When Less Is More: Sex Ratios for the Mass-Rearing of Anastrepha ludens (Diptera: Tephritidae)

2019 ◽  
Author(s):  
G I González-López ◽  
E Solís-Echeverría ◽  
F Díaz-Fleischer ◽  
D Pérez-Staples
Keyword(s):  
Sex Ratio ◽  
Egg Production ◽  
Sex Ratios ◽  
Pupal Stage ◽  
Mass Rearing ◽  
Anastrepha Ludens ◽  
Adult Density ◽  
Genetic Sexing ◽  
Male Harassment ◽  
Less Is More

Abstract Anastrepha ludens (Loew) is one of the most important pests of citrus and mango crops in Mexico. A method used to control this pest is the sterile insect technique, which consists in the mass production, irradiation, and release of insects in affected areas. The production of insects begins with the establishment of colonies to produce eggs, which must be highly fertile to ensure an adequate production of larvae. However, female fecundity and fertility can be affected by adult density and sex ratio, thus an optimal sex ratio in mass-rearing cages must be used. The genetic sexing strain of A. ludens (Tapachula-7) allows the identification of the sex at the pupal stage, making it possible to establish rearing cages with different sex ratios. We determined if different sex ratios have an effect on egg production. Two sex ratios (4♀: 1♂ and 1♀: 1♂) were compared. Fecundity, fertility and survival at different ages were also determined. Higher fertility and fecundity per female were observed at a ratio of 4:1. However, females with higher fecundity had reduced survival probabilities. In conclusion, maintaining colonies with a lower proportion of males in cages ensures a greater fecundity and fertility. Further research is necessary to understand whether results can be attributed to lower male harassment in cages.

Host size-dependent sex allocation behaviour in a parasitoid: implications forCatolaccus grandis(Hymenoptera: Pteromalidae) mass rearing programmes

1998 ◽  
Vol 88 (1) ◽  
pp. 37-45 ◽  
Author(s):  
K.M. Heinz
Keyword(s):  
Biological Control ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Boll Weevil ◽  
Mass Rearing ◽  
Host Size ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Control Programmes

AbstractAn often encountered problem associated with augmentative and inundative biological control programmes is the high cost of producing sufficient numbers of natural enemies necessary to suppress pest populations within the time constraints imposed by ephemeral agroecosystems. In many arrhenotokous parasitoids, overproduction of males in mass-rearing cultures inflates costs (per female) and thus limits the economic feasibility of these biological control programmes. Within the context of existing production technologies, experiments were conducted to determine if the sex ratio ofCatolaccus grandis(Burks), an ectoparasitoid of the boll weevilAnthonomous grandisBoheman, varied as a function of boll weevil larval size. Results from natural and manipulative experiments demonstrate the following behavioural characteristics associated with C.grandissex allocation behaviour: (i) femaleC. grandisoffspring are produced on large size hosts and male offspring are produced on small hosts; (ii) whether a host is considered large or small depends upon the overall distribution of host sizes encountered by a female parasitoid; and (iii) female parasitoids exhibit a greater rate of increase in body size with host size than do male parasitoids. The observed patterns cannot be explained by sex-specific mortality of immature parasitoids developing on the different host size categories. In subsequent experiments, laboratory cultures ofC. grandisexposed daily to successively larger sizes ofA. grandislarvae produced successively greater female biased offspring sex ratios, cultures exposed daily to successively smaller sizes of host larvae produced successively greater male biased offspring sex ratios, and cultures exposed daily to equivalent host size distributions over time maintained a uniform offspring sex ratio. By increasing the average size ofA. grandislarval hosts exposed toC. grandisby 2.5 mg per day in mass rearing cultures, the percentage of male progeny can be reduced from 33% to 23% over a period of four consecutive exposure days.

Pre- and Post-Copulatory Competitiveness of the Genetic Sexing Strain Tapachula-7 of Anastrepha ludens (Diptera: Tephritidae)

2020 ◽  
Vol 113 (5) ◽  
pp. 2163-2170
Author(s):  
Yair Contreras-Navarro ◽  
Diana Pérez-Staples ◽  
Dina Orozco-Dávila ◽  
Francisco Díaz-Fleischer
Keyword(s):  
Sterile Insect Technique ◽  
Copulatory Behavior ◽  
Mass Rearing ◽  
Economic Importance ◽  
Anastrepha Ludens ◽  
Sexual Performance ◽  
Field Cage ◽  
Wild Female ◽  
Genetic Sexing ◽  
Genetic Sexing Strain

Abstract Anastrepha ludens (Loew) (Diptera: Tephritidae) is an endemic pest of Mexico, attacking several fruits of economic importance. The Sterile Insect Technique (SIT), consisting of mass-rearing, irradiation and release of adults, is used to control this pest in affected areas. Currently, a genetic sexing strain (Tapachula 7, Tap-7) consisting only of A. ludens males is being released, yet we lack information on its sexual performance at the early ages when they are released and on its post copulatory behavior in terms of sperm transfer and mating inhibition. Here, sexual competitiveness at young ages and ability to inhibit female re-mating was compared between sterile Tap-7, Standard Bisexual (SB), or wild males both in laboratory and field cage conditions. Sperm stored by females mating with wild, Tap-7, or SB strain males was also compared. Six-day-old sterile Tap-7 males had low mating rates, however, by 7 d of age 80% of males had mated. Tap-7 males were just as likely as wild males to inhibit wild female re-mating. In field cages, sterile Tap-7 males mated faster than wild and sterile males from the SB strain and had comparable mating success to wild males. Females mated to sterile Tap-7 males stored more sperm than those mated to sterile SB males. Females mated to wild males stored more sperm than females mated to any other type of male. Mass-rearing had a greater effect on decreasing sperm stored by females than irradiation. We recommend continuing the release of the GSS strain of A. ludens.

Validation of a methodology for rearingSpalangia cameroni(Hymenoptera: Pteromalidae) onCeratitis capitata(Diptera: Tephritidae)

2014 ◽  
Vol 146 (6) ◽  
pp. 676-683 ◽  
Author(s):  
J. Tormos ◽  
B. Sabater-Muñoz ◽  
J.D. Asís ◽  
F. Beitia
Keyword(s):  
Sex Ratio ◽  
Ceratitis Capitata ◽  
Biocontrol Agent ◽  
Sex Ratios ◽  
Mass Rearing ◽  
Laboratory Rearing ◽  
Pupal Parasitoid ◽  
Mass Rear ◽  
Laboratory Colony ◽  
Potential Biocontrol Agent

AbstractSpalangia cameroniPerkins (Hymenoptera: Pteromalidae) is a pupal parasitoid of the Medfly,Ceratitis capitata(Wiedmann) (Diptera: Tephritidae), one of the principal pests of Spanish agriculture.Spalangia cameroniis a potential biocontrol agent for this pest if methods can be developed to mass-rear it effectively onC. capitata. Here, we report on the use of freeze-killed pupae ofC. capitatato maintain a laboratory colony ofS. cameroni, with a view to setting up a mass-rearing protocol. Realised fecundity, adult progeny, sex ratio, and superparasitism level were the principal parameters analysed. No significant differences were found in respect of these parameters between living or freeze-killed Medfly pupae used as hosts, although sex ratios showed a bias towards females in the case of freeze-killed pupae. Freeze-killed pupae were concluded to present the best option for the laboratory-rearing ofS. cameroni, on account of ease of rearing, and avoidance of the emergence of Medfly adults.

Selection by mating competitiveness improves the performance of Anastrepha ludens males of the genetic sexing strain Tapachula-7

2016 ◽  
Vol 106 (5) ◽  
pp. 624-632 ◽  
Author(s):  
L. Quintero-Fong ◽  
J. Toledo ◽  
L. Ruiz ◽  
P. Rendón ◽  
D. Orozco-Dávila ◽  
...  
Keyword(s):  
Development Time ◽  
Mass Rearing ◽  
Quality Parameters ◽  
Anastrepha Ludens ◽  
Sexual Performance ◽  
Genetic Sexing ◽  
Mating Competitiveness ◽  
Colony Management ◽  
Management Method ◽  
Genetic Sexing Strain

AbstractThe sexual performance of Anastrepha ludens males of the Tapachula-7 genetic sexing strain, produced via selection based on mating success, was compared with that of males produced without selection in competition with wild males. Mating competition, development time, survival, mass-rearing quality parameters and pheromone production were compared. The results showed that selection based on mating competitiveness significantly improved the sexual performance of offspring. Development time, survival of larvae, pupae and adults, and weights of larvae and pupae increased with each selection cycle. Differences in the relative quantity of the pheromone compounds (Z)-3-nonenol and anastrephin were observed when comparing the parental males with the F4 and wild males. The implications of this colony management method on the sterile insect technique are discussed.

scholarly journals Building a transgenic sexing strain for genetic control of the Australian sheep blow fly Lucilia cuprina using two lethal effectors

BMC Genetics ◽  
2020 ◽  
Vol 21 (S2) ◽  
Author(s):  
Ying Yan ◽  
Maxwell J. Scott
Keyword(s):  
Genetic Control ◽  
Insect Pests ◽  
Ectopic Expression ◽  
Pupal Stage ◽  
Mass Rearing ◽  
Lucilia Cuprina ◽  
Hatching Rate ◽  
Pest Species ◽  
Genetic Sexing ◽  
Stage Of Development

Abstract Background The sterile insect technique (SIT) has been successfully used in many pest management programs worldwide. Some SIT programs release both sexes due to the lack of genetic sexing strains or efficient sex separation methods but sterile females are ineffective control agents. Transgenic sexing strains (TSS) using the tetracycline-off control system have been developed in a variety of insect pests, from which females die by either of two commonly used lethal effectors: overexpression of the transcription factor tetracycline transactivator (tTA) or ectopic expression of a proapoptotic gene, such as head involution defective (hid). The lethality from tTA overexpression is thought to be due to “transcriptional squelching”, while hid causes lethality by induction of apoptosis. This study aims to create and characterize a TSS of Lucilia cuprina, which is a major pest of sheep, by combining both lethal effectors in a single transgenic strain. Results Here a stable TSS of L. cuprina (DH6) that carries two lethal effectors was successfully generated, by crossing FL3#2 which carries a female-specific tTA overexpression cassette, with EF1#12 which carries a tTA-regulated LshidAla2 cassette. Females with one copy of the FL3#2 transgene are viable but up to 99.8% of homozygous females die at the pupal stage when raised on diet that lacks tetracycline. Additionally, the female lethality of FL3#2 was partially repressed by supplying tetracycline to the parental generation. With an additional LshidAla2 effector, the female lethality of DH6 is 100% dominant and cannot be repressed by maternal tetracycline. DH6 females die at the late-larval stage. Several fitness parameters important for mass rearing such as hatching rate, adult emergence and sex ratio were comparable to those of the wild type strain. Conclusions Compared to the parental FL3#2 strain, the DH6 strain shows stronger female lethality and lethality occurs at an earlier stage of development. The combination of two tTA-dependent lethal effectors could improve strain stability under mass rearing and could reduce the risk of resistance in the field if fertile males are released. Our approach could be easily adapted for other pest species for an efficient, safe and sustainable genetic control program.

scholarly journals Slow Larvae Mutant and Its Potential to Improve the Pupal Color-Based Genetic Sexing System in Mexican Fruit Fly, (Diptera: Tephritidae)

2019 ◽  
Vol 112 (4) ◽  
pp. 1604-1610
Author(s):  
José S Meza ◽  
Carlos Cáceres ◽  
Kostas Bourtzis
Keyword(s):  
Large Scale ◽  
Principal Component ◽  
Fruit Fly ◽  
Mass Rearing ◽  
Anastrepha Ludens ◽  
Wild Type ◽  
Mexican Fruit Fly ◽  
Genetic Sexing ◽  
Scale Population ◽  
Fly Control

Abstract For many years, an area-wide fruit fly control campaign against the Mexican fruit fly, Anastrepha ludens (Loew) has been implemented in some regions of Mexico and Texas, using the sterile insect technique (SIT) as its principal component. To improve the efficiency of the SIT, a genetic sexing strain based on black pupae mutation (bp) was developed for A. ludens, namely, ‘Tapachula-7’ (Tap-7 genetic sexing strains [GSSs]). This strain was introduced into the AW-IPM program recently and allows male-only releases for SIT applications. Here, we report the genetic and biological characterization of a new mutation, slow larvae (sl), which was introduced to the original translocation of the Tap-7 GSS resulting in two new GSS (slow-7 and Tap/slow-7). In both GSSs, the translocated wild-type males emerge from brown pupae that develop faster than females. The females are homozygous for sl mutation in the slow-7 GSS and homozygous for sl and bp mutations in the Tap/slow-7 GSS, reaching larval maturity 2 d after most of the wild-type males, allowing the separation of most males during pupariation. The potential use of the slow-7 and Tap/slow-7 GSSs in mass rearing and large-scale population suppression programs is discussed.

scholarly journals Sex-specific deaths in Norway and Sweden during the COVID-19 pandemic: Did mandates make a difference?

2021 ◽  
pp. 140349482110100
Author(s):  
Ralph Catalano
Keyword(s):  
Sex Ratio ◽  
Infection Control ◽  
Temporal Variation ◽  
Risky Behavior ◽  
Control Strategies ◽  
Sex Ratios ◽  
Female Mortality ◽  
All Cause Mortality ◽  
Societal Expectations ◽  
Male To Female

Aims: To determine whether differences between Norway’s and Sweden’s attempts to contain SARS-CoV-2 infection coincided with detectably different changes in their all-cause mortality sex ratios. Measuring temporal variation in the all-cause mortality sex ratio before and during the pandemic in populations exposed to different constraints on risky behavior would allow us to better anticipate changes in the ratio and to better understand its association with infection control strategies. Methods: I apply time Box–Jenkins modeling to 262 months of pre-pandemic mortality sex ratios to arrive at counterfactual values of 10 intra-pandemic ratios. I compare counterfactual to observed values to determine if intra-pandemic ratios differed detectably from those expected as well as whether the Norwegian and Swedish differences varied from each other. Results: The male to female mortality sex ratio in both Norway and Sweden increased during the pandemic. I, however, find no evidence that the increase differed between the two countries despite their different COVID-19 containment strategies. Conclusion: Societal expectations of who will die during the COVID-19 pandemic will likely be wrong if they assume pre-pandemic mortality sex ratios because the intra-pandemic ratios appear, at least in Norway and Sweden, detectably higher. The contribution of differences in policies to reduce risky behavior to those higher ratios appears, however, small.

scholarly journals Sex Ratios in a Warming World: Thermal Effects on Sex-Biased Survival, Sex Determination, and Sex Reversal

2021 ◽  
Vol 112 (2) ◽  
pp. 155-164
Author(s):  
Suzanne Edmands
Keyword(s):  
High Temperature ◽  
Sex Ratio ◽  
Sex Determination ◽  
Heat Tolerance ◽  
Sex Ratios ◽  
Sex Reversal ◽  
Survival Sex ◽  
Ratio Distortion ◽  
Warming World ◽  
Sex Ratio Distortion

Abstract Rising global temperatures threaten to disrupt population sex ratios, which can in turn cause mate shortages, reduce population growth and adaptive potential, and increase extinction risk, particularly when ratios are male biased. Sex ratio distortion can then have cascading effects across other species and even ecosystems. Our understanding of the problem is limited by how often studies measure temperature effects in both sexes. To address this, the current review surveyed 194 published studies of heat tolerance, finding that the majority did not even mention the sex of the individuals used, with <10% reporting results for males and females separately. Although the data are incomplete, this review assessed phylogenetic patterns of thermally induced sex ratio bias for 3 different mechanisms: sex-biased heat tolerance, temperature-dependent sex determination (TSD), and temperature-induced sex reversal. For sex-biased heat tolerance, documented examples span a large taxonomic range including arthropods, chordates, protists, and plants. Here, superior heat tolerance is more common in females than males, but the direction of tolerance appears to be phylogenetically fluid, perhaps due to the large number of contributing factors. For TSD, well-documented examples are limited to reptiles, where high temperature usually favors females, and fishes, where high temperature consistently favors males. For temperature-induced sex reversal, unambiguous cases are again limited to vertebrates, and high temperature usually favors males in fishes and amphibians, with mixed effects in reptiles. There is urgent need for further work on the full taxonomic extent of temperature-induced sex ratio distortion, including joint effects of the multiple contributing mechanisms.

scholarly journals Pupation Substrate Type and Volume Affect Pupation, Quality Parameters and Production Costs of a Reproductive Colony of Ceratitis capitata (Diptera: Tephritidae) VIENNA 8 Genetic Sexing Strain

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 337
Author(s):  
Carlos Pascacio-Villafán ◽  
Luis Quintero-Fong ◽  
Larissa Guillén ◽  
José Pedro Rivera-Ciprian ◽  
Reynaldo Aguilar ◽  
...  
Keyword(s):  
Wheat Bran ◽  
Ceratitis Capitata ◽  
Mass Rearing ◽  
Physicochemical Characteristics ◽  
Production Costs ◽  
Cellulose I ◽  
Coconut Fiber ◽  
Genetic Sexing ◽  
Recycled Paper ◽  
Genetic Sexing Strain

Adequate pupation substrates and substrate volume are critical factors in the mass-rearing of insects for Sterile Insect Technique (SIT) applications. To identify an ideal pupation substrate for a reproductive colony of Ceratitis capitata (Wiedemann) VIENNA 8 genetic sexing strain, we first examined pupation in cellulose from recycled paper (cellulose I), sawdust, fine wheat bran, vermiculite and coconut fiber using a volume of 2.5–12.5 mL of substrate for each 5 mL volume of fly larvae. We found a positive relationship between substrate volume and pupation, with cellulose I generating the highest proportions of pupation and coconut fiber the lowest. Higher proportions of female flies (white pupae) pupated in sawdust. The proportion of female fliers increased as substrate volume rose in sawdust and coconut fiber, whereas it decreased in vermiculite and cellulose. In a second experiment, we tested three types of cellulose differing in physicochemical characteristics (celluloses I, II and III), sawdust, and fine wheat bran using a substrate:larvae ratio of 1:1. The three types of cellulose produced the highest pupation levels. The highest proportions of female fliers were observed in sawdust, and cellulose types III and II. Cellulose III and sawdust at relatively low volumes were more cost-effective to produce one million pupae than other substrates, including fine wheat bran used in a mass-rearing facility in Mexico.

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