Insect quality control: synchronized sex, mating system, and biological rhythm

Abstract

The sterile insect technique (SIT) is a method of eradicating insects by releasing mass-reared sterilized males into fields to reduce the hatchability of eggs laid by wild females that have mated with the sterile males. SIT requires mass-production of the target insect, and maintenance of the quality of the mass-reared insects. The most important factor is successful mating between wild females and sterile males because SIT depends on their synchronized copulation. Therefore, understanding the mating systems and fertilization processes of target insects is prerequisite. Insect behavior often has circadian rhythms that are controlled by a biological clock. However, very few studies of relationships between sterile insect quality and circadian rhythm have been performed compared with the amount of research on the mating ability of target insects. The timing of male copulation attempts with receptivity of females is key to successful mating between released males and wild females. Therefore, we should focus on the mechanisms controlling the timing of mating in target insects. On the other hand, in biological control projects, precise timing of the release of natural enemies to attack pest species is required because behavior of pests and control agents are affected by their circadian rhythms. Involving both chronobiologists and applied entomologists might produce novel ideas for sterile insect quality control by synchronized sex between mass-reared and wild flies, and for biological control agent quality by matching timing in activity between predator activity and prey behavior. Control of the biological clocks in sterile insects or biological control agents is required for advanced quality control of rearing insects.

Assessment of hybrid vigor between flightless lines to restore survival and reproductive characteristics in the ladybird beetle Harmonia axyridis

“…Inbreeding depression accumulates over generations, and does so more rapidly in smaller populations (Miyatake 1998(Miyatake , 2011Frankham et al 2002). Characteristics most closely related to reproductive fitness show greater inbreeding depression than those that are peripherally related to fitness (Mousseau and Roff 1987;Falconer and Mackay 1996;Lynch and Walsh 1998).…”

Comparison of two polymorphic sites in the clock gene cryptochrome in the Taiwan strain of the melon fly, Bactrocera cucurbitae (Diptera: Tephritidae): a possible quick method to estimate the mating time of trapped invading flies

“…However, the species is still distributed in Africa, India, and Southeast Asia, including China and Taiwan (Dhillon et al 2005). Thus, we still need to pay attention to prevent a reinvasion of Okinawa Prefecture from these areas (Ishii et al 1985;Koyama et al 2004;Matsuyama andKuba 2004, 2009;Miyatake 2011). Indeed, monitoring for the melon fly using a trap and SIT as countermeasures against reinvasion of B. cucurbitae continues to be applied in Okinawa Prefecture (Matsuyama and Kuba 2009).…”

“…SIT is a method for eliminating a target pest that combines several methods, that is, mass-rearing of the target insect, sterilization, insect release, monitoring mating competitiveness with the wild type, and confirmation of its elimination (e.g., Knipling 1955;Koyama et al 2004;Miyatake 2011). Most importantly, the success of SIT depends on successful mating with the wild type (Calkins and Parker 2005;Miyatake 2011).…”

“…Most importantly, the success of SIT depends on successful mating with the wild type (Calkins and Parker 2005;Miyatake 2011). However, mating behavior is restricted to a particular time in a day in many insects (Tychsen and Fletcher 1971;Hardeland 1972), and B. cucurbitae mates only during dusk (Kuba and Koyama 1985).…”

“…Additionally, there is a marked intraspecific variation in the time of mating (Miyatake and Shimizu 1999;Matsuyama and Kuba 2009). Therefore, synchronization of the mating time between wild females and released males becomes an important factor for SIT (Matsumoto et al 2008;Miyatake 2011). To synchronize the mating time in B. cucurbitae, several approaches have been suggested, for instance, a molecular technique to control mating time after elucidating the mechanism that controls mating time (Matsumoto et al 2008) and chronobiological manipulation of released males by shifting the LD (light:dark) cycle (Matsuyama 2011).…”