Abstract
Classical biological control is a pest control tool involving the release of imported natural enemies. The Sterile Insect Technique (SIT) comprises releasing sexually sterile insects of a pest into the wild population for suppression or eradication. Both these approaches are environmentally friendly and their combination can result in a synergistic impact on pest populations and improve eradication. However, stringent regulation surrounding the introduction of biological control agents limits their use in eradication owing to the perceived risk of effects on non-target organisms. We investigated the irradiation biology of the egg parasitoid Trissolcus basalis to ascertain whether sterile parasitoids could mitigate the risk of potential sustained non-target impacts. Mated female T. basalis were gamma-irradiated at doses between 120 and 150 Gy and exposed to egg masses of their host Nezara viridula throughout their lifespans. This resulted in host mortality, despite a substantial reduction in developing parasitoid offspring, which followed a negative dose–response. There was no emergence of parasitoid offspring at 140 Gy and above. Irradiation did not affect oviposition behaviour but caused an increase in longevity. Consequently, sterile parasitoids could possibly alleviate concerns regarding the irreversibility of biological control release, which promotes further investigation of their potential role in eradication.
Highlights
Classical biological control is a pest control tool involving the release of imported natural enemies
The Sterile Insect Technique (SIT) is primarily utilised as a component of area-wide integrated pest management (IPM), which involves managing a pest population within a defined area[10], but is used in eradication programmes[9,11]
The percentage of host eggs attacked throughout the lifetime of T. basalis females, which resulted in developing T. basalis offspring, decreased with an increasing irradiation dose (F = 13.39, df = 3, P < 0.001) (Fig. 1)
Summary
Classical biological control is a pest control tool involving the release of imported natural enemies. Classical biological control (CBC) involves the introduction of natural enemies to reduce the impact of target pests[1], and is often a fundamental component of integrated pest management (IPM) programmes[2,3]. Some governments impose risk-attentive regulations to assess potential risk prior to the release of new CBC agents, which increases the expense of biological control release applications and limits their a pproval[6,7,8]. Another effective and benign approach—the Sterile Insect Technique (SIT)—involves mass-rearing and repeatedly releasing sexually sterile conspecifics into the target pest population, at a ratio higher than the wild population. The possibility of the CBC agent persisting on non-target organisms post-eradication would restrict the implementation of biological control in such a programme
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