Demography and predatory potential of Orius strigicollis on eggs of Plutella xylostella at two temperatures.

Background: The polyphagous predatory bug Orius strigicollis Poppius (Heteroptera: Anthocoridae) is an active predator used to control many insect pests of agricultural crops. Orius species are significantly affected by the type of food and temperature. Method: A study of O. strigicollis feeding on Plutella xylostella L. (Lepidoptera: Plutellidae) eggs in climate chambers at 28 and 32 °C, 70 ± 5% relative humidity, 16:8 photoperiod, was conducted to determine the effects of different temperatures on the predation activity, biological characteristics and demographic parameters of O. strigicollis. Twosex-MS Charts were used to determine the age-stages and characteristics of this species. Results: The results showed that the daily consumption of pre-adults on eggs of P. xylostella was highest at 28 °C, and at this temperature, there was a greater probability that O. strigicollis would survive to adulthood (42.5%) than at 32 °C (25.0%). It has also been found that at 28 °C there was a long oviposition period (9.38 days) and the greatest female fecundity (44.2 eggs/female) In addition to the highest life expectancy of O. strigicollis (16.96 days) at 28 °C, the intrinsic rate of increase (0.087 d-1) was also highest. According to our results, O. strigicollis has the potential to grow and develop on the eggs of P. xylostella at 28 °C and, therefore, could potentially be used as a biological control agent in integrated pest management (IPM) programs.

Invasive brown algae (Sargassum spp.) as a potential source of biocontrol against Aedes aegypti.

Influxes of sargassos are responsible for economic and environmental disasters in areas where they bloom, especially in regions whose main income relies on tourism and with limited capacity for sanitation and public health response. A promising way of valorization would be to convert this incredible biomass into tools to fight the deadly vector mosquito Aedes aegypti. In the present study, we generated hydrolates and aqueous extracts from three main Sargassum morphotypes identified in Guadeloupe (French West Indies): Sargassum natans VIII, Sargassum natans I and Sargassum fluitans. We conducted a chemical characterization and a holistic evaluation of their potential to induce toxic and behavioral effects in Ae. aegypti. Despite the low insecticidal potential observed for all the extracts, we found that S. natans VIII and S. fluitans hydrolates deterred oviposition, induced contact irritancy and stimulated blood feeding behavior in host seeking Ae. aegypti females, while aqueous extracts from S. natans I and S. fluitans deterred both blood feeding behavior and oviposition. Chemical characterization evidenced the presence of phenylpropanoid, polyphenols, amino acids and esters. Thus, Sargassum spp. aqueous extracts and hydrolates could be used to manipulate Ae. aegypti behavior and be valorized as control tools against this mosquito.

Role of eggplant trichome in whitefly oviposition and its relevance to biological control under greenhouse conditions.

The combined release of the predatory mite Amblyseius swirskii (Athias-Henriot) and the mirid Nesidiocoris tenuis (Reuter) provides effective biological control of the tobacco whitefly (Bemisia tabaci (Gennadius)) in greenhouse eggplant. However, knowing how plants' trichomes affect pest-predator interactions could improve whitefly management. Here, the effect of two varieties with either the presence or absence of trichomes was assessed on naturally occurring whitefly populations and predator abundance in a first experiment under field conditions. Predator-prey models were developed to assess the effect of trichomes on pest and predator population dynamics under field conditions. In a second semi-field experiment, the occurrence and oviposition preferences of B. tabaci and A. swirskii in the same eggplant varieties were compared. Significantly higher numbers of whitefly and mite, adults and eggs, were found on the hairy variety in both experiments. However, no differences were found in N. tenuis abundance between varieties under field conditions. Predator-prey models showed that whitefly growth rate increased in the hairy variety. N. tenuis and A. swirskii showed different fitness parameters according to the variety, with the former displaying better performance in the hairless variety and the latter in the hairy variety. Both predators effectively controlled the increase in whitefly populations in both varieties. Overall, the findings suggest that the hairless variety is more effective in deterring whiteflies. Additionally, the higher population of A. swirskii on the hairy variety indicates that this predator benefited from both the presence of trichomes and the prey.

Genome-wide variation study and inter-tissue communication analysis unveil regulatory mechanisms of egg-laying performance in chickens.

Egg-laying performance is of great economic importance in poultry, but the underlying genetic mechanisms are still elusive. In this work, we conduct a multi-omics and multi-tissue integrative study in hens with distinct egg production, to detect the hub candidate genes and construct hub molecular networks contributing to egg-laying phenotypic differences. We identifiy three hub candidate genes as egg-laying facilitators: TFPI2, which promotes the GnRH secretion in hypothalamic neuron cells; CAMK2D, which promotes the FSHß and LHß secretion in pituitary cells; and OSTN, which promotes granulosa cell proliferation and the synthesis of sex steroid hormones. We reveal key endocrine factors involving egg production by inter-tissue crosstalk analysis, and demonstrate that both a hepatokine, APOA4, and an adipokine, ANGPTL2, could increase egg production by inter-tissue communication with hypothalamic-pituitary-ovarian axis. Together, These results reveal the molecular mechanisms of multi-tissue coordinative regulation of chicken egg-laying performance and provide key insights to avian reproductive regulation.

The change of albumen quality during the laying cycle and its potential physiological and molecular basis of laying hens.

To elucidate the regulatory mechanisms that impact variability in albumen quality of laying hens from the peak of lay to the late production phase. A 60-wk study was conducted on a cohort of 20,000 Hy-Line Brown laying hens from 20 to 80 wk old. Before commencement at 20 wk, the 10-wk-old hens were acclimatized for 10 wk. This study examined changes in albumen quality, serum, and liver antioxidant capacity, magnum morphology, and expression of albumen-protein-related genes in the magnum. To reduce sampling error, we collected eggs (n = 90) from pre-determined cages at every sampling point (5-wk intervals), and 8 hens were selected at 10-wk intervals for blood and tissue collection. Our findings revealed that age significantly affected most evaluated parameters. Albumen gel properties, including hardness, gumminess, and chewiness, increased significantly with age (P < 0.05). With the increasing of hens' age from 20 to 80 wk, the albumen proportion of eggs was decreased, but eggshell proportion, yolk proportion, thick albumen proportion, thick to thin ratio, thick albumen solid content, albumen height, Haugh units (HU), and yolk color were increased and then decreased (P < 0.05). Compared to hens aged 20 to 60 wk, the hens (70-80 wk) had significantly reduced total antioxidant capacity (TAC) and glutathione levels (GSH) in the liver and lower serum TAC and superoxide dismutase levels (SOD) (P < 0.05). The magnum mucosal folds were highest in 40 to 60 wk-old hens, and the luminal diameter increased with age (P < 0.05). In the magnum, the mRNA expression levels for OVA, CPE, and NUP205 increased significantly between 30 and 40 wk, while FBN1 expression was higher between 30 and 50 wk (P < 0.05). At 70 to 80 wk, the expression of BRCA2 was significantly downregulated (P < 0.05). Albumen height, thick albumen proportion with protein secretion-related genes, enhanced antioxidant function, and luminal diameter correlated positively. However, the thick-to-thin albumen ratio negatively correlated with BRCA2, downregulated in aged laying hens. We used principal component and cluster analysis to deduce albumen quality changes during 3 phases: 25 to 35, 40 to 55, and 60 to 80 wk. The decline in albumen quality in aging hens is linked with decreased antioxidant capacity, magnum health, and downregulation of key genes involved in protein synthesis and secretion. These findings emphasize critical albumen quality changes in laying hens and suggest molecular pathways underlying age-related albumen quality alterations.

Host plant selection is linked to performance in Phthorimaea absoluta (Lepidoptera: Gelechiidae).

The evolution of oviposition preference in insects is considered a key evolutionary strategy in the context of host-plant interaction. It is hypothesized that insects maximize the survival and fitness of the subsequent generations by preferring specific host plant(s), known as the "preference-performance hypothesis." In this study, we tested whether adult host preference reflects the immature performance in an oligophagous insect, Phthorimaea absoluta Meyrick, a rapidly emerging invasive pest in Asia, Africa, and Europe. Based on a preliminary survey of the potential host plants of P. absoluta, we selected 6 Solanaceae species, namely, tomato, potato, eggplant, black nightshade, sweet pepper, and tobacco, for the oviposition preference studies. The results indicated that the tomato was the most preferred host in no-, dual- and multiple-choice assays, followed by potato, eggplant, and black nightshade. Subsequently, the insect life-table parameters were found to be superior on tomato compared to other hosts. The order of oviposition preference on the host plants was strongly correlated with the life-table parameters of P. absoluta. Thus, we provide clear evidence for the preference-performance hypothesis in the host selection behavior of P. absoluta. We also emphasize the necessity of conducting oviposition behavior research at various geographic locations to develop tailor-made integrated pest management programs.

The TCTP is essential for ovarian development and oviposition of Rhipicephalus haemaphysaloides.

Tick infestations transmit various infectious agents and result in significant socioeconomic consequences. Currently, the primary focus of tick control efforts is identifying potential targets for immune intervention. In a previous study, we identified a highly conserved protein abundant in tick haemolymph extracellular vesicles (EVs) known as translationally controlled tumour protein (TCTP). We have found that native TCTP is present in various tissues of the Rhipicephalus haemaphysaloides tick, including salivary glands, midgut, ovary, and fat body. Notably, TCTP is particularly abundant in the tick ovary and its levels increase progressively from the blood-feeding stage to engorgement. When the TCTP gene was knocked down by RNAi, there was a noticeable delay in ovarian development, and the reproductive performance, in terms of egg quantity and survival, was also hindered. Our investigations have revealed that the observed effects in ovary and eggs in dsRNA-treated ticks are not attributable to cell death mechanisms like apoptosis and autophagy but rather to the reduction in the expression of vitellogenin (Vg1, Vg2, and Vg3) and ferritin (ferritin 1 and ferritin 2) proteins crucial for ovarian development and embryo survival in ticks. Additionally, phylogenetic analysis and structural comparisons of RhTCTP and its orthologues across various tick species, vertebrate hosts, and humans have shown that TCTP is conserved in ticks but differs significantly between ticks and their hosts, particularly in the TCTP_1 and TCTP_2 domains. Overall, TCTP plays a vital role in tick reproductive development and presents itself as a potential target for tick control in both humans and animals.

Vertical distribution and tissue selection of Helicoverpa zea (Lepidoptera: Noctuidae) adult oviposition and neonates on soybean with an indeterminate or determinate growth habit.

Helicoverpa zea (Boddie) is a polyphagous pest that can cause serious damage to crops, including soybeans (Glycine max L.). In soybeans with both determinate and indeterminate growth habits, H. zea larvae are more commonly found on leaves compared to blooms, stems, and pods. Past research demonstrated that H. zea adults tend to oviposit near the upper part of the plant canopy in soybeans with a determinate growth habit. However, ovipositional selection on soybeans with an indeterminate growth habit is unknown. We hypothesized that H. zea would oviposit more uniformly throughout the canopy on indeterminate soybean growth habits due to more diffuse reproductive tissue. We planted field and greenhouse experiments with varieties sharing a similar relative maturity (2 maturity group [MG] 5.2 varieties and 2 MG 5.4/5.5 varieties) but with different growth habits. To test oviposition selection, adult H. zea females were allowed to oviposit under field and caged conditions. We counted the number of H. zea eggs and neonates on each plant tissue type from each of 3 equal parts in the plant canopy: upper, middle, and lower. In both experiments, eggs and neonates were most common on leaves at the top of the plant regardless of soybean growth habit. Consequently, ovipositional selection is likely independent of reproductive tissue availability, and patterns of oviposition through the canopy are similar in growth habits. An improved understanding of H. zea ecology in soybeans relative to indeterminate growth habits may improve recommendations for managing this significant pest of soybean.

The impact of yeast-encapsulated orange oil in Aedes aegypti oviposition.

The yeast-encapsulated orange oil (YEOO) is a novel larvicide under development against vector mosquitoes. Despite its efficiency against Aedes aegypti (L.) in small scale experiments, its applicability in vector control can be influenced by other effects on mosquito behaviour or physiology. For this reason, the impact of YEOO particles in mosquito oviposition was evaluated in laboratory and semi-field conditions. Oviposition assays with one gravid Aedes aegypti female were carried under laboratory and semi-field conditions with natural light and temperature fluctuation. For all ovitraps, the number of eggs was manually counted in the wooden paddle and in the solution of each ovitrap. The proportion of eggs between substrates (wooden paddle and solution) varied between conditions, with females in laboratory presenting a lower preference to lay eggs in paddles when compared with studies in semi-field. This behaviour shifts in laboratory can create challenges to extrapolate results from laboratory to the field. Here, studies in both conditions indicate a similar impact of YEOO particles in Aedes aegypti oviposition. The potential treatment concentration of YEOO particles presents a strong repellent/deterrent effect (-0.559 > OAI > -0.760) within the initial 72h of application when compared with water, and weak repellent/deterrent signal (OAI = -0.220) when compared against inactivated yeast. Control ovitraps with water were more positive for egg presence than treated ovitraps, while ovitraps with YEOO particles and inactivated yeast present similar number of positive ovitraps. It is possible that the repellent/deterrent action is partially driven by the delivery system, since most times Citrus sinensis EO oviposition repellent/deterrent signal is weak, and it seem influenced by solvent/delivery used. However, it is unclear how the yeast wall that protect/surrounds the orange oil will negatively affect oviposition since live yeast are normally consider an attractant for mosquito oviposition.

Pigeon pea crop stage strongly influences plant susceptibility to Helicoverpa armigera (Lepidoptera: Noctuidae).

Helicoverpa armigera Hübner (Lepidoptera: Noctuidae; Hübner) is the major insect pest of pigeon pea [Cajanus cajan; Fabales: Fabaceae; (L.) Millspaugh] worldwide. Research to develop pest management strategies for H. armigera in pigeon pea has focused heavily on developing less susceptible cultivars, with limited practical success. We examined how pigeon pea crop stage influences plant susceptibility to H. armigera using a combination of glasshouse and laboratory experiments. Plant phenology significantly affected oviposition with moths laying more eggs on flowering and podding plants but only a few on vegetative plants. Larval survival was greatest on flowering and vegetative plants, wherein larvae mostly chose to feed inside flowers on flowering plants and on the adaxial surface of expanding leaves on vegetative plants. Larval survival was poor on podding plants despite moths laying many eggs on plants of this stage. When left to feed without restriction on plants for 7 days, larvae feeding on flowering plants were >10 times the weight of larvae feeding on plants of other phenological stages. On whole plants, unrestricted larvae preferred to feed on pigeon pea flowers and on expanding leaves, but in no-choice Petri dish assays H. armigera larvae could feed and survive on all pigeon pea reproductive structures. Our results show that crop stage and the availability of flowers strongly influence pigeon pea susceptibility to H. armigera. An increased understanding of H. armigera-pigeon pea ecology will be useful in guiding the development of resistant varieties and other management tactics.

The development of Spodoptera frugiperda (Lepidoptera: Noctuidae) on 8 major crops in Japan and its oviposition preference for maize and soybean.

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a polyphagous pest native to the Americas. It first invaded Japan in July 2019, and the most damaged crop in this region to date has been maize. To determine pest control strategies, the range of crops potentially damaged by S. frugiperda in Japan should be identified. In this study, the effects of 8 major crops in Japan-forage maize Zea mays subsp. mays, sugarcane Saccharum officinarum, forage and edible rice Oryza sativa subsp. japonica, soybean Glycine max, eggplant Solanum melongena, green bell pepper Capsicum annuum var. grossum, sweet potato Ipomoea batatas, and taro Colocasia esculenta-on the development of S. frugiperda were analyzed by feeding leaves of domestic cultivars during larval stage. Spodoptera frugiperda developed from hatching to adulthood and laid eggs in all 7 treatments, except for taro. However, among them, only soybean showed comparable developmental suitability to maize. Therefore, its oviposition preference for maize and soybean was examined using further nonchoice and choice tests. In the nonchoice test, the number of egg masses oviposited for 3 days on soybean plants was significantly less than that on test containers, while that on maize was comparable to that on containers. These findings can explain partly why major damage has been limited to maize in Japan.

An improved medium for in vitro studies of female reproduction and oviposition in Schistosoma japonicum.

BACKGROUND: Schistosomiasis is a disease primarily caused by eggs laid by pathogens called schistosomes. Among the schistosome species infecting humans, Schistosoma japonicum possesses the largest fecundity; each adult female produces an average of 3500 eggs per day. The lack of proper culture conditions supporting continuous oviposition in vitro has precluded detailed investigation of mechanisms regulating sexual maturation and egg production in Schistosoma japonicum. METHODS: We optimized in vitro culture conditions by replacing reagents that are part of the classical ABC169 medium. Fast Blue BB staining and 4',6-diamidino-2-phenylindole (DAPI) labeling were applied to observe the sexual development status of the females. In vitro RNA interference (RNAi) technology was used to validate the capability of the modified medium. The detection of male ß-alanyl-tryptamine (BATT) was conducted using liquid chromatography-mass spectrometry (LC-MS). RESULTS: Both m-AB169 (1640) and AB169 (1640) media are capable of facilitating the sexual development of paired virgin female S. japonicum, as well as sustaining the mature reproductive organs and egg production of adult S. japonicum for at least 22 days in vitro. M-AB169 (1640) provided a more stable condition for supporting the sexual maturity of female S. japonicum, as evidenced by the consistent initiation of egg production compared with AB169 (1640). Through a comparative analysis of S. japonicum and S. mansoni in diverse media, we demonstrated that these closely related species display distinct demands for their sexual development and egg production, suggesting a potential influence of nutritional factors on the observed variations in host ranges among different schistosome species. Importantly, we successfully identified the presence of the pheromone ß-alanyl-tryptamine (BATT) in S. japonicum, previously identified in S. mansoni, highlighting its conserved role in schistosome reproductive development. Through the employment of double-stranded RNA (dsRNA) treatment to silence two genes that are involved in either the male (gli1, glioma-associated oncogene homolog 1) or female (vf1, vitellogenic factor 1) side in male-induced female reproductive development of S. mansoni, we confirmed that the combination of m-AB169 (1640) and RNAi technology has the capacity to facilitate in vitro studies of S. japonicum's reproductive and oviposition processes. CONCLUSIONS: We developed a novel medium, m-AB169 (1640), that not only maintains the mature reproductive organs and continuous oviposition of adult female Schistosoma japonicum for up to 22 days but also supports the reproductive development and subsequent egg-laying of virgin females after pairing with male worms. This study provides a valuable in vitro platform for functional studies of the mechanisms underlying the fascinating biology of the female sexual development and egg production of S. japonicum, which may accelerate the development of new strategies targeting schistosome egg production.

Integrated transcriptomic and metabolomic analyses reveal potential regulatory pathways regulating bone metabolism pre- and postsexual maturity in hens.

At the onset of sexual maturity, the increasing circulating estrogen stimulates the formation of medullary bone, which provides available calcium for eggshell formation. The bone loss of laying hens is caused by the continuous dynamic changes of structure bone leading to bone fragility and susceptibility. The degree of medullary bone mineralization in sexual maturity is positively correlated with bone quality in the late laying stage. This study aimed to explore the molecular regulation mechanism of bone metabolism pre- and postsexual maturity in hens based on the joint analysis of transcriptome and metabolome. A total of 50 Hy-line Sonia pullets with comparable body weight at 13 wk were selected. Eight pullets were killed at 15 wk (juvenile hens, JH) and 19 wk (laying hens, LH), and LHs were killed within 3 h after oviposition. Differentially expressed genes and metabolites in tibia were analyzed based on transcriptome and metabolome, and then combined to construct the relevant metabolisms and hub genes. In the LH hens, plasma levels of estrogen and tartrate-resistant acid phosphatase were significantly elevated by 1.7 and 1.3 times. In addition, the midpoint diameter, bone mineral density and bone mineral content of the tibia and femur were higher at 19 wk of age. A total of 580 differentially expressed genes were found between the JH and LH group in the tibia, including 280 up-regulated, and 300 down-regulated genes in the LH group. Gene set enrichment analysis (GSEA) showed that the intracellular biosynthesis and secretion of matrix vesicles were significantly enrichment in the LH hens. A total of 21 differential metabolites were identified between JH and LH group. Estradiol valerate positively correlated with L-theanine, tryptophan betaine, dopamine, and perindopril. Joint analysis showed that the top 20 hub genes were enriched in cholesterol biosynthesis and phospholipid metabolism, which played a key regulatory role in bone metabolism during pre- and postsexual maturity. These results provide a theoretical foundation for maintaining efficient egg production and reducing bone health problems in laying hens.

Insect neurobiology: Oviposition crowd control.

A new study examines how Helicoverpa armigera females detect chemicals released by conspecific eggs in order to avoid laying more eggs on the same substrate. This work opens new avenues for basic research inquiries and offers a potential strategy for controlling insect pests.

Plant defensive responses to insect eggs are inducible by general egg-associated elicitors.

Egg deposition by herbivorous insects is well known to elicit defensive plant responses. Our study aimed to elucidate the insect and plant species specificity of these responses. To study the insect species specificity, we treated Arabidopsis thaliana with egg extracts and egg-associated secretions of a sawfly (Diprion pini), a beetle (Xanthogaleruca luteola) and a butterfly (Pieris brassicae). All egg extracts elicited salicylic acid (SA) accumulation in the plant, and all secretions induced expression of plant genes known to be responsive to the butterfly eggs, among them Pathogenesis-Related (PR) genes. All secretions contained phosphatidylcholine derivatives, known elicitors of SA accumulation and PR gene expression in Arabidopsis. The sawfly egg extract did not induce plant camalexin levels, while the other extracts did. Our studies on the plant species specificity revealed that Solanum dulcamara and Ulmus minor responded with SA accumulation and cell death to P. brassicae eggs, i.e. responses also known for A. thaliana. However, the butterfly eggs induced neoplasms only in S. dulcamara. Our results provide evidence for general, phosphatidylcholine-based, egg-associated elicitors of plant responses and for conserved plant core responses to eggs, but also point to plant and insect species-specific traits in plant-insect egg interactions.

Ovipositional responses of tortricid moths to sugars, salts and neem oil.

Oviposition is essential in the life history of insects and is mainly mediated by chemical and tactile cues present on the plant surface. Oviposition deterrents or stimulants can modify insect oviposition and be employed in pest control. Relatively few gustatory oviposition stimuli have been described for tortricid moths. In this study the effect of NaCl, KCl, sucrose, fructose and neem oil on the number of eggs laid by Cydia pomonella (L.), Grapholita molesta (Busck) and Lobesia botrana (Dennis & Schifermüller) was tested in laboratory arenas containing filter papers loaded with 3 doses of a given stimulus and solvent control. In general, salts increased oviposition at the mid dose (102 M) and sugars reduced it at the highest dose (103 mM), but these effects depended on the species. Neem oil dramatically reduced the number of eggs laid as the dose increased, but the lowest neem oil dose (0.1% v/v) increased L. botrana oviposition relative to solvent control. Our study shows that ubiquitous plant chemicals modify tortricid moth oviposition under laboratory conditions, and that neem oil is a strong oviposition deterrent. The oviposition arena developed in this study is a convenient tool to test the effect of tastants on the oviposition behavior of tortricid moths.

Temperature-dependent reproduction of Spodoptera eridania: developing an oviposition model for a novel invasive species.

BACKGROUND: Temperature plays a critical role in the development and reproductive process of insects, therefore understanding how insects respond to temperature is vital for comprehending and predicting their population dynamics, particularly when it comes to agricultural pests. Spodoptera eridania Stoll is a polyphagous pest that has recently expanded its distribution beyond its native range. In this study, we assessed the impact of temperature on the reproduction of S. eridania and used the obtained data to develop an oviposition model that could be used to predict egg-laying behavior under field conditions. The reproductive parameters were evaluated at temperatures of 15, 20, 25, 28, and 32 °C. RESULTS: Temperature had a significant impact on the reproductive parameters examined. Overall, as temperature increased, the pre-oviposition period, oviposition period, and longevity decreased. Total fecundity exhibited a bell-shaped response to temperature, with peak egg-laying observed at 20 and 25 °C. In line with the experimental data, our model predicted higher rates of oviposition between 20 and 26 °C, thus reinforcing that this temperature range may represent the optimal conditions for the reproduction of S. eridania. CONCLUSION: The findings from our study provide a significant contribution to the understanding of the ecology of an important agricultural pest. The information generated can have practical applications in developing control strategies by enabling the aligning of the timing of control measures with peaks of reproductive activity. © 2023 Society of Chemical Industry.

Mating- and oviposition-dependent changes of the spermatheca and colleterial glands in the pest termite Cryptotermes brevis (Blattaria, Isoptera, Kalotermitidae).

The spermatheca and colleterial glands of female insects are organs associated with the reproductive system, responsible for sperm storage and secretion of egg coverings, respectively. Here we compared the development, secretory activity, and chemical nature of the secretion in the spermatheca and colleterial glands of different-aged females of the drywood termite Cryptotermes brevis. We also provide the ultrastructure of these organs in alate females. These structures have been poorly investigated in termites when compared to other eusocial insects (Hymenoptera) and termite-related dictyopterans (mantises and cockroaches). The spermatheca of C. brevis comprises a cone-shaped structure, connected to the genital chamber by a short duct. The colleterial glands, in turn, are divided into anterior and posterior tubules, each showing a basal trunk, and join into a common duct. Histological and histochemical analyses showed that the secretion of proteins and polysaccharides by the spermatheca takes place before pairing, but increases as females mate and store sperm. Colleterial glands of alates showed non-synchronous secretory activity, but the synthesis of products increased in egg-laying queens, together with the epithelium height. Ultrastructure of the spermatheca and colleterial glands revealed epithelia composed of class III secretory cells. Richness of mitochondria and electron-dense secretion in the spermatheca indicates synthesis and transport of content. Presence and absence of colleterial gland secretion in different individuals may reflect variable maturation stages of the females and secretory cells. Assuming that termites are iteroparous, the development and secretion of the spermatheca and colleterial glands play a crucial role for C. brevis queens.

A female-specific odorant receptor mediates oviposition deterrence in the moth Helicoverpa armigera.

Finding ideal oviposition sites is a task of vital importance for all female insects. To ensure optimal conditions for their progeny, females of herbivorous insects detect not only the odors of a relevant host plant but also chemicals released by eggs, named oviposition-deterring pheromones (ODPs). It is reported that such chemicals play critical roles in suppressing female oviposition behavior; however, the molecular mechanism underlying the detection of egg-derived ODPs remains elusive. Here, we have identified three specific fatty acid methyl esters from the surface of eggs of Helicoverpa armigera serving as ODPs-methyl oleate (C18:1ME), methyl palmitate (C16:0ME), and methyl stearate (C18:0ME). We demonstrated that these ODPs are detected by the receptor, HarmOR56, exclusively expressed in sensilla trichodea on female antennae. To assess the significance of this receptor, we disrupted HarmOR56 in H. armigera using CRISPR-Cas9 and found that mutant females did not respond to the ODPs, neither in behavioral nor in electrophysiological tests. We therefore conclude that HarmOR56 is indispensable for identifying the ODPs. This study explores, for the first time, how a female-specific odorant receptor detects chemicals from conspecific eggs. Our data elucidate the intriguing biological phenomenon of repulsion to conspecific eggs during oviposition and contribute new insight into a female-specific olfactory pathway linked to reproduction.

High population levels lead Glycaspis brimblecombei (Hemiptera: Aphalaridae) to unrecorded feeding and oviposition behaviors on Eucalyptus urograndis plants / Altos níveis populacionais levam Glycaspis brimblecombei (Hemiptera: Aphalaridae) a diferentes comportamentos de alimentação e oviposição em plantas de Eucalyptus urograndis

The red gum lerp psyllid, Glycaspis brimblecombei Moore, 1964 (Hemiptera: Aphalaridae), an insect pest originating in Australia and which feeds only on Eucalyptus L'Hér. (Myrtales: Myrtaceae) plants, has spread to several countries. The populations of this insect commonly reach high populations on Eucalyptus plants since its entry into Brazil, and also indicated an unrecorded behavioral. The objectives of this study were to describe a peculiar adaptation in the feeding habit of G. brimblecombei and to register the new habit. The oviposition and feeding by G. brimblecombei, commonly, on the leaves of Eucalyptus, started to occur, also, on lignified twigs. This suggests a not yet recorded adaptation of this insect to reduce insect × plant intraspecific competition.

O psilídeo de concha, Glycaspis brimblecombei Moore, 1964 (Hemiptera: Aphalaridae), um inseto praga originário da Austrália e que se alimenta apenas de plantas de Eucalyptus L'Hér. (Myrtales: Myrtaceae), se espalhou por vários países. Esse inseto, geralmente, atinge grandes populações em plantas de Eucalyptus desde sua entrada no Brasil e, também, indicou um comportamento diferente. Os objetivos deste estudo foram descrever uma adaptação peculiar no hábito alimentar de G. brimblecombei e registrar o novo hábito. A oviposição e alimentação por G. brimblecombei, geralmente, nas folhas de Eucalyptus, passaram a ocorrer, também, em ramos lignificados. Isso sugere uma adaptação diferente desse inseto para reduzir a competição intraespecífica inseto × planta.