Studies in the proactive biological control of Lycorma delicatula in California (US)
Lycorma delicatula (Hemiptera: Fulgoridae - EPPO A1 List) is a polyphagous pest native to China and South-East Asia. It was first detected in the United States in 2014 and has since spread through the Mid-Atlantic region via natural dispersal and human assisted spread. Although L. delicatula is not present in California, if it arrives, it will threaten the multi-billion-dollar industry of perennial crops (e.g., grape and nut production). Thus, a proactive (pre-emptive) biological control programme was initiated in California where the aim is to complete all scientific studies to assess the safety of the biological control agent (host range, host specificity and behaviour), before the pest arrives. This would enable the biological control agent to be released rapidly at an early stage of the outbreak while the pest population is low. Anastatus orientalis (Hymenoptera: Eupelmidae) is a potential biological control agent and was found parasitising L. delicatula eggs in China in 2011. The host feeding behaviour of A. orientalis was studied on L. delicatula eggs. Parasitism rates were higher after 96 h of exposure time and offspring sex ratio was unaffected by time. Older females (72 h old mated and 120 h mated and unmated) spent more time exploring and ovipositing in L. delicatula egg masses compared to younger unmated females. An increase in host feeding behaviour was always associated with increased oviposition behaviour confirming that A. orientalis can use the same host egg for feeding and parasitism. Host range testing was conducted with eggs of 34 insect species (both native and non-native to the South-Western United States). The results showed that A. orientalis is likely to be polyphagous and can parasitise and develop in host species belonging to two orders (Hemiptera and Lepidoptera) and seven families (Coreidae, Erebidae, Fulgoridae, Lasiocampidae, Pentatomidae, Saturniidae and Sphingidae). Due to the wide host range of A. orientalis, it is likely that it poses an unacceptable risk to non-target species and will not be used as a biological control of L. delicatula in California.
Sources
Gómez Marco F, Hoddle MS (2024) Proactive biological control of spotted lanternfly: Parasitism and host feeding behavior of Anastatus orientalis (Hymenoptera: Eupelmidae) on Lycorma delicatula (Hemiptera: Fulgoridae) egg masses. Biological Control 195, 105551. https://doi.org/10.1016/j.biocontrol.2024.105551
Gómez Marco F, Yanega D, Ruiz M, Hoddle MS (2023) Proactive classical biological control of Lycorma delicatula (Hemiptera: Fulgoridae) in California (U.S.): Host range testing of Anastatus orientalis (Hymenoptera: Eupelmidae). Frontier in Insect Science 3, 1134889. https://doi/org/10.3389/finsc.2023.1134889