**2. Methodology**

#### **2.1. Insecticides**

insecticides, fungicides, herbicides, rodenticides, molluscicides, nematicides, plant growth

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

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

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

regulators, defoliant, and others [2].

44 Insecticides - Agriculture and Toxicology

product useful and effective for the purpose claimed [6].

incompatibility on mixes with other agrochemicals [18].

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 lambda-cyhalothrin, 5% p/v microcapsule suspension (Karate Zeon® 050 CS; Syngenta S.A.) and 5% emulsifiable concentrate (EC) (Zero® 5 EC; Anasac Chile S.A.) formulations were compared, and finally, for imidacloprid insecticide, 20% p/p soluble liquid (SL) (Confidor® Forte 200 SL; Bayer CropScience AG), 35% p/v suspension concentrate (Confidor® 350 SC; Bayer CropScience AG), and 70% p/p wettable powder (Punto® 70 WP; Anasac Chile S.A.) were used.

(A.I.), given a total of 10 treatments and control included. Then, two treatments contained 50 g of diazinon/100 l of water; two treatments contained 8.4 g of acetamiprid/100 l; two treatments contained 1 cc of lambda-cyhalothrin/100 l; and three treatments contained 21 g of

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

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

47

All applications were performed just once on the season, on November 2, with a conventional hydraulic sprayer (Line Ecofrut 2000, Parada S.A) dosing each treatment for 2000 l of water per hectare. Between treatments were left at least 30 m free of evaluations to avoid interfer-

Four apple samples (4 kg per experimental unit) for determination of each insecticide residues were taken at 1–25 DAA from all treatments [41]. Apple samples from each replicate of each treatment were chopped into small pieces and mixed, and subsample (100 g) was used

Determination of acetamiprid and imidacloprid residues was done using P-002 Luke, method based on gas chromatography with mass detector (GC-MS) and high-performance liquid chromatography (HPLC) with triple quadrupole detector (MS/MS) [42, 43]. Determination of diazinon and l-cyhalothrin residues was done using gas chromatography (GC) with triple quadrupole detector (MS/MS) [44]. Finally, the data obtained on the initial and final deposits of different formulations of each active ingredient were subjected to ANOVA. For imidaclo-

Major knockdown effect and longer residual period to control *D. perniciosus* (**Figure 1**, **Table 1**) and *P. viburni* (**Figure 2**, **Table 2**) was achieved by using emulsion in water (EW) than wettable powder (WP). In addition, higher levels of mortality of both pests were achieved with the use of EW formulation. One work performed with diazinon against the attack of San Jose scale crawlers showed that diazinon provided 12–13 days of protection [45], which can be considered similar to results obtained on this chapter for WP formulation, but apparently it is underestimated for EW formulation. On both parameters (mean of infested fruits by scales or mealybugs and mean of living scales or mealybugs on fruits), EW seems to be effective even

On the other hand, about *C. pomonella* control (**Figure 3**), both formulations showed and optimal and similar control until 10 DAA, and then, better results—but not optimal—were obtained with EW formulation. One work conducted in 1965 proposed that for diazinon, optimal insecticide activity against *C. pomonella* would have an approximate duration of 6 days [46]; in the present work, demanding for 90% minimum of larvae mortality, both formulations deliver 10 days of control. On 14 DAA evaluations, EW formulation showed a mortality level close to 80%, which is considered insufficient from the economic point of view for the

prid, mean comparisons were performed using ANOVA and Tukey's test (*p* ≥ 0.05).

imidacloprid/100 l.

for extraction.

ence in the measurements.

**2.4. Residue estimation of insecticides**

**3. Results and discussion**

**3.1. Efficacy of diazinon formulations**

until the last evaluation carried out at 25 DAA.

#### **2.2. Efficacy evaluations**

During the spring of 2016, an apple orchard, cultivar *Royal Gala* located in the main pome fruit-growing area of Chile (34°46′45.9″S 71°02′50.0″W), was selected for this study. This orchard was naturally infested with the San Jose scale (*D. perniciosus*) and obscure mealybug (*P. viburni*). Prespraying evaluation was performed, determining that the appropriate statistical design was completely randomized with four replicates (each one with 50 plants, equivalents to 0.125 hectares).

The climatic conditions at the study period were as follows: average air temperature of 18.5°C (8.8–28.1°C) and relative humidity of 65.4% (33.2–97.6%). The first 22 days were free of precipitation, and then a total of 4 mm were recorded between days 23 and 25 post application. The phenological status at the beginning and the end of the study was 16 and 25 mm of diameter of fruits, respectively.

For *C. pomonella* evaluations, artificial infestations with neonate larvae (L1 ) were performed on laboratory over 100 uninfested fruits collected per experimental unit. Neonate larvae were obtained from previous breeding in the laboratory, with insects coming from orchards not previously treated with insecticides. The fruits were collected from the experimental units at 3, 7, 10, 14, 21, and 25 days after application (DAA); collecting them from the pedicel to avoid the excessive manipulation of the residue of insecticides or removal. One larva was used per fruit, and mortality was recorded under microscope at 24 h post each infestation. Between infestation and evaluation, the fruits were maintained in breeding chamber at light conditions: darkness 16: 8 h, with 16 ± 2°C.

For *D. perniciosus* and *P. viburni* evaluations, the number of infested fruits and the number of live scales and live mealybugs were counted under microscope on 100 fruits collected per experimental unit, reaping 2 apples randomly per tree from each repetition at 3, 7, 10, 14, 21, and 25 DAA. In all cases to score insects as dead, failure of the insect to respond when probed with a dissecting needle, shriveling, and color variation was considered.

Mortality of codling moth larvae percentage was calculated for each insecticide and corrected using the Abbott's formula [40]. The data of efficacy on San Jose scale and obscure mealybug obtained from the experiment described above separately by active ingredient were subjected to analysis of variance (ANOVA) by taking appropriate transformations. Mean comparisons in significant ANOVAs were performed with a Tukey's test (*p* ≥ 0.05). Statistical analyses were conducted using the software Minitab®16.1.0 (Minitab Inc.).

### **2.3. Treatments**

A control treatment without insecticide applications was considered. In order to represent the use of insecticides under equal conditions, a single dose was used per active ingredient (A.I.), given a total of 10 treatments and control included. Then, two treatments contained 50 g of diazinon/100 l of water; two treatments contained 8.4 g of acetamiprid/100 l; two treatments contained 1 cc of lambda-cyhalothrin/100 l; and three treatments contained 21 g of imidacloprid/100 l.

All applications were performed just once on the season, on November 2, with a conventional hydraulic sprayer (Line Ecofrut 2000, Parada S.A) dosing each treatment for 2000 l of water per hectare. Between treatments were left at least 30 m free of evaluations to avoid interference in the measurements.

#### **2.4. Residue estimation of insecticides**

lambda-cyhalothrin, 5% p/v microcapsule suspension (Karate Zeon® 050 CS; Syngenta S.A.) and 5% emulsifiable concentrate (EC) (Zero® 5 EC; Anasac Chile S.A.) formulations were compared, and finally, for imidacloprid insecticide, 20% p/p soluble liquid (SL) (Confidor® Forte 200 SL; Bayer CropScience AG), 35% p/v suspension concentrate (Confidor® 350 SC; Bayer CropScience AG), and 70% p/p wettable powder (Punto® 70 WP; Anasac Chile S.A.) were used.

During the spring of 2016, an apple orchard, cultivar *Royal Gala* located in the main pome fruit-growing area of Chile (34°46′45.9″S 71°02′50.0″W), was selected for this study. This orchard was naturally infested with the San Jose scale (*D. perniciosus*) and obscure mealybug (*P. viburni*). Prespraying evaluation was performed, determining that the appropriate statistical design was completely randomized with four replicates (each one with 50 plants, equiva-

The climatic conditions at the study period were as follows: average air temperature of 18.5°C (8.8–28.1°C) and relative humidity of 65.4% (33.2–97.6%). The first 22 days were free of precipitation, and then a total of 4 mm were recorded between days 23 and 25 post application. The phenological status at the beginning and the end of the study was 16 and 25 mm of diam-

on laboratory over 100 uninfested fruits collected per experimental unit. Neonate larvae were obtained from previous breeding in the laboratory, with insects coming from orchards not previously treated with insecticides. The fruits were collected from the experimental units at 3, 7, 10, 14, 21, and 25 days after application (DAA); collecting them from the pedicel to avoid the excessive manipulation of the residue of insecticides or removal. One larva was used per fruit, and mortality was recorded under microscope at 24 h post each infestation. Between infestation and evaluation, the fruits were maintained in breeding chamber at light condi-

For *D. perniciosus* and *P. viburni* evaluations, the number of infested fruits and the number of live scales and live mealybugs were counted under microscope on 100 fruits collected per experimental unit, reaping 2 apples randomly per tree from each repetition at 3, 7, 10, 14, 21, and 25 DAA. In all cases to score insects as dead, failure of the insect to respond when probed

Mortality of codling moth larvae percentage was calculated for each insecticide and corrected using the Abbott's formula [40]. The data of efficacy on San Jose scale and obscure mealybug obtained from the experiment described above separately by active ingredient were subjected to analysis of variance (ANOVA) by taking appropriate transformations. Mean comparisons in significant ANOVAs were performed with a Tukey's test (*p* ≥ 0.05). Statistical analyses were

A control treatment without insecticide applications was considered. In order to represent the use of insecticides under equal conditions, a single dose was used per active ingredient

) were performed

For *C. pomonella* evaluations, artificial infestations with neonate larvae (L1

with a dissecting needle, shriveling, and color variation was considered.

conducted using the software Minitab®16.1.0 (Minitab Inc.).

**2.2. Efficacy evaluations**

46 Insecticides - Agriculture and Toxicology

lents to 0.125 hectares).

eter of fruits, respectively.

tions: darkness 16: 8 h, with 16 ± 2°C.

**2.3. Treatments**

Four apple samples (4 kg per experimental unit) for determination of each insecticide residues were taken at 1–25 DAA from all treatments [41]. Apple samples from each replicate of each treatment were chopped into small pieces and mixed, and subsample (100 g) was used for extraction.

Determination of acetamiprid and imidacloprid residues was done using P-002 Luke, method based on gas chromatography with mass detector (GC-MS) and high-performance liquid chromatography (HPLC) with triple quadrupole detector (MS/MS) [42, 43]. Determination of diazinon and l-cyhalothrin residues was done using gas chromatography (GC) with triple quadrupole detector (MS/MS) [44]. Finally, the data obtained on the initial and final deposits of different formulations of each active ingredient were subjected to ANOVA. For imidacloprid, mean comparisons were performed using ANOVA and Tukey's test (*p* ≥ 0.05).
