Reproductive performance and longevity of female European corn borer,Ostrinia nubilalis: effects of multiple mating,delay in mating,and adult feeding

In a recent study on the pheromone-mating disruption of the European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), we recorded a significant reduction in mating frequency, as well as a marked delay in mating in feral females captured in disruptant-treated fields. In order to be able to accurately interpret the results in terms of effective population control, the current study was undertaken on the effects of multiple matings and a delay in mating on reproductive performance. Female O. nubilalis that mated at least twice had significantly higher fecundity and fertility, compared with once-mated females. In addition, multiple-mated females deposited a significantly larger portion of their egg complement, relative to single-mated or unmated females. Females that experienced a 3-day delay in mating showed a significant reduction in fecundity compared with females that mated soon after emergence. A 1-week delay in mating resulted in a further reduction in fecundity and a near zero fertility. The effect of sugar feeding on reproduction was not significant. In general, unmated females lived longer than mated females, and sugar-fed mated females had a higher longevity than water-fed mated females.     

Survival and development of Campoletis chlorideae on various insect and crop hosts: implications for Bt-transgenic crops

Abstract:  The parasitic wasp, Campoletis chlorideae is an important larval parasitoid of Helicoverpa armigera a serious pest of cotton, grain legumes and cereals. Large-scale deployment of Bt -transgenic crops with resistance to H. armigera may have potential consequences for the development and survival of C. chlorideae . Therefore, we studied the tritrophic interactions of C. chlorideae involving eight insect host species and six host crops under laboratory conditions. The recovery of H. armigera larvae following release was greater on pigeonpea and chickpea when compared with cotton, groundnut and pearl millet. The parasitism by C. chlorideae females was least with reduction in cocoon formation and adult emergence on H. armigera larvae released on chickpea. Host insects also had significant effect on the development and survival of C. chlorideae . The larval period of C. chlorideae was prolonged by 2–3 days on Spodoptera exigua , Mythimna separata and Achaea janata when compared with H. armigera , Helicoverpa assulta and Spodoptera litura . Maximum cocoon formation and adult emergence were recorded on H. armigera (82.4% and 70.5%, respectively) than on other insect hosts. These studies have important implications on development and survival of C. chlorideae on alternate insect hosts on non-transgenic crop plants, when there is paucity of H. armigera larvae on transgenic crops expressing Bt -toxins.     

Effect of Delayed Mating on Oviposition Pattern, Fecundity and Fertility in Codling Moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae)

Female codling moth ( Cydia pomonella ) were mated either on the day of emergence or 2 or 4 d after emergence. Oviposition was checked daily and fertility (% egg hatch) of eggs laid 1–4 d and 5 + d after mating was determined from a sub-sample of females in each treatment. From these data, net reproduction rate (R₀) was calculated. the effect of delayed mating of males was also determined. Mean fecundity, fertility and net reproduction rate of females mated 4 d after emergence were significantly lower than for females mated either on the day of emergence (day 0) or 2 d after emergence. There were no significant differences between the three treatments in terms of the proportion of females that mated or female longevity, although there was a trend towards increased longevity with increasing delays in mating. Mean longevity of unmated females was significantly greater than that of mated females. Oviposition pattern was similar in females regardless of when they were mated and in all cases maximum oviposition took place 2 d after mating. There was no effect on the fecundity of 2 d old females or on the fertility of their eggs when they were paired with either 2 or 6 d old males. the significance of these findings in relation to control of codling moth by mating disruption is discussed.     

Effects of transgenic Cry1A＋CpTI cotton and Cry1Ac toxin on the parasitoid, Campoketis chlorideae （Hymenoptera：Ichneumonidae）

Abstract The effect of transgenic double genes, Cry1A + CpTI cotton and Cry1Ac toxin on the parasitoid, Campoketis chlorideae Uchida of cotton bollworm, Helicoverpa armigera (Hübner), was investigated in the laboratory. Helicoverpa armigera larvae when in the first, second and third instar could not survive if fed on transgenic cotton leaves. Consequently, C. chlorideae larvae could not complete their development if parasitizing on such hosts. After H. armigera larvae were reared on transgenic or traditional cotton leaves for 12J48 hours, they were parasitized by C. chlorideae females. Parasitized larvae continued to feed on transgenic or traditional cotton for 12–48 h. The present results showed that the body weight of larvae of the parasitoids were significantly reduced when parasitized hosts fed on transgenic cotton leaves compared to those fed on traditional cotton. Duration of egg and larvae stage were significantly prolonged, pupal and adult weight of C. chloridae was decreased when the host larvae fed on transgenic cotton leaves longer than 48 h. The development duration of C. chlorideae pupae on the hosts fed on transgenic cotton leaves in each treatment was not significantly different from those of controls. The longevity of parasitoid females and males fed with a solution containing Cry1Ac toxin was not significantly different with that of the control.     

The parasitoid of a fruit moth caterpillar utilizes fruit components as nutrient source to increase its longevity and fertility

Longevity and fecundity of female wasps are two decisive factors for the effectiveness of parasitoid species as biological control agents. Accessibility and suitability of nutrient sources determine parasitoid survival and reproduction. Host, nectar and honeydew feeding are frequent adult parasitoid behaviors to cover nutritional needs. Here we postulate that especially parasitoid species of endophytic herbivores might use plant tissue as a nutrient source that becomes accessible upon herbivory. We investigated the influence of plant consumption and host feeding on longevity and fecundity of Hyssopus pallidus, a gregarious ecto-parasitoid of caterpillars of the codling moth that feed inside apple fruits. Longevity of unmated and mated ovipositing female parasitoids was highest in treatments with fruit pulp. While longevity in this treatment was not significantly different from that with honey, it was significantly higher than in treatments without food, with water or with a host alone.Reproduction was significantly increased by these sugar-rich nutrient sources compared to the control with a host alone. In contrast, host feeding did not yield any significant contribution to longevity and fecundity in a series of bioassays with different host–parasitoid ratios and with differently aged and sized hosts, compared to controls without food.We conclude that in this synovigenic species host feeding does not contribute to longevity and fecundity, but females can increase survival and reproduction in the field relying solely on the plant tissue damaged by their host caterpillar.     

豆野螟延迟交尾和多次交尾对生殖的影响

豆野螟Maruca vitrata(Fabricius)是一种严重的泛热带豆类蔬菜害虫。本文研究了豆野螟延迟交尾和多次交尾对其生殖的影响。延迟交尾实验结果表明:豆野螟雌雄同时延迟交尾,雌雄虫的寿命、产卵量均表现为先上升后下降的趋势,但是对卵的孵化率没有显著影响;雌虫延迟交尾,随着延迟时间的增加,雌虫的寿命、产卵量、卵的孵化率表现为下降的趋势,而雄虫的寿命延迟交尾第3天达到最大值;雄虫延迟交尾,随着延迟交尾时间的增加,雌雄虫的寿命、产卵量均表现为先上升后下降的趋势,卵的孵化率随着延迟逐渐下降。多次交尾实验结果表明,随着雄虫交尾次数的增加,成功交尾率逐渐降低,用于交尾的时间延长,雌虫和相应雄虫的寿命逐渐缩短,雌虫的产卵量下降,但对卵的孵化率影响不大;豆野螟雌虫一生只交尾一次,未见到雌虫2次交尾。     

Effect of male and female multiple mating on the fecundity, fertility, and longevity of diamondback moth, Plutella xylostella (L.)

Abstract:  The effect of diamondback moth (DBM), Plutella xylostella (Lep., Plutellidae) male and female multiple mating on fecundity, fertility, and longevity was studied. Males could mate for five times with virgin females during scotophase. The successful copulation rates, fecundity of female, and longevity of both females and males decreased when male mating times increased, whereas copulation duration increased. Correlation coefficient between copulation duration and male mating times was significant ( r  = 0.7358, P = 0.0001, spearman rank-order correlation). There were linear relationships between mating history of males and longevities of males and females, and regression relationships between them were significant. Mated females had similar daily reproductive pattern, which laid the most eggs on the first day after mating in spite of their mates' mating history. Virgin females laid some infertile eggs before they died. Most of the females mated once during their lifespan but 19.9% of females mated twice when one female kept with one male during scotophase. There were no significant differences in the fecundity, fertility and longevity between the single- and twice-mated females. Correlation coefficient between copulation duration and female mating times was not significant ( r  = 0.0860, P = 0.8575). Results suggested that DBM females may be monandrous. Multiple mating did not increase male or female mating fitness.     

Effects of mating rates on oviposition,sex ratio and longevity in a predatory mite <Emphasis Type="Italic">Neoseiulus cucumeris</Emphasis> (Acari: Phytoseiidae)

Two aspects of mating effects on the fecundity, sex ratio and longevity of Neoseiulus cucumeris (Acari: Phytoseiidae) were examined in laboratory experiments: (1) females mated by one, two or three different males (unmated and 3 days old) at 5-day intervals, and (2) females mated by males with different age/mating status (number of females mated previously by the male). Females allowed to mate with a second or third male at 5-day intervals produced 39 eggs on average, but those mated with a single male produced 28 eggs on average. Matings with additional males 5 or 10 days after the first male increased the duration of the oviposition period of these females by 5–7 days and at the same time reduced the post-oviposition period by about 10 days. Overall, females with additional matings by one or two different males at 5-day intervals survived a few days shorter than females without additional males. Mating with a different female each day, a male of N. cucumeris could mate with 5–8 females, which produced a total of 85–116 eggs: females mated with a male during days 1 and 2 in its adulthood and with a male of the last 2 days of life (days 7 and 8) produced about half as many eggs as females mated with a male during 3–6 days of its adulthood. Females mated with males that are too young or too old had a shorter oviposition period and a longer post-oviposition period and longevity than females mated with middle-aged males. In both experiments, rates of oviposition remained similar in females with high or low fecundity. This indicates that in both cases, the increased fecundity is due to the extension of the oviposition period through additional sperm supplied by the second male and or third male (in experiment 1) or more sperm by males not too young nor too old (experiment 2).     

Reproductive biology of the microtype tachinid fly Zenillia dolosa (Meigen) (Diptera: Tachinidae)

Reproductive biology including mating, adult longevity, fecundity and development of the tachinid fly Zenillia dolosa was investigated for optimizing rearing procedures using Mythimna separata as a host in the laboratory. Females lay microtype eggs containing a first instar larva on food plants of the host and then the eggs must be ingested by the host for parasitization. Mating success was 58.5% with mating duration of 80.7 min. Mating was most successful when day 0–1 females were kept with day 2–4 male flies. Female body size was positively correlated with its fecundity but not with longevity. However, females that survived longer produced more eggs during their lifetime. Parasitoids successfully developed in 4th to 6th instar host larvae. Host instars at the time of parasitoid egg ingestion significantly influenced development time of the immature parasitoid, but did not affect body size of the emerging parasitoid. We suggest that pairing newly emerged females with day 2–4 males should result in higher mating success and using the last instar hosts for parasitization should minimize development time of the parasitoid for rearing.     

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.     

Effects of age at mating of both sexes on female longevity and fecundity performance in Ophraella communa LeSage (Coleoptera: Chrysomelidae)

Life-history strategies of animals are governed by fitness-related trait trade-offs. In particular, the age at which either one of the two sexes copulate has been shown to affect insect reproductive output and longevity. This suggests that trade-offs between longevity and reproduction might drive the choice of a mating partner based on their age and ultimately such choices might select for different life-histories. Although several studies indicate that female age at mating dictates subsequent insect longevity, fecundity, and egg hatch rate, it is unclear how male age at copulation affects these life-history traits. In this study, we simultaneously investigated the effects of female and male age on female fecundity, eggs hatch rate, and adult longevity in Ophraella communa LeSage (Coleoptera: Chrysomellidae), the primary biological control agent of the invasive common ragweed, Ambrosia artemisiifolia L. We found that young mature females lived significantly longer when they were mated with older males. Maximum female fecundity and subsequent egg hatch rate occurred when young females mated with 3-day-old males. On the other hand, females lived longer when mating with an older male. These findings are in accordance with the cost-of-reproduction concept.     

Body size as an indicator of parasitoid quality in male and female Anagyrus kamali (Hymenoptera: Encyrtidae)

The parasitoid Anagyrus kamali Moursi was recently introduced into the Caribbean as a biological control agent against the hibiscus mealybug, Maconellicoccus hirsutus Green. In the laboratory, parasitoid size, as measured by left hind tibia length, was positively correlated with several indicators of the parasitoid's fitness: longevity, mating preference, fecundity, reproductive longevity, progeny emergence and sex-ratio. When fed ad libidum with honey drops, large male parasitoids lived significantly longer (29.1 +/- 6.5 days) than small ones (18.4 +/- 5.7 days). Large females also lived significantly longer (35.4 +/- 10 days) than small females (27.9 +/- 9.6 days). Females showed no significant mating preference between large and small males. Lifetime fecundity was positively correlated with the size of adult females and ranged from 37 +/- 21 eggs for small females to 96 +/- 43 eggs for large ones. The reproductive longevity, daily oviposition rate, and number of progeny were also higher among large parasitoids. The sex ratio of progeny from small female parasitoids was higher (0.76 +/- 0.24) than that of large individuals (0.47 +/- 0.18).     

Impact of mating on Anagyrus kamali Moursi (Hym., Encyrtidae) lifetime fecundity, reproductive longevity, progeny emergence and sex ratio

Abstract: The solitary endoparasitoid Anagyrus kamali Moursi (Hym., Encyrtidae) and the Hibiscus mealybug Maconellicoccus hirsutus Green (Hom., Pseudococcidae), were used as a parasite/host model to test the effect of mating on several fitness parameters, i.e. longevity, lifetime fecundity, progeny emergence and sex ratio. At 27 ± 2°C, 8 h light : 16 h dark, mating significantly affected the survival of male parasitoids. Virgin males lived longer (32.2 ± 9.51 days) than mated males (23.9 ± 7.52 days). Female longevity (40.7 ± 16.3 days for virgins and 36.2 ± 10.7 days for mated females) was not affected by mating. The lifetime fecundity of female parasitoids and their oviposition period was not significantly affected by mating. However, the number of hosts parasitized was greater for mated wasps (7.54 ± 4.85 hosts parasitized/day) compared with virgin ones (5.12 ± 2.19 hosts parasitized/day). This resulted in greater progeny production from mated A. kamali females. The progeny of virgin females consisted only of males, whereas the mated ones had a more female‐biased sex ratio. The lowest sex ratio (0.41 M/F ± 0.123) was attained when females had free access to males and were multi‐mated.     

交配对小地老虎成虫寿命和繁殖的影响

通过室内饲养小地老虎,研究了交配对其成虫寿命和繁殖的影响.结果 表明,小地老虎成虫的寿命随其交配状况而有所变化,无论雌蛾还是雄蛾,未能得到及时交配时,则寿命稍长些,交配过的雌蛾产卵前期缩短、产卵期延长、产卵量增大.小地老虎的交配次数对其产卵量和幼虫孵化率有明显的影响,0次交配的产卵量最低,并且产的是不育卵,均不能孵化;随着交配次数的增加,其产卵量和幼虫孵化率都显著增大.     

Strong material benefits and no longevity costs of multiple mating in an extremely polyandrous leaf beetle, Chrysochus cobaltinus (Coleoptera: Chrysomelidae)

It is well established that females of many species exhibitpolyandry. Although such behavior often increases female fitnessby augmenting fecundity or enhancing the genetic diversity andvigor of their offspring, it often reduces female longevity.It has been argued that trade-offs between these costs and benefitsshould limit the degree to which females remate. However, theexistence of highly polyandrous species suggests substantialpolyandry benefits and/or minimal costs in some systems. Femalesof the leaf beetle, Chrysochus cobaltinus, are extremely polyandrous,providing an opportunity to examine the factors influencingthe evolution of such behaviors. We compared the fecundity andlongevity of singly mated females, females that mated multipletimes with the same male, and females that mated multiple timeswith different males. Compared with females in the single matingtreatment, females in both multiple mating treatments exhibiteda significant reduction in latency to oviposition and, due toan increase in daily egg production, significant increases inlifetime fecundity. This difference diminished as the time sincelast mating increased. There were no differences in fecunditybetween the 2 multiple mating treatments, indicating that mateidentity does not influence the material benefits of multiplemating. Surprisingly, female longevity did not differ amongtreatments. The pronounced fecundity benefits that females gainfrom multiple mating, coupled with a lack of longevity costs,apparently explains the extreme polyandry in this species. Inaddition, the existence of material fitness benefits via conspecificmatings raises the intriguing possibility that in a C. cobaltinus–Chrysochusauratus hybrid zone, heterospecific matings may confer similarbenefits to Chrysochus females.     

Effect of age at first mating on primary sex-ratio of the two-spotted spider mite

This paper determines the influence of initial age at mating on the primary sex-ratio of the two-spotted spider miteTetranychus urticae Koch. The specific question asked is whether females that mate at ages beyond ecdysis, or are inseminated at ecdysis by virgin males of set ages, have daughter productions different from control females mated at ecdysis by randomly aged males.Age of initial female mating did not effect survival. Females mated at ecdysis produced more daughters than those mated at age 5 or 10 days. However, daughter production was equal for all female treatments in the post-mating period. All treatments stopped producing daughters at approximately the same age, regardless of when mated. Son production was lowest for females mated at ecdysis. However, son production by females mated when 5 or 10 days old was lower than that of females mated at ecdysis.Male age at mating did not effect female survival. Females exposed to virgin males either 1 or 7 days old produced more daughters than those exposed to males either 11 or 20 days of age. However, a substantial proportion of females in these latter cohorts were not mated. If only mated females are considered, daughter production is the same between all cohorts.Delayed age at first mating influenced sex-ratio only via the females, specifically by changes in daughter production (as opposed to changes in survivorship). Daughters that would have been produced between ecdysis and mating were never recovered by females that mated at ages beyond ecdysis. Thus, these daughters were lost from a sex-ratio viewpoint. Initial age of male mating did not change sex-ratio.     

Reproductive Biology and Behavior of <Emphasis Type="Italic">Tranosema rostrale</Emphasis> (Hymenoptera: Ichneumonidae), a Parasitoid of Low-Density Spruce Budworm (Lepidoptera: Tortricidae) Populations

Tranosema rostrale (Brischke) (Hymenoptera: Ichneumonidae) is an important parasitoid of low-density spruce budworm Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) populations. To investigate the effectiveness of this parasitoid in attacking low-density spruce budworm populations, we conducted a detailed laboratory study on its reproductive biology and behavior including mating behavior, potential fecundity, longevity, host searching, and oviposition behavior. We found that the occurrence of mating increases with the number of males present in the cage but that it drastically decreases when females mated previously. Females may mate multiple times with different males in one breeding session and mating duration is significantly longer when a male mates the second time with the same female. Dissections of T. rostrale’s oviducts showed that it is a synovigenic species emerging with about 17 % of its lifetime egg load and develops most of its eggs in the first three days after emergence at 20 °C. Sugar, but not pollen, significantly increased the insect’s longevity compared to water. Spruce budworm larvae, silk from larvae and damaged balsam fir foliage triggered probing in T. rostrale females significantly more often than larval feces. The sequence of the parasitoid’s behaviors leading to successful attack is described as antennation, probing, insertion of the ovipositor, oviposition, and subsequent disinterest or resuming of the sequence. Defense mechanisms of the host larva such as vigorous movements, biting, and/or regurgitation and behavioral countermeasures by T. rostrale are described in detail.     

Diel flight pattern and flight performance of Cactoblastis cactorum (Lepidoptera: Pyralidae) measured on a flight mill: influence of age, gender, mating status, and body size

Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) is an invasive herbivore that poses a serious risk to Opuntia cacti in North America. Knowledge of the flight behavior of the cactus moth is crucial for a better understanding of natural dispersal, and for both monitoring and control. We used computer-linked flight mills to investigate diel flight activity and flight performance in relation to gender, age, mating status, and body size. Maximal flight activity for both mated and unmated moths occurred during twilight, whereas flight activity was low during photophase. The total distance flown and the number of initiated flights within a diel cycle were higher in both unmated and mated females than in males, but the longest single flight was similar in both genders. These findings suggest that pheromone trap captures of males likely indicate the simultaneous presence of females and that mated females might even be in areas where males are not detected yet. Flight performance heterogeneity was large, with a small portion of the population (both males and females) performing long unbroken flights, whereas the majority made short flights. Females had higher pupal and adult body size and shorter longevity than males. A few individuals, particularly young mated females, flying long distances may be important for active spread of a population and the colonization of new habitats. Implications of this study in the control of the cactus moth by using the sterile insect technique are discussed.     

Assortative Mating by Size in the American Rubyspot Damselfly (<Emphasis Type="Italic">Hetaerina americana</Emphasis>)

Assortative mating refers to the non-random nature of mating patterns between certain males and females. Thus, males and females may associate negative- or positively, based on different traits. Amongst these associations, assortative mating by size is one of the most common patterns found in natural populations of animals. Two main hypotheses have been proposed to account for the occurrence of assortative mating by size. First, it may be the result of mechanical, temporal, or physiological constraints. Second, it may occur in response to direct or indirect selection on mating preferences. Here we investigate whether the American rubyspot damselfly exhibits true assortative mating by size. Males of this species exhibit high levels of male-male competition, as they compete over territories, to which females are attracted for copulation. There is a documented large male body size advantage: the largest males are better able to hold their territories and thus secure more copulations. Our major results show that i) mated males are more likely to be larger than unmated males, whereas mated and unmated females tend to have similar body sizes; ii) H. americana exhibits true assortative mating by size; as such, this pattern is not driven by seasonal changes in the body sizes of males and females. We suggest that this mating pattern occurs in this species given the advantages of large male size, and the advantages of large female body size (i.e. higher fecundity). We believe that males may be able to evaluate a female’s reproductive value and exert mate choice.     

The costs and benefits of multiple mating in a mostly monandrous wasp

The taxonomically widespread nature of polyandry remains a puzzle. Much of the empirical work regarding the costs and benefits of multiple mating to females has, for obvious reasons, relied on species that are already highly polyandrous. However, this makes it difficult to separate the processes that maintain the current level of polyandry from the processes that facilitate its expression and initiated its evolution. Here we consider the costs and benefits of polyandry in Nasonia vitripennis, a species of parasitoid wasp that is “mostly monandrous” in the wild, but which evolves polyandry under laboratory culture conditions. In a series of six experiments, we show that females gain a direct fecundity and longevity benefit from mating multiply with virgin males. Conversely, mating multiply with previously mated males actually results in a fecundity cost. Sexual harassment may also represent a significant cost of reproduction. Harassment was, however, only costly during oviposition, resulting in reduced fecundity, longevity, and disrupted sex allocation. Our results show that ecological changes, in our case associated with differences in the local mating structure in the laboratory can alter the costs and benefits of mating and harassment and potentially lead to shifts in mating patterns.