**Role of the Formulation in the Efficacy and Dissipation of Agricultural Insecticides of Agricultural Insecticides**

**Role of the Formulation in the Efficacy and Dissipation** 

DOI: 10.5772/intechopen.72340

#### Karina Buzzetti Karina Buzzetti Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.72340

#### **Abstract**

Considering the implications the formulation may have on the effectiveness and residuality of an active ingredient, four trials were conducted comparing two commercial formulations of the diazinon insecticide, two of acetamiprid, two of lambda-cyhalothrin, and, finally, three formulations of imidacloprid. For diazinon and acetamiprid, the comparison parameters used correspond to efficacy against three key pests in apple trees: *Cydia pomonella*, *Diaspidiotus perniciosus*, and *Pseudococcus viburni*; for l-cyhalothrin, efficacy against *C. pomonella* was compared; and for imidacloprid, differences in control *P. viburni* were established. In all cases, their persistence was established in terms of initial and final residue levels in samples of fruits, at 1 and 25 days after application (DAA). Different formulations of the same insecticide correspond to a relevant factor in the general behavior that each product presents in field conditions, being able to affect parameters such as its persistence in the fruit and/or initial deposit of the active ingredient. This variation was demonstrated in the comparison performed on acetamiprid, imidacloprid, and diazinon, but it was not so in l-cyhalothrin. Efficacy was affected in all parameters evaluated for each group of insecticides, demonstrating that different formulations can deliver different biological activity in the control of various pests.

**Keywords:** pesticide formulations, efficacy, dissipation, residues, insecticide

### **1. Introduction**

The use of multiple crop protection chemicals is a common practice in fruit production, given the requirements of different markets such as the search for plant health, organoleptic quality, and higher yields. In this context, pesticides are applied to agricultural systems for the purpose of protecting plants from damage due to weeds, insects, or diseases [1]. Then, the term pesticide or agrochemical is used to define a wide range of compounds including

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© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

insecticides, fungicides, herbicides, rodenticides, molluscicides, nematicides, plant growth regulators, defoliant, and others [2].

the organophosphate insecticides diazinon [24], chlorpyrifos [25]; and with the pyrethroid insecticide lambda-cyhalothrin [26], among others. All these insecticides are commonly used

Role of the Formulation in the Efficacy and Dissipation of Agricultural Insecticides

http://dx.doi.org/10.5772/intechopen.72340

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Acetamiprid and imidacloprid are widely used to control obscure mealybug (*Pseudococcus viburni*) (Hemiptera: Pseudococcidae), San Jose scale (*Diaspidiotus perniciosus*) (Hemiptera: Diaspididae), wooly apple aphid (*Eriosoma lanigerum*) (Hemiptera: Aphididae) [27] and also, in the case of acetamiprid, is used to control codling moth (*Cydia pomonella*) (Lepidoptera: Tortricidae) on apple orchards [28, 29]. Diazinon is mainly used in the control of wooly apple aphid [30] and mealybugs [31] until the first stages of fruit development, while l-cyhalothrin is used up to the preharvest period to control codling moth [32]. The use of these pesticides is suggested based on their control objective, respecting a preharvest interval estimated to comply with the maximum residue limits. These intervals are currently estimated for the active ingredient independent of the formulation used [33], even when different works propose that formulations can affect dissipation of residues [34] and residue amount [35]. Likewise, formulation can affect efficacy of the application, generating a direct impact on the number of applications required to achieve adequate control [36, 37]. Also, formulation type might impact on the proportionality of residues, especially when changes in rate (kg active ingredient ha−1) are accomplished by changing the spray concentration, because depending on the type of formulation, increasing spray rate will also increase surfactant and other adjuvant concentrations in the spray solution which can help the crop to retain for a longer period the residue [38]. About the influence on the efficacy, for example, a comparison performed between two formulations of imidacloprid and carbofuran found an increase in the control period of aphid and leafhopper in potato, when using encapsulated formulations of those insecticides compared with commercial formulations WP and G, respectively, but not in the dissipation of its residues [39]. The aim of this chapter is to evaluate effectiveness and residuality of two commercial formulations of the diazinon insecticide; two commercial formulations of acetamiprid, two commercial formulations of active ingredient lambda-cyhalothrin, and finally, three commercial formulations of imidacloprid insecticide. For diazinon and acetamiprid formulations, the comparison parameters used correspond to the efficacy in the simultaneous control of three primary importance pests in apple trees: *C. pomonella*, *D. perniciosus*, and *P. viburni*; for l-cyhalothrin formulations, efficacy against *C. pomonella* was compared; and for imidacloprid

formulations, differences in control *P. viburni* were stablished.

Assays were conducted using commercial formulations of insecticides. Then, diazinon 50% p/v emulsion in water (EW) emulsion (Diazol® 50 EW; Adama Makhteshim Ltd.) and diazinon 40% p/p wettable powder (WP) (Diazinon® 40 WP; Anasac Chile S.A.) were compared. Also was performed the comparison between acetamiprid 70% wettable powder (Hurricane® 70 WP; Anasac Chile S.A.) and 20% soluble powder (Mospilan® 20 SP; Nippon Soda Co., Ltd.). For

**2. Methodology**

**2.1. Insecticides**

in apple orchards in Chile.

The role of pesticides in global agriculture has been questioned by United States Environmental Protection Agency (EPA), the European Community, and institutions focused on the consequences of pesticides in human health and environmental subjects [3, 4]. The continuous revaluation of registered pesticides combined with major restrictions like lesser tolerance to residues of pesticides on food has led to an overall trend of reduced risk from pesticides using, for example, innovations in the development of new formulations [5]. It is understood by new formulation a new way of presenting the pesticide for sale, which generally includes, in addition to the active ingredien(s), different adjuvant(s), and/or other formulants combined to render the product useful and effective for the purpose claimed [6].

The supply of plant protection products is wide, although it varies from country to country according to its internal regulations and requirements. However, global development makes it possible to commercially find the same active ingredient formulated in various ways, which is expected to affect the final behavior of the pesticide, with consequences on the efficacy [7]. Some of the first pesticide formulations developed in the agricultural industry (like granules, aqueous solutions, dusts, powders, and mineral oil in water emulsions) was based on simple technologies. However, since the 1980s, the pesticide industry has made great strides for the development of new formulations, focusing in particular on the search for greater chemical stability, optimization of biological activity, differentiation, and greater safety in use [8]. In addition, the search for decreasing the dose required per hectare to reduce the amounts of pesticides distributed in the environment has focused on the development of new formulations [9, 10]. The main factors that determine the design of a formulation are the solubility characteristics of the active ingredient (AI), cost of manufacture, and the intended use, so interdisciplinary sciences are required in each new formulation development [11].

The efficacy of agrochemicals as crop protection agents is generally a function of the intrinsic properties of the active ingredients, such as their toxicity, plant movement, penetration capacity, and mechanism of action [12] but also can be influenced by the formulation and the mode of application of the commercial product and the participation of surfactants and adjuvants among other parameters [13]. Formulation is a key tool because different formulations can promote stability to photochemical degradation, or decrease the amount of active ingredient necessary to achieve pest control [14]. Different works propose that a formulation can improve handling safety and can play a crucial role in the duration of delivery of the active ingredient [15, 16]. The formulation may also be a key point in avoiding phytotoxicity [17] or incompatibility on mixes with other agrochemicals [18].

The production of fruit in Chile corresponds to an industry focused on the export of fresh fruit [19], so it is subject to different phytosanitary requirements [20]. Within them, pest management is a relevant item, where the main management is carried out based on the chemical synthesis insecticides [21]. Due to the high rate of use of these products in developing countries like Chile [22], the chemical industry has found an attractive market, generating a wide range of insecticides, with several formulations of the same active ingredient. The above occurs, for example, with neonicotinoid insecticides acetamiprid and imidacloprid [23]; with the organophosphate insecticides diazinon [24], chlorpyrifos [25]; and with the pyrethroid insecticide lambda-cyhalothrin [26], among others. All these insecticides are commonly used in apple orchards in Chile.

Acetamiprid and imidacloprid are widely used to control obscure mealybug (*Pseudococcus viburni*) (Hemiptera: Pseudococcidae), San Jose scale (*Diaspidiotus perniciosus*) (Hemiptera: Diaspididae), wooly apple aphid (*Eriosoma lanigerum*) (Hemiptera: Aphididae) [27] and also, in the case of acetamiprid, is used to control codling moth (*Cydia pomonella*) (Lepidoptera: Tortricidae) on apple orchards [28, 29]. Diazinon is mainly used in the control of wooly apple aphid [30] and mealybugs [31] until the first stages of fruit development, while l-cyhalothrin is used up to the preharvest period to control codling moth [32]. The use of these pesticides is suggested based on their control objective, respecting a preharvest interval estimated to comply with the maximum residue limits. These intervals are currently estimated for the active ingredient independent of the formulation used [33], even when different works propose that formulations can affect dissipation of residues [34] and residue amount [35]. Likewise, formulation can affect efficacy of the application, generating a direct impact on the number of applications required to achieve adequate control [36, 37]. Also, formulation type might impact on the proportionality of residues, especially when changes in rate (kg active ingredient ha−1) are accomplished by changing the spray concentration, because depending on the type of formulation, increasing spray rate will also increase surfactant and other adjuvant concentrations in the spray solution which can help the crop to retain for a longer period the residue [38]. About the influence on the efficacy, for example, a comparison performed between two formulations of imidacloprid and carbofuran found an increase in the control period of aphid and leafhopper in potato, when using encapsulated formulations of those insecticides compared with commercial formulations WP and G, respectively, but not in the dissipation of its residues [39].

The aim of this chapter is to evaluate effectiveness and residuality of two commercial formulations of the diazinon insecticide; two commercial formulations of acetamiprid, two commercial formulations of active ingredient lambda-cyhalothrin, and finally, three commercial formulations of imidacloprid insecticide. For diazinon and acetamiprid formulations, the comparison parameters used correspond to the efficacy in the simultaneous control of three primary importance pests in apple trees: *C. pomonella*, *D. perniciosus*, and *P. viburni*; for l-cyhalothrin formulations, efficacy against *C. pomonella* was compared; and for imidacloprid formulations, differences in control *P. viburni* were stablished.
