Proactive biological control of spotted lanternfly: Parasitism and host feeding behavior of Anastatus orientalis (Hymenoptera: Eupelmidae) on Lycorma delicatula (Hemiptera: Fulgoridae) egg masses

Abstract

Lycorma delicatula (Hemiptera: Fulgoridae) is a recognized threat to perennial vine, tree crops, and forest ecosystems. Native to China, L. delicatula has invaded eastern Asian countries (The Republic of Korea [i.e., South Korea] and Japan) and is spreading rapidly through the eastern and mid-western regions of the USA. Stablished populations in these regions present a significant incursion threat to California’s multi-billion-dollar perennial crops (e.g., grape and nut production). As a part of a proactive classical biological control program targeting L. delicatula in California, USA, the egg parasitoid, Anastatus orientalis (Hymenoptera: Eupelmidae), is being evaluated for possible use against this pest should it establish in California. In support of this proactive research, the oviposition and host feeding behavior of A. orientalis was investigated. The effect of time exposure (i.e., 48-, 72-, 96-, 168-hours) on the percentage of eggs parasitized by 7-day old female parasitoids previously exposed to L. delicatula egg masses in presence/absence of a conspecific male was also investigated. Parasitism rates were significantly higher after 96 h of exposure time and offspring sex ratio did not change in any of the treatments (i.e., exposure time, presence/absence of a male). In another experiment, mated and unmated female parasitoids of three different ages (i.e., ≤ 24-, 72- and 120 h of age) were digitally video recorded for 24 h while foraging on L. delicatula egg masses and host use behaviors were quantified. Anastatus orientalis females that were 72 h old (mated) and 120 h (mated and unmated) spent significantly more time antennating and probing/ovipositing in L. delicatula egg masses than younger unmated females. An increase in host feeding behavior was always associated with increased oviposition behavior. No detrimental effects of host feeding on rates of parasitism and A. orientalis offspring emergence were detected. This finding confirms that A. orientalis is a concurrent parasitoid and can use the same host egg for feeding and parasitism. Implications of these results on possible rearing and release strategies of A. orientalis as a biological control agent of L. delicatula are discussed.