Effect of gamma irradiation on sperm utilization in twice-mated female Phthorimaea operculella Zeller (Lep., Gelechiidae)

The effects of the second mating on fecundity and fertility of potato tuber moth (PTM) Phthorimaea operculella (Zeller), when females were mated with 450 Gy-irradiated and normal males or vice versa, were studied. The percentage of eggs fertilized by sperm of the second mating (P₂ value) was 0.99, indicating that sperm transferred during the last mating were predominantly utilized in egg fertilization. Females, mated first with irradiated males, remated after 2 days, whereas those mated with normal males, remated after 3.3 days. Fecundity of twice-mated females was higher than those mated only once. Females started to lay their eggs 1.9 days after the first mating, regardless of the type of male. However, virgin females did not lay eggs at all. Duration of copulation varied from 102 to 117 min for normal and irradiated males, respectively. The present study elucidated important aspects of mating behaviour of PTM which could improve the efficiency of its control by the sterile insect technique.     

Spermatophore formation and regulation of egg maturation and oviposition in female Heliothis virescens by the male

This study was undertaken, using various surgical manipulations, to examine the role and functions of accessory sex glands and testes in Heliothis virescens in spermatophore formation and stimulation of egg maturation in mated females. Normal females mated to accessory sex glandectomized (-ASG) males produced fewer eggs and retained most of their eggs in ovarioles compared with females mated to sham-operated (+ASG) or normal males. The ASG are the source of the components for spermatophore formation in H. virescens. Females mated to castrated (-Testes) males showed similar pattern of egg production as did females mated to -ASG males. Females mated to -Testes males and those mated to sham-operated (+Testes) or normal males were found to have spermatophore in the bursa after uncoupling. Normal females mated to allatectomized (-CA) males developed similar numbers of total eggs as did females mated to sham-operated (+CA) males and normal males.     

Effect of irradiation on Mexican leafroller (Lepidoptera: Tortricidae) development and reproduction

The effects of irradiation on egg, larval, and pupal development, and adult reproduction in Mexican leafroller, Amorbia emigratella Busck (Lepidoptera: Tortricidae), were examined. Eggs, neonates, early instars, late instars, early pupae, and late pupae were irradiated at target doses of 60, 90, 120, or 150 Gy, or they were left untreated as controls in replicated factorial experiments. Survival to the adult stage was recorded. Tolerance to radiation increased with increasing age and developmental stage. A radiation dose of 90 Gy applied to neonates and early instars prevented adult emergence. A dose of 150 Gy was not sufficient to prevent adult emergence in late instars or pupae. The effect of irradiation on sterility was examined in late pupae and adult moths. For progeny produced by insects treated as late pupae, a total of three out of 3,130 eggs hatched at 90 Gy, 0 out of 2,900 eggs hatched at 120 Gy, and 0 out of 1,700 eggs hatched at 150 Gy. From regression analysis, the dose predicted to prevent egg hatch from the progeny of irradiated late pupae was 120 Gy, with a 95% confidence interval of 101-149 Gy. The late pupa is the most radiotolerant stage likely to occur with exported commodities; therefore, a minimum absorbed radiation dose of 149 Gy (nominally 150 Gy) has potential as a quarantine treatment. Reciprocal crosses between irradiated and unirradiated moths demonstrated that males were more radiotolerant than females. Irradiation of female moths at a target dose of 90 Gy before pairing and mating with irradiated or unirradiated males resulted in no viable eggs, whereas irradiated males paired with unirradiated females produced viable eggs at 90 and 150 Gy.     

Effects of delayed mating and male mating history on the reproductive potential of Leucoptera coffeella (Lepidoptera: Lyonetiidae)

Abstract 1 Despite the importance of Leucoptera coffeella (Guérin‐Mèneville) in coffee production worldwide, there is a lack of information on its reproduction. This knowledge will help in mass rearing, and support the development of behavioural control techniques for this insect. The present study determined the effects of delayed mating and previous matings of male L. coffeella on fecundity, egg viability and frequency of female remating. 2 The highest levels of fecundity and egg viability were obtained from matings of 1–3‐day‐old females. When females mated at 5 days of age, there were reductions of 40% in oviposition and of 43% in egg viability. 3 Females mated with 2‐day‐old virgin males were more fecund than those mated with older males; egg viability was also low (18%) from females mated with older males. 4 Virgin females that mated with virgin males laid a greater number of eggs than those mated with previously copulated males. Egg viability decreased with the increase in the number of previous male matings. 5 Five‐day‐old females remated in greater proportion than 2–3‐day‐old females. Females that copulated with males that had previously mated three times had higher rates of remating than those that copulated with virgin males. 6 The results obtained indicate that 1–3 days after emergence is the optimum age for mating. The implications of these findings for the control of L. coffeella by synthetic sex pheromone are discussed.     

Egg presence, egg loss, and female mate preferences in the sand goby (Pomatoschistus minutus)

We studied the effect of egg presence on female mate choicein a fish with paternal care. Females who were allowed a freechoice between two males mated within a shorter time than femaleswho were randomly assigned to a particular male. When a secondfemale was allowed to choose among the males, she preferredthe same male as the previous female. This result shows thatfemales are concordant in their mate choice. When the initialfemale was randomly assigned to mate with one of two males (forcedchoice), the second female mated randomly with respect to thefirst one. Thus females do not prefer males with eggs. If theinitial female was given a free choice, but the eggs were removedfrom the chosen male, the test female mated randomly. When boththe males initially had mated but one randomly determined male'seggs were removed, the test female preferred the male who wasstill guarding eggs. These experiments show that females avoidspawning in unsuccessful nests. When the females in the freechoice/egg removal experiment mated with the unsuccessful malethere was a considerably bigger size difference in favor ofthis male than when the females mated with the other male. Weconclude that female sand gobies show clear mate preferences,but that they do not prefer males with eggs over males withouteggs. They do, however, avoid mating with males guarding unsuccessfulnests. We therefore suggest that egg loss could be an importantfactor selecting for egg preference.     

The effect of male mating history on paternal investment, fecundity and female remating in the seed beetle Callosobruchus maculatus

1. In many organisms, males provide nutrients to females via ejaculates that can influence female fecundity, longevity and mating behaviour. The effect of male mating history on male ejaculate size, female fecundity, female longevity and female remating behaviour in the seed beetle Callosobruchus maculatus was determined.
2. The quantity of ejaculate passed to females declined dramatically with successive matings. Despite the decline, a male's ability to fertilize a female fully did not appear to decline substantially until his fourth mating.
3. When females multiply mated with males of a particular mated status, the pattern of egg production was cyclic, with egg production increasing after mating. Females multiply mated to virgins had higher fecundity than females mated to non-virgins, and females mated to twice-mated males had disproportionately increased egg production late in their life.
4. Females that mated to multiple virgins, and consequently laid more eggs, experienced greater mortality than females mated only once or mated to non-virgins, suggesting that egg production is costly, and rather than ameliorating these costs, male ejaculates may increase them by allowing or stimulating females to lay more eggs.
5. Females mating with non-virgin males remated more readily than did females mated to virgins. Females given food supplements were less likely to remate than females that were nutritionally stressed, suggesting that females remate in part to obtain additional nutrients.     

SPERM MIXING IN THE COCKROACH DIPLOPTERA PUNCTATA

Females of the viviparous cockroach Diploptera punctata store sperm from their first mating, and do not remate until after giving birth to their first batch of young. The irradiated male technique was used to determine the outcome of sperm competition in the second batch of eggs of females mated sequentially to normal and irradiated males. It is estimated that the second male to mate with a female fertilizes approximately two thirds of the eggs in a female's second batch of eggs. Direct evidence for sperm mixing was obtained. Undeveloped eggs (fertilized by irradiated sperm) and developing embryos (fertilized by normal sperm) were found interspersed throughout oothecae that were extruded from females, demonstrating that normal and irradiated sperm were released from the spermathecae at oviposition and that they competed for fertilizations.     

Mating affects reproductive investment into eggs,but not the timing of oogenesis in the flesh fly <Emphasis Type="Italic">Sarcophaga crassipalpis</Emphasis>

We examined the effects of mating on reproductive investment and the timing of oogenesis in the flesh fly Sarcophaga crassipalpis by exposing females to males or not. All females exposed to males were mated within a few days and we found that mating affected reproductive investment. Virgin females not exposed to males produced a large clutch of eggs (∼91), but females exposed to males and mated produced 10% more. There was no effect of mating on egg length or mass. There was also no effect of mating on the timing of oogenesis. Females in both treatments provisioned their eggs at the same rate with yolk first becoming visible in the oocytes on day three of adulthood and complete provisioning of eggs occurring by the seventh day of adulthood. We examined the biochemical basis of egg provisioning by identifying the yolk proteins and quantifying their blood titer during the oogenic period in both, females exposed to males and mated and those not exposed to males. There was no difference in the timing of the first appearance, peak titer, or disappearance of yolk proteins in the blood between the two treatments. However, consistent with our observation of greater egg production in mated females, these females contained a greater peak yolk protein titer.     

Effects of gamma radiation on the reproduction biology and mating competitiveness of citrus leafminer Phyllocnistis citrella Stainton

The citrus leafminer (CLM), Phyllocnistis citrella Stainton, is one of the most serious pests of Iran's citrus nursery stocks. In this study, the effects of gamma radiation at doses of 100–450?Gy on the biological and reproductive parameters of P. citrella were determined. The results showed that the mean percentage of pupal mortality increases with a rise in the dose. Also, the mean values of this parameter were higher for irradiated females, indicating higher sensitivity. The mean fertility of the irradiated females mated with normal males was affected drastically and reached zero at 300?Gy. The hatchability of the eggs laid by normal females mated with irradiated males dropped to 2% at the highest irradiation dose of 450?Gy. The results of this test showed that females have a higher radio-sensitivity than males. The competitiveness values fluctuated from 0.2 to 0.6 at doses higher than 200?Gy. The results showed that the male CLMs irradiated with sterilizing doses could compete suitably with the untreated males in laboratory conditions.     

Is egg carrying attractive? Mate choice in the golden egg bug (Coreidae,Heteroptera)

In several species of fish, females select males that are already guarding eggs in their nests. It is a matter of debate as to whether a female selects a good nest site for her offspring (natural selection) or a male for his attractiveness (sexual selection). The golden egg bug, Phyllomorpha laciniata Vill, resembles fish in the sense that mating males carry more eggs than single males, but in the bugs, female mate choice is decoupled from egg site choice. The sexual selection hypothesis predicts that if females select males using male egg load as a cue for male quality, they should not mate with a male when eggs are removed, regardless of his mating attempts. When individual females were enclosed with an egg-loaded male and an unloaded male, they mated equally often with both males, although the loaded males courted more. In addition, when only successful males were used, females mated equally often with the loaded male and the unloaded male irrespective of sex ratio. Male choice rather than female choice affected mating frequency when sex ratio was equal. Therefore, females do not select the male by the eggs he carries, but successful males may receive many eggs due to egg dumping by alien females while they mate or as a consequence of mate guarding.     

Genome instability in the F1-progeny of mice irradiated by ionizing radiation as determined by micronucleus assay

The F1-progeny of BALB/c male mice chronically exposed to low-dose gamma-radiation (0.1; 0.25 and 0.5 Gy; dose rate 0.01 Gy/day) as well as the F1-progeny of females exposed to acute X-radiation (0.5; 1.0 and 2.0 Gy; dose rate 0.1 Gy/min) shown the significant elevated micronuclei frequencies in bone marrow erythrocytes, as compared to the F1-progeny of unirradiated males and females. The increase in the micronuclei frequency in the F1-progeny was determined by the dose of irradiation of parents. The values of elevated micronuclei frequency in the F1-progeny of chronically irradiated males and acutely irradiated females for a dose of 0.5 Gy were comparable. The micronuclei frequencies in the F1-progeny of irradiated females and males for this dose were in 1.5 and in 1.6 times higher than ones in the F1-progeny of unirradiated mice correspondingly. The results suggest the possibility of transfer of genome instability from irradiated parents to the somatic cells of the F1-progeny via non-lethally damaged germ cells of parents.     

Studies of the reproductive physiology of Cimicidae (Hemiptera)—I. Fecundation and egg maturation

Observations were made under controlled conditions to determine the time required for the spermatozoa to reach various points in their migration. Special organs at the base of the ovarioles serve to hold the sperm until eggs are ready for fertilization. In virgin and mated females egg maturation is similar up to an early stage of yolk deposition, at which time eggs of the virgin females are resorbed. Ligation and implantation experiments indicate that the corpus allatum is essential for egg maturation. Its secretion does not become effective until at least 10 hr after feeding and is required for egg maturation to continue. Virgin females may be induced to produce eggs by corpora allata implants. Implants from males and virgin females as well as mated females are effective. External application of farnesol has an effect on egg maturation similar to corpus allatum implantation.     

Laboratory breeding studies of freshwater crayfish, Austropotamobius pallipes (Lereboullet)

SUMMARY. 1. Mature crayfish, collected from an Irish lake before breeding had started, were held in breeding combinations and their mating and brooding activities observed.
2. All mating attempts were initiated by the male. A single mating led to spawning within 6 days but a subsequent mating cancelled the effects of the first. Males mated more often when there were more females present. Males lacking a major cheliped mated less often than did normal males.
3. Larger males mated more often than did smaller males, and although males showed no female size preference, matings were less frequent and generally unsuccessful when males were much larger than females; the female was usually killed. Large females mated successfully with smaller males.
4. Females held at high densities with a larger male mated earlier than at low densities. However, aggression also increased with density; at high densities males fought and killed females.
5. Males held in pairs without females fought; in occasional mating attempts spermatophores were not positioned correctly. Paired females rarely fought; all spawned normally although unmated. Although their eggs soon died and were removed during grooming, brooding behaviour continued for at least 2 months.
6. Brooding females held in pairs shed pleopodal eggs during aggressive encounters. Females held singly showed a lower initial rate of egg loss.     

Forced Copulations and Intra-specific Parasitism: Two Costs of Social Living in the White-fronted Bee-eater

White-fronted bee-eaters are colonially breeding birds that exhibit highly developed helping-at-the-nest. Through long-term studies of an individually-marked population, we have documented two costs of social living: 1) harassment of mated females by extra-pair males, and 2) intra-specific parasitism by females who lay eggs in the nests of others. Breeding females are sexually chased and, occasionally, forceably mated by males other than their mates. Focal-sampling of females throughout their period of receptivity revealed that the average female is involved in 5 to 8 sexual chases and is forceably copulated 0.15 to 0.23 times per breeding season. This risk to females would be much greater were it not for the behavior of male mates who remain close to, and actively defend, their partners. Such mate-guarding is highly effective — females entering and leaving the colony in consort with their mates are sexually harassed only 1/10 as often as females travelling alone. Although sexual harassment of females is common at bee-eater colonies, the risk of paternity uncertainty arising from forced copulations is thought to be low. The reason is that females copulate repeatedly with their male mates on all days immediately prior to as well as during egg laying. This point has been overlooked in previous reports and has led to an exaggeration of the paternity risks associated with forced sexual chases. We conclude that sexual chasing of extra-pair females is a low yield reproductive tactic employed primarily by monogamously mated males whose presence at the colony is required to allofeed and mateguard their own egg-laying females. Female white-fronted bee-eaters lay eggs in nests other than their own. This intraspecific parasitism constitutes a greater threat to certainty of parentage than does forced copulation. Over four years of study, 16% of nests were parasitized and 7 % of all eggs were laid by a female other than the breeder (Table 2). Parasitizing females come primarily from two sources: (1) members of mated pairs whose own breeding attempt is disrupted at the time of egg laying, and (2) single females who opportunistically add an egg at the nest of their parents (or parent plus step-parent). In each case of kin-parasitism, the “parasitic” female remained socially integrated with the host group and helped in the rearing of the young. In contrast, 9 of 10 females that parasitized the nests of non-relatives had no other interactions with the hosts (Table 3). Parasitizing females exhibited two specialized behaviors that enhanced their reproductive effectiveness: (1) they spent many hours observing, investigating, and testing the defenses of potential host nests, and (2) they preferentially laid in hosts' nests at the appropriate chronological stage of development. Breeding females also exhibited counterbehaviors against being parasitized. These included: (1) remaining sequestered in their nest chambers for 64%-65% of the daylight hours and 94 % of the pre-roost hours during their days of egg laying, (2) aggressively defending their nest entrances against all investigating (potentially parasitic) females, and (3) actively removing any eggs laid in their nests prior to the initiation of their own clutch. These tactics and countertactics suggest a long evolutionary history of parasitic opportunities and risks among white-fronted bee-eaters.     

Mating, cross-mating and related behaviours of Neoseiulus californicus and Neoseiulus fallacis (Acari: Phytoseiidae)

The pairings of Neoseiulus californicus (McGregor) and Neoseiulus fallacis (Garman) from western North America were monitored for tending by adult males, males in the mating position and oviposition and the activity of female deutonymphs and adults. The N. fallacis × N. californicus (♂ × ♀) tests had fewer males tending the deutonymphs but more in the mating position with new females than the reciprocal test. Afterwards, most of the females appeared gravid and approximately 20% produced an egg. Some eggs did not hatch but others became adult males, which mated with their mothers, but no eggs were produced. F1 males tended and mated with new N. fallacis females which had normal offspring. When held with new N. californicus females, F1 males tended the deutonymphs but were not seen mating and no eggs were laid. The pairings of N. californicus× N. fallacis had more males tending, less in the mating position and the females appeared non-gravid and produced no eggs. When same-species males were added to females held with F1 males for 15–20 days, normal levels and sexes of the progeny were produced. The female and male adults of N. fallacis were more active (ambulatory) than those of N. californicus. In within-species tests, the males had a high activity except while tending and mating, the female deutonymphs were inactive and the just mated females were more active than the ovipositing females. The timing of the tending and mating differed in the cross-pairings. Overall, these and other life-history data show that these two mites are distinct species, but that their males are promiscuous in tending and mating. This revised version was published online in November 2006 with corrections to the Cover Date.     

Induced sterility of Glossina pallidipes Austen males after irradiation in a nitrogen atmosphere

The sterile insect technique relies on sterilization of males using ionizing radiation. Life cycle stage, and the environmental conditions under which irradiation is carried out are crucial to the provision of good‐quality insects. To identify an optimal radiation strategy for Glossina pallidipes Austen, 1903, 13‐day‐old males were irradiated at different doses in a nitrogen atmosphere. The following day the males were mated with 8‐day‐old virgin females. Pupal production of mated females was monitored for 6 weeks, and induced sterility was determined by probit analysis. Survival of the males that mated was also monitored. At least 95% sterility of irradiated males was achieved with a 158 Gy dose in nitrogen and a 125 Gy in air. Irradiation significantly lowered the probability of survival between 30 and 100 days of age (especially flies irradiated in air), but probabilities of survival were similar outside this period for irradiated and unirradiated flies. Exposure of 2‐ or 13‐day‐old males to sterilizing radiation induced similar levels of sterility in both air and nitrogen.     

Protein consumption by mated, unmated, sterile and fertile adults of the Queensland fruit fly, Bactrocera tryoni and its relation to egg production

Abstract. Female adults of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) at 25 °C require more than 0.1 mg of yeast autolysate per day to mature their oocytes to the vitellogenic stage and mate. Those given 0.2 mg per day from day 2 of adult life mated (when given the opportunity between 11 and 13 days) and each laid approximately 100 eggs (just over one egg per ovariole) by day 56. Females allowed to feed ad libitum from day 2, then 0 or 0.2 mg per day from day 14, laid approximately 75 and 100 eggs, respectively (after mating), whereas those fed ad libitum from day 2 to day 56 laid approximately 540 eggs after mating (averaging just over six eggs per ovariole). The developmental pattern of intake of normal females when on an ad libitum diet showed a rise to a peak at 5–7 days, followed by a decline to sustained low levels if not mated, but rising to a lower peak if mated between days 11–13 followed by a steady decline. Female flies that had been sterilized by 80 Gy gamma irradiation at the puparial stage had a pattern of food consumption similar to that of normal females mated at 7 days but they produced no yolky oocytes and had a darkened fat body. Normal and irradiated males had a feeding pattern similar to that of unmated nonirradiated females but at a lower level. The results are discussed in terms of the control of protein intake and the rate of its conversion to yolk.     

Genetic variation in male effects on female reproduction and the genetic covariance between the sexes

Abstract.— Males of many insect species increase the fecundity and/or egg size of their mates through the amount or composition of their nuptial gifts or ejaculate. The genetic bases of such male effects on fecundity or egg size are generally unknown, and thus their ability to evolve remains speculative. Likewise, the genetic relationship between male and female investment into reproduction in dioecious species, which is expected to be positive if effects on fecundity are controlled by at least some of the same genes in males and females, is also unknown. Males of the seed beetle Stator limbatus contribute large ejaculates to females during mating, and the amount of donated ejaculate is positively correlated with male body mass. Females mated to large males lay more eggs in their lifetime than females mated to small males. We describe an experiment in which we quantify genetic variation in the number of eggs sired by males (mated to a single female) and found that a significant proportion of the phenotypic variance in the number of eggs sired by males was explained by their genotype. Additionally, the number of eggs sired by a male was highly positively genetically correlated with his body mass. The between-sex genetic correlation, that is, the genetic correlation between the number of eggs sired by males and the number of eggs laid by females, was highly positive when eggs were laid on Acacia greggii seeds. This indicates that males that sire many eggs have sisters that lay many eggs. Thus, some of the genes that control male ejaculate size (or some other fecundity-enhancing factor) when expressed in males appear to control fecundity when expressed in females. We found no significant interaction between male and female genotype on fecundity.     

Effect of multiple mating on the reproductive performance of the rice leaffolder moth,Cnaphalocrocis medinalis (Lepidoptera: Crambidae)

To clarify whether multiple mating of females and males affects the reproductive performance of the rice leaffolder moth, Cnaphalocrocis medinalis (Guenée), we examined the effect of the number of matings (once, twice, or three times) for females (female treatment) and males (male treatment) on the incidence of moth mating, number of eggs laid, egg hatchability, and adult longevity. We also compared the effect of multiple mating imposed on males or females separately with the effect of that imposed on both sexes simultaneously (both sexes treatment). The incidence of mating of females and males that mated three times (3-mated females and males) was significantly lower than for females and males that mated twice or once (2-mated or 1-mated females and males). The incidence of mating of 1-mated moths (both sexes) was significantly higher than for 2-mated or 3-mated moths (both sexes). Two-mated or 3-mated females laid significantly more eggs with significantly higher hatchability than 1-mated females. Females that mated with 1-mated males (second male mating) or 2-mated males (third male mating) laid significantly fewer eggs than those that mated with virgin males (first male mating). Females laid significantly more eggs after the second and third matings for moths of both sexes than after the first mating for moths of both sexes. The mechanisms of improvement and decline of female reproductive performance when multiple mating was imposed on males or females are also discussed in relation to the reproductive biology of C. medinalis.     

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).