Data Beretta et al. 2024 Biological Control 188 105437. https://doi.org/10.1016/j.biocontrol.2023.105437
<p dir="ltr">Biological pest control is successful in many agricultural systems, yet various pests can still not be controlled with</p><p dir="ltr">natural enemies. Examples are invasive thrips species such as Echinothrips americanus Morgan and Thrips parvispinus</p><p dir="ltr">(Karny) in Europe. The lack of biological control of these pests in several crops has been subscribed to</p><p dir="ltr">their complex life cycle and cryptic behaviours, but their antipredator behaviours may prevent successful control</p><p dir="ltr">and have not been studied extensively. One of these behaviours is the potential of thrips to kill the eggs of</p><p dir="ltr">predatory mites, which we quantified. Furthermore, we observed the behaviour of first- and second-instar thrips</p><p dir="ltr">larvae when attacked by starved predatory mites Amblyseius swirskii Athias-Henriot. For comparison, we included</p><p dir="ltr">Frankliniella occidentalis (Pergande), which shows an array of defensive behaviours, but can be controlled successfully</p><p dir="ltr">by several species of predatory mites. Second-instar larvae and adults of F. occidentalis and T. parvispinus</p><p dir="ltr">killed predator eggs, but E. americanus did not. First- and second-instar larvae of all three species swung their</p><p dir="ltr">abdomen to defend themselves, and F. occidentalis and T. parvispinus produced anal droplets, which are also</p><p dir="ltr">involved in defence. Predators were not successful in attacking any second-instar larvae during 15-minute observations,</p><p dir="ltr">which is sufficiently long for an attack. First-instar larvae of F. occidentalis and T. parvispinus were</p><p dir="ltr">sometimes successfully attacked by the predatory mite before they could mount a defence, but first-instar</p><p dir="ltr">E. americanus always defended themselves and were almost never preyed upon. Cooling thrips larvae to suppress</p><p dir="ltr">antipredator behaviour increased predation for all species and stages, except for first instars of</p><p dir="ltr">F. occidentalis. In conclusion, the lack of successful control of E. americanus is not caused by killing predator eggs,</p><p dir="ltr">but by the efficient defensive behaviour of both larval instars. Our study furthermore suggests that T. parvispinus</p><p dir="ltr">can potentially be controlled by A. swirskii.</p>
