Managing the white grub beetle Dasylepida ishigakiensis (Coleoptera: Scarabaeidae) in sugarcane fields on Miyako Island, Japan, using sex attractant pheromone: effects of mating delay on the reproductive ability of laboratory-reared and field-collected females

Abstract

The use of pheromones to disrupt mating behaviours is perhaps the most promising method for controlling the sugarcane pest Dasylepida ishigakiensis Niijima et Kinoshita, also known as the white grub beetle. Herein, based on laboratory observations of mating, oviposition and hatching behaviours in the white grub beetle, we suggest guidelines for the timing and length of sex-pheromone release in the field. In the present study, we collected virgin female adults early in the mating season (4 February) in sugarcane fields in Okinawa, Japan and mated them in the laboratory after different time intervals with males collected at the same time. We investigated the effects of delayed mating on mating success, timing of oviposition, female longevity after mating and progeny hatchability. Mating success -defined as the proportion of mated females that produced progeny -and hatchability were not significantly affected by mating delays of less than 31 days, although further delays dramatically decreased these parameters. Female life span and the time between mating and oviposition were unaffected by mating delay. Similar results were obtained for laboratory-reared adults mated on day 45, 60 or 80 after adult emergence. Based on these findings, we propose that releasing synthetic sex pheromones between mid-January (i.e. shortly before the start of the mating season) and late March would be optimal for disrupting the mating behaviours of this beetle in the field.

Effects of Delayed Mating on the Reproductive Performance of Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae)

“…This pattern supports the hypothesis that if the female or male of an insect delays mating, the success rate of the mating will be significantly reduced. This is different from Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae) [59], but similar to results reported for several other species, including Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) [60], Coccinella septempunctata (Linnaeus) (Coleoptera: Coccinellidae) [61], Dasylepida ishigakiensis (Coleoptera: Scarabaeidae) [33], and Plutella xylostella (L.) (Lepidoptera: Plutellidae) [62,63]. This may be because as insects age, the decrease in mating success rate is caused by depletion of resources, or by the ultimate age for the eggs [64].…”

“…Reproduction rate is an important physiological consideration that affects the population growth of a species. Because mating and oviposition are the two most important behaviors related to reproduction, the age at first mating is an important factor influencing mate preference and fitness outcome in insects [31][32][33]. However, age-dependent mating success and fitness consequences can be highly variable in different species.…”

“…However, only the hatching rate of the eggs was affected when the mating age of males increased [34]. Hata et al [33] found that delayed mating significantly lowered mating success in Dasylepida ishigakiensis (Niijima et Kinoshita) (Coleoptera: Scarabaeidae), and it apparently resulted in reduced reproductive outputs. In the scarab beetle, Anomala orientalis (Waterhouse) (Coleoptera: Scarabaeidae), delaying mating for more than 6 days resulted in an approximate 35-50% decrease in fecundity [35].…”

“…This phenomenon has been shown to exist in many species [35,[40][41][42][43]. Due to the effects generated by sex pheromones, both males and females have readily identifiable targets for their selection of mates [32,33,[44][45][46][47]. As a result, most mating can be prevented by pheromone-mediated mating disruption [48][49][50][51][52].…”

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

“…In this study, delayed mating of C. japonicus reduced the number of eggs laid and increased the preoviposition time. However, in some insects, such as Eurema hecabe L. and Dasylepida ishigakiensis Niijima & Kinoshita, delaying the mating of females as opposed to that of males does not have a notable impact on the number of eggs laid 56 , 57 , and as the number of mating increases, the longevity decreases. Unmated femalesdid not able to lay eggs in an unparasitised host.…”