Demography and mass-rearing of Carposina sasakii Matsumura (Lepidoptera: Carposinidae) reared on Golden Delicious and Red Fuji apples in the laboratory

Highlights

• The development and reproductivity of C. sasakii on two apple varieties was studied.

• C. sasakii on Golden Delicious apple has higher harvest rate and potential harm.

• Golden Delicious apple is the better economical choice for the mass-rearing system.

Abstract

Carposina sasakii Matsumura (Lepidoptera: Carposinidae), is one of the most serious fruit-boring pests in over ten species of fruit trees, and is especially damaging apples in the northern of China. The application of new planting systems, i.e., high-density and dwarfing rootstock orchard systems with mixed apple varieties, makes it important to study the fitness of C. sasakii on these apple varieties to gain fundamental knowledge for use in pest management involving this insect. In this study, life table data of C. sasakii were collected using Golden Delicious and Red Fuji apples as hosts. The egg-larva duration of male C. sasakii reared on Golden Delicious apples (22.81 d) was significantly shorter than that reared on Red Fuji apples (24.27 d). The egg-larva mortality in Golden Delicious apples (59.00%) was lower than that in Red Fuji apples (72.49%). The mortality of the pupal stage, however, was higher in Golden Delicious (10.51%) than in Red Fuji (0%). The total oviposition period (TPOP) on Golden Delicious apples (32.94 d) was significantly shorter than in individuals reared on Red Fuji apples (34.19 d). The intrinsic rate of increase (r = 0.0581 d⁻¹), net reproductive rate (R₀ = 7.57 offspring), and finite rate of increase (λ = 1.0598 d⁻¹) were all higher on Golden Delicious than those on Red Fuji. When the net reproductive rate (R₀) was used, the harvest rate of pupae was higher (0.8678) when reared on Golden Delicious apples than when reared on Red Fuji apples (0.8398). When a large cohort size (n = 200) was used for effective bootstrap sample, the P_E values for C. sasakii reared on Golden Delicious apples and Red Fuji apples were both almost equal to 1. For C. sasakii culturing purposes, Golden Delicious apples would be more productive than Red Fuji.

Introduction

The peach fruit moth, Carposina sasakii Matsumura (Lepidoptera, Carposinidae), is one of the most serious fruit-boring pests of many fruits including apple, jujube, hawthorn, peach, etc. especially in the north of China (Wu and Huang, 2014, Li et al., 2018). Among these, pome and stone fruit tree fruits are especially susceptible to this pest (Liu et al., 1997). The C. sasakii was originally distributed across most of Asia, including eastern Russia, Japan, Korea, and China (Zhang et al., 2016). Currently, C. sasakii has spread to many other areas including the United States, Uruguay, Australia, and several other countries due to rapidly expanding international agricultural trade (Pei and Yuan, 1996, Fan et al., 2010), and has been listed as a quarantine pest in the United States, Russia, Canada, Chile, and South Africa (CABI/EPPO, 1990, Liu et al., 2010, Lei et al., 2012). In China, C. sasakii is widely distributed throughout more than 27 provinces (Xue et al., 2010). The extent of damage caused by C. sasakii to fruit production is particularly serious in northern China. In the 1990s, the infectious rate of C. sasakii in Shaanxi province apple orchards peaked at 100%. The maximum number of larvae found within a single apple was as high as 19 (Hua et al., 1996). This seriously restricted the fruit production and related industries (Zhang et al., 2017). The notable occurrence of C. sasakii as a serious pest is a collective result of their long and asynchronous emergence period after diapause (Kim et al., 2000), their concealed feeding inside of fruits, and their pupation in the soil; the combination of these features led to serious difficulties in effective orchard management in northern China (Liu et al., 1997).

Changes in insect growth and development can be used as an evaluation index for the study of host preference of C. sasakii. The life table is an important tool for the statistics of insect growth and development. Thus, the age-stage, two-sex life table was constructed to study the damage rate and economic cost of C. sasakii in the two apple varieties. Of all the host plants, C. sasakii prefers to bore into apples (Li et al., 2012). With the development of mixed apple varieties and utilization of the high-density, dwarfing rootstocks system in the orchards, it is crucial to determine the survival, development and fecundity of the pest on different apple varieties (Li et al., 2012, Zhang et al., 2014). In all apple varieties, C. sasakii has a stronger preference for the Golden Delicious apple (Malus pumila Mill. ‘Golden Delecious’) and Red Fuji apple (Malus pumila Mill. ‘Red Fuji’) (Li et al., 2012, Zhang et al., 2014, Zhang et al., 2018). Golden Delicious apple is the most cultivated variety in the world and is the main apple variety in European Union member states (Li, 2013a). The price is relatively low, but the shelf-life is shorter (Lan et al., 2015). Red Fuji apple is the dominant cultivated variety across Asia, and it has longer shelf-life, but the price is higher (Wei et al., 1999). In order to study the damage rate and economic cost of C. sasakii to the two apple varieties, the age-stage, two-sex life table was constructed which can not only express the growth and development status of each individual clearly, but also predict the total cost of future large-scale breeding by calculating the cost of each egg. In addition, being able to sustainably maintain a laboratory population of C. sasakii on suitable apple varieties is not only important in studies involving biological characters of C. sasakii, but also necessary in toxicological studies, mass-rearing of biological control agents, etc. In order to fully understand the effects that different apple varieties may have on the survival, development, and reproduction of C. sasakii, the age-stage, two-sex life table was used in this study. It can describe the stage differentiation, and the variable developmental rate that occurs among individuals and both sexes. With the life table data we also constructed a method for sustainably mass-rearing C. sasakii.