Hydrogels have been extensively used in agriculture to
improve
crop yields for their excellent properties. However, they are currently
used either as pesticide delivery platforms or water retention agents
alone; the combination of these two functions into one agricultural
hydrogel formulation has never been reported, which is crucial to
promote sustainable development in agriculture. Herein, using poly(β-cyclodextrin)
and adamantane-grafted poly(acrylic acid) (PAA–Ada) as the
host and guest, respectively, an easy operating, multi-responsive,
and safer hydrogel delivery system for insecticides is fabricated
by the host–guest interaction between cyclodextrin and adamantane,
which can load uniformly dispersed insecticides (fipronil, imidacloprid,
and thiamethoxam) up to 60%. Benefiting from the carboxyl and hydroxyl
groups on polymer chains, different temperatures (25, 35, and 45 °C)
and pH values (5.0, 6.8, and 10.0) change the intermolecular forces
within the hydrogel network and then the diffusion of the content,
finally resulting in controlled release behaviors. Besides, this platform
can rapidly release the insecticides in the presence of amyloglucosidase
due to its ring-opening effect on cyclodextrin. Moreover, this platform
exhibits high water-retaining capacity toward soil, which can increase
the maximum water absorption of nutrient soil and quartz sand by 31.6
and 13.9%, respectively, and slows down the water loss. Compared with
commercial formulation, this smart system reduces the acute toxicity
to non-target organism earthworms by 52.4% and improves the efficacy
against target organism aphids by 47.3%, showing better durability,
lower environmental toxicity, and higher efficiency. To our knowledge,
this is the first idea that simultaneously adopts the water-retaining
capacity and controlled release ability of hydrogels to improve insecticide
efficacy. In this regard, this smart hydrogel platform holds great
potentials as slow-release granules with water-holding ability for
protection against insect pests, providing an alternative platform
for the sustainable development in green agriculture.