Non-diapausing Adults Research Articles

Impact of diapause on the cuticular hydrocarbons and physiological status of Hippodamia variegata.

The spotted amber ladybird, Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae), is known to be a potent predator of aphids, psyllids, whiteflies, mealybugs, and some butterfly species. This ladybeetle overwinters in the diapausing adult stage. The current study aimed to evaluate the impact of diapause on the energy resources and cuticular hydrocarbons (CHCs) of the female ladybeetle, specifically comparing the changes in glycogen, lipid, and protein contents, and CHCs profile of diapausing and non-diapausing adults. In this study, gas chromatography-mass was used to analyze whole-body extracts of the beetles. Results showed no significant differences between the amount of glycogen, lipid, and protein contents of diapausing and non-diapausing ladybeetle. The CHCs profile of H. variegata consisted of 24 hydrocarbons categorized into 2 groups: linear aliphatic hydrocarbons (n-alkanes) and methyl-branched hydrocarbons (17 molecules), as well as unsaturated cyclic compounds (7 molecules). The n-alkanes, with 14 compounds, were identified as the primary constituents of the CHCs of the ladybeetle. Six molecules were common to non-diapausing and diapausing beetles, 5 were exclusive to non-diapausing beetles, and 13 were exclusive to diapausing beetles. Moreover, we noted a significant difference in the quantity and quality of CHCs between diapausing and non-diapausing beetles, with diapausing beetles synthesizing more CHCs with longer chains. This disparity in CHC profiles was concluded to be an adaptation of H. variegata to survive harsh environmental conditions during diapause.

Differential metabolism of juvenile hormone III between diapause and non-diapause of Aspongopus chinensis Dallas (Hemiptera: Dinidoridae) revealed by transcriptome sequencing

Abstract Aspongopus chinensis Dallas, 1851 is an important insect resource with a long utilization history as traditional Chinese medicine and food owing to its various health benefits, including anti-cancer, anti-bacteria, and anti-clotting properties. However, the long period of reproductive diapause during the overwintering stage has limited the broad utilization and artificial cultivation of A. chinensis. Diapause is largely regulated by juvenile hormones. Therefore, understanding the relationship between juvenile hormone metabolism and A. chinensis diapause may provide useful insight for developing genetic engineering strategies to regulate diapause. We identified differentially expressed genes in diapause and non-diapause adults of A. chinensis by transcriptome sequencing. A total of 336,230,260 clean reads were assembled into 80,769 unigenes. Overall, 3,524 differentially expressed genes were identified, including 2,174 down-regulated and 1,350 up-regulated genes in diapause adults. Among these differentially expressed genes, 22 were significantly enriched in the JH III metabolism-related pathway based on Kyoto Encyclopedia of Genes and Genomes analysis. These results provide insight into the molecular-level mechanism of diapause regulation and highlight new targets for preventing diapause to improve A. chinensis cultivation and productivity.

Late autumn occurrence of non-diapause male adults in various geographic populations of a pierid butterfly, Eurema mandarina

ABSTRACT Adult-overwintering insects show diversity in the occurrence of reproductive diapause of males. Mating can occur both before and after winter in different species, and pre-winter mating allows males to reproduce without overwintering. In a pierid butterfly, Eurema mandarina, both diapause and non-diapause male adults emerge in the late autumn generation. Diapause females mate with non-diapause males before winter and re-mate with diapause males the following spring. Although this species is distributed from sub-tropical regions to cool-temperate regions, the geographic variation of this characteristic mating system has not been examined. A rearing experiment and a field survey were conducted to determine the geographic patterns of the mating system of the late autumn generation of E. mandarina for various populations from sub-tropical to cool temperate regions. Non-diapause males were observed in the late autumn generation in all populations examined. The frequency of pre-winter mating of females was not correlated with latitude. These results show that the mating system of the late autumn generation is similar among various populations distributed over a wider range, suggesting that the characteristic mating system may be evolutionarily stable.

Effects of Diapause on Halyomorpha halys (Hemiptera: Pentatomidae) Cold Tolerance.

Diapause and cold tolerance can profoundly affect the distribution and activity of temperate insects. Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), an alien invasive species from Asia, enters a winter dormancy in response to environmental cues. We investigated the nature of this dormancy and its effects on H. halys cold tolerance, as measured by supercooling points, lower lethal temperatures, and overwintering field mortality. Dormancy was induced by rearing individuals in the laboratory or under field conditions. We confirmed H. halys dormancy to be a state of diapause and not quiescence, and the life stage sensitive to diapause-inducing cues is between the second and fifth instar. In the laboratory, supercooling points of diapausing adults reached significantly lower temperatures than nondiapausing adults, but only when given enough time after imaginal ecdysis. Supercooling points of diapausing adults in overwintering microhabitats also decreased over time. Diapause increased adult survival after acute cold exposure in the laboratory and prolonged cold exposure in the field. Following diapause induction in the laboratory, changes to temperature and photoperiod had no significant effect on lower lethal temperatures and changes to photoperiod had no effect on supercooling points. Additionally, induction of diapause in the laboratory did not result in significantly different cold tolerance than natural field induction of diapause. This work demonstrates that H. halys diapause confers greater cold tolerance than a nondiapausing state and likely improves the probability of successful overwintering in some temperate climates. Hence, knowledge of diapause status could be used to refine forecasts of H. halys overwintering field mortality.

Reference gene selection and evaluation for expression analysis using qRT-PCR in Galeruca daurica (Joannis).

Quantitative real-time PCR (qRT-PCR) has been used extensively to analyze gene expression and decipher gene function. To obtain the optimal and stable normalization factors for qRT-PCR, selection and validation of reference genes should be conducted in diverse conditions. In insects, more and more studies confirmed the necessity and importance of reference gene selection. In this study, eight traditionally used reference genes in Galeruca daurica (Joannis) were assessed, using qRT-PCR, for suitability as normalization genes under different experimental conditions using four statistical programs: geNorm, Normfinder, BestKeeper and the comparative ΔC t method. The genes were ranked from the most stable to the least stable using RefFinder. The optimal suite of recommended reference genes was as follows: succinate dehydrogenase (SDHA) and tubulin-alpha (TUB-α) for temperature-treated larvae; ribosomal protein L32, SDHA and glutathione S-transferase were best for all developmental stages; ACT and TUB-α for male and female adults; SDHA and TUB-α were relatively stable and expressed in different tissues, both diapause and non-diapause adults. Reference gene evaluation was validated using expression of two target genes: the P450 CYP6 gene and the heat shock protein gene Hsp70. These results confirm the importance of custom reference gene selection when studies are conducted under diverse experimental conditions. A standardized qRT-PCR analysis procedure for gene functional studies is provided that could be useful in studies on other insect species.

Influence of Photoperiod on the Accumulation of Metabolites during Diapause Induction inCotesia vestalis(Haliday) (Hymenoptera: Braconidae)

Abstract Most insects must accumulate certain metabolites before entering diapause by virtue of photoperiodic regulation. Photoperiods influence diapause beyond the maternal generation in Cotesia vestalis (Haliday) (Hymenoptera: Braconidae), which is one of the most important larval endoparasitoid of Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae). The accumulation of metabolites in the non-diapausing prepupae, adults, and eggs (before and after oviposition) in progeny from C. vestalis cultures reared at 25°C under three photoperiods (8:16, 12:12, and 16:8 (L:D) hr), along with diapausing prepupae were measured to investigate the effects of photoperiod on the accumulation of metabolites during diapause induction. Compared with those of non-diapausing prepupae, free water, trehalose, total lipid titer, and total polyol contents in diapausing prepupae showed no significant differences; but weight, bound water, total sugar, glycogen, triglyceride, and protein contents were significantly higher. Und...

Deoxidant-induced anoxia as a physical measure for controlling spider mites (Acari: Tetranychidae)

Tiny agricultural pests such as spider mites (Acari: Tetranychidae) attached to seedlings grown outdoors often invade greenhouses, thereby triggering pest outbreaks. To solve the problem, we examined whether differences in anoxia tolerance between animals and plants would permit the application of an anoxic environment to control spider mites without the aid of acaricides. Under an anoxic environment created by using a commercial deoxidant at 25 °C, the time for 50 % mortality of eggs, non-diapausing adults (summer form), and diapausing adults (winter form) were 6.1, 5.5, and 23.6 h, respectively, for Tetranychus urticae Koch and 5.4, 3.9, and 23.2 h, respectively, for Tetranychus kanzawai Kishida. With anoxia for 12 h, no eggs and non-diapausing adults survived in either species, whereas most diapausing adults (98 % for T. urticae and 88 % for T. kanzawai) survived. Under this treatment, host Phaseolus vulgaris L. seedlings showed serious physiological disorders in their primary leaves and apical buds, and unusual lateral buds developed in the cotyledon axils. The spider mites acquire anoxia tolerance during diapause, but anoxia can potentially control them during the summer if no negative effects are observed in the treated seedlings.

Optimization of Orius majusculus release: photoperiodic sensitivity at different temperatures and storage of diapausing adults

The photoperiodic sensitivity and storage of Orius majusculus (Reuter) from Antalya was investigated to obtain data for the optimization of its release. In the current study, it was not possible to induce a high (up to 100%) incidence of diapause unless all the nymphal instars and adults were successively exposed (i.e. full exposure) to a short day length (11.5 h) at constant temperatures of 18 and 26 °C, and fluctuating temperatures of 10/26 °C. Hence an intermittent exposure to long day lengths, even for short periods of time (only during instars IV–V or adult stage), would avoid a high incidence of diapause at 10/26 °C and 26 °C. The response of O. majusculus nymphal instars and adults to a short day length with a low incidence of diapause under fluctuating temperatures suggests that greenhouses, where such temperatures prevail, provide an environment that is conducive to diapause prevention. The release of adults is a better approach than the release of nymphs, since the adults and their nymphs, until the eclosion of new adults, are expected to respond to short day lengths with a low incidence of diapause in greenhouses. When nymphs are released, on the other hand, a high incidence of diapause would be inevitable. Increasing the constant temperature to 30 °C at full exposure did not prevent diapause and consequently did not change the incidence of diapause. Storage of diapausing O. majusculus adults was possible for 1 month with a higher survival rate and fecundity than in a study based on the storage of nondiapausing adults at a lower temperature.

Classification of Diapause Status by Color Phenotype inLygus hesperus

Recent studies on adult diapause in the western tarnished plant bug, Lygus hesperus Knight (Heteroptera: Miridae), have highlighted the need to identify a reliable external marker for the internal changes that differentiate a normal animal from one that is overwintering. To test the efficacy of a color based discrimination system, L. hesperus of both genders were reared from eggs through day 10 of adulthood under a 10 hour photophase at a constant temperature. They were separated into three color groups (yellow, pale green, dark green), then dissected for diapause categorization based on internal development. Most yellow individuals were in diapause, dark green individuals were not, and pale green ones were mixed. A group of 25 assessors, naïve with regard to L. hesperus development, were then asked to use a simplified color criteria (yellow = diapause, green = non-diapause) to estimate the status of a mixture of diapausing and non-diapausing adults of both genders aged two to seven days post-eclosion. After dissection to verify diapause status, assessor accuracy was found to be ineffective for assessing adults of both sexes younger than four days because color differences, which increased with age, were subtle or non-existent at this stage. For four to seven-day-old bugs, 84% of females and 67% of males were correctly categorized, on average. Incorrect assessments in all but the youngest males over-identified diapause, but for females there was no trend in miscategorizations. Overall, the results indicate that diapause status can be adequately discriminated by color assessment, and with greatest accuracy when sampling older females. However, factors other than photoperiod appear to also influence coloration.

Influence of Photoperiod on Hydrogen Peroxide Metabolism during Diapause Induction in Cotesia vestalis (Haliday) (Hymenoptera: Braconidae)

Abstract Hydrogen peroxide is a toxic metabolite of oxidative metabolism, but may also serve as a broad spectrum signaling molecule controlling a variety of essential physiological processes. Photoperiod influences diapause beyond the maternal generation in Cotesia vestalis and we speculated that intracellular hydrogen peroxide was a possible signal mediating this generational effect. To investigate the signaling functions of hydrogen peroxide in diapause induction in C. vestalis, hydrogen peroxide and activities of the antioxidant enzymes superoxide dismutase, peroxidase, and catalase were measured at diapause, and in maternal non-diapausing prepupa, adult, and offspring egg stages form the cultures reared at 25°C under the photoperiods of 8∶16, 12∶12, and 16∶8 (L∶D) h. The hydrogen peroxide contents and activities of superoxide dismutase and peroxidase in maternal non-diapausing prepupae and adults declined as the light period was reduced, whereas catalase activity increased significantly. Compared to d...

Induction of Reproductive Diapause inHabrobracon hebetor(Hymenoptera: Braconidae) When Reared at Different Photoperiods at Low Temperatures

Development of the parasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) at low temperatures was determined to identify rearing conditions that might result in adults that were in reproductive diapause. Diapausing adults would be expected to survive cold storage longer than nondiapausing adults for use in biological control programs. Only a few eggs were found in the ovaries when H. hebetor females were reared during the immature stages at 17.5 and 20°C with a 16-h photoperiod, and the ovaries were poorly developed and contained no eggs when females were reared with a 10-h photoperiod in these low temperatures. Rearing H. hebetor at 17.5 and 20°C did not result in diapause of immature stages, but did appear to result in possible adult reproductive diapause when the immature stages were reared with a 10-h photoperiod. Females reared during the immature stages at 17.5°C with a10-h photoperiod lived longer and took longer to lay their first eggs and to lay 50% of their eggs than those females reared at 17.5°C with a16-h photoperiod. Females reared during the immature stages at 20°C with a10-h photoperiod took longer to lay their first eggs and to lay 50% of their eggs, and they had a lower respiration rate, than those females reared at 20°C with a16-h photoperiod. Females that were reared in conditions that appeared to induce reproductive diapause resumed oviposition and their respiration rate increased soon after being transferred to a higher temperature (27.5°C). Thus, females reared at a 10-h photoperiod at 17.5 and 20°C appear to enter reproductive diapause.

Diapause Induction inGratiana boliviana(Coleoptera: Chrysomelidae), a Biological Control Agent of Tropical Soda Apple in Florida

AbstractThe South American leaf-feeding beetle Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) has been released since 2003 in the southeastern United States to control the invasive weed tropical soda apple, Solanum viarum Dunal (Solanaceae). Successful establishment of a biological control agent in temperate and subtropical regions depends on several life-history adaptations, including winter diapause. The timing of diapause allows the syncronization of insect herbivores with the phenology of plants, and field observations in Florida suggested that G. boliviana overwinters as an adult in diapause. The objectives of this study were to describe the diapause of G. boliviana and determine the effect of temperature and photoperiod on diapause induction. Compared with nondiapause adults, diapausing adults were yellow rather than green, had hypertrophied fat bodies, contained little food in the digestive tract, showed negligible ovarian development, and minimal movement of the hind wings when the beetles were placed on their dorsal sides. Although all nondiapause females laid eggs during a 30-d period, only five of 76 diapausing females laid eggs and this occurred only during the first 15 d of the treatment period. Consistent with morphological indicators of diapause, the respiration rate was 2.3 times lower and fat content was 2–3 times greater in diapausing adults compared with nondiapause adults. In a laboratory study, the critical daylength for diapause induction was found to be 12 h:28 min.

A comparison of internal and external lipids of nondiapausing and diapause initiation phase adult Colorado potato beetles, Leptinotarsa decemlineata

The Colorado potato beetle, Leptinotarsa decemlineata, reared under diapause-inducing conditions will emerge from the soil as an adult and enter the diapause initiation phase, a period where metabolic reserves are stockpiled before the beetles enter the nonfeeding diapause maintenance phase. Internal and external lipids were characterized during the diapause initiation phase (IP) and compared to the lipid profiles of nondiapausing adults. The primary internal lipids of both diapause IP and nondiapausing adults are triacylglycerols. Only trace amounts of internal lipids were detected in day 1 diapause IP adults. A dramatic increase in internal lipids was observed between day 7 and day 15 post-emergence in the diapause IP adults. The majority of the triacylglycerol isomers were identified as C50, C52 and C54 chain lengths by GC-MS. There were no observed differences in the isomeric distribution of the major internal lipids between diapause IP and nondiapausing adults. External lipids were mainly methyl-branched alkanes containing a 25 to 53 carbon backbone. The quantity of external lipids increased from day 1 to day 7 post-emergence in both the diapause IP and nondiapausing adults, with the bulk of the increase occurring in the longer chain-length methylalkanes.

Photo-response of the brown marmorated stink bug, Halyomorpha halys (Stål) (Heteroptera: Pentatomidae), and its role in the hiding behavior

As part of a study aimed at determining the factors affecting overwintering habitat choice by Halyomorpha halys, we examined the behavioral response to light of diapausing adults (which have no reproductive activity) and non-diapausing adults. Bugs were tested individually in a choice chamber (14, 18 and 24°C) containing a dark refuge with opaque (black) sides and roof. Each bug’s position in the choice chamber was recorded at regular intervals. The results indicated that diapausing bugs prefer to settle in a dark place (p < 0.05). This preference appeared to weaken at 24°C; however, this apparent trend was probably due to the greater overall activity of the bugs under warmer conditions. In tests of non-diapausing bugs, lower proportions of the bugs were observed inside the dark refuge at higher temperatures; however, the preference for dark places was exhibited under all temperature conditions. Based on these results, we infer that H. halys adults have a fundamental preference for dark places whether or not they are in diapauses, which plays a main role in hiding behavior. This preference becomes most obvious in the winter, with the decrease in behavioral activity resulting from lower temperatures. We propose that this common preference for location is one of the factors responsible for the bugs’ convergence on specific microhabitats and the overwintering aggregate formation of H. halys.

Enhancing bio-suppression of Parthenium hysterophorus L.: Diapause in Zygogramma bicolorata Pallister and its manipulation through insulin-like peptides (ILPs)

In-depth investigations on diapause behaviour of Z. bicolorata revealed that the adults entered diapause at any time from August to December and that the number peaked (42.00%) during the last half of November. The percentage of adults entering diapause increased with a decrease in day length. Weight of diapausing adults was significantly higher than weight of non-diapausing adults. The percentage of adults undergoing diapause at 30 °C was significantly lower than those undergoing diapause at 15 and 25 °C. The percentage of adults burrowing increased with increasing moisture. In silty soil and soil with high organic matter, 46.7% and 49.2% of adults entered diapause, respectively, whereas in sandy soil, only 23.5% of adults entered diapause. When newly emerged beetles were exposed to 5 μg of human insulin 30/70, a significantly lower percentage of treated adults underwent diapause compared to untreated adults under both feeding and no feeding conditions. Insulin treatment also influenced the emergence period from diapause (93.92 ± 1.73 days), percent emergence (81 ± 1.54%) and fecundity/month (512.7 ± 25.38 eggs) of Z. bicolorata in treated adults as compared to untreated adults (109.05 ± 2.2, 74.00 ± 1.82 and 438.3 ± 19.33 eggs, respectively). However, there was no significant impact of insulin on adult longevity. These findings are of great utility in the biological suppression of Parthenium as it will enhance the effectiveness of this beetle through manipulation of diapause.

Down-regulation of gene expression between the diapause initiation and maintenance phases of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

The diapause initiation and maintenance phases of the Colorado potato beetle, Leptinotarsa decemlineata, were screened. Eight transcripts were found to be downregulated as the beetles enter the diapause maintenance phase of diapause development after day 15 postemergence. These transcripts were also expressed in early nondiapausing adults. Using BlastX, the transcripts were placed into six broad categories: regulatory (serpin), structural (apidermin), protease (serine protease), retinol binding protein (CRALBP), carbohydrate metabolism (s-glucosidase, s-mannosidase, and cellulose II), and unknown function.

Characterization of gene expression patterns during the initiation and maintenance phases of diapause in the Colorado potato beetle, Leptinotarsa decemlineata

Using differential display, 55 differentially regulated transcripts were isolated from the Colorado potato beetle, Leptinotarsa decemlineata (Say). The insert sizes of the clones ranged from 114 to 795 bp. Fourteen of the transcripts were confirmed by northern blot analysis to be differentially regulated transcripts with respect to the diapause initiation and maintenance phases. Based on Blast search results, these 14 transcripts were assigned putative identities and placed into four broad categories of proteins: unknown function, defensive, structural/glycine-rich, and digestive. The transcripts were highly expressed for the first 13–15 days postemergence during the diapause initiation and early diapause maintenance phases and were then substantially down-regulated. These down-regulated transcripts were also highly expressed for the first seven days postemergence in nondiapausing adults and their expression became more variable on day 9 or 11 in most individuals examined. The glycine-rich protein transcripts were all down-regulated by day 11 in the nondiapausing adults. A comparison of the transcript expression patterns between diapause initiation phase and nondiapausing adults showed that elevated levels of expression of the glycine-rich transcripts and two transcripts with unknown functions persisted for approximately four days longer in the diapause-programmed beetles.

EVOLUTION OF THERMOTOLERANCE IN SEASONAL ENVIRONMENTS: THE EFFECTS OF ANNUAL TEMPERATURE VARIATION AND LIFE-HISTORY TIMING IN WYEOMYIA SMITHII

In organisms with complex life cycles, the adaptive value of thermotolerance depends on life-history timing and seasonal temperature profiles. We illustrate this concept by examining variation in annual thermal environments and thermal acclimation among four geographic populations of the pitcher plant mosquito. Only diapausing larvae experience winter, whereas both postdiapause and nondiapause adults occur only during the growing season. Thus, adults experience transient cold stress primarily during the spring. We show that adult cold tolerance (chill coma recovery) is enhanced in spring-like conditions via thermal acclimation but is unaffected by diapause state. Moreover, adult mosquitoes from northern populations were more cold tolerant than those from southern populations largely because acclimation responses were steeper in the north. In contrast to cold tolerance, there was no significant acclimation of heat tolerance (heat knockdown), and no significant differences in heat tolerance between northern and southern populations. Field temperature data show that because of evolved differences in diapause timing, adult exposure to cold stress is remarkably consistent across geography. This suggests that geographic variation in cold tolerance may not be the result of direct selection on adults. Our results illustrate the importance of the interplay between phenological and thermal adaptation for understanding variation along climatic gradients.

Establishment potential of the predatory mirid Dicyphus hesperus in northern Europe

The predatory mirid Dicyphus hesperus Knight (Hemiptera: Miridae) is native to North America. The species has been used for the control of glasshouse whitefly on aubergine in the Netherlands, and is currently being evaluated for continued and wider release in Europe. Field and laboratory studies were conducted on a population collected from southern California, USA, to assess the cold tolerance and potential for outdoor establishment under prevailing northern European climates. The supercooling points (whole animal freezing temperatures) of nymphal and adult insects were around −20°C. The lethal temperatures (LTemp50) of non-diapausing nymphs and adults and diapausing adults were close to their respective freezing temperatures at −17.6, −17.6 and −19.2°C. At 5°C, the LTime50 was 54, 101.7 and 117.5 days for fed nymphs, non-diapausing and diapausing adults respectively. When first instar nymphs were placed in the field in winter, starved samples died out after 70 days, but 5% of the fed nymphs survived until the end of winter (140 days) and developed to adult on return to the laboratory. After a similar 5-month field exposure, 50% of fed diapausing adults and 15% of fed non-diapausing adults were still alive at the end of winter, whereas starved diapausing adults died after 140 days. On return to the laboratory after 5 months in the field, both diapausing and non-diapausing adults mated and laid eggs, forming viable populations. Overall, the field and laboratory experiments indicate that this population of D. hesperus is able to enter diapause and that winter temperatures are not a barrier to establishment in northern Europe.

Parental effects: Physiological age, mating pattern, and diapause duration on diapause incidence of progeny in the cabbage beetle, Colaphellus bowringi Baly (Coleoptera: Chrysomelidae)

The cabbage beetle, Colaphellus bowringi Baly, is a short-day species that has both a facultative summer and winter adult diapause. In this study, we systematically investigated the effects of parental physiological age, mating pattern (including mating frequency and delayed mating), and diapause duration on the diapause incidence of progeny in the beetle. As parents aged, progeny diapause incidences showed considerable inter-parental variability and an abnormally varying pattern, but their predicting line was approximate to horizontal when reared under constant conditions. There was significant difference in progeny diapause incidence between multiple-mating and once-mating treatments. Higher diapause incidences in the progeny were observed in delayed-mating treatments. Progeny diapause incidences increased as diapause duration in the parental generation increased, and hibernating individuals produced more diapausing progeny than aestivating ones. Reciprocal cross tests between the post-diapause adults and non-diapause adults with no diapause history showed that the effect of parental diapause duration on the progeny diapause incidence was determined by both mothers and fathers but the mothers appeared to have a stronger effect than the fathers. Our results suggest that the parental age effect in Colaphellus bowringi might not be simply age-dependent, but may be controlled by the interaction of multiple factors, including physiological, environmental, behavioral and genetic factors. We discuss the ecological and physiological significance of these findings.