Female Oviposition Research Articles

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

BackgroundSchistosomiasis 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.MethodsWe 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 β-alanyl-tryptamine (BATT) was conducted using liquid chromatography–mass spectrometry (LC–MS).ResultsBoth 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 β-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.ConclusionsWe 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.Graphical

Sex‐specific oviposition site selection in an arboreal treefrog with a resource‐defense mating system

AbstractOviposition site selection by parents is an important factor that affects offspring survival and parental fitness. The relative importance of sexes in oviposition site selection in anurans is rarely evaluated, especially in species with resource‐defense mating systems, where males defend territory containing eventual oviposition sites before advertising for females. Using a phytotelm‐breeding frog (Kurixalus eiffingeri) with male territoriality, we examined 310 bamboo stumps (potential for oviposition sites) to determine whether male and female choice of oviposition site based on physical characteristics (stump height, inner diameter, stump depth, water depth, and water volume). We found that males preferred a site with higher stumps that were deeper and contained more water, while females showed no preference for sites based on the characteristics observed. Although we do not exclude the possibility that K. eiffingeri female oviposition site selection can be relied on and/or correlates to male advertisement calls, this study is one of few studies to examine the role of both sexes in oviposition site selection simultaneously, and provides empirical evidence that oviposition site selection is primarily determined by males in an amphibian with a resource‐defense mating system.

Sox21b underlies the rapid diversification of a novel male genital structure between Drosophila species

The emergence and diversification of morphological novelties is a major feature of animal evolution.1,2,3,4,5,6,7,8,9 However, relatively little is known about the genetic basis of the evolution of novel structures and the mechanisms underlying their diversification. The epandrial posterior lobes of male genitalia are a novelty of particular Drosophila species.10,11,12,13 The lobes grasp the female ovipositor and insert between her abdominal tergitesand, therefore, are important for copulation and species recognition.10,11,12,14,15,16,17 The posterior lobes likely evolved from co-option of a Hox-regulated gene network from the posterior spiracles10 and have sincediversified in morphology in the D.simulans clade, in particular, over the last 240,000 years, drivenby sexual selection.18,19,20,21 The genetic basis of this diversification is polygenic but, to the best ofour knowledge, none of the causative genes have been identified.22,23,24,25,26,27,28,29,30 Identifying the genes underlyingthe diversification of these secondary sexual structures is essential to understanding theevolutionary impact on copulation and species recognition. Here, we show that Sox21b negatively regulates posterior lobe size. This is consistent with expanded Sox21b expression in D.mauritiana, which develops smaller posterior lobes than D.simulans. We tested this by generating reciprocal hemizygotes and confirmed that changes in Sox21b underlie posterior lobe evolution between these species. Furthermore, we found that posterior lobe size differences caused by the species-specific allele of Sox21b significantly affect copulation duration. Taken together, our study reveals the genetic basis for the sexual-selection-driven diversification of a novel morphological structure and its functional impact on copulatory behavior.

ВЛИЯНИЕ МЕТЕОРОЛОГИЧЕСКИХ УСЛОВИЙ НА РАСПРОСТРАНЕННОСТЬ СОСУЩИХ ВРЕДИТЕЛЕЙ

The article presents the actual results of observations on the prevalence of sugescent pests in the Rostov region, the dynamics of abundance, population, and the peculiarities of the phenological development of pests on technical varieties, depending on meteorological conditions. It is noted that an air temperature of +14 ... +30 ºC and a relative humidity of 52 % are necessary to maintain viability and fertility. The eggs of the buffalo ceresa leafhopper overwinter in the branches and trunks of trees of woody species, often in young annual shoots. The female ovipositor cuts the bark and lays eggs in two rows of 5-11 eggs. Damage by the buffalo ceresa leafhopper causes a violation of the flow of nutrients to the tops of shoots, weakening and a sharp decrease in their growth. The rose leafhopper gives up to 4 generations during the summer. Damaged leaves turn yellow, photosynthesis processes are disrupted in them, plant nutrition deteriorates, which affects the reduction of economically valuable indicators. The presence of sucking pests increases the risk of spreading viral diseases. Insecticides and phytosanitary monitoring are most effective in fruit-bearing vineyards only in combination with high agricultural techniques of cultivation. In this connection, there is a decrease in yield losses and environmental pollution with chemicals. Therefore, it is necessary to deal with weeds in a timely manner, to carry out maintenance work to ensure good ventilation of grape bushes, to regularly carry out phytosanitary monitoring of the population with sugescent pests and diseases, to carry out row-to-row tillage. Chemical treatments are necessary only if the threshold number of pests is exceeded. The article provides suggestions on how to contain the number of pests at a low level to obtain an environmentally safe grape yield.

Relationship between parasitism and morphology of Trichogramma (Hymenoptera: Trichogrammatidae) on Spodoptera frugiperda (Lepidoptera: Noctuidae).

In this study, 5 species of Trichogramma Westwood were evaluated for the biological control of Spodoptera frugiperda (JE Smith), concerning the physical characteristics of female Trichogramma. The results showed that Trichogramma chilonis Ishii, Trichogramma dendrolimi Matsumura, and Trichogramma ostriniae Pang et Chen exhibited high parasitism rates, emergence rates, and offspring numbers, with the highest values observed for T. ostriniae. The ovipositor length of Trichogramma japonicum Ashmead and T. dendrolimi were longer than those of other species, and the hind tibia length was the shortest in Trichogramma cacoeciae Marchal. We further evaluated relationships between the parasitism ability of Trichogramma and various morphological indexes based on Spearman's rank correlation coefficients. A positive correlation was found between the parasitism rate and hind tibia length of T. cacoeciae. In T. dendrolimi, the parasitism rate was negatively correlated with ovipositor width and positively correlated with the length-width ratio of the ovipositor. A significant positive correlation was observed between the proportion of female offspring and the mother's ovipositor length in T. japonicum. However, there were no significant correlations between morphological indexes and indexes of parasitism in T. ostriniae. Overall, the parasitic abilities of T. chilonis on S. frugiperda eggs were significantly correlated with the morphology of the female ovipositors.

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.

Exploring Life History Choices: Using Temperature and Substrate Type as Interacting Factors for Blowfly Larval and Female Preferences.

Blowflies (Diptera: Calliphoridae) present a wide range of larval lifestyles, typically classified as obligate parasitism, facultative parasitism, and complete sapro-necrophagy. Several parasitic species, both obligate and facultative, are considered to be of sanitary and economic importance, as their larvae can cause myiasis (maggot infestation in live tissue). However, it is noteworthy that the adult female plays a decisive role as she chooses the oviposition site, and, therefore, largely determines the feeding habit and developmental conditions of the larvae. In this study, two protocols are proposed to test larval feeding preference and female oviposition site preference considering two interacting factors: meat substrate type and temperature. The setups presented here allowed to test Lucilia cuprina larvae and gravid females in a four-choice assay with two temperatures (33 ± 2 °C and 25 ± 2 °C) and two types of meat substrates (fresh meat supplemented with blood and 5-day-old rotten meat). Larvae or gravid females can choose to burrow or lay their eggs, respectively, in either of the following: rotten meat at 25 °C (simulating a necrophagous species condition), fresh meat supplemented with blood at 33 °C (simulating a parasitic species condition), and two controls, rotten meat at 33 °C, or fresh meat supplemented with blood at 25 °C. The preference is assessed by counting the number of larvae or eggs laid in each option for each replicate. Comparing the observed results to a random distribution allowed for the estimation of the statistical significance of the preference. The results indicated that L. cuprina larvae have a strong preference for the rotten substrate at 25 °C. Conversely, oviposition-site preference by females was more varied for the meat type. This methodology can be adapted to test the preference of other insect species of similar size. Other questions can also be explored by using alternative conditions.

Differences in perch height and response to intruders for territorial and non-territorial Calopteryx maculata (Odonata: Calopterygidae)

In the damselfly Calopteryx maculata, territorial males court potential mates and guard ovipositing females near the surface of the water. We conducted a survey and an experiment to determine whether there was a relationship between territoriality (site fidelity and agonistic behavior) and perch height. In the survey, males were captured, numbered, and released, and their perch height and location along a stream was noted for two weeks. Mean perch height was positively correlated with total distance travelled and negatively correlated with the number and percentage of times observed at the same site. Males that travelled less than 4 m had a significantly lower mean perch height than males that travelled more than 4 m. We conclude that males with greater site fidelity perch lower than males that travel widely. To test for a relationship between agonistic behavior and perch height, live male and female decoys, and a stick control, were run along a 20 m zip-line at two heights (25 cm and 75 cm), and the responses of resident males were recorded. Resident males that perched low (< 1 m high) approached decoys more often than resident males that perched high, and low-flying decoys were approached more than high-flying decoys. We conclude that territorial males—identified by greater site fidelity and agonistic behavior—perch lower than other males and are particularly responsive to low flying intruders. The benefits and costs of perching low and responding to low-flying intruders are discussed.

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

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

Determination of Blood Biochemistry Reference Intervals in Eastern Collared Lizards (Crotaphytus collaris)

Abstract Eastern collared lizards (Crotaphytus collaris) are growing in popularity as exotic pets in the United States and worldwide. However, clinical biochemistry reference data to support interpretation of health and disease for this species remains lacking. This study evaluated 87 apparently healthy Eastern collared lizards (Crotaphtyus collaris). Blood samples were collected from the ventral coccygeal vein and assayed via Abaxis VetScan VS2 and Avian Reptile rotor. While lizard weight and snout-vent length (SVL) were normally distributed, most biochemical analytes, except albumin and total protein, were not. Many analytes were affected, albeit slightly, by lizard age, SVL, body condition score, gravidity and/or recent ovoposition, sex, health status, and color/locality. However, except for calcium, phosphorous, and albumin for gravid or immediately post oviposition females, biochemical values remained within the generated reference interval. Limitations of this study included that the VetScan VS2 avian / reptile profile plus rotor was unable to successfully provide values for bile acids for most of these apparently healthy lizards. When compared to biochemistry analyte values of lizards from the suborder Iguania from the western hemisphere, Eastern collared lizard biochemistries were similar for some analytes, but a relatively increased plasma glucose and uric acid occurs in this species which could affect the diagnosis of clinical disease or other health abnormalities.

Female treefrog preference for breeding sites matches offspring performance in the presence of two anuran competitors.

Preference-performance theory predicts that females should select breeding sites that maximize offspring performance. Amphibians have been a model system for investigating habitat selection, yet most studies have focused on habitat selection in response to predators and conspecifics. We investigated female oviposition site selection and larval performance in eastern gray treefrogs (Hyla versicolor) among pools with and without one of two ecologically distinct heterospecific larvae, the green frog (Rana clamitans) and the American bullfrog (R. catesbeiana). Pools without heterospecifics were used on more nights and had more eggs deposited compared to pools with heterospecifics. In a competition experiment, treefrog larval performance matched this female preference: tadpoles developed faster and grew larger in the absence of either heterospecific. Although we hypothesized that bullfrogs would more strongly affect female treefrog preference and offspring performance because of previous work demonstrating that bullfrogs have stronger negative effects on other tadpoles, both heterospecifics elicited similar responses. The effects of heterospecifics on anuran breeding site selection are understudied and not well understood, and our results demonstrate that female selection of breeding sites is an adaptive behavior for offspring in the presence of heterospecific competitors.

Mosquito Oviposition Deterring and Larvicidal Effect of Cinnamaldehyde and Eugenol

Aedes spp. females feed from various hosts including humans and can vector arboviruses of public health importance like dengue, Zika and chikungunya viruses. These infections affect millions of people so insect populations need to be monitored and effectively controlled. Cinnamaldehyde and eugenol are naturally occurring compounds found in essential oils of various spices like cinnamon, cloves, cassia and have different biological activities. I investigated the larvicidal and oviposition deterrence effects of cinnamaldehyde and eugenol against Ae. aegypti and Ae. albopictus. Both chemicals effectively killed mosquito larvae and deterred female oviposition for both mosquito species at 50-200 μg/mL concentration. Larvicidal and oviposition-deterrent compounds like cinnamaldehyde and eugenol are useful in biological control of mosquitoes. They offer the potential to reduce population numbers by killing immature stages and repelling mosquitoes away from human settlements.

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

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

Reproductive benefits and reduced investment in parental care behavior associated with reproductive groups of males in Abudefduf troschelii.

Fishes of the family Pomacentridae present a wide diversity of mating systems, ranging from polygyny to promiscuity and from individual territorial defense to the establishment of reproductive colonies of males. The damselfish species Abudefduf troschelii has a reproductive colony mating system, in which males temporarily aggregate in reproductive areas to court and attract females. Males defend an individual territory where they receive eggs and perform paternal care behaviors for their offspring. The present study evaluated the advantages of the colonial mating system in A. troschelii. During an entire reproductive period, in a breeding colony within a rocky reef, we located, marked, geo-referenced, and measured the distances between the territories of all males. We quantified the variance among males in their patterns of paternal care investment, eggs acquired, hatching success, reproductive success, body size, and changes in body coloration. We found that males spatially distributed their nests in groups or independently (i.e., solitary nests). Nesting groups are formed by larger males that show intense nuptial coloration during the entire receptivity period. They are located centrally to the colony and consist of three to six males whose territories overlap. In contrast, small solitary males that fail to acquire or maintain nuptial coloration during the receptivity period establish their nests peripherally to the colony, away from the territories of other males. Our results highlight that the reproductive benefits of colonial nesting are unequal for males, as the spatial distribution of nests within the colony determines the reproductive success of males. Group nesting confers the highest reproductive benefits to males regarding eggs obtained, hatching success, and relative fitness and also enables males to reduce their parental investment in brood care behaviors. The preference of females for oviposition could be associated with greater intrasexual competitiveness, defense ability, body condition, or experience of group-nesting males located at the center of the colony or because their progeny will have a lower probability of predation than they would in solitary nests males.

A review of Asian mayfly species of Habrophlebiodes (Ephemeroptera: Leptophlebiidae)

The mayfly genus Habrophlebiodes Ulmer, 1920 has four Asian species (three from China). To show the real characters of Asian species and to ensure the differences between the two clades of the genus, we studied all three endemic Chinese species (H. gilliesi Peters, 1963, H. tenella Kang & Yang, 1994, H. zijinensis You & Gui, 1995) with examining specimens from more than 30 sites. Adults of Chinese Habrophlebiodes can be separated by the male genitalia, female ovipositor and spots on adult wings, nymphs can be recognized by the abdominal color and prostheca shape of mandibles. Comparatively, the fourth species H. prominens Ulmer, 1939 is more different by its longer apical segment of maxillary palpi and colored wings. A key to the four Asian species is given. The status of the latter species, the exact difference between Asian and American clades, and their distribution pattern need more fresh materials to confirm.

Development and life table parameters of the Phytoseius corniger Wainstein (Acari: Phytoseiidae) feeding on the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions

Phytoseiid mites are important for biological control of some pest species including phytophagous mites and small insects. The species, Phytoseius corniger Wainstein is one of the most abundant predatory mite in fruit orchards and urban green spaces in Razavi Khorasan province, Iran. Biological parameters of this predatory feeding on the two-spotted spider mite Tetranychus urticae Koch was studied for the first time under the laboratory conditions (25±2 ºC, 55±5 % RH and 16L: 8D photoperiod). The results indicated that the mean developmental periods for egg, larva, protonymph and deutonymph were 1.12±0.09, 0.73±0.03, 1.01±0.03, and 3.05±0.09 days for females, and 0.95±0.37, 0.67±0.39, 1.05±0.88, and 3.05±0.85 days for males, respectively. The pre-oviposition, oviposition, post-oviposition periods and adult longevity for females were 4.63±0.11, 11.63±0.16, 7.93±0.13 and 24.18±0.21 days, respectively. The females laid an average of 0.48 eggs per day, and 5.60 eggs during their life span. In addition, larvae of P. corniger may molt to the protonymph stage without feeding. Consumption rate during nymphal stage was 1.95 prey per day. The highest rate of prey consumption was recorded during the oviposition period, with an average of 3.35 prey items prey per day. Regarding life-history traits, the intrinsic rates of increase (rm) of this predatory mite 0.064±0.02 (♀♀/♀/day) and its finite rate of increase (λ), net reproduction rate (R0), generation time (T), and doubling time (DT) were 1.066±0.23 (day-1), 3±0.07 (♀♀/♀/generation), 17.14±0.11 (days), and 10.83±0.65 (days), respectively. Further laboratory and field studies regarding its diet preference and predation capacity are needed.

Biology and Ecology of Delia planipalpis (Stein) (Diptera: Anthomyiidae), an Emerging Pest of Broccoli in Mexico.

Delia planipalpis (Stein) (Diptera: Anthomyiidae) is a pest of crucifers, such as broccoli, radish, cauliflower, turnip and cabbage. It has been recently described in Mexico as a significant emerging pest of broccoli. Due the lack of knowledge of this pest, the present study aimed to determine its life cycle, female sexual maturation, copulation, oviposition behavior and adult longevity. The identity of the fly in Mexico was confirmed genetically by sequencing the cytochrome oxidase subunit 1 gene (COI). The mean development time of D. planipalpis was 32-33 days on radish at 24 °C under laboratory conditions. Females became sexually mature 1-2 days after emergence, and the highest incidence of matings was recorded on the second day (60%). Under choice conditions, D. planipalpis females preferred to oviposit on radish plants, rather than broccoli plants, possibly due to the use of radish for rearing the laboratory colony. Oviposition and the mean number of eggs laid varied among the broccoli varieties, with the highest oviposition observed on the Tlaloc variety. Repeated attempts to rear the laboratory colony on broccoli plants failed. Radish-reared insects of both sexes lived longer when individualized in the adult stage (14.5-22.5 days) than when adult flies were maintained in groups (10-11 days). This study contributes to the understanding of D. planipalpis biology and provides information that can be used to establish future control strategies against this pest.

Sublethal Effects of Flonicamid on Life Table of Myzus persicae (Sulzer)

The green peach aphid, Myzus persicae (Sulzer) (Aphididae: Hemiptera) is a cosmopolitan polyphagous pest of more than five hundred plant species belonging to at least forty different plant families including several economically important agricultural crops. The sublethal effect of LC25 concentration of flonicamid on M. persicae was assessed by using an age-stage two-sex life table approach for integrated management of this pest. A leaf-dip bioassay showed that flonicamid was very toxic to the adults of M. persicae at 48 h with the calculated LC25 concentration value of 0.0115 g a.i./L. The adults (parental generation) of M. persicae exposed to the LC25 concentration (sublethal dose) of flonicamid showed inhibitory effects on the life history traits across its generations such as reduction in adult longevity and fecundity of parental generation (F0); shortening the durations of fifth instar nymphs, adult female longevity, oviposition period, total longevity and fecundity of F1 & F2 generations. On the other hand, stimulatory effects were observed on the duration of first, second, third, and fourth instar nymphs; and pre-adults in F2 generation in the flonicamid-treated aphids. Consistently with the effects on individual traits, a higher mean generation time (T) and shorter intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R0) of F2 generation were observed in the flonicamid treated aphids, although r, λ, R0, T, and gross reproductive rate (GRR) of F1 generation were not significantly affected. The findings revealed the exposure of parental adults of M. persicae to sublethal concentration of flonicamid could induce hormetic (both inhibitory and stimulatory) effects on their succeeding generations. This study is useful for assessing the overall effects of flonicamid on M. persicae. The hormetic effects should be considered when it used flonicamid in the integrated management of M. persicae in crop fields.

Behavioral, Electrophysiological, and Toxicological Responses of Plutella xylostella to Extracts from Angelica pubescens.

Plutella xylostella L. is a destructive pest affecting cruciferous vegetables, causing massive economic losses worldwide. Plant-based insecticides are considered promising insect control agents. The Angelica pubescens extract inhibited female oviposition, with an oviposition deterrence index (ODI) of 61.65% at 12.5 mg/mL. We aimed to identify the bioactive compounds in A. pubescens extract. The compounds from A. pubescens extract were analyzed using LC-MS techniques. The toxicity and behavioral responses of larvae and adults of P. xylostella to ten compounds were investigated. We found that the caryophyllene oxide and 3,4-dimethoxycinnamic acid inhibited female oviposition; the ODIs were 98.31% and 97.59% at 1.25 mg/mL, respectively. The A. pubescens extract, caryophyllene oxide, and 3,4-dimethoxycinnamic acid caused larval mortality, with LC50 values of 21.31, 4.56, and 5.52 mg/mL, respectively. The EAG response of females was higher than that of males under A. pubescens extract conditions, while the EAG response of males was higher than that of females in caryophyllene oxide and 3,4-dimethoxycinnamic acid conditions. The A. pubescens extract and caryophyllene oxide showed repellent activity against both female and male adults, while the 3,4-dimethoxycinnamic acid did not elicit any notable behavioral responses from P. xylostella adults. A. pubescens extract and caryophyllene oxide are potential insecticides, oviposition deterrents, and behavioral regulators against P. xylostella, and they could be potential candidates for the development of biological insecticides to control P. xylostella.

Mutation of brain aromatase disrupts spawning behavior and reproductive health in female zebrafish.

Aromatase (Cyp19a1) is the steroidogenic enzyme that converts androgens into bioactive estrogens, and hence is in a pivotal position to mediate reproduction and sexual behavior. In teleosts, there are two aromatase paralogs: cyp19a1a that is highly expressed in granulosa and Leydig cells in the gonads with critical function in sexual differentiation of the ovary, and cyp19a1b that is highly expressed in radial glial cells in the brain with unknown roles in reproduction. Cyp19a1 -/- mutant zebrafish lines were used to investigate the importance of the cyp19a1 paralogs for spawning behavior and offspring survival and early development. Mutation of cyp19a1b was found to increase the latency to the first oviposition in females. Mutation of cyp19a1b in females also increased the number of eggs spawned; however, significantly more progeny died during early development resulting in no net increase in female fecundity. This finding suggests a higher metabolic cost of reproduction in cyp19a1b -/- mutant females. In males, the combined mutation of both cyp19a1 paralogs resulted in significantly lower progeny survival rates, indicating a critical function of cyp19a1 during early larval development. These data establish the specific importance of cyp19a1b for female spawning behavior and the importance of the cyp19a1 paralogs for early larval survival.