Reproductive behavior of the honeydew moth,Cryptoblabes gnidiella

Summary

The reproductive behavior of the honeydew moth, Cryptoblabes gnidiella (Millière) (Lepidoptera: Pyralidae), was studied in the laboratory. The sex ratio was 1.1:1, males to females, in both laboratory and field stocks. Most of the females that mated did so during the first night after emergence; males began mating on the following night. Mating occurred 1–2 h before dawn and averaged 100 min. Both sexes mated only once in one night. Most females mated only once in their lifetime, a few mated 2–4 times, whereas males mated up to six times per lifetime. Insects that lived longer also mated more times. When the sex ratio was altered from 3:1 to 1:3, males to females, the percentage of females that mated in one night dropped from 90 to 65, whereas the number of matings per male rose from 0.32 to 2.25. When fresh one-day-old females were provided daily at a ratio of three per male, the males averaged 1.4 matings per lifetime vs. 2.6 with 2- to 3-day-old females. A delay in mating did not affect the percentages of males and females that mated; highest percentages were obtained with 2- to 4-day-old males and females, but a delay in mating resulted in egg fertility dropping from 91 % to 73 %. The preoviposition period lasted a full day after mating, and then most of the eggs were laid during the first night. Average fecundity was 105 eggs per female (maximum: 230).     

Male-Biased Capture in Light Traps in <Emphasis Type="Italic">Spodoptera exigua</Emphasis> (Lepidoptera: Noctuidae): Results from the Studies of Reproductive Activities

Nocturnal insects show phototactic behavior. Interestingly, males are caught by light traps more often than females in many species. In the present study, the male-biased capture in light traps in the field was evaluated to test the hypothesis that male-biased capture was associated with the reproductive activities of Spodoptera exigua. During a 16-wk. period in 2011, a total of 5075 moths caught by light traps in the field revealed a significant male-biased capture. However, the sex ratio of the natural population was not significantly different from 1:1 from July to October 2011. The ratio of moths caught per hour by light traps showed that females were captured in the first half of the night, whereas the peak capture by light traps for males occurred in the second half of the night. Among the captured adults, the percentage of unmated females was significantly lower than that of the mated females and males. Experiments in the laboratory indicated that the time of activities for both sexes was consistent with the active patterns of oviposition and copulation. The percentage of flight-to-light of the unmated females was significantly lower than that of the mated females and males. Thus, the lower capture of the unmated females, which is associated with reduced positive phototactic responses of S. exigua, probably is one of the reasons resulting in the male-biased sex ratio in light traps.     

Comparative Analysis of the Reproductive Attributes of Three Commercially-Produced Trichogramma Species (Hymenoptera: Trichogrammatidae)

The reproductive attributes of commercially-produced Trichogramma platneri, T. minutum and T. pretiosum reared from eggs of both Ephestia kuehniella and Sitotroga cerealella were monitored at 25 C. The age-specific fecundity, longevity and progeny sex ratio and adult size were determined for individual females from all six combinations of Trichogramma and rearing host, using E. kuehniella as the experimental host. Rearing host had a significant influence on the lifetime fecundity, 3-day fecundity and longevity of all three Trichogramma species. In general, the performance of T. minutum and T. pretiosum was better when reared from S. cerealella, but that of T. platneri was superior when reared from E. kuehniella. The lifetime fecundity of the Trichogramma species was linearly related to longevity and the ranking between species was T. pretiosum > T. minutum > T. platneri. The age-specific pattern of oviposition for T. platneri was distinctly precocious, with 40% of its lifetime fecundity oviposited on the first day, in contrast to 17-24% for the other two species. Progeny sex ratio over the lifetime of the Trichogramma females was slightly male biased and differed significantly from 0.5 for T. minutum and T. platneri. Daily sex ratio for parasitoids reared from the most productive rearing host was female biased only for the first day of oviposition for T. platneri in contrast to the first 5-6 days of oviposition for the other two species. There was little evidence that any of the reproductive attributes of these Trichogramma species, reared from small host eggs, was dependent on the size of the adult females.     

Lucilia sericata strain from Colombia: Experimental colonization, life tables and evaluation of two artificial diets of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae), Bogotá, Colombia strain

The objective of this work was to establish, under experimental laboratory conditions, a colony of Lucilia sericata, Bogotá-Colombia strain, to build life tables and evaluate two artificial diets. This blowfly is frequently used in postmortem interval studies and in injury treatment. The parental adult insects collected in Bogotá were maintained in cages at 22°C±1 average temperature, 60%±5 relative humidity and 12 h photoperiodicity. The blowflies were fed on two artificial diets that were evaluated over seven continuous generations. Reproductive and population parameters were assessed. The life cycle of the species was expressed in the number of days of the different stages: egg = 0.8±0.1, larvae I = 1.1±0.02, larvae II = 1.94±0.16, larvae III = 3.5±0.54, pupae = 6.55±0.47, male adult = 28.7±0.83 and female adult = 33.5±1.0. Total survival from egg stage to adult stage was 91.2% for diet 1, while for diet 2 this parameter was 40.5%. The lifetime reproductive output was 184.51±11.2 eggs per female. The population parameters, as well as the reproductive output of the blowflies that were assessed, showed relatively high values, giving evidence of the continuous increase of the strain over the different generations and making possible its maintenance as a stable colony that has lasted for more than two years.     

Litter sex ratio affects lifetime reproductive success of free‐living female Alpine marmots Marmota marmota†

In litter‐bearing mammals, adult phenotype is influenced during prenatal life by the sex of neighbouring foetuses. This phenomenon, found so far only in laboratory studies, may have ecological importance in nature. We present the first evidence that litter sex ratio has consequences for lifetime reproductive success in mammals. Female Alpine marmots born in a male‐biased litter, i.e. more likely to be located in utero next to male foetuses, are more likely to be dominant later in life – a prerequisite for reproduction in this species. We found no evidence for lower reproductive output of these females, a common cost of prenatal masculinization.     

截头堆砂白蚁性比的研究

为了解截头堆砂白蚁Cryptotermes domesticus（Haviland）群体中不同品级、不同虫态的雌雄性比,本文研究了该种白蚁自行配对室温条件下饲养4年巢龄的实验群体与采集的自然群体的各个品级和不同虫态的雌雄性比。结果表明：自行配对室温饲养4年巢龄群体与自然环境群体中原始繁殖蚁、幼蚁、若蚁、兵蚁都有雌雄之分,其中自行配对室温饲养群体的原始繁殖蚁雌雄比例为1：1,兵蚁雌雄比例为1：1．24,幼蚁和若蚁雌雄比例为1：1．46;自然环境群体原始繁殖蚁雌雄比例为1：1,兵蚁雌雄比例为1：1．15,幼蚁和若蚁雌雄比例为1：1．43。     

Oviposition behavior and progeny allocation of the polyembryonic waspCopidosoma floridanum (Hymenoptera: Encyrtidae)

Oviposition behavior was used to determine the primary clutch size and sex ratio of the polyembryonic wasp Copidosoma floridanumAshmead (Hymenoptera: Encyrtidae) parasitizing Pseudoplusia includens(Walker) (Lepidoptera: Noctuidae). The laying of a female egg was associated with a pause in abdominal contractions during oviposition, while the laying of a male egg was associated with uninterrupted abdominal contractions. Although unmated females produced only male broods, they also displayed male and female egg oviposition movements. Wasps always laid a primary clutch of one or two eggs. For mated females if only one egg was laid, the emerging secondary clutch was all male or female, but if two eggs were laid a mixed brood of males and females was almost always produced. The secondary clutch of single sex broods was usually between 1000 and 1200 individuals, but the secondary clutch of mixed broods averaged 1143 females and 49 males. Thus, the primary sex ratio for mixed broods was 0.5 (frequency males), but the secondary sex ratio was 0.042. Manipulation of the sequence of male and female egg oviposition or of the primary clutch did not produce major alterations in the secondary clutch size or sex ratio.     

Sex allocation and clutch size in the gregarious larval endoparasitoid wasp, Cotesia glomerata

The ability of the gregarious larval endoparasitoid Cotesia glomerata L. (Hymenoptera: Braconidae) to adjust progeny sex ratio and clutch size was investigated. The sex ratios (proportion of males) of field clusters were diverse, but many (70%) were female-biased. Nearly 10% yielded males only, suggesting a low percentage of unmated females in the field. In over half of the clusters containing females, the sex ratio was below 0.3. Superparasitism was common in the field, and females were believed to increase progeny sex ratio when attacking previously-parasitized hosts. However, in a single oviposition bout, sex allocation was not precisely controlled both in the field and laboratory. In the laboratory, the number of eggs laid in a day tended to decrease with increasing female age. For females which were offered two hosts per day and for those offered three hosts per day, this value became nearly the same several days after the start of oviposition. The total number of hosts which a female could parasitize during her lifetime was often less than 40. Some of the old females which attacked more than 40 hosts produced male-biased clutches; this was due to sperm depletion, because sperm remained viable throughout a female's lifetime. The amount of sperm used in a single oviposition bout seemed fixed and was not dependent on the number of eggs laid. Females with much oviposition experience did not produce new eggs to compensate for deposited eggs, and the efficiency of egg use (deposited eggs/total eggs) was more than 80%.     

Costs and benefits of maternal behaviour in the green lynx spider (Oxyopidae,Peucetia viridans)

I examined the adaptiveness of maternal behaviour in the green lynx spider Peucetia viridans (Hentz), by measuring the costs and benefits to the female of egg-sac tending. P. viridans guards her egg sac for 6–8 weeks until the young have emerged and dispersed. I removed females from egg sacs in the field either immediately after oviposition or after they had guarded the egg sacs for 2 weeks, and compared the fate of these sacs with that of control sacs which had females present throughout. Survival rates of egg sacs were significantly improved by the presence of a female. The major sources of mortality were ant predation and sac dislodgement, both of which were significantly reduced by a guarding female, and mantispid brood parasitism, which was not affected by the female. To measure the spiders' lifetime reproductive output, I allowed caged females to construct egg sacs. Half had their first egg sac removed shortly after oviposition, while half were allowed to guard. Significantly more non-guarding than guarding females produced second egg sacs. Thus for the green lynx spider, egg sac guarding decreases lifetime egg production, but increases offspring survival. Under north Florida conditions, the benefits of guarding outweight the costs, and the females have a higher lifetime reproductive success than if they did not guard.     

Laboratory and field studies on the reproductive ecology of Parocneria orienta (Lepidoptera: Lymantriidae) in China

To lay a foundation for the monitoring, prevention and control of Parocneria orienta, a pest moth in China, we investigated the reproductive ecology of P. orienta, including the environmental factors affecting reproduction and the effects of pheromones in field traps. The results showed that the mating duration is shorter when the temperature is higher, with the optimal temperature range for P. orienta reproduction being 22–27°C. The sex ratio had an effect on the male mating capacity, which significantly increased when the sex ratio was ♀:♂ ≥ 3:1. The average number of matings was 2.44 for males, while female P. orienta mated only once in a lifetime. Males were more attracted to virgin females than to mated females, and the temperature and light period had an effect on the release of sex pheromones by females. Field trap tests using virgin females supported the results obtained in the laboratory, showing that the release of sex pheromones by P. orienta follows a distinct circadian rhythm.     

Synchronized oviposition triggered by migratory flight intensifies larval outbreaks of beet webworm

Identifying the reproductive consequences of insect migration is critical to understanding its ecological and evolutionary significance. However, many empirical studies are seemingly contradictory, making recognition of unifying themes elusive and controversial. The beet webworm, Loxostege sticticalis L. is a long-range migratory pest of many crops in the northern temperate zone from 36 °N to 55 °N, with larval populations often exploding in regions receiving immigrants. In laboratory experiments, we examined (i) the reproductive costs of migratory flight by tethered flight, and (ii) the reproductive traits contributing to larval outbreaks of immigrant populations. Our results suggest that the beet webworm does not initiate migratory flight until the 2nd or 3rd night after emergence. Preoviposition period, lifetime fecundity, mating capacity, and egg hatch rate for adults that experienced prolonged flight after the 2nd night did not differ significantly from unflown moths, suggesting these traits are irrelevant to the severity of beet webworm outbreaks after migration. However, the period of first oviposition, a novel parameter developed in this paper measuring synchrony of first egg-laying by cohorts of post-migratory females, for moths flown on d 3 and 5 of adulthood was shorter than that of unflown moths, indicating a tightened time-window for onset of oviposition after migration. The resulting synchrony of egg-laying will serve to increase egg and subsequent larval densities. A dense population offers potential selective advantages to the individual larvae comprising it, whereas the effect from the human standpoint is intensification of damage by an outbreak population. The strategy of synchronized oviposition may be common in other migratory insect pests, such as locust and armyworm species, and warrants further study.     

Effects of age and mated status on flight potential of Helicoverpa armigera (Lepidoptera: Noctuidae)

Abstract The effects of ageing and female mated status on the flight potential of Helicoverpa armigera (Hübner), collected as larvae from a pigeonpea crop in southern India, were investigated using a tethered-flight technique. In non-mated moths fed sugar solution, from the first night after adult eclosion, the durations of both total and longest continuous flight per night increased up to night 4 and remained at this level until at least night 6. Ovarian maturation was rapid with 77% of unmated moths having commenced oviposition by the third night. On the basis of field evidence it is likely that most females would be mated by the third or fourth night, provided plants with nectar or sugary exudates were locally available. In successfully-mated females a 15-fold decrease in total flight duration and a 28-fold decrease in longest continuous flight duration was observed in contrast to non-mated females of similar age. As host plants suitable for adult feeding and oviposition were locally available during the time of feral adult emergence, synchronous pre-reproductive migration was unlikely to occur in the population studied.     

Effect of host deprivation on egg quality,egg load,and oviposition in a solitary parasitoid,Chetogena edwardsii (Diptera: Tachinidae)

Solitary parasitoids are limited to laying one egg per host because larvae compete within hosts. If host encounter rate is low, females should not increase the number of eggs/host in response. The tachinid fly, Chetogena edwardsii,was used to evaluate the effect of host deprivation on egg accumulation, oviposition behavior, and egg quality in a solitary parasitoid. Females deprived of hosts for 2– 7 days accumulate about 1 day's supply of eggs. Egg output of deprived females once hosts are restored does not differ from that of control females. Deprived females retain one egg in the uterus where it undergoes embryogenesis. Maggots emerging from retained eggs are more likely to survive in hosts molting in 40 h or less after receipt of an egg than are maggots emerging from eggs fertilized shortly before oviposition. Egg retention is a consequence of host deprivation that permits females to broaden the range of hosts they can exploit to include soon-to-molt hosts and possibly multiply parasitized hosts.     

Temporal variation in sex allocation in the mealybug Planococcus citri: adaptation, constraint, or both?

Sex ratio theory has been very successful in predicting under which circumstances parents should bias their investment towards a particular offspring sex. However, most examples of adaptive sex ratio bias come from species with well-defined mating systems and sex determining mechanisms, while in many other groups there is still an on-going debate about the adaptive nature of sex allocation. Here we study the sex allocation in the mealybug Planococcus citri, a species in which it is currently unclear how females adjust their sex ratio, even though experiments have shown support for facultative sex ratio adjustment. Previous work has shown that the sex ratio females produce changes over the oviposition period, with males being overproduced early and late in the laying sequence. Here we investigate this complex pattern further, examining both the robustness of the pattern and possible explanations for it. We first show that this sex allocation behaviour is indeed consistent across lines from three geographical regions. Second, we test whether females produce sons first in order to synchronize reproductive maturation of her offspring, although our data provide little evidence for this adaptive explanation. Finally we test the age at which females are able to mate successfully and show that females are able to mate and store sperm before adult eclosion. Whilst early-male production may still function in promoting protandry in mealybugs, we discuss whether mechanistic constraints limit how female allocate sex across their lifetime.     

Effect of mating frequency on fecundity and longevity of the predatory mite <Emphasis Type="Italic">Kampimodromus aberrans</Emphasis> (Acari: Phytoseiidae)

The effect of single versus multiple mating on longevity and fecundity as well as the number of matings required to maximize a female’s reproductive success of the predatory mite Kampimodromus aberrans Oudemans were studied under laboratory conditions. Newly emerged adult females of the stock colony of K. aberrans were placed individually on a bean leaf disc, and maintained at 25°C and 16:8 LD. A young male remained with a female for limited periods or continuously. Mating was a requisite for oocyte maturation and oviposition. Females which mated three to four times during their life and females in continuous presence of males, laid significantly and considerably more eggs than single-mated females. Virgin females lived the longest, and those in continuous presence of males the shortest. In all cases and irrespective of the number of matings, the sex ratio of the offspring was male-biased in the first three to four days of oviposition period, and female-biased in later days.     

Effect of <Emphasis Type="Italic">Fopius arisanus</Emphasis> oviposition experience on parasitization of <Emphasis Type="Italic">Bactrocera dorsalis</Emphasis>

Fopius arisanus (Sonan) (Hymenoptera: Braconidae) is an important fruit fly parasitoid, successfully introduced in programs of classical biological control around the world. One aspect of its reproductive biology that has received increasing attention is the role of learning on parasitization by individual females. In this study, we examined the effect of previous oviposition opportunities on the reproductive success and progeny sex ratio of F. arisanus on eggs of Bactrocera dorsalis Hendel (Diptera: Tephritidae). Our results indicate that the proportion of eggs parasitized and parasitoid yield both increase with increasing experience, as acquired by individual females via previous oviposition opportunities. These effects are shown to be unrelated to parasitoid age out to three weeks, which we found not to have an effect on parasitization, yield, or sex ratio. We discuss the implications of our results on mass rearing and also in terms of the efficiency of this biological control agent in the field.     

Effect of temperature on the reproductive biology of Peristenus spretus (Hymenoptera: Braconidae), a biological control agent of the plant bug Apolygus lucorum (Hemiptera: Miridae)

Peristenus spretus Chen et van Achterberg (Hymenoptera: Braconidae), a parasitoid of the plant bug Apolygus lucorum (Hemiptera: Miridae), has been studied for use in augmentative biological control in China. Under laboratory conditions, we explored the development, survival, age-specific and potential lifetime fecundity, oviposition period and progeny sex ratio of P. spretus reared at six constant temperatures (15°C, 19°C, 23°C, 27°C, 31°C, 35°C) on the second instar nymphs of A. lucorum. At 15°C, male and female P. spretus took 48.7 ± 0.3 and 52.5 ± 0.3 days to complete their immature development, while developmental time was reduced by more than half at 23°C and 27°C. The parasitoid can only develop to the larval stage at 31°C and neither larva nor pupa survived at 35°C. The estimated lower developmental threshold of the immature stage was 7.3°C. When parasitoid adults were exposed at 15°C, females laid 90% of their eggs at first 19 days of oviposition and had an extended reproductive life. In contrast, females held at 27°C laid most of their eggs (90%) in their first of 10 days of oviposition and had shorter longevity. The highest potential lifetime fecundity of P. spretus was 671.2 ± 34.7 SE eggs produced over 23.4 ± 1.4 SE days at 23°C. At 15°C, 19°C and 23°C, sex ratios of reared parasitoids were male-biased, but at 27°C there was no male bias.     

Circadian rhythms of feeding, oviposition, and emergence of the boll weevil （Coleoptera： Curculionidae）

Circadian rhythm of feeding, oviposition, and emergence of boll weevil adults were determined at five different photophases （24, 14, 12, 10, and 0 hours） and a constant 27℃ temperature, 65% RH in the laboratory. Squares from Petri dishes, where they were exposed to boll weevil females, were removed and examined for feeding and oviposition punctures every 4 hours during daylight （0700-1900 h） and every 12 h at night （1900-0700 h） over eight consecutive days. Cohorts of randomly selected egg-punctured squares were sampled from ovipositing females at 0700, 1100, 1500, and 1900 during 24 hours and under different photophase treatments, and maintained in Petri dishes at 27 ＋ I℃, 65% RH. Dishes were observed twice daily （1900 and 0700 h） for adults emerging at day or night. Circadian rhythm of oviposition was not affected by the length of the photophase. The boll weevil has round-the-clock circadian rhythm of oviposition, with a daytime preference. We observed that 82.4%-86.0% of the boll weevil eggs were deposited between 0700 and 1900 h, and 14.0%-17.6% between 1900 and 0700 h during a 24-h period. Feeding of boll weevil females in photoperiods 24：0 h （complete light） and 0：24 h （complete darkness） did not significantly change between 0700-1900 h versus 1900-0700 h, while the d .ally cycle of light and darkness in other photoperiods significantly increased the feeding punctures from 0700-1900 compared with 1900-0700 h. The circadian rhythm of emergence depended significantly on the time of oviposition and the length of the photophase. Investigation of boll weevil circadian rhythm provides a better understanding of boll weevil ecology and reveals potential weak links for improving control technologies targeting their reproductive strategies.     

Nocturnal activity and resource utilization in the aphid hyperparasitoid, Dendrocerus carpenteri

Abstract.

• 1 Females of the aphid hyperparasitoid Dendrocerus carpenteri (Curtis) search successfully for hosts during both day and night. Oviposition numbers per host patch did not differ significantly between day and night.
• 2 D.carpenteri females also displayed a nocturnal flight activity, showing that they are not only capable of searching on a given host plant but also of dispersing between host plants.
• 3 Nocturnal oviposition activity was mainly influenced by egg load. Females with a high egg load laid more eggs at night than females with a comparatively low egg load. Thus, D.carpenteri females may use nocturnal foraging to compensate for the lack of oviposition opportunities during day.
• 4 D.carpenteri females which foraged continuously for hosts both day and night (= for 24 h per day) benefitted from an 1.4-fold increase in lifetime reproductive success when compared to females which foraged only by day (= for 16 h per day).
• 5 The benefit of night foraging for this species is a significantly increased reproductive success.

     

Biological aspects of Cirrospilus neotropicus Diez & Fidalgo (Hymenoptera: Eulophidae), parasitoid of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae)

The biology of Cirrospilus neotropicus Diez & Fidalgo reared on third instar Phyllocnistis citrella Stainton larvae having Citrus limonia Osbeck as host plant, was evaluated under controlled conditions (25 +/- 1 masculineC; 12h photophase). The survival, immatures development, longevity, sex ratio, host feeding and oviposition ratio of C. neotropicus, were registered. Two groups of parasitoid females were evaluated: one, with parasitoids obtained from P. citrella pupae collected in citrus orchards and the other group came from laboratory rearing. These females, after mating, were maintained individually on gerbox containers with honey and pollen as food source. At each 48h, 12 P. citrella larvae were changed. The average biological cycle of the female progenies from orchard and laboratory generation groups were 11.8 and 11.6 days, respectively. The males progenies had biological cycles of 11.6 and 10.9 days, as well. The shortest immature survival period, for both studied groups was the larval (57.3% - orchard group and 57.4% - lab group). The mated females average longevity (21.8 days) was superior than the non mated ones (9.1 days) for the orchard group. The average daily oviposition rate for this last group was also significantly superior (2.8 eggs /day) than the lab group (1.6 eggs / day). The same trend was observed for the average daily host feeding rate (1.7 larvae /day for the orchard group and 0.9 larvae/ day for the lab group). These data suggest that C. neotropicus have potencial as a biological control agent of P. citrella.