Mating Rate Research Articles

Exploration of the transfluthrin effects on fertility and pregnancy outcomes: An in-vivo study in rat

Transfluthrin (TFL) is a rapid-acting pyrethroid insecticide, commonly used worldwide, however its overuse and or misuse has been associated with adverse effects on human health. This study was designed to investigate the impact of TFL on fertility and pregnancy in Sprague–Dawley rats exposed orally and by inhalation. In this study, 48 adult Sprague–Dawley rats of 6–8 months age group were randomly selected with equal numbers of males and females. Each group was housed separately in a standard laboratory condition and their daily consumption of food and water, along with weight of each group were monitored. The blood was collected from each rat on 0 (zero) and 85th day of oral and inhalation exposure to TFL to determine the hormone levels by ELISA. The findings revealed that TFL exposure through oral and inhalation route reduced hormones level in serum such as testosterone, follicle-stimulating hormone, luteinizing hormone, progesterone, estrogen, and prolactin in both male and female rats. In conclusion, current research suggest the negative effects of TFL exposure on fertility, adversely affecting pregnancy outcomes, reducing the mating rate, and lowering the number of pups. It also stresses the significance of controlling its use to prevent any negative consequences.

Reconstruction and Prediction of Invasive Cydia pomonella Population Dynamics: A Laboratory Study

ABSTRACTInvasive species pose a significant threat to global biodiversity and ecological services. The specific threshold of the initial population size necessary for the successful establishment of an invasive species remains uncertain. This research delves into the effects of different initial population sizes on the colonisation and population dynamics of the globally recognised invasive pest, Cydia pomonella, within a controlled laboratory setting. The results revealed that even a single pair of C. pomonella displayed notable eggs laid (fecundity) and hatched (fertility) by producing offspring upon mating. Larger initial population size exhibited increased mating rates, leading to enhanced fecundity and subsequently more offspring, indicating that the development of C. pomonella population is directly impacted by the mating rate of the initial individuals. Projections based on F1 data indicate that the C. pomonella population size could persistently increase over a span of 150 days, with varying growth rates influenced by the initial population size. These findings indicate the importance of heightened monitoring and management in non‐invaded regions to avert early colonisation of C. pomonella, thus mitigating the threat of invasion and subsequent population expansion.

Berberine alters the gut microbiota metabolism and impairs spermatogenesis.

Berberine (BBR) is used to treat diarrhea clinically. However, its reproductive toxicity is unclear. This study aims to investigate the impact of BBR on the male reproductive system. Intragastric BBR administration for 14 consecutive days results in a significant decrease in the serum testosterone concentration, epididymal sperm concentration, mating rate and fecundity of male mice. Testicular treatment with testosterone propionate (TP) partially reverses the damage caused by BBR to the male reproductive system. Mechanistically, the decrease in Muribaculaceae abundance in the gut microbiota of mice is the principal cause of the BBR-induced decrease in the sperm concentration. Both fecal microbiota transplantation (FMT) and polyethylene glycol (PEG) treatment demonstrate that Muribaculaceae is necessary for spermatogenesis. The intragastric administration of Muribaculaceae intestinale to BBR-treated mice restores the sperm concentration and testosterone levels. Metabolomic analysis reveals that BBR affects arginine and proline metabolism, of which ornithine level is downregulated. Combined analysis via 16S rRNA metagenomics sequencing and metabolomics shows that Muribaculaceae regulates ornithine level. The transcriptomic results of the testes indicate that the expressions of genes related to the low-density lipoprotein receptor (LDLR)-mediated testosterone synthesis pathway decrease after BBR administration. The transcriptional activity of the Ldlr gene in TM3 cells is increased with increased ornithine supplementation in the culture media, leading to increased testosterone synthesis. Overall, this study reveals an association between a BBR-induced decrease in Muribaculaceae abundance and defective spermatogenesis, providing a prospective therapeutic approach for addressing infertility-related decreases in serum testosterone triggered by changes in the gut microbiota composition.

Effects of dietary cholesterol on ovary development and reproductive capacity in Pacific white shrimp broodstock, Litopenaeus vannamei

Cholesterol is an important component of fresh biological baits and essential precursor to synthesize steroid hormones for crustacean. However, the cholesterol demand in Pacific white shrimp broodstock and its roles on ovary development and reproductive capacity are unknown. In the present study, female Pacific white shrimp broodstock (initial weight 51.3 ± 0.5 g) were fed with three diets contained 0.5 %, 1 % or 1.5 % cholesterol for 45 days. The results found that dietary cholesterol levels did not affect survival rate, weight gain, egg-laying number, vitellogenin content and vitellogenin receptor gene expression in the hepatopancreas. However, the hepatosomatic index, gonadosomatic index, egg diameter, vitellogenin level in the ovary and fertilized egg, C22:6n-3 (DHA) level in the fertilized egg, total protein, triglyceride and cholesterol contents were all increased in the 1.0 % and 1.5 % cholesterol groups than those in the 0.5 % cholesterol group. Moreover, compared with the 0.5 % and 1.0 % cholesterol groups, the 1.5 % cholesterol group had significantly higher gonad maturation number, mating rate, estradiol level in the hemolymph, steroid hormones synthesis related genes (HMGCR, StAR, 17βHSD and 1vMFBP) expression in the ovary and hepatopancreas. In conclusion, dietary 1.5 % cholesterol could promote ovary development and reproductive capacity in female Litopenaeus vannamei broodstock by improving nutrients accumulation and steroid hormones synthesis pathway. Our results provide guidance for design of artificial compound feed and healthy development of shrimp broodstock farm.

Detection of the effect of the KISS1 gene on reproductive parameters in Saanen goats

The KISS1 gene, which activates G protein-coupled receptor-54 (GPR54) and plays a crucial role in the neuroendocrine regulation of GnRH secretion, is known to encode a family of neuropeptides called kisspeptins. Therefore, the KISS1 gene is thought to be associated with sexual maturity, offspring development, and estrus. The g.2124T>A polymorphism of the KISS1 gene, is believed to affect the reproductive system, has been studied in Indonesian goat breeds, Damascus, Zarabi, Baladi, Gaddi, Kaligesing, Guanzong, Xinong Saanen and Boer goat breeds until now. These studies are generally related determining polymorphism frequencies or the effect of genotype on litter size. The study aims to determine the allele and genotype frequencies of the KISS1 gene g.2124T>A SNP by the PCR-RFLP method and define the relationship between the genotypic structures and reproductive parameters such as luteal growth, maximum corpus luteum diameter, and mating rate in Saanen goats (n=30). According to the results, the genotype frequencies in Saanen goats for the KISS1 gene g.2124T>A were 10.35%, 55.17%, and 34.48% for AA, TT and AT, respectively. Moreover, the genotypic structure did not have a statistically significant effect on the investigated fertility characteristics. The average values of expected heterozygosity (He), observed heterozygosity (Ho), the effective number of alleles (Ne), fixation index values (FIS), and the polymorphism information content (PIC) were 0.3996, 0.3448, 1.6655, 0.8629 and 0.855, respectively. The Hardy-Weinberg chi square (χ2) value was found to be 0.5435. In conclusion, it was found necessary to study the KISS1 - g.2124T>A polymorphism in larger herds with different gene pools as a reason for the existence of genotypic variation and the narrow population size.

Family flock size and age-sex structure of indigenous village chickens.

Indigenous village chickens (IVCs) significantly contribute to rural development. There is considerable variation in family flock size and age-sex structure of IVCs. This study reports the family flock size, age-sex group structure, and demographic history of IVCs. This work involved a cross-sectional study conducted using face-to-face general informants' individual interviews with 119 smallholder farmers in highland and lowland agroecological zones. The average family flock size of the sampled households was small (mean = 7.28, range: 1-38). Female birds (hens and pullets) represented the largest proportion of the family flocks (50.2%). The proportion of chicks (26.4%) and pullets (14.4%) was lower than that of hens (35.8%), which creates a considerable challenge in producing replacement breeding flocks. Similarly, the proportion of cockerels (9.1%) was lower than that of cocks (14.3%). The average cock-to-hen ratio (one cock to seven hens) was better than the commonly recommended proportion (1 cock to 8-10 hens). As a result, smallholder farmers have not faced the problem of producing infertile eggs. The estimated effective population size (Ne) of 4.02 and the corresponding inbreeding coefficient of 0.12 at the family flock level show that to some extent inbreeding may occur at the family flock level; besides, the estimated Ne represents 55.2% of the census size. However, inbreeding could be offset by the high rate of flock turnover and uncontrolled mating among scavenging birds. Family flocks contain a few birds, which may lead to consanguineous mating. Inbreeding is, however, considerably reduced by uncontrolled breeding among birds that share a common scavenging ground. The driving factors behind the low proportion of chicks and juvenile birds and the family flock size need to be further investigated to improve the contribution of local chickens to rural livelihoods.

Physiological Status of Rice Leaf-Roller Cnaphalocrocis medinalis (Lepidoptera: Crambidae) Adults Trapped by Sex Pheromone and Floral Odor.

The rice leaf-roller Cnaphalocrocis medinalis is an important migratory pest of rice. We conducted a study to determine the physiological status of adults trapped by a sex pheromone and floral odor. In the immigrant group, the number of males trapped by the floral odor was greater than the number caught by sex pheromone trapping. The volume of testes was similar in the above two trapping methods but was smaller than in the sweep net method. The ovary developmental grade, mating rate, and number of matings of females caught in floral odor trap were higher than in those caught in the sweep net. In the local breeding group, the number of males trapped by sex pheromones was greater than the number trapped by the floral odor. The volume of testes was smaller in the floral odor trap compared to the pheromone trap group, with the largest in the sweep net group. The ovarian developmental grade, mating rate, and number of matings of females were significantly higher in the floral odor trap group than in the sweep net group. In the emigrant group, the adult olfactory response to the sex pheromone and floral odor was low. The volume of testes was larger in the sweep net group compared to the moths caught by floral odor trapping. The number of eggs laid by female immigrants trapped by the floral odor and sweep net was similar, while the number in the local breeding group was greater in moths caught with the sweep net in comparison with those caught by the floral odor trap. The difference in egg hatchability between the two trapping methods in both immigrants and local breedings was not significant.

Beyond Simple vs Complex: Exploring the Nuanced and Unexpected Effects of Spatial Environmental Complexity on Mating Patterns and Female Fecundity.

The features of the physical environment set the stage upon which sexual selection operates, and consequently can have a significant impact on variation in realized individual fitness, and influence a population's evolutionary trajectory. This phenomenon has been explored empirically in several studies using fruit flies (Drosophila melanogaster) which have found that changing the spatial complexity of the mating environment influenced male-female interaction dynamics, (re)mating rates and realized female fecundities. However, these studies did not explore mating patterns, which can dramatically alter the genetic composition of the next generation, and frequently only compared a single, small "simple" environment to a single larger "complex" environment. While these studies have shown that broadly changing the characteristics of the environment can have big effects on reproductive dynamics, the plasticity of this outcome to more subtle changes has not been extensively explored. Our study set out to compare patterns of mating and courtship between large- and small-bodied males and females, and female fecundities in both a simple environment and two distinctly different spatially-complex environments. We found that realized offspring production patterns differed dramatically between all three environments, indicating that the effects of increasing spatial complexity on mating outcomes are sensitive to the specific type of environmental complexity. Furthermore, we observed female fecundities were higher for flies in both complex environments compared those in the simple environment, supporting its role as a mediator of sexual conflict. Together, these results show that the union of gametes within a population can be greatly influenced by the specific spatial features of the environment and that while some outcomes of increased environmental complexity are likely generalizable, other phenomena like mating patterns and courtship rates may vary from one complex environment to another.

Sexual conflict and sexual networks in bed bugs: the fitness cost of traumatic insemination, female avoidance and male mate choice.

Sexual conflict is prevalent among animals and is primarily caused by the fact that the optimal mating rates are often higher in males than in females. While there is a growing appreciation that females can also gain from multiple matings, we still know relatively little about which sex controls the observed mating rates and how close it is to the optimal female mating rates. To address this issue, we tracked female bed bugs (Cimex lectularius) inseminated daily versus weekly and found that weekly inseminated females lived longer and produced over 50% more offspring. In a follow-up experiment employing a social network framework, we placed 24 bed bugs into a semi-naturalistic arena and recorded all sexual interactions. While recently inseminated females did not avoid males more often, they were more frequently rejected by males. Finally, we tracked avoidance behaviour in a single cohort of female bed bugs as they received six successive daily inseminations. Avoidance rates increased and insemination durations decreased with increasing number of prior inseminations. Overall, our results indicate high costs of polyandry. Although females possess some plastic avoidance strategies, the observed rates of insemination fall closer to the male rather than female optimum.

Neuropeptide natalisin regulates reproductive behaviors in Spodoptera frugiperda

Natalisin (NTL) is a conserved neuropeptide, only present in insects, that has been reported to regulate their sexual activity. In this study, we investigated the involvement of NTL in the reproductive behaviors of a major invasive pest, Spodoptera frugiperda. We identified NTL precursor-encoded transcripts, and evaluated their transcript levels in different stages and tissues of S. frugiperda. The results showed that the NTL transcript level was expressed in both male and female pupae and both male and female adults in the later stage. It was highly expressed in male pupae, 3-day-old male and female adults, and 5-day-old male adults. In different tissues, the expression level is higher in the male and female adult brain and male testis. Immunohistochemical staining of the brain of S. frugiperda female and male adults revealed that three pairs of brain neurons of S. frugiperda adults of both sexes secreted and expressed NTL. To study the role of NTL in reproductive behaviors, NTL was silenced in S. frugiperda male and female adults by RNA interference (RNAi) technology, the results showed that silencing NTL could significantly affect the sexual activity behavior of the adults, reducing the calling rate of females, the courtship rate of males, and the mating rate. In summary, this study emphasizes the important role of NTL in regulating the mating behavior and sexual activity of S. frugiperda in both male and female adults, potentially laying a foundation to employ NTL as a new insect-specific target to control populations of pest insects.

A red flag: an experimental analysis of the function of pink colouration in males of Calopteryx haemorrhoidalis asturica (Odonata: Calopterygidae).

Males display phenotypic characteristics that may be associated with their quality, allowing non-random mating and post-copulatory female choice. In the damselfly Calopteryx haemorrhoidalis asturica, males have a conspicuous pink colouration in the underside of abdominal segments 8-10, which they exhibit during pre- and post-copulatory courtship. We hypothesized that this colouration functions to increase male mating success and/or to elicit females to oviposit. We estimated mating and oviposition success of 27 males, and on the following day, treated males had their segments 8-10 painted black and control males the seventh segment. We recorded the number of male-male fights and courtships, whether the courtship ended in copulation, and whether the female remained in the territory and laid eggs. Our results indicate that the mating success of male C. h. asturica was not significantly affected by the removal of the pink colouration of the abdominal tip, but this colouration clearly affected their success in enticing females to oviposit. Courtship frequency, fat content and muscle mass were positively correlated to male mating rate, and the number of aggressive encounters was negatively correlated. Our study yields experimental evidence for the function of pink colouration of male C. h. asturica, in the context of post-copulatory sexual selection.

CRISPR/Cas9-mediated knockout of a male accessory glands-specific gene takeout1 decreases the fecundity of Zeugodacus cucurbitae female.

The melon fly, Zeugodacus cucurbitae (Coquillett), is an invasive Tephritidae pest with robust fertility. The male accessory glands (MAGs) form a vital organ that ensures insect reproductive efficiency. Most of the secreted proteins by MAGs exhibit a male bias expression. Takeout, one of these proteins, is abundantly present in the MAGs of many insects. In this study, we identified 32 takeout genes in Z. cucurbitae. The phylogenetic analysis and multiple sequence alignment results showed that Zctakeout1 is the most related homolog to the MAGs-specific takeout in Tephritidae. The real-time quantitative PCR results showed that Zctakeout1 was exclusively expressed in the male adult stage, and its expression level gradually increased with the increase in age and then remained stable at the sexually matured stage. The distribution among tissues demonstrated the specific expression of Zctakeout1 in the MAGs, and fluorescence immunohistochemical results confirmed the presence of Zctakeout1 in close proximity to binuclear cells of the mesoderm epidermal MAGs. In continuation, CRISPR/Cas9-mediated genome editing was employed, resulting in successfully generating a homozygous strain with an +8 bp insertion. The mating experiments with the Zctakeout1-/- males resulted in significant reductions in both the mating rate and egg production of females. These findings prove that the MAGs-specific Zctakeout1 is essential in regulating fecundity in female Z. cucurbitae fruit flies. Our data suggests its utilization in future essential insect-specific gene-directed sterility insect technique (SIT) by the genetic manipulation to keep these important Tephritidae populations under control. © 2024 Society of Chemical Industry.

Small-bodied males invest in larger testes when highly ornamented.

Sperm competition and male mating rate are two non-mutually exclusive key evolutionary pressures selecting for larger testes within and across animal taxa. A few studies have tried to test the role of mating rate in the absence of sperm competition. Under the mating rate hypothesis, particular phenotypes of a given population that are expected to gain more mates (e.g., more ornamented males) are expected to make higher investments in testes size (a proxy for sperm production). We test this prediction in Polistes simillimus, a neotropical paper wasp in which females are single mated (no sperm competition) and males can mate with multiple partners. Testes size was predicted by body size (positive association), sexual ornamentation (negative association), and their interaction (among small males, testes size was positively related to ornamentation, but the opposite pattern was observed among large males). We propose that small-bodied well-ornamented males may face the highest risk of sperm depletion. Small-bodied males make relatively higher investment in testes size when highly ornamented. This strategy might be less profitable to large males, as they have overall larger testes. Our results provide strong evidence for the mating rate hypothesis.

No fitness effects of same-sex copulations in male red flour beetles.

Same-sex sexual behavior occurs in diverse animal taxa, yet its evolutionary maintenance is poorly understood as such behavior seems to be costly and does not directly increase reproductive success. We used male Tribolium castaneum beetles, which frequently engage in same-sex copulations, to test if same-sex sexual behavior influences future male mating behavior and reproductive success of males. Furthermore, we tested whether same-sex sexual behavior has benefits via indirect sperm translocation. We conducted a series of mating trials demonstrating that males exposed to same-sex behavior did not sire less offspring compared to control males that did not engage in same-sex behavior. This suggests that same-sex copulations did not lead to fitness costs in subsequent mating interactions. In addition, we found no evidence that indirect sperm translocation via an intermediate male occurs in T. castaneum. Taken together, these results imply that same-sex sexual behavior in males is associated with no costs in terms of lower mating rate and reduced siring success and does not seem to entail benefits. Moreover, our data conform to the hypothesis that sexual indiscrimination is prevalent in this species, which may explain the relatively high frequency of same-sex sexual behavior in T. castaneum.

The Effect of Subcutaneously Administered Crystal's Oily Solution on Estrus and Conception Rates in Ewes

The study aims to evaluate the effects of subcutaneously (SC) injected oily solution of melatonin crystal at different doses in 2-3 years, healthy, multiparous sheep during the anoestrus period on serum melatonin and prolactin levels, estrus occurrence, mating, conception, and pregnancy rates. The study group consists of 350 ewes. The ewes were divided into 5 groups: MEL10 (n=70, 10mg melatonin), MEL20 (n=70, 20mg melatonin), MEL40 (n=70, 40mg melatonin), placebo (n=70), and control (n=70) groups. The melatonin groups received SC injections of the oily melatonin solution 11 days before ram introduction. The placebo group received only the oily solution. The control group did not receive any treatment. Blood samples were collected from all groups before the melatonin injection and on the 11th day after the injection. The data showed that the melatonin level in the blood samples collected before and after the injection increased in the MEL10 (P:0.045) and MEL20 (P:0.0359) groups. Additionally, the prolactin level decreased in the second blood sample collected from all groups (P>0.05). Regarding reproductive parameters, the estrus rate in the MEL10, MEL20, MEL40, placebo, and control groups was 75.71%, 58.57%, 54.28%, 51.42%, and 52.85%, respectively. The mating rate was 61.42%, 57.14%, 52.85%, 48.57%, and 50% in the same groups, and the pregnancy rate was 60%, 52.85%, 42.85%, 41.42%, and 38.57%, respectively. The conception rate was determined as 97%, 92%, 81%, 85%, and 77% in the MEL10, MEL20, MEL40, placebo, and control groups, respectively. In conclusion, subcutaneous injection of melatonin at appropriate doses to sheep can indirectly simulate the breeding season, and stimulate heat. Additionally, it can increase pregnancy and conception rates. This method can considered a potential alternative to melatonin implants or different synchronization methods in the future.

On the expression of reproductive plasticity in Drosophila melanogaster females in spatial and socially varying environments.

Individuals often adjust their behaviour based on their perception and experiences with the social and/or physical environment. In this study, we examined the extent of reproductive plasticity expressed in mating rates, mating latencies, mating durations, and offspring production in female fruit flies, Drosophila melanogaster , that encountered different numbers of males in different sized chambers. We found that mating latency length decreased with more courting males and smaller environments and that matings durations were longer in larger chambers and in the presence of two males. These results illustrate the sensitivity of these behavioural phenotypes to changes in local environmental conditions.

In vivo induction of male sexual behavior in zebrafish by adding agents to water.

Successful fertilization in fish mating occurs when egg maturation in the ovary of the female, ovulation, sperm maturation in the testis of the male, and reproductive behaviors in both sexes are triggered in synchrony. The male sexual behavior of fish is induced by hormones and pheromones. In a previous study, we demonstrated that externally applied hormones added to the water can induce oocyte maturation and ovulation in female zebrafish. Here, we attempted to establish a similar method to induce the sexual behavior of male zebrafish. The male sex steroid testosterone (Tes) triggered sexual behavior within several hours in vivo when administered directly into the surrounding water. A selective agonist for membrane progesterone receptor (mPR), Org OD-02 (Org), also induced sexual behavior. Through trials of various combinations of compounds, we found that the most effective conditions were achieved by treatment with a mixture of testosterone (Tes) and Org. The effect of treatment was evaluated by the number of fertilized eggs obtained by pairing with females with induced ovulation in vivo. The period necessary for the induction of male sexual behavior was evaluated by time course experiments. The success rate of mating and the number of fertilized eggs reached the maximum level at 3-4 hours of treatment. The duration of hormonal treatment was confirmed by counting the number of hooking occurrences, which is the final cue to induce spawning by females. In summary, we have established a method to induce male sexual behavior in zebrafish in vivo. The method can be used to obtain fertilized eggs in zebrafish by simply adding agents into the water.

Mutagenesis of Odorant Receptor Coreceptor Orco Reveals the Odorant-Detected Behavior of the Predator Eupeodes corollae.

The successful mating of the hoverfly and the search for prey aphids are of great significance for biological control and are usually mediated by chemical cues. The odorant receptor co-receptor (Orco) genes play a crucial role in the process of insect odor perception. However, the function of Orco in the mating and prey-seeking behaviors of the hoverfly remains relatively unexplored. In this study, we characterized the Orco gene from the hoverfly, Eupeodes corollae, a natural enemy insect. We used the CRISPR/Cas9 technique to knock out the Orco gene of E. corollae, and the EcorOrco-/- homozygous mutant was verified by the genotype analysis. Fluorescence in situ hybridization showed that the antennal ORN of EcorOrco-/- mutant lack Orco staining. Electroantennogram (EAG) results showed that the adult mutant almost lost the electrophysiological response to 15 odorants from three types. The two-way choice assay and the glass Y-tube olfactometer indicated that both the larvae and adults of hoverflies lost their behavioral preference to the aphid alarm pheromone (E)-β-farnesene (EBF). In addition, the mating assay results showed a significant decrease in the mating rate of males following the knock out of the EcorOrco gene. Although the mating of females was not affected, the amount of eggs being laid and the hatching rate of the eggs were significantly reduced. These results indicated that the EcorOrco gene was not only involved in the detection of semiochemicals in hoverflies but also plays a pivotal role in the development of eggs. In conclusion, our results expand the comprehension of the chemoreceptive mechanisms in the hoverflies and offers valuable insights for the advancement of more sophisticated pest management strategies.

Physiological and behavioral basis of diamondback moth Plutella xylostella migration and its association with heat stress.

Migration is a strategy that shifts insects to more favorable habitats in response to deteriorating local environmental conditions. The ecological factors that govern insect migration are poorly understood for many species. Plutella xylostella causes great losses in Brassica vegetable and oilseed crops, and undergoes mass migration. However, the physiological and behavioral basis for distinguishing migratory individuals and the factors driving its migration remain unclear. Daily light trap catches conducted from April to July in a field population of P. xylostella in central China revealed a sharp decline in abundance from late-May. Analysis of ovarian development levels showed that the proportion of sexually immature females gradually increased, while the mating rate decreased, indicating that generations occurring in May mainly resulted from local breeding and that emigration began in late-May. Physiological and behavioral analyses revealed that emigrant populations had a higher take-off proportion, stronger flight capacity and greater energy reserves of triglyceride compared to residents. Furthermore, a gradual increase in temperature from 24 °C to >30 °C during larval development resulted in a significant delay in oogenesis and increased take-off propensity of adults compared with the control treatment reared at a constant temperature of 24 °C. Our results provide the physiological and behavioral factors that underpin mass migration in P. xylostella, and demonstrate that exposure to increased temperature increases their migration propensity at the cost of reproductive output. This study sheds light on understanding the factors that influence population dynamics, migratory propensity and reproductive tradeoffs in migratory insects. © 2023 Society of Chemical Industry.

Prolonged Exposure to Plant Volatiles does not Significantly Affect Pban Expression and Mating Behavior in Diamondback Moth [Plutella Xylostella (Lepidoptera: Plutellidae)

Herbivorous insects use plant volatiles to locate hosts, find food, and identify oviposition sites to aid survival and reproduction. Plant volatiles not only regulate the synthesis and release of sex pheromones in insects, but also help them in the search and orientation of sources of sex pheromones. However, after prolonged exposure to plant volatiles, the changes mediating the mating behavior of diamondback moth (DBM) [Plutella xylostella (L.) (Lepidoptera: Plutellidae)] are unclear. DBMs treated with allyl isothiocyanate, a volatile from cruciferous vegetables, did not show improved rates of mating with a limited effect on mating rhythm. This treatment inhibited mating behaviors in 3-day-old DBMs and decreased mating duration in 5-day-old DBMs. After prolonged exposure to allyl isothiocyanate, the total mating duration of DBM was not significantly different from that after prolonged exposure to n-hexane (control). The longest mating duration after emergence in DBM after prolonged exposure to allyl isothiocyanate was delayed by 1day compared with exposure to n-hexane. Prolonged exposure to plant volatiles intensified the response behavior of DBM to sex pheromones. However, the amount of Z11-16: Ald, a major component of the sex pheromone blend exhibited no change in female pheromone glands. Pheromone biosynthesis activating neuropeptide gene (PBAN) was down-regulated in DBMs after prolonged exposure to plant volatiles. These findings suggest that prolonged exposure (6h) to plant-derived volatiles have little effect on the mating behavior of DBM. This study provides practical guidance for applying phytochemicals in pest control by regulating insect behavior.