Life-History Traits and Flight Capacity of Grapholita molesta (Lepidoptera: Tortricidae) Using Artificial Diets With Varying Sugar Content

Abstract

Successful application of the sterile insect technique (SIT), an environmentally friendly control technology, mainly depends on mass-rearing of high-quality and high-performance insects. For mass-rearing of insects, the development of artificial diets is a key component. For optimal insect growth and development, sugar is an essential nutrient as it provides energy for flight. To date, few studies have analyzed the effects of different sugar contents on the biological parameters, including the flight capacity of Grapholita molesta, a globally important economic pest. Artificial diets with different sucrose contents (0, 15, and 30 g) were evaluated in two consecutive generations. The insect flight mill was used to study the G. molesta flight capacity. The larval and pupal periods, adult longevity and pupal weight of the first-generation of G. molesta reared on artificial diets with different sucrose contents were significantly different. Insects of the second-generation had a shorter larval period, greater adult longevity, and heavier larvae and pupae in the treatment with 30 g of sucrose than using 15 g. Among the males, strong, medium, and weak flight capacities were recorded and the weakest one was observed in the diet without sucrose. Results showed that the proportion of insects with highest flight capacity increased with increasing sucrose content in insects of the second generation. It can be concluded that sucrose content is a key determinant in the biological traits, including flight capacity of G. molesta, and should be taken into consideration during the mass-rearing of the pest for SIT.

Floral Resources Enhance Fecundity, but Not Flight Activity, in a Specialized Aphid Predator, Hippodamia convergens (Coleoptera: Coccinellidae)

“…Maes et al (2014) showed that body size was positively correlated with greater flight distance in both Harmonia axyridis Pallas and Cryptolaemus montrouzieri Mulsant, although not in Adalia bipunctata (L.), so it is possible our observation period was not sufficiently long to resolve a body size effect. Although nectar can be an essential source of energy fueling flight in many insects, including Diptera (Dunn et al, 2020), Hymenoptera (Suarez et al, 2005), and Lepidoptera (Su et al, 2021), most of the energy obtained by nectar feeding is stored as lipids in the fat body, the "coordination center" of lipid metabolism in insects (Toprak et al, 2020), and lipids are the energy currency of sustained flight in most insects (Canavoso et al, 2003;Van der Horst et al, 2003). Our results indicate that H. convergens adults do not require access to sugar to fuel flight, but likely rely upon stored lipids, as do most other insects (Arrese and Soulages, 2010;Toprak, 2020).…”

Effects of Adult Feeding Treatments on Longevity, Fecundity, Flight Ability, and Energy Metabolism Enzymes of Grapholita molesta Moths

“…The larvae of G. molesta were collected from peach orchards in Yangling (34°15′53′ N, 108°3′42′ E), Shaanxi Province, China from April to August 2017. The collected larvae were reared on an artificial diet ( Table S1 ) [ 26 ] in glass tubes (Renyuan, Cangzhou, Hebei, China) with a cotton stopper to establish a laboratory colony [ 7 ]. Around 20 larvae were reared in each tube till pupation.…”

“…The males of G. molesta can mate multiple times with females, whereas females seldom mated more than once [ 6 ]. SIT could be an effective method to control G. molesta [ 7 ].…”

“…In a rearing facility, the insects should be fed on appropriate low-cost diets that ensure advantageous traits for the insects, such as adequate longevity and high fecundity [ 9 , 10 , 11 ]. The dominant traits of insects are significantly affected by the nutritional status of both the larval stage and the adult stage [ 7 , 12 ]. The larvae of most lepidopteran typically have extensive and large fat body tissue as they approach pupation.…”

“…The larvae of most lepidopteran typically have extensive and large fat body tissue as they approach pupation. However, the adult dipteran and hymenopteran tend to have only small amounts of fat body after emergence [ 7 , 12 ]. Water dew or sugar from nectar and oozing fruit juices is enough for the reproductive processes and normal life activities of lepidopteran adults, but the dipteran and Hymenoptera adults need to be fed some foods [ 13 ].…”