Towards an attract-and-kill strategy for sustainable tick control: combined effects of Metarhizium anisopliae and phytochemical attractants from Senna didymobotrya against Amblyomma variegatum and Rhipicephalus appendiculatus

Publication Type

Journal Article

Journal Name

Experimental Applied Acarology

Publication Date

3-7-2026

Abstract

Amblyomma variegatum and Rhipicephalus appendiculatus are ticks of veterinary and zoonotic importance in sub-Saharan Africa. Presently, their control mainly relies on synthetic acaricides, which are limited by resistance and environmental harm. Sustainable alternatives, such as combining tick attractants with entomopathogenic fungi in attract-and-kill strategies, are therefore needed. This study aimed to determine (i) the effect of attractants from Senna didymobotrya (methanol extract of S. didymobotrya flowers, squalene, linoleic acid, and squalene: linoleic acid (1:1) blend) on Metarhizium anisopliae ICIPE 7 germination and virulence; (ii) adhesion and horizontal transmission of ICIPE 7 among ticks; and (iii) tick behavioural responses to the most compatible attractant. Throughout the study, methanol extract and squalene maintained the highest overall mean germination (> 90%), while the blend and linoleic acid slightly reduced it (> 80%). The 10% squalene: linoleic acid (1: 1) blend formulated with ICIPE 7 was the most consistently effective treatment against both A. variegatum and R. appendiculatus. Both tick species retained more conidia at 0 h, but R. appendiculatus adhesion declined significantly over 72 h (p < 0.0001). Horizontal transmission of ICIPE 7 was confirmed, causing 100% mortality in A. variegatum recipients and lower mortality in R. appendiculatus recipients. Semi-field assays demonstrated that most ticks were attracted from 1 m, with dry ice, attraction-aggregation-attachment pheromone, and both undiluted and diluted (1 mg/mL) squalene: linoleic acid (1: 1) blends showing similar efficacy. These results support the potential use of M. anisopliae ICIPE 7 combined with squalene: linoleic acid blend in attract-and-kill devices for sustainable tick management.

Keywords

Biological control, Compatibility, Entomopathogenic fungi, Horizontal transmission, Integrated pest management, Linoleic acid, Squalene

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