Sex chromosomes, sex ratios and sex gaps in longevity in plants

In animals, males and females can display markedly different longevity (also called sex gap in longevity, SGLs). Recent work has revealed that sex chromosomes contribute to establishing these SGLs. X-hemizygosity and toxicity of the Y chromosomes are two mechanisms that have been suggested to reduce male longevity (Z-hemizygosity and W toxicity in females in ZW systems). In plants, SGLs are known to exist but the role of sex chromosomes remains to be established. Here, by using adult sex ratio as a proxy for measuring SGLs, we explored the relationship between sex chromosome and SGLs across 43 plant species. Based on the knowledge recently accumulated in animals, we specifically asked whether: (i) species with XY systems tend to have female-biased sex ratios (reduced male longevity) and species with ZW ones tend to have male-biased sex ratios (reduced female longevity), and (ii) this patterns was stronger in heteromorphic systems compared to homomorphic ones. Our results tend to support these predictions although we lack statistical power because of a small number of ZW systems and the absence of any heteromorphic ZW system in the dataset. We discuss the implications of these findings, which we hope will stimulate further research on sex-differences in lifespan and ageing across plants.

Parasitism of Trichogramma Pretiosum in Eggs of Corcyra Cephalonica on the Age of the Parasitoid and the Density of the Host

Several biological control programs use Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). The parasitism capacity and the functional response of T. pretiosum parasitizing eggs of Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) were studied. To determine the parasitism capacity, females of the parasitoid were individualized, being offered to each female eggs from the host. Daily observations determined the number of parasitized eggs per female, accumulated percentage of parasitism, female longevity and percentage of parasitoid emergence. To establish the functional response, T. pretiosum females were individualized and offered C. cephalonica eggs. Number of parasitized eggs and percentage of adults’ emergence were evaluated, being calculated handling time (Th) and attack rate (a). On the first day of the parasitoid’s life there was parasitism in more than 80% of the host eggs, similar to the percentage of adult emergence throughout the life cycle, and the daily percentage of parasitism. The percentages of eggs of C. cephalonica parasitized were statistically different, with the quadratic model better describing the parasitoid-host relationship, with a positive value of 0.00594, since with the increase in the availability of eggs of C. cephalonica, parasitism was increased. The attack rate was approximately 0.00158, while the handling time of the host eggs was 0.6884 h.

Lethal and sublethal effects of several plant compounds compared to spiromesifen against Tetranychus turkestani

Summary Tetranychus turkestani Ugarov and Nikolski is one of the main agricultural pests of southwestern Iran and some other tropical regions. In the present study, fumigant activity of three essential oils extracted from Rosmarinus officinalis L., Mentha longifolia L. and Eucalyptus globulus Labill., and contact toxicity of two biopesticides (Tondexir and Palizin) on T. turkestani mite females were investigated and compared with that of spiromesifen, a chemical acaricide. Also, sublethal effects of the tested compounds at 50% lethal concentration (LC50) were estimated on the biological parameters of T. turkestani. The LC50 values for E. globulus, R. officinalis and M. longifolia essential oils were 12.50, 11.52 and 4.00 μl/l air and for spiromesifen, Tondexir and Palizin were 10.98, 327.34 and 858.13 ppm, respectively. All tested compounds significantly reduced adult female longevity, equally to the chemical acaricide spiromesifen. Fecundity also decreased in all treatments and this reduction was even higher for plant essential oils than the other compounds. Palizin, E. globulus and M. longifolia significantly reduced the hatchability of T. turkestani eggs similarly to spiromesifen. According to the results, the tested plant compounds are effective against T. turkestani and may be applied as suitable alternatives to synthetic pesticides against this crop pest.

Effects of mating on reproductive performance of Coccophagus japonicus Compere (Hymenoptera: Aphelinidae)

Coccophagus japonicus Compere, an endoparasitoid of Parasaissetia nigra Nietner, has great potential for biological control. To assess the influence of mating on the reproductive performance of this parasitoid, we examined the effects of mating on ovarian development, female longevity and number of eggs laid. The results showed that the egg volume in the ovary of C. japonicus first increased and then decreased with increases in the age of female adults. The peak egg volume in the ovary of mated females occurred 2 days earlier than that of virgin females. Within the female age range of 0–15 days, the numbers of eggs at stages I, II, and III first increased and then decreased with increases in the age of female C. japonicus, whereas the number of eggs at stage IV increased. The duration of the coexistence of females and males significantly influenced the length and width of the female ovaries, and the longest ovary tube and the highest number of eggs were obtained with a coexistence duration of 0 days. C. japonicus female longevity decreased with increases in the number of matings, and the number of eggs laid by females within 15 days decreased with increasing delays in mating. In conclusion, mating can shorten the longevity of C. japonicus females, and selecting newly emerged virgin females for mating can significantly improve the number of eggs laid and the breeding efficiency of the parasitoid.

Forty-year natural history study of Bahalana geracei Carpenter, 1981, an anchialine cave-dwelling isopod (Crustacea, Isopoda, Cirolanidae) from San Salvador Island, Bahamas: reproduction, growth, longevity, and population structure

Almost nothing has been reported on the natural history of any of the world’s 92 species of cave cirolanids, including those from saltwater caves (anchialine). Over 1400 specimens of Bahalana geracei Carpenter, 1981 were collected in two caves from 1978–2018; size-frequency data provided insight into population structure. Some specimens were maintained alive over multiple years to study rarely reported activities for cave cirolanids: feeding, molting, growth, longevity, and reproduction. Photographs document these phenomena. Mating occurred after gravid females shed both halves of reproductive molts. Females can have multiple broods (iteroparous) with ~2.0–3.5 years per reproductive cycle: egg production (~9–24 months), mating, brooding (5–6 months), release of 6–55 mancas (2.3–3.3 mm long), and oostegite molt (~2–13 months after manca release). Estimated lifetime fecundity is 58 mancas per female; probable range is 20–120. In Lighthouse Cave, females outnumbered males (~4:1), grew larger (16.8 vs. 9.5 mm), and lived longer. Growth rates were slow: ~1–2 years for three instars of post-marsupial manca development (from ~2.3–4.0 mm); estimated adult growth rate was 0.8 mm/year (1.6 molts/year) for males, and 0.5 mm/year (1.5 molts/year) for females. Longevity estimates for females are 25–28 years with 23–30 instars, vs. 6–8 years for males with 13–15 instars. Males from Major’s Cave were nearly as numerous and as large (14.8 mm) as females; estimated longevity for males is >20 years. Longevity estimates of >20 years appear to be the longest for any isopod species. Female longevity probably increased by being starvation resistant, surviving multiple broods, cannibalizing smaller B. geracei, and living in a low-stress environment. Populations appear to be stable, relatively large, and not currently threatened.

Effects of temperature on development, reproduction and size of Trichogramma achaeae: implications for biological control

The performance of biological control agents (BCAs) in outdoor crops is strongly regulated by ambient temperature. Understanding the thermal biology of BCAs and manipulating their thermal performance could improve biological control efficacy. In this study, the effects of temperature on several life history parameters (longevity, fecundity, development time, wing size) of the recently commercialised egg parasitoid Trichogramma achaeae Nagaraja & Nagarkatti (Hymenoptera: Trichogrammatidae) was examined. First, parasitoids were reared at 23 °C and tested in the laboratory at four constant temperatures (15, 20, 25 and 30 °C). Results demonstrated that temperature significantly altered all above parameters. Second, developmental acclimation was applied to manipulate the laboratory performance. Parasitoids were allowed to develop at either of the above four temperatures and their performance were compared at 23 °C. Results showed that developmental acclimation had a significant impact on fecundity, development time and wing size but not on female longevity. Our results have implications for improving the performance of T. achaeae in mass production and for its application for biological control under different thermal conditions.

Development, biology, and life table parameters of the predatory species, Clitostethus brachylobus Peng, Ren & Pang 1998 (Coleoptera: Coccinellidae), when fed on the whitefly, Bemisia tabaci (Genn.)

The predatory species, Clitostethus brachylobus Peng, Ren & Pang 1998 (Coleoptera: Coccinellidae), native to China, has been reported as a predator of the whitefly species, Bemisia tabaci (Genn.). Present study describes the development and biological characteristics of C. brachylobus. Developmental periods of different immature stages showed significant differences, when fed on different life stages of B. tabaci. Prey consumption capacity was reduced by the increase in prey age. Female longevity was 193.5 days, whereas fecundity was 154.70 eggs/female. Net reproductive rate was 53.60, whereas the mean generation time was 102.64 days. The daily adult survival rates gradually decreased 120 h post-adult emergence.

Ovariectomy uncouples lifespan from metabolic health and reveals a sex-hormone-dependent role of hepatic mTORC2 in aging

Inhibition of mTOR (mechanistic Target Of Rapamycin) signaling by rapamycin promotes healthspan and longevity more strongly in females than males, perhaps because inhibition of hepatic mTORC2 (mTOR Complex 2) specifically reduces the lifespan of males. Here, we demonstrate using gonadectomy that the sex-specific impact of reduced hepatic mTORC2 is not reversed by depletion of sex hormones. Intriguingly, we find that ovariectomy uncouples lifespan from metabolic health, with ovariectomized females having improved survival despite paradoxically having increased adiposity and decreased control of blood glucose levels. Further, ovariectomy unexpectedly promotes midlife survival of female mice lacking hepatic mTORC2, significantly increasing the survival of those mice that do not develop cancer. In addition to identifying a sex hormone-dependent role for hepatic mTORC2 in female longevity, our results demonstrate that metabolic health is not inextricably linked to lifespan in mammals, and highlight the importance of evaluating healthspan in mammalian longevity studies.

Selectivity and sublethal effect of botanical extracts on adults of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)

The objective was to assess the selectivity and sublethal effect of botanical extracts on adults of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). Plant species used: Rosmarinus officinalis L., Mikania glomerata Spreng., Varronia curassavica Jacq., Chenopodium ambrosioides L., Vermonia polyanthes Spreng., Plectranthus amboinicus Spreng., Tetradenia riparia Codd., Artemisia absinthium L., Cymbopogon citratus Stapf. Plant material were reared in laboratory and leaves collected during the morning were used to prepare the extracts as following: 100 g of leaves from each plant were macerated and immersed in 300 mL of triple-extracted methyl alcohol and evaporated on rotavapor. Then, 250 mg of crude extract was diluted in 1000 mL of water. The experimental design for selectivity was done in randomized blocks with five repetitions, following a standardized protocol of the International Organization for Biological Control (IOBC) and accordingly classified. In sublethal effect, the design was completely randomized with twenty repetitions, where the eggs exposed to parasitism were sprayed with the treatments. In both experiments the control was twofold (water and chlorpyrifos). Regarding selectivity, the botanical extracts of M. glomerata, C. ambrosioides, V. polyanthes, P. amboinicus, A. absinthium and C. citratus were classified as slightly harmful (class 2), chlorpyrifos as moderately harmful (class 3). In the evaluation of sublethal effects, the botanical extracts of C. ambrosioides and C. citratus initially presented reduced number of parasitized eggs, reduction in total parasitized eggs and female longevity. It can be concluded that C. citratus botanical extract has small selectivity and causes sublethal effects on T. pretiosum adults.

Selectivity and sublethal effect of botanical extracts on adults of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)

The objective was to assess the selectivity and sublethal effect of botanical extracts on adults of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). Plant species used: Rosmarinus officinalis L., Mikania glomerata Spreng., Varronia curassavica Jacq., Chenopodium ambrosioides L., Vermonia polyanthes Spreng., Plectranthus amboinicus Spreng., Tetradenia riparia Codd., Artemisia absinthium L., Cymbopogon citratus Stapf. Plant material were reared in laboratory and leaves collected during the morning were used to prepare the extracts as following: 100 g of leaves from each plant were macerated and immersed in 300 mL of triple-extracted methyl alcohol and evaporated on rotavapor. Then, 250 mg of crude extract was diluted in 1000 mL of water. The experimental design for selectivity was done in randomized blocks with five repetitions, following a standardized protocol of the International Organization for Biological Control (IOBC) and accordingly classified. In sublethal effect, the design was completely randomized with twenty repetitions, where the eggs exposed to parasitism were sprayed with the treatments. In both experiments the control was twofold (water and chlorpyrifos). Regarding selectivity, the botanical extracts of M. glomerata, C. ambrosioides, V. polyanthes, P. amboinicus, A. absinthium and C. citratus were classified as slightly harmful (class 2), chlorpyrifos as moderately harmful (class 3). In the evaluation of sublethal effects, the botanical extracts of C. ambrosioides and C. citratus initially presented reduced number of parasitized eggs, reduction in total parasitized eggs and female longevity. It can be concluded that C. citratus botanical extract has small selectivity and causes sublethal effects on T. pretiosum adults.