DOI: 10.5061/dryad.mgqnk9996
title: Impact of irradiated Drosophila melanogaster pupae on the quality and population parameters of Trichopria drosophilae

description: Trichopria drosophilae is a globally distributed pupal parasitoid that
 targets various species within the Drosophilidae family, including the
 invasive Drosophila suzukii. The mass rearing of T. drosophilae
 is a crucial step in ensuring their successful application for field D.
 suzukii. control. The pupae of Drosophila melanogaster are currently used
 as a host for the mass rearing of T. drosophilae. The impact of utilizing
 irradiated pupae on T. drosophilae was investigated. Our results showed
 that irradiated pupae had a significant impact on the parasitism rate,
 offspring eclosion rate, offspring number, and female body size of F1 T.
 drosophilae, all of which were significantly lower than those in the
 normal group. However, there was no significant difference in parasitism
 rate, body size, offspring eclosion rate, offspring number, and offspring
 sex ratio between F2 T. drosophilae emerging from the two types of
 Drosophila pupae. Compared to F2, F1 had a significantly higher net
 reproductive rate (R₀, t49 = 19.07, P &lt; 0.01), mean generation time
 (T, t49 = 146.26, P &lt; 0.01), and doubling time (DT, Z = -6.20, P
 &lt; 0.01), while the intrinsic rate of increase (r, Z = -6.28, P
 &lt; 0.01) was significantly lower. Using irradiated D. melanogaster
 pupae provides an efficient method for the mass rearing of T. drosophilae
 and offers valuable insights into its potential effectiveness in field D.
 suzukii control.
description: <strong>Insects</strong>
 Laboratory colonies of <em>D. melanogaster</em> and
 <em>T. drosophilae </em>were collected from blueberry orchards
 in Huangtai Village, Wuhu, Anhui Province, P.R. China. All collected
 insects were reared in controlled environments within artificial climate
 chambers (25 ± 1℃, 65 ± 5% RH, 12:12 h (L/D)).<em> Drosophila
 melanogaster</em> were collected from Anhui Normal University, Anhui
 Province, China, in 2010 (31.33°<em>N</em>,<em>
 </em>118.37<em>°E</em>), reared in nylon cube cages
 (35×35×35 cm). <em>Drosophila melanogaster</em> were fed a
 240-ml plastic cup containing 80 ml of solid food (water: 1000 ml, corn
 flour: 44.67 g, sucrose: 71.33 g, agar: 16.00 g, yeast: 25.00 g, propionic
 acid: 6.30 ml, 100% ethanol: 22.30 ml).<em> </em>The plastic
 cup containing food is replaced daily, and the removed cups are kept in
 the climate chamber. Once the larvae pupate on the walls of the plastic
 cups, the cup walls are removed and provided for parasitism by
 <em>T. drosophilae</em>.<em> T. drosophilae
 </em>were reared in plastic insect rearing containers (diameter: 10
 cm, height: 8 cm) are fitted with nylon mesh on the top, which ensures
 adequate ventilation while effectively preventing the escape of the
 parasitoids. Fresh 2-day-old<em> D. melanogaster </em>pupae
 are provided to the <em>T. drosophilae</em> at a ratio of 1:20
 daily for parasitism. After 24 hours, the <em>Drosophila</em>
 pupae are removed from the rearing container and transferred to a new
 rearing container to develop until eclosion, where they serve as the
 maternal generation for the next cycle of parasitoid reproduction.
 Additionally, cotton soaked in a 10% honey-water solution is placed inside
 the container to serve as a food source for the parasitoids.
 <strong>Irradiation treatment of
 <em>Drosophila</em> pupae</strong> On
 day 0, the plastic cups with pupae not yet formed on the walls, are
 selected. On day 1 (24 hours later), <em>Drosophila </em>pupae
 of similar size are carefully selected from the cup walls and placed into
 50 μL transparent thin-walled tubes. To prevent damage to the pupae during
 collection, a small amount of sterile water is sprayed on the cup walls,
 and a soft brush is used to gently sweep the pupae into the thin-walled
 tubes. On day 2, the 2-day-old pupae of <em>D. melanogaster
 </em>are subjected to a 1200 Gy γ-irradiation treatment using the
 HFY-YC γ-irradiation device from the Crop and Nuclear Technology
 Utilization Institute, Zhejiang Academy of Agricultural Sciences, with a
 dose rate of 240 Gy/h. <strong>Utilization of
 irradiated <em>D. melanogaster</em> pupae by
 </strong><strong><em>T.
 drosophilae</em></strong> After 24 hours of
 parasitism by <em>T. drosophilae</em>, each <em>D.
 melanogaster</em> pupa is individually placed into a 50 μl
 transparent thin-walled tube. The eclosion of <em>T.
 drosophilae</em> inside the thin-walled tubes is checked daily.
 Newly eclosed <em>T. drosophilae</em> are selected, with 60
 pairs chosen. After mating, they are fed a 10% honey water until they
 reach 4 days of age because the number of mature eggs of <em>T.
 drosophilae</em> was boosted during the first four days (Wang et al.
 2016). The female<em> T. drosophilae</em>
 are placed into <em>Drosophila</em> tubes (24 mm in diameter,
 95 mm in height). The tubes are contained with cotton balls soaked in a
 10% honey-water solution to provide food. Irradiated or normal 2-day-old
 <em>D. melanogaster</em> pupae are provided as hosts, with the
 irradiated pupae designated as the irradiated group and the normal pupae
 as the normal group. After 24 hours of parasitism, the female<em> T.
 drosophilae</em> are removed, and the parasitized pupae are
 individually placed into thin-walled tubes for further processing. The
 number and sex of eclosed<em> T. drosophilae</em> in each
 group are observed and recorded daily at 10:00 AM and 8:00 PM. For
 <em>Drosophila</em> pupae that neither eclose into flies nor
 parasitoids, dissection is performed under a microscope 10 days after the
 first eclosion to determine their status (un-eclosed<em>
 Drosophila</em>, parasitized but un-eclosed parasitoids, or
 unknown). The eclosed <em>T. drosophilae</em> are recorded as
 F1. <strong>Effect of parasitism on irradiated
 <em>D. melanogaster</em> pupae on parasitoid offspring
 reproduction</strong> <em>T.
 drosophilae</em> eclosed from irradiated pupae will be continuously
 reared on normal <em>D. melanogaster</em> pupae for two
 generations, and life table experiments will be conducted. One female and
 one male <em>T. drosophilae</em>, both within 12 hours of
 eclosion, are placed into a <em>Drosophila</em> tube. The tube
 contains cotton soaked in 10% honey-water solution for feeding, as well as
 20 normal 2-day-old <em>D. melanogaster</em> pupae as hosts.
 Every 24 hours, fresh cotton with honey-water and normal
 <em>Drosophila</em> pupae are provided. After the death of the
 female <em>T. drosophilae</em>, no additional hosts are
 supplied, and only the male <em>T. drosophilae</em> is
 provided with cotton soaked in honey-water for feeding. The parasitized
 pupae removed during replacement are placed in 3 mL sample tubes and kept
 for<em> T. drosophilae</em> eclosion. The survival status of
 adult <em>T. drosophilae</em>, as well as the number and sex
 of eclosed offspring, are observed and recorded daily. Ten days after the
 first eclosion, pupae that neither eclosed into
 <em>Drosophila</em> nor parasitoids are dissected. The
 <em>T. drosophilae</em> in the sample tubes are frozen at
 -20°C for preservation. Afterward, their hind tibia length is measured
 under a microscope (VHX-5000, Osaka Japan, Keyence Corporation).
 <strong>Data analyses</strong> In
 the obtained data, groups that produced only male offspring are excluded
 from statistical analysis. Statistical comparisons are conducted to assess
 the effects of using irradiated <em>D. melanogaster</em> pupae
 on parental parasitoid parasitism rate, eclosion rate, offspring sex
 ratio. We analyzed the differences in lifespan, body size, parasitism
 rate, offspring eclosion rate, offspring sex ratio, offspring number and
 population life table parameters when F1 and F2 generation <em>T.
 drosophilae</em> parasitized irradiated and normal pupae. Eclosion
 rate is calculated as the number of eclosed parasitoids divided by the sum
 of eclosed parasitoids and parasitized but non-eclosed individuals.
 Parasitism rate is calculated as the sum of eclosed parasitoids and
 parasitized but non-eclosed individuals divided by the total number of
 pupae provided. Sex ratio, is equal to the number of male parasitoids
 divided by the total number of offspring. Based on the
 obtained data, standard life table includes four parameters: the intrinsic
 rate of natural increase (<em>r</em>), net reproductive rate
 (<em>R<sub>0</sub></em>), mean generation time
 (<em>T</em>), and doubling time (<em>DT</em>). The
 value of <em>r</em> was calculated as =1, where
  is expressed as female age in days,  is expressed
 as the age-specific survival rate, and  is the number of
 daughters produced per female alive at age ,
 <em>R<sub>0</sub>=</em>,
 <em>T</em>= ln
 <em>R<sub>0</sub></em>/<em>r</em>,
 <em>DT</em> =ln (2)/<em>r</em> (Carey 1993).
 For continuous data, we performed a Shapiro-Wilk normality test
 on longevity and body size. For normally distributed data, a
 <em>t</em>-test was used, while non-parametric tests were
 applied for skewed data. For binary data, the eclosion rate, parasitism
 rate and sex ratio were analyzed by a generalized linear model (GLM) as
 the effect using a quasibinomial error due to a large residual deviance
 value relative to the degrees of freedom. For count data, the number of
 offspring was analyzed by GLM as the effect of a quasipoisson error due to
 a large residual deviance value relative to the degrees of freedom. All
 the tests mentioned above were performed with R version 4.2.2 (R Core Team
 2013).
description: # Impact of irradiated Drosophila melanogaster pupae on the quality and
 population parameters of Trichopria drosophilae
 [https://doi.org/10.5061/dryad.mgqnk9996](https://doi.org/10.5061/dryad.mgqnk9996) #### Description of the data and file structure F1/F2 normal/irradiated tab: Group number, Longevity of female *T. drosophilae* (F0), Longevity of male *T. drosophilae* (F0), Days, *Drosophila* number, Number of female offspring, Number of male offspring, Unemerged *Drosophila*, Unemerged *T. drosophilae*, Unknown (indistinguishable emerged offspring: fruit flies or *T. drosophilae*) F1/F2 normal/irradiated life table tab: Group number, Days (duration from egg to death experienced by the *T. drosophilae*), Longevity of female *T. drosophilae* (F0), Longevity of male *T. drosophilae* (F0), Number of male offspring, Number of female offspring, Drosophila number, Number of dissection of *T. drosophilae*, Number of dead pupae, Days (duration from egg to death experienced by the *T. drosophilae*), x, Number of female (F0), Number of male (F0), Number of female offspring, Number of male offspring, Drosophila number, Number of dissection of *T. drosophilae*, Number of dead pupae, lxf, lxm, mxf, mxm, Mx, dxf, dxm, pxf, pxm, qxf, qxm, Lxf, Lxm, Txf ,Txm, exf, exm, Lxf*mxf, x*lxf*mxf, lxf*mxf, T, R0, r, EXP(-rm*x)*mxf*Lxf,  rm, T,  DT, λ Life table of F1 *T. drosophilae* in normal group Life table of F1 *T. drosophilae* in irradiated group Life table of F2 *T. drosophilae* in normal group Life table of F2 *T. drosophilae* in irradiated group The longevity, number of offspring, and eclosion of F1, F2 *T. drosophilae* in irradiated and normal group ### Files and variables **File: Data.xls; Figure 1** **Description:**  **Basic Parameters** * **x**: Age (days). * **lxf**: Survivorship of females at age *x* (%). * **lxm**: Survivorship of males at age *x* (%). * **mxf**: Age-specific fecundity of females at age *x* (individuals). * **mxm**: Age-specific fecundity of males at age *x* (individuals). * **Mx**:  age-specific mean number of offspring produced per individual at age x (individuals). **Mortality and Survival Rates** * **dxf**: Age-specific mortality of females (%). * **dxm**: Age-specific mortality of males (%). * **pxf**: Probability of female survival from age *x* to *x+1* (%). * **pxm**: Probability of male survival from age *x* to *x+1* (%). * **qxf**: Probability of female death from age *x* to *x+1* (%). * **qxm**: Probability of male death from age *x* to *x+1* (%). **Life Expectancy Calculation** * **Lxf**: Average number of surviving females at age *x* (individuals). * **Lxm**: Average number of surviving males at age *x* (individuals). * **Txf**: Total time lived by all females beyond age *x* (days). * **Txm**: Total time lived by all males beyond age *x* (days). * **exf**: Life expectancy of females at age *x* (days). * **exm**: Life expectancy of males at age *x* (days). **Reproductive Value Calculation** * **Lxf * mxf**: Reproductive value of females at age *x* (dimensionless). * **x * lxf * mxf**: Age-weighted reproductive output of females (dimensionless). * **lxf * mxf**: Age-specific reproductive contribution of females (dimensionless). **Overall Life Table Parameters** * **T**: Generation time (days). * **R0**: Net reproductive rate (dimensionless). * **r**: Intrinsic rate of increase (dimensionless). * **EXP(-rm*x) * mxf * Lxf**: Equation for calculating intrinsic rate of increase (dimensionless). * **rm**: Numerical value of intrinsic rate of increase (dimensionless). * **DT**: Doubling time of the population (days). * **λ**: Finite rate of increase (dimensionless). **Figure 1** Illustrates our experimental procedure, which will help you better understand the data in the Excel file. NOTE: Grey shading in each tab indicates empty cells.