Coacervates to wormlike micelles transition enables lower-temperature-triggered pesticide release for nocturnal pest management

Temperature-triggered coacervates to micelles transition is realized. • Coacervates possess high encapsulation capacity for hydrophobic pesticides. • Disintegrated coacervates boost pesticide release against nocturnal pests. • Assemblies exhibit excellent spreading and deposition on leave. • Calorimetry provides thermodynamic insights into aggregate transition. To enhance pesticide release efficiency at lower temperature while keeping pesticide encapsulated at higher temperature would largely improve pesticide utilization against Noctuidae pests active at night. However, such a kind of carrier has been rarely reported. Herein, a temperature-induced reversible aggregate transformation is adopted to fabricate temperature-responsive pesticide carrier by cationic surfactant N -dodecyl- N, N -2-dihydroxyethyl- N -methyl ammonium bromide (DDHAB) and 8-hydroxypyrene-1, 3, 6-trisulfonic acid trisodium salt (HPTS). At higher temperatures (> 25 °C), the HPTS/DDHAB complexes associate into coacervates with high encapsulation efficiency for hydrophobic pesticide, Emamectin Benzoate. At lower temperatures (≤ 25 °C), the coacervates transform into wormlike micelles and facilitate rapid pesticide release. Thus, the system shows an advantage of killing Noctuidae pests with high activity at nights. The median lethal concentration (LC 50 ) at 25 °C toward two kinds of pests ( Helicoverpa armigera and Spodoptera exigua ) are reduced by 42.4% and 45.9% relative to those at 35 °C. The HPTS/DDHAB solution droplets exhibit superior spreading and deposition behavior on both hydrophilic and hydrophobic leaves. Furthermore, DDHAB achieves better biocompatibility after binding with HPTS. This study establishes a method to realize intelligent temperature-response pesticide release with application potential for Noctuidae pest control. Download: Download high-res image (96KB) Download: Download full-size image