus. Further research should explore the potential for these land cover-dependent population dynamics to influence LACV transmission cycles. [ABSTRACT FROM AUTHOR]

Abstract Background Aedes albopictus is a major arbovirus vector with small stagnant water containers being its oviposition sites. Mosquitoes search for these sites based on their olfactory cues (odor and moisture emanating from the water at the oviposition site), visual cues (size and color of the site), and gustatory cues (ion and nutrient concentration in that water). The gustatory mechanism through which mosquitoes search for oviposition sites remains unknown. Methods To investigate the role of taste receptors in Ae. albopictus oviposition site selection, we developed a laboratory model. This model assessed mosquito behavior in locating and detecting oviposition sites, using a location index to quantify site preference and detection time to measure response to water presence. We compared oviposition site-searching efficiency between mosquitoes with blocked and unblocked appendages, targeting the taste organs. Transcriptome sequencing was conducted to identify differentially expressed genes between water-exposed and unexposed mosquitoes. CRISPR/Cas9 technology was then employed to generate a mutant strain with a targeted gene knockout. Results There was no significant difference between the blocked and unblocked groups in the location index. In contrast, the detection time of the unblocked group differed significantly from all other groups, including those with blocked foreleg tarsus, midleg tarsus, hindleg tarsus, all tibia, and all tarsus. Transcriptome sequencing analyses of water-exposed and unexposed mosquitoes revealed that the taste-related gene gustatory receptor 11(gr11) was differentially expressed. This gene was knocked out with CRISPR/Cas9 technology to generate a pure mutant strain with 2- and 4-bp deletions, which exhibited a significantly longer detection time than the wild-type strain. Conclusions This study reveals the role of Ae. albopictus gr11 in water detection at oviposition sites, thereby providing a theoretical basis and scientific guidelines for managing the breeding sites of these mosquitoes. Graphical Abstract

Abstract Plants are attacked by diverse herbivorous pests with different host specializations. While host plant resistance influences pest pressure, how resistance impacts the behaviors of generalist and specialist herbivores, and the relationship to resistance, is less well known. Here, we investigated the short-term (

Abstract As the most numerous group of animals on Earth, insects are found in almost every ecosystem. Their useful role in the environment is priceless; however, for humans, their presence may be considered negative or even harmful. For years, people have been trying to control the number of pests by using synthetic insecticides, which eventually causes an increased level of resistance to applied compounds. The effects of synthetic insecticides have encouraged researchers to search for alternatives and thus develop safe compounds with high specificity. Using knowledge about the physiology of insects and the functionality of compounds of insect origin, a new class of bioinsecticides called peptidomimetics, which are appropriately modified insect analogues, was created. One promising compound that might be successfully modified is the thirteen amino acid peptide alloferon (HGVSGHGQHGVHG), which is obtained from the hemolymph of the blue blowfly Calliphora vicinia. Our research aimed to understand the physiological properties of alloferon and the activity of its peptidomimetics, which will provide the possibility of using alloferon or its analogues in the pharmaceutical industry, as a drug or adjuvant, or in agriculture as a bioinsecticide. We used alloferon and its three peptidomimetics, which are conjugates of the native peptide with three unsaturated fatty acids with various chain lengths: caprylic, myristic, and palmitic. We tested their effects on the morphology and activity of the reproductive system and the embryogenesis of the Tenebrio molitor beetle. We found that the tested compounds influenced the growth and maturation of ovaries and the expression level of the vitellogenin gene. The tested compounds also influenced the process of egg laying, embryogenesis, and offspring hatching, showing that alloferon might be a good peptide for the synthesis of effective bioinsecticides or biopharmaceuticals.

The silkworm is an economically important insect known for its uniqueness in silk production. Oviposition is an important aspect of insect seed production which needs in-depth study. The aim of this study was to determine the effect of the mating period on the fecundity, egg fertility and performance of bivoltine silkworm. Adult males and females were allowed to mate for 1, 2, 3, 4, 5, and 6 hours respectively. The eggs laid by the mother moth were acid treated, incubated and hatched larvae were reared following standard protocol. The treatments were replicated 5 times and laid out in a Completely Randomized Design. Data were collected on female fecundity, egg fertility, larval and pupal weights, larval survival and cocoon parameters. Data were subjected to analysis of variance and means were separate using DMRT (P

Drosophila suzukii poses a significant threat to berry fruits with its uncontrolled spread. Essential oils (EOs) have emerged as potential bioinsecticides due to their natural origin, mode of action, and biodegradability. Although EOs show potential for use in agriculture due to ecotoxicologically favourable characteristics, additional research is required to enhance their effectiveness, stability, and application for practical implementation in pest management. The primary objective of this research was the development of a bioinsecticide formulation based on a combination of three EOs - Pelargonium graveolens, Anethum graveolens, and Pinus sylvestris followed by the assessment of formulated bioinsecticide physicochemical properties. Using a two-choice bioassay, this study aimed to evaluate the effects of formulated bioinsecticides on D. suzukii, regarding their insecticidal properties through oviposition deterrence. The developed formulation exhibited favourable physicochemical properties and demonstrated a decrease in the number of larvae in fruits. Bioinsecticides present an environmentally friendly approach to pest control. However, further research and development are imperative to fully exploit their potential for effective crop protection in the field, followed by comprehensive research to evaluate the potential side effects on natural enemies, ensuring that their implementation doesn't harm beneficial organisms and maintain ecological equilibrium.

The house fly, Musca domestica L. (Diptera: Muscidae), is a significant pest in livestock farms and a major concern for both humans and farmed animals due to its ability to transmit over 200 pathogens. The use of pupal parasitoids is a sustainable strategy for controlling this pest. Spalangia cameroni Perkins (Hymenoptera: Spalangiidae) and Muscidifurax zaraptor Girault & Sanders (Hymenoptera: Pteromalidae) are commonly used as biocontrol agents for M. domestica. The objective of this study was to determine the oviposition peak of female parasitoids in relation to their age and the sex ratio of the adult progeny. For both species, 20 fresh M. domestica pupae (24–48 h old) were provided daily to each fertilised female for 14 days, after which the pupae were checked for parasitoid emergence. A control group of 20 pupae without female parasitoids was maintained. The results showed that S. cameroni had a higher overall percentage of parasitisation (57.7%) compared with M. zaraptor (32.4%). The parasitisation ratio of S. cameroni remained almost constant throughout the 14‐day period, whereas that of M. zaraptor decreased drastically after Day 11. Peak oviposition for S. cameroni was on Day 5 with 13 parasitised pupae per female, whereas M. zaraptor parasitised eight pupae per day on 4 days during its peak oviposition period (between Days 3 and 8). The newly emerged parasitoids had a skewed sex ratio towards females: 81% for S. cameroni and 66% for M. zaraptor. The presence of these parasitoid species resulted in fewer new house fly emergences than in the control group, where natural pupal mortality was lower in the absence of parasitoids. These findings may be useful for optimising the mass production and time‐use of the two parasitoid species for the management of house flies in livestock farms. [ABSTRACT FROM AUTHOR]

Summary Recent studies show that nocturnal pollinators may be more important to ecosystem function and food production than is currently appreciated. Here, we describe an agricultural field study of pyrethrum (Tanacetum cinerariifolium) flower pollination. Pyrethrum is genetically self‐incompatible and thus is reliant on pollinators for seed set. Our pollinator exclusion experiment showed that nocturnal insects, particularly moths, significantly contribute to seed set and quality. We discovered that the most abundant floral volatile, the sesquiterpene (−)‐germacrene D (GD), is key in attracting the noctuid moths Peridroma saucia and Helicoverpa armigera. Germacrene D synthase (GDS) gene expression regulates the specific GD production and accumulation in flowers, which, in contrast to related species, lose the habit of closing at night. We did observe that female moths also oviposited on pyrethrum leaves and flower peduncles, but found that only a small fraction of those eggs hatched. Larvae were severely stunted in development, most likely due to the presence of pyrethrin defense compounds. This example of exploitative mutualism, which blocks the reproductive success of the moth pollinator and depends on nocturnal interactions, is placed into an ecological context to explain why it may have developed. [ABSTRACT FROM AUTHOR]

Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), has a long association with maize (Zea mays mays L., Poaceae) and is among the crop's most significant pests worldwide. We contrasted the preference for and performance of FAW on three maize cultivars: the Mexican landrace Tuxpeño, the USA inbred B73 and B73‐lox10; B73‐lox10 is deficient in production of jasmonic acid (JA), green leaf volatiles (GLVs) and herbivore‐induced plant volatiles (HIPVs). Female oviposition and neonate colonization preferences were assessed in triple‐choice tests in greenhouse settings. Performance was assessed on the bases of larval, pupal and adult weights, larval and pupal development times, and adult longevity. We expected females to preferentially oviposit on plants on which their offspring performed best, and neonates to randomly colonize plants because they disperse aerially, presumably oriented solely by wind currents. Females preferred to oviposit on Tuxpeño plants, followed by B73‐lox10 and B73 plants, whereas their offspring performed best on B73‐lox10 and poorest on Tuxpeño. In contrast, neonates preferentially colonized plants on which they performed best, B73‐lox10, though initially and transiently they colonized plants on which they performed poorly, B73 and Tuxpeño. Altogether, our results showed that FAW females preferred to oviposit on maize plants on which their offspring's performance was poorest (Tuxpeño), and neonates preferentially colonized plants on which their own performance was best (B73‐lox10), though they initially colonized plants that were detrimental to their performance (Tuxpeño, B73). These results suggested that the ovipositional choices of FAW mothers are uncoupled from their offspring's performance, but newborn offspring rectified their mother's sub‐optimal host plant choice by colonizing plants that enhanced their own performance. Notably, these results also suggested that aerially dispersing (ballooning) FAW larvae do not colonize plants randomly, and that plant volatiles (GLVs, HIPVs) and JA may be relevant to host plant selection by ballooning larvae. [ABSTRACT FROM AUTHOR]

Background: Aedes albopictus is a major arbovirus vector with small stagnant water containers being its oviposition sites. Mosquitoes search for these sites based on their olfactory cues (odor and moisture emanating from the water at the oviposition site), visual cues (size and color of the site), and gustatory cues (ion and nutrient concentration in that water). The gustatory mechanism through which mosquitoes search for oviposition sites remains unknown. Methods: To investigate the role of taste receptors in Ae. albopictus oviposition site selection, we developed a laboratory model. This model assessed mosquito behavior in locating and detecting oviposition sites, using a location index to quantify site preference and detection time to measure response to water presence. We compared oviposition site-searching efficiency between mosquitoes with blocked and unblocked appendages, targeting the taste organs. Transcriptome sequencing was conducted to identify differentially expressed genes between water-exposed and unexposed mosquitoes. CRISPR/Cas9 technology was then employed to generate a mutant strain with a targeted gene knockout. Results: There was no significant difference between the blocked and unblocked groups in the location index. In contrast, the detection time of the unblocked group differed significantly from all other groups, including those with blocked foreleg tarsus, midleg tarsus, hindleg tarsus, all tibia, and all tarsus. Transcriptome sequencing analyses of water-exposed and unexposed mosquitoes revealed that the taste-related gene gustatory receptor 11(gr11) was differentially expressed. This gene was knocked out with CRISPR/Cas9 technology to generate a pure mutant strain with 2- and 4-bp deletions, which exhibited a significantly longer detection time than the wild-type strain. Conclusions: This study reveals the role of Ae. albopictus gr11 in water detection at oviposition sites, thereby providing a theoretical basis and scientific guidelines for managing the breeding sites of these mosquitoes. [ABSTRACT FROM AUTHOR]

Plants are attacked by diverse herbivorous pests with different host specializations. While host plant resistance influences pest pressure, how resistance impacts the behaviors of generalist and specialist herbivores, and the relationship to resistance, is less well known. Here, we investigated the short-term (< 1 h) behavioral changes of a generalist herbivore, the two-spotted spider mite (TSM), and a specialist herbivore, the Banks grass mite (BGM), after introduction to no-choice Tanglefoot leaf-arenas (2 × 2 cm) of three maize inbred lines (B73, B75, and B96). The widely-used inbred line B73 is susceptible to spider mites, while B75 and B96 are known to be mite resistant, especially to TSM. Video tracking was used to record TSM and BGM walking, probing, feeding, resting, web-building and travel distance on arenas of each line. Mite oviposition was also recorded after 72 h. B75, a resistant line, decreased the feeding behavior (i.e., time) of both mite species compared to B73 (susceptible control) and B96. Moreover, TSM appeared to be sensitive to both resistant lines (B75 and B96) with reduced oviposition, and increased resting and web-building times compared to susceptible B73. In contrast, the specialist BGM showed no difference in oviposition, resting and web-building time across all maize inbred lines. Our findings of quite broad and short-term responses of TSM to B75 and B96 are consistent with a role for constitutive or rapidly induced plant defenses in maize in conferring TSM resistance. Other mechanisms of plant resistance may be needed, however, for defense against specialists like BGM. [ABSTRACT FROM AUTHOR]

Aminergic nuclei in mammals are generally composed of relatively small numbers of cells with broad projection patterns. Despite the gross similarity of many individual neurons, recent transcriptomic, anatomic and behavioral studies suggest previously unsuspected diversity. Smaller clusters of aminergic neurons in the model organism Drosophila melanogaster provide an opportunity to explore the ramifications of neuronal diversity at the level of individual cells. A group of approximately 10 tyraminergic/octopaminergic neurons innervates the female reproductive tract in flies and has been proposed to regulate multiple activities required for fertility. The projection patterns of individual neurons within the cluster are not known and it remains unclear whether they are functionally heterogenous. Using a single cell labeling technique, we show that each region of the reproductive tract is innervated by a distinct subset of tyraminergic/octopaminergic cells. Optogenetic activation of one subset stimulates oviduct contractions, indicating that the cluster as a whole is not required for this activity, and underscoring the potential for functional diversity across individual cells. Using whole cell patch clamp, we show that two adjacent and morphologically similar cells are tonically inhibited, but each responds differently to injection of current or activation of the inhibitory GluCl receptor. GluCl appears to be expressed at relatively low levels in tyraminergic/octopaminergic neurons within the cluster, suggesting that it may regulate their excitability via indirect pathways. Together, our data indicate that specific tyraminergic/octopaminergic cells within a relatively homogenous cluster have heterogenous properties and provide a platform for further studies to determine the function of each cell. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH, Nilaparvata lugens) is a notorious sap‐sucking insect pest that damages rice (Oryza sativa) plants throughout Asia. During BPH feeding, saliva enters rice plant tissues, whereas during oviposition egg‐associated secretions (EAS) are deposited in damaged plant tissue. Dynamic changes in rice to planthopper salivary effectors have been widely reported. However, the effects of EAS from planthopper on rice immunity remains largely unexplored. In this study, we found that both infestation of rice by gravid BPH female adults and treatment with the EAS elicited a strong and rapid accumulation of jasmonic acid (JA), JA‐isoleucine, and hydrogen peroxide in rice. EAS enhanced plant defenses not only in rice but also in tobacco, and these impaired the performance of BPH on rice, as well as the performance of aphids and whiteflies on tobacco. High‐throughput proteome sequencing of EAS led to 110 proteins being identified and 53 proteins with 2 or more unique peptides being detected. Some proteins from BPH EAS were also found in the salivary proteome from herbivores, suggesting potential evolutionary conservation of effector functions across feeding and oviposition; however, others were only identified in EAS, and these are likely specifically related to oviposition. These findings point to novel proteins affecting interactions between planthoppers and rice during oviposition, providing an additional source of information for effector studies. [ABSTRACT FROM AUTHOR]

The black soldier fly, Hermetia illucens, comes with big promises for industrial purposes since its larvae feed polyphagously on a broad spectrum of organic substrates. However, research focusing on adult flies is scarce, which is inconsistent with their reproductive relevance within the rearing cycle. In particular, directed oviposition is a challenge in artificial systems. Currently, decomposing organic matter is commonly used as oviposition substrate, which has extensive potential for improvement in view of the lack of standardization and the risk of microbial contamination. Here, we identified three fatty acids and one fatty acid methyl ester derived from the surface of old oviposition sites and targeted to elucidate their effect on preference behavior and oviposition site selection using Y‐olfactometry and prepared oviposition sites, respectively. Exposure to tetradecanoic acid attracted gravid females and stimulated oviposition most strongly, while decanoic acid demonstrated a repulsive effect. Females kept in mixed‐sex populations were attracted by tetradecanoic acid, resulting in a higher egg mass found in the compound box (3.0–11.4 fold), a ≥ 2.3 fold reduction of nonspecifically deposited eggs, and the highest total egg mass. Conversely, decanoic and dodecanoic acid caused females to lay a greater proportion of eggs nonspecifically outside both boxes. Our data suggest that fatty acids, especially tetradecanoic acid, are important cues for oviposition site selection in black soldier flies. In order to achieve a directed oviposition behavior, the role of further short‐ and long‐chain fatty acids as attractants should be examined. [ABSTRACT FROM AUTHOR]

The honeybee queen is the engine of the colony, laying thousands of eggs that develop into larvae, nurse bees, and foragers. In turn, pollen and nectar from the environment, matured into bee bread and honey in the hive, transformed by digestion to royal jelly by the worker community, fuel queen egg-laying. The queen relies on this food supply chain to produce large numbers of eggs during the high season when pollen and nectar are in abundance. Despite the importance of egg-laying for the productivity of a colony, few studies have evaluated the influence of nutrition on the quantity and quality of eggs. This review aims to describe food processing from the queen’s mouth to egg provisioning, by exploring the nutritional cues that trigger queen egg-laying, the subsequent pathways involved, and the factors that influence them. [ABSTRACT FROM AUTHOR]

Pollinating fig wasps are believed to adjust their sex ratios according to standard local mate competition (LMC) theory.Standard LMC theory assumes that all mothers ovipositing in a patch or fig does so simultaneously. However, it has been shown that fig wasps can oviposit sequentially.We counted the number of figs containing dead and living mothers in figs where mothers entered naturally to estimate the incidence of sequential and simultaneous oviposition.Single mothers were the norm in two wasp species, and multiple mothers the norm in the other two. However, contrary to LMC theory, in all four species, when multiple mothers occurred, sequential oviposition seems to occur more frequently than simultaneous oviposition.The sex allocation problem fig wasp mothers face is thus more complicated than the widely assumed simultaneous ovipositing situation, and it leads to several expectations. Single mother's sex ratios should increase as the probability of additional mothers increases. Naturally founded multi‐mother figs should have more female‐biased sex ratios than the standard LMC model predicts for the final number of mothers. This is because early‐arriving mothers underestimate the number of mothers and lay more daughters than the final number of mothers would require and later‐arriving mothers can lay fewer sons to be competitive against the first mothers' too female‐biased clutches.Mothers must produce sex ratios that are optimised across a probabilistic range of foundress densities they experience. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) and nanoplastics (NPs) are pervasive environmental pollutants that are commonly ingested by organisms at different trophic levels. While the effects of MPs on aquatic organisms have been extensively studied, the impacts of MP ingestion on the host fitness of terrestrial organisms, mainly insects, have been relatively unexplored. This study investigates the effects of MP and NP ingestion on the survivorship and reproduction of 2 medically important mosquito species, Aedes aegypti Linnaeus (Diptera: Culicidae) and Aedes albopictus Skuse (Diptera: Culicidae). Larval and pupal survivorship of Ae. albopictus were not significantly affected by particle size or concentration, but there was a reduction of Ae. aegypti pupal survivorship associated with the ingestion of 0.03 µm NPs. In addition, there was little observed impact of 0.03 µm NP and 1.0 µm MP ingestion on adult survivorship, fecundity, and longevity. To further investigate the effects of MP ingestion on mosquito fitness, we also examined the effects of MPs of varying shape, size, and plastic polymer type on Ae. aegypti immature and adult survivorship. The data suggest that the polymer type and shape did not impact Ae. aegypti immature or adult survivorship. These findings highlight that understanding the effects of microplastic ingestion by mosquitoes may be complicated by the size, composition, and amount ingested. [ABSTRACT FROM AUTHOR]

Agroclimatic variables may affect insect and plant phenology, with unpredictable effects on pest populations and crop losses. Bactrocera oleae Rossi (Diptera: Tephritidae) is a specific pest of Olea europaea plants that can cause annual economic losses of more than one billion US dollars in the Mediterranean region. In this study, we aimed at understanding the effect of olive tree phenology and other agroclimatic variables on B. oleae infestation dynamics in the Umbria region (Central Italy). Analyses were carried out on B. oleae infestation data collected in 79 olive groves during a 7-year period (from 2015 to 2021). In July-August, B. oleae infestation (1% attack) was negatively affected by altitude and spring mean daily temperatures and positively by higher wintermean daily temperatures and olive tree cumulative degree days. In September-October, infestation was negatively affected by a positive soil water balance and high spring temperatures. High altitude and cumulative plant degree days were related to delayed attacks. In contrast, high winter and spring temperatures accelerated them. Our results could be helpful for the development of predictive models and for increasing the reliability of decision support systems currently used in olive orchards. [ABSTRACT FROM AUTHOR]

As the most numerous group of animals on Earth, insects are found in almost every ecosystem. Their useful role in the environment is priceless; however, for humans, their presence may be considered negative or even harmful. For years, people have been trying to control the number of pests by using synthetic insecticides, which eventually causes an increased level of resistance to applied compounds. The effects of synthetic insecticides have encouraged researchers to search for alternatives and thus develop safe compounds with high specificity. Using knowledge about the physiology of insects and the functionality of compounds of insect origin, a new class of bioinsecticides called peptidomimetics, which are appropriately modified insect analogues, was created. One promising compound that might be successfully modified is the thirteen amino acid peptide alloferon (HGVSGHGQHGVHG), which is obtained from the hemolymph of the blue blowfly Calliphora vicinia. Our research aimed to understand the physiological properties of alloferon and the activity of its peptidomimetics, which will provide the possibility of using alloferon or its analogues in the pharmaceutical industry, as a drug or adjuvant, or in agriculture as a bioinsecticide. We used alloferon and its three peptidomimetics, which are conjugates of the native peptide with three unsaturated fatty acids with various chain lengths: caprylic, myristic, and palmitic. We tested their effects on the morphology and activity of the reproductive system and the embryogenesis of the Tenebrio molitor beetle. We found that the tested compounds influenced the growth and maturation of ovaries and the expression level of the vitellogenin gene. The tested compounds also influenced the process of egg laying, embryogenesis, and offspring hatching, showing that alloferon might be a good peptide for the synthesis of effective bioinsecticides or biopharmaceuticals. [ABSTRACT FROM AUTHOR]

In northeast China, the invasive woodwasp., Sirex noctilio, attacks Pinus sylvestris var. mongolica Litv and often shares habitat with native Sirex nitobei. Previous research showed that S. noctilio can utilize the volatiles from its symbiotic fungus (A. areolatum IGS-BD) to locate host trees. Consequently, symbiotic fungi (A. areolatum IGS-D and A. chailletii) carried by S. nitobei may influence the behavioral selection of S. noctilio. This study aimed to investigate the impact of fungal odor sources on S. noctilio’s behavior in laboratory and field experiments. Our observations revealed that female woodwasps exhibited greater attraction toward the fungal volatiles of 14-day-old Amylostereum IGS-D in a “Y”-tube olfactometer and wind tunnel. When woodwasps were released into bolts inoculated separately with three strains in the field, females of S. noctilio exhibited a preference for those bolts pre-inoculated with A. areolatum IGS-BD. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that the volatiles emitted by the two genotypes of A. areolatum were similar yet significantly distinct from those of Ampelopsis chailletii. Hence, we postulate that the existence of native A. areolatum IGS-D could potentially facilitate the colonization of S. noctilio in scenarios with minimal or no A. areolatum IGS-BD present in the host. [ABSTRACT FROM AUTHOR]

Population of the tropical bed bug Cimex hemipterus (F.) (Hemiptera: Cimicidae), a temporary ectoparasite on both humans and animals, have surged in many tropical countries. Tropical bed bugs preferences when selecting a suitable harbourage and oviposition site were investigated. Two-choice and three choice colour assays were conducted to determine whether bed bugs will choose black, red or white coloured harbourages. Then, 50 1st instar were reared in containers containing black, red and white (control) paper served as the harbourages and observed for 12 weeks. Both fed and starve male, female and nymph strongly preferred red and black coloured harbourage compared to white coloured harbourage. Oviposition assays showed that female bed bugs prefered to laid their eggs on red coloured harbourages compared to black coloured harbourages. Rearing experiment showed that there was no significant difference (p > 0.05) between final population size of tropical bed bug. However, tropical bed bugs reared in container with red paper (600 ± 89.238) have the highest number of individuals followed by black (473 ± 133.841) and white (485 ± 84.234) paper. Bed bug preference towards coloured harbourage provide useful information for those developing new bed bug control method or improving bed bug infestation monitoring devices. [ABSTRACT FROM AUTHOR]

This study examined the ovipositional and olfactory preferences of gravid pod moths in both choice and non-choice settings. In terms of olfactory preferences, pod moth neonates strongly preferred Abutilon indicum under choice conditions, showing nil interest in other hosts. Under non-choice conditions, both neonates and final-instar larvae thrived on A. indicum but refrained from feeding on other hosts or diets, leading to neonate mortality. Remarkably, neonates exhibited an absolute preference for A. indicum seeds, being unable to feed on Abutilon seed diets or green cotton bolls, resulting in starvation-induced mortality. A majority of the final-instar larvae successfully fed, entered pupation and completed their life cycle on A. indicum seeds but the majority entered diapause when exposed to other hosts or diets as compared to A. indicum at a temperature of 21°C, a relative humidity of 60% and a photoperiod of 14:10 hours (light:dark). Cage studies confirmed pod moth's strong preference for A. indicum , allowing for successful larval feeding and adult emergence. However, pod moth failed to establish on cotton green bolls, underscoring their exclusive reliance on A. indicum as a host. These findings illuminate the intricate host preferences and behaviour of pod moth, underscoring the pivotal role of A. indicum in their life cycle, and is helpful for further research to exploit pod moth as an agent for biological control of the weed A. indicum. [ABSTRACT FROM AUTHOR]

The silkworm is an economically important insect known for its unique silk production. Oviposition is an important aspect of insect reproduction which needs in-depth study. The aim of this study was to determine the effect of the mating period on the fecundity, egg fertility, and performance of bivoltine silkworm (Bombyx mori L). Adult males and females were allowed to mate for 1, 2, 3, 4, 5, and 6 hours respectively. The eggs laid by the mother moth were acid treated, incubated, and subsequent hatched larvae were reared following standard protocols. The treatments were replicated five times and placed in a completely randomized design. Data were collected on female fecundity, egg fertility, larval and pupal weights, larval survival, and cocoon parameters. Data were subjected to analysis of variance and means were separated using DMRT (P <0.05). The results showed that the number of eggs laid, larval weight, number of cocoons harvested, shell ratio, and effective rate of rearing were significantly higher in progeny whose parents were allowed to mate for one hour. The cocoon weight, pupal weight, and shell weight were highest in progeny whose parents were allowed to mate for five hours, but not significantly different from the ones of other mating durations. There was a negative linear relationship between mating duration and hatchability (r=-0.88) at P<0.05. The study conclusively established that mating duration of one hour in bivoltine silkworms is enough to produce the best larval and cocoon performance. Hence, one-hour mating duration can be recommended for silkworm producers in the sericulture industry. [ABSTRACT FROM AUTHOR]

Stick insects (Phasmatodea) have many different oviposition strategies, reflecting a range of adaptive behaviours and morphologies to best place and secure eggs in their environments. Oviposition strategies in Aotearoa New Zealand phasmids are not well documented, but the literature so far suggests that they drop individual eggs to the ground from their position in the foliage. Here, we present evidence for an oviposition strategy unique among the Rō stick insects of Aotearoa New Zealand. Individual female Spinotectarchus acornutus were observed inserting their eggs in a range of substrates, in particular the bark of trees and in spaces within the textured surfaces of tree fern trunks. We also highlight how the specific morphology of their eggs may be an adaptation to assist in substrate attachment, while their elongated secondary ovipositor could aid in egg insertion into substrates. [ABSTRACT FROM AUTHOR]

Intercropping is drawing increasing attention as a strategy to increase crop yields and manage pest pressure, however the mechanisms of associational resistance in diversified cropping systems remain controversial. We conducted a controlled experiment to assess the impact of co-planting with silverleaf Desmodium (Desmodium uncinatum) on maize secondary metabolism and resistance to herbivory by the spotted stemborer (Chilo partellus). Maize plants were grown either in the same pot with a Desmodium plant or adjacent to it in a separate pot. Our findings indicate that co-planting with Desmodium influences maize secondary metabolism and herbivore resistance through both above and below-ground mechanisms. Maize growing in the same pot with a Desmodium neighbor was less attractive for oviposition by spotted stemborer adults. However, maize exposed only to above-ground Desmodium cues generally showed increased susceptibility to spotted stemborer herbivory (through both increased oviposition and larval consumption). VOC emissions and tissue secondary metabolite titers were also altered in maize plants exposed to Desmodium cues, with stronger effects being observed when maize and Desmodium shared the same pot. Specifically, benzoxazinoids were strongly suppressed in maize roots by direct contact with a Desmodium neighbor while headspace emissions of short-chain aldehydes and alkylbenzenes were increased. These results imply that direct root contact or soil-borne cues play an important role in mediating associational effects on plant resistance in this system. [ABSTRACT FROM AUTHOR]

Spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is one of the most detrimental pests of small fruit crops worldwide and its control relies heavily on pesticides, so there is a need to develop alternative management practices. Cultural practices that make the microclimate hotter, drier, and brighter than optimal conditions for the pest may be highly effective. In this two-year study, we evaluated how black, white, and metallic plastic mulches influence the raspberry plants' microclimate to reduce D. suzukii larval infestation of fruit in the canopy and increase mortality of fallen larvae and pupae on the ground. All three plastic mulches reduced D. suzukii larval infestation of fruit by 40–72% and killed 80–100% of larvae and pupae placed on the mulch surface. The mechanisms at play are likely the compounded effects of increased ultraviolet (UV) light, hotter and drier conditions in the low canopy, and hot mulch surface temperature. UV light may be especially important since it reduced D. suzukii oviposition in the lab. Overall, plastic mulches can effectively modify the microclimate to make it less favorable for D. suzukii, reducing infestation in fruit and on the ground. [ABSTRACT FROM AUTHOR]

Simple Summary: Mass outbreaks of the pine sawfly Diprion pini can cause severe damage to pine forests. The larvae of this herbivorous insect feed selectively on the needles of pine trees, notably Pinus sylvestris. During mass outbreak periods, the females release large amounts of sex pheromones. A prior study revealed that the survival rate of sawfly eggs laid on pheromone-exposed pine needles was lower than that of eggs on unexposed pine. In our study, we found that D. pini females avoided oviposition on pheromone-exposed pine, possibly as a counter-adaptation to the enhanced defenses of previously pheromone-exposed trees against sawfly eggs. The females only discriminated between pheromone-exposed and unexposed trees when they had the chance to touch the needles, but not when exposed to the odor of these types of trees. However, the performance of larvae did not significantly differ on pheromone-exposed and unexposed trees. These results underscore the complexity of the chemical ecology of sawfly–pine interactions and highlight the nuanced roles that pheromones play in shaping the relationships between herbivores and their host plants. Insect pheromones have been intensively studied with respect to their role in insect communication. However, scarce knowledge is available on the impact of pheromones on plant responses, and how these in turn affect herbivorous insects. A previous study showed that exposure of pine (Pinus sylvestris) to the sex pheromones of the pine sawfly Diprion pini results in enhanced defenses against the eggs of this sawfly; the egg survival rate on pheromone-exposed pine needles was lower than that on unexposed pine. The long-lasting common evolutionary history of D. pini and P. sylvestris suggests that D. pini has developed counter-adaptations to these pine responses. Here, we investigated by behavioral assays how D. pini copes with the defenses of pheromone-exposed pine. The sawfly females did not discriminate between the odor of pheromone-exposed and unexposed pine. However, when they had the chance to contact the trees, more unexposed than pheromone-exposed trees received eggs. The exposure of pine to the pheromones did not affect the performance of larvae and their pupation success. Our findings indicate that the effects that responses of pine to D. pini sex pheromones exert on the sawfly eggs and sawfly oviposition behavior do not extend to effects on the larvae. [ABSTRACT FROM AUTHOR]

Simple Summary: The spotted lanternfly (SLF) is an invasive generalist that is spreading throughout the eastern United States. They feed in large aggregations, but the mechanisms they use to form these aggregations and find each other for mating are poorly understood. Laboratory evidence that they use pheromones is based on volatiles from their bodies and from honeydew excretions, but, due to their broad sensory capabilities, the pheromone components have been difficult to isolate and identify. This is the first evidence gathered in a field study that demonstrates, using naturally collected SLF odors as lures, that volatiles from SLF bodies and honeydew are both required to attract males at mating time and females during oviposition time. Using semiochemicals collected from spotted lanternflies Lycorma delicatula (Hemiptera: Fulgoridae) (SLF) and deployed in the field with circle traps, we demonstrated that SLF responded to SLF pheromones: in particular, this was the case for males while seeking mates and for females while ovipositing. The attractants consisted of SLF body extract emitted from diffuser lures and SLF honeydew on burlap ribbons, collected from heavily infested locations. Traps with attractants were deployed in field sites with very light SLF infestations to avoid competing signals of pre-existing aggregations. The number of SLF equivalents emitted by each diffuser per trapping period was used in a dose–response analysis. Three trees per block received either (1) a control hexane lure and a clean ribbon, (2) a lure containing SLF extract and a clean ribbon, or (3) a lure containing SLF extract and a honeydew-laden ribbon. Ten blocks were sampled three times per week for twelve weeks. We found a significant positive dose–response by males to SLF body extract only in the presence of SLF honeydew, indicating a synergistic effect between honeydew volatiles and body volatiles. This dose–response occurred for five weeks after mating started, after which males no longer responded. Subsequently, females had a significant positive dose–response to SLF extract only in the presence of honeydew when oviposition was their primary activity, continuing for two weeks, suggesting that females may use pheromones to aggregate for oviposition. The extract in the absence of honeydew did not result in a positive dose–response, nor did the hexane control. These findings suggest that SLF respond synergistically to the combination of pheromones present in both SLF honeydew and SLF bodies. Thus, combining key components from both sources may aid the development of semiochemical lures for SLF. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) released by plants can serve as a cue for regulating insect behaviors. Hyphantria cunea is a widely distributed forestry pest that may use CO2 as a cue for foraging and oviposition. However, the molecular mechanism underlying its ability to sense CO2 has not been elucidated. Our initial study showed that CO2 is significantly attractive to H. cunea adults. Subsequently, 44 H. cunea gustatory receptors (GRs) were identified using transcriptome data, and 3 candidate CO2 receptors that are specifically expressed in the labial palps were identified. In vivo electrophysiological assays revealed that the labial palp is the primary organ for CO2 perception in H. cunea, which is similar to findings in other lepidopteran species. By using the Xenopus oocyte expression system, we showed that the HcunGR1 and HcunGR3 co-expressions produced a robust response to CO2, but HcunGR2 had an inhibitory effect on CO2 perception. Finally, immunohistochemical staining revealed sexual dimorphism in the CO2-sensitive labial pit organ glomerulus (LPOG). Taken together, our results clarified the mechanism by which H. cunea sense CO2, laying the foundation for further investigations into the role of CO2 in the rapid spread of H. cunea. [ABSTRACT FROM AUTHOR]

Since widespread monitoring began in 1976 in the UK, habitat‐specialist butterfly populations have declined dramatically. The main driver is habitat degradation, caused primarily by land‐use change, perhaps interacting with changes in vegetation phenology.Here, we focus on two declining species: Boloria selene (Dennis & Schiffermüller) and Boloria euphrosyne L., Lepidoptera: Nymphalidae. We hypothesise that these species differ in their preferred breeding habitat, and this is driven by differences in their temperature preferences, mediated by vegetation cover.We use mark‐release‐recapture techniques and oviposition observations to characterise and compare adult distribution, habitat use and oviposition site preferences of the two species.Egg‐laying females of both species are shown to occur in areas with relatively high abundance of the larval food plants, Viola spp. (violets), principally V. riviniana, and they oviposit where Viola spp. abundance is locally high. However, in contrast to B. selene, ovipositing B. euphrosyne tends to occur in areas with relatively short and sparse cover of vegetation.B. euphrosyne oviposit in sites with a relatively high plant surface temperature irrespective of ambient temperatures, in contrast with B. selene in which the temperature of oviposition sites increases as ambient temperature increases. These differential temperature strategies likely underlie differences in breeding habitat preference.Microclimatic cooling caused by increased vegetation growth in spring may be one reason B. euphrosyne is declining in the UK, while both B. euphrosyne and B. selene may be affected by declining Viola spp. availability. Our data provide further evidence that drivers of butterfly declines can be multi‐factorial, and paradoxically, that thermophilic species do not necessarily benefit from climate warming if responses of other species result in cooling of their habitats. [ABSTRACT FROM AUTHOR]

Conservation breeding programs (CBPs) are often the lifeline between extinction and survival for many imperilled amphibian species. With the goal of recovering wild populations, CBP success is reliant on their ability to successfully manage ex situ populations over time, breed viable offspring, and maintain genetic diversity and adaptive potential. Reproductive technologies have emerged as an important tool in the conservation toolkit to allow managers to improve reproductive output and genetic management, and their use in amphibian conservation is expanding. To date, studies investigating the efficacy of hormone therapies in amphibians typically only report spawning and fertility rates and do not monitor offspring to later stages of development. For the first time, here we assess the effect of hormone therapies on captive breeding outcomes beyond oviposition, to the point of metamorphosis, in the critically endangered Baw Baw frog, Philoria frosti. To determine the effect of hormone therapy on spawning success and offspring viability, male-female pairs were administered either 0 µg/g gonadotropin-releasing hormone agonist (GnRHa), 0.5 µg/g GnRHa, or 0.5 µg/g GnRHa + 10 µg/g metoclopramide (MET) (n = 12 pairs/treatment), and the number of pairs ovipositing, time to oviposition, clutch size, metamorph mass, and the proportion and number (mean and total) of offspring to metamorphosis were quantified. Overall, the percentage of pairs that oviposited was high across all treatment groups (92-100%). The percentage of fertile clutches was highest in the GnRHa group (92%) and lowest in the GnRHa + MET group (82%), though differences were not statistically significant. Both hormone treatment groups took significantly less time to oviposit than the control pairs. Notably, the proportion of eggs developing to metamorphosis was significantly higher in the GnRHa group, resulting in 74% (total eggs=539) metamorphosing compared to approximately 50% in the control and GnRHa+MET treatments (total eggs= 273 and 264, respectively). Interestingly, weight at metamorphosis was statistically similar across all groups, and results are consistent with previous studies in this species that show a narrow range in size at metamorphosis. The continued application of GnRHa is recommended to improve conservation outcomes for the critically endangered Baw Baw frog. The outcomes of this research advance our understanding of the impact of hormone therapies on reproductive outcomes and will inform amphibian conservation breeding programs globally.