Evaluation of pesticide reduction strategies in cropping systems. A review

The unsustainable and excessive use of pesticides in agriculture causes multi-faceted problems worldwide. Numerous strategies are proposed to reduce the intensity of pesticides; however, the knowledge regarding their performances is scattered. To move forward, it is crucial to identify efficient pesticide reduction strategies. For the first time, based on a systematic review of ten secondary literatures, we reviewed 97 primary literatures reporting 135 studies assessing pesticide reduction strategies. Sixteen types of individual strategy were identified, among which the most investigated strategies were site-specific pesticide application, physical/mechanical control, and advanced machinery. Herbicide was the most studied pesticide group regarding pesticide reduction. The most frequent method considered to assess pesticide reduction strategies was field experiment (83%), followed by lab experiment, interview, and modelling (5% each), and human health study (2%). Fifty-one indicators reflecting the impacts of pesticide reduction strategies were collected and grouped into four impact categories: economic output, pest control efficacy, pesticide related input, and side effect (non-target species, human health, and the environment). Based on generalized linear mixed-effects models, we found that pesticide reduction strategies had higher chance to reduce pesticide input and side effects than to improve economic output and pest control efficacy. Through topic modelling analysis, we were able to allocate the primary literatures to two main topics: topic 1 includes weed management in cereals, and topic 2 is about insect and disease management in fruits. Studies focusing on topic 2 and studies combining several pesticide reduction strategies had higher probabilities to report positive effects from pesticide reduction strategies than topic 1 and single strategies respectively. We also found that organic system produces more positive results than low-input system, especially regarding side effects.