Asymmetry in Herbivore Effector Responses: Caterpillar Frass Effectors Reduce Performance of a Subsequent Herbivore.

Multiple species of phytophagous insects may co-occur on a plant and while plants can defend themselves from insect herbivory, plant responses to damage by different species and feeding guilds of insects may be asymmetric. Plants can trigger specific responses to elicitors/effectors in insect secretions altering herbivore performance. Recently, maize chitinases present in fall armyworm (FAW, Spodoptera frugiperda) frass were shown to act as effectors suppressing caterpillar-induced defenses in maize while increasing caterpillar performance. We investigated the effect of frass chitinase-mediated suppression of herbivore defenses in maize on the performance and preference of a subsequent insect herbivore from a different feeding guild, corn leaf aphid (Rhopalosiphum maidis). Aphid performance was highest on plants with FAW damage without frass chitinases compared to damaged plants with frass chitinases or undamaged plants. Plant exposure to frass chitinases post FAW damage also altered the production of herbivore-induced volatile compounds compared to damaged, buffer-treated plants. However, aphid preference to damaged, frass chitinase-treated plants was not different from damaged, buffer-treated plants or undamaged plants. This study suggests that frass effector-mediated alteration of plant defenses affects insect herbivores asymmetrically; while it enhances the performance of caterpillars, it suppresses the performance of subsequent herbivores from a different feeding guild.

Testing a hybrid risk assessment model: Predicting CSAM offender risk from digital forensic artifacts.

BACKGROUND: Recent research argues for a formalized hybrid risk assessment model that combines the current online child sex abuse risk measures with digital forensics artifacts. OBJECTIVE: We conducted a feasibility study as an initial step toward formalizing the hybrid risk assessment model by identifying high-level digital forensic artifacts that have the potential to be valid and reliable indicators of risk, with a focus on CPORT Items 5, 6, and 7. DATA: Law enforcement investigators from a High Tech Crime Unit (HTCU) randomly selected seven closed cases; selection criteria included: male offender over 18, mobile device, child sexual abuse material (CSAM) offense, and 2019-2023 index offense. Investigation details related to probable cause, final charges, conviction, and offender risk were not disclosed. Statistical information (f, %) for the following digital forensics artifacts was examined: 1) pornography collection (e.g., % of media, content type, gender ratio) and 2) evidence of networking/grooming and other problematic online activities (e.g., number of native messages vs. application messages; type of installed apps). METHOD: The analysis predicted whether the offender was a CSAM-only or dual offender and if our findings agreed with the level of risk for reoffending suggested by CPORT Items 5, 6, and 7. Results were shared with the HTCU and scored for accuracy. RESULTS: The hybrid model was accurate in 6 of 7 cases. CONCLUSION: We conclude a hybrid model is feasible, and the findings illustrate the importance of analyzing app artifacts for context. Study limitations and future research recommendations are discussed.