Study area

The experiment was carried out at the "Los Compadres" farm of Agroconcordia S.P.R. de C.V. group, in Xalisco, Nayarit (21° 25' 36'' N and 104° 54' 20.6'' W at 1,001 masl) with the blueberry varieties Biloxi, Victoria, and Ventura. It was also carried out at the "Agrícola Frutane" ranch in Tepic, Nayarit (21° 30'04.54.54'' N and 104° 52'10.35'' W at 949 masl), with 2 ha of the Biloxi variety.

Thrips capture

Thrips sampling was carried out weekly during 2020 in the "Los compadres" and "Agrícola Frutane" farms; 30 plants per block were randomly selected for capture, one inflorescence per plant was shaken on a white plastic tray of 25 cm × 25 cm, the samples were collected in the direction of the four cardinal points and with the support of a triple "0" camel hair brush were preserved in 2 mL Eppendorf tubes with 70 % alcohol for later mounting and identification (^{Castañeda et al., 2003}).

Thrips were collected on the weeds present within the crop and the peripheries using the roundup technique. It consisted of giving 100 blows in five representative points of each farm with an entomological net of 30 cm diameter (^{Cambero et al., 2009}); the collected insects were deposited in a 2 L plastic bag. All collected specimens were transferred to the Agricultural Parasitology Laboratory CEMIC 03 at the Universidad Autónoma de Nayarit for processing and identification.

Assembly and taxonomic identification

Adult thrips were mounted with the technique suggested by ^{Johansen & Mojica (1997}), which consisted of progressive dehydration with 80, 90 and 100 % alcohol; were placed in Petri dishes for 15 min in each concentration; later, for clarification, the specimens were placed in xylene for 3 min. Finally, with the aid of a stereoscopic microscope (Motic® SMZ-143), thrips were mounted on slides and coverslips and left on a plate (IKA®, Model: C-IMAG) at 30°C for 24 h for drying.

For specimen identification, a compound microscope (Labomed®, Model: C x L), and the taxonomic keys of ^{Mound & Marullo, (1996}); ^{Soto & Retana, (2003}); ^{Hoddle & Mound, (2012}) were used. Species confirmation was performed by M.C Jesús Alexander Rodríguez Arrieta of the Centro de Investigación en Estructuras Microscópicas (CIEMIC) at the Universidad de Costa Rica.

Evaluation of biorational insecticides

The evaluation was carried out at Los Compadres farm with the Biloxi variety. Treatments were applied during the flowering stage (June-August 2020) since this coincides with the highest incidence of the pest. Treatments were applied with manual sprinklers (KAWASHIMA AK5L) of five liters, with application schedules that ranged between 7:00 and 8:00 hours. Five applications were made at 15 d intervals (Table 1). Thrips mortality was recorded 72 h after application. The response variable was the number of thrips per plant.

Experimental design and statistical analysis

A randomized complete block design was used, with six treatments and three replicates. The experimental unit (E.U.) was a 10 m plantation of the Biloxi variety, with an average of 14 plants; seven plants were quantified as a useful plot. An analysis of variance (ANOVA) was applied to the obtained data to determine differences in biological effectiveness between insecticides, as well as between applications, using the statistical package IBM SPSS Statistics^® Version 25 for Windows^®. A comparison of means was performed with Tukey's test (α ≤ 0.05).

Thrips capture

31 samples obtained at Los Compadres, Xalisco, and 16 at Agrícola Frutane, Tepic (Table 2) were analyzed. A total of 3,077 thrips were captured with both techniques; in Agrícola Frutane, the largest number of individuals collected was obtained.

Taxonomic identification

Of the total number of individuals captured, 702 (22.8 %) adult specimens were mounted in good condition, of which 343 corresponded to Xalisco municipality and 164 to Tepic municipality. Two suborders were found, Terebrantia (99.93 %) and Tubulifera (0.06 %). In Terebrantia, thrips were identified: Scolothrips sexmaculatus (Pergande), Caliothrips phaseoli (Hood), F. gardeniae (Moulton), F. bruneri (Watson), F. occidentalis (Pergande), and Scirtothrips dorsalis (Hood), the latter being the most dominant species with 321 individuals. In Tubulifera, Leptothrips sp. was identified (2) (Table 3).

In this regard, ^{Cambero et al. (2010}) and ^{Cambero et al. (2011a)}, recorded a thrips complex in the avocado crop Persea americana Mill (Lauraceae) in Nayarit, where they coincide with the species presented in this study, such as F. occidentalis, F. gardeniae, F. orizabensis, S. sexmaculatus, and specimens of the genus Leptothrips sp. sexmaculatus and specimens of the genus Leptothrips sp. On the other hand, ^{Ortiz et al. (2020}) recorded damage by thrips of the species S. dorsalis, F. occidentalis, and F. cephalica in the crop of V. corymbosum L. and raspberry Rubus idaeus L. in Michoacán state, Mexico. While ^{Zamora et al. (2020}) recorded damage by thrips of the species F. fortissima, F. bruneri, and Thrips palmi on blueberries in Michoacán, Mexico. Highlighting that the species F. orizabensis is considered a predator and is used in a biological control context, as a predator of thrips eggs, larvae, and pupae (^{Hoddle, 2003}), while, ^{Johansen & Mojica, (2006}) and, ^{Hoddle et al. (2008)}, reported the species S. sexmaculatus as a predator of Tetranychus spp. mites and thrips of the genus Scirtothrips. Both F. orizabensis and S. sexmaculatus were previously recorded for Nayarit by ^{Cambero et al. (2011b)}.

Evaluation of biorational insecticides

In the insecticides analysis, among applications only treatment 1 (Spintor^®) showed significant differences between the 4^th and 5^th applications with an increase in thrips per plant (Figure 1).

Insecticides reached a percentage of higher effectiveness ranging from 32.4 to 73.5 % with respect to the control, on the other hand, Mix Protectivee C^®, obtained higher effectiveness (73.5 %) than Spinosad, while the treatment with Mix Protectivee M^®, obtained 32.44 % effectiveness. These results are similar to those reported by ^{Lemus et al. (2017}) when registering 91 and 93 % of effectiveness in the control of thrips of the Thripidae family, in cv. Hass avocado, using botanical insecticides based on Neem and Cinnamon.

Similarly, ^{Zamora (2019}), reported for the cultivation of blueberry and blackberry 92 % biological effectiveness on Thrips sp., Frankliniella bruneri, and F. fortissima, with the products FLY-NOT^® (quilaya plant extract), Grandevo^® (Chromobacterium subtsugae), Venerate^® (Burkholderia rinojensis) and BIODie^® (Argemonine, Berberine, Ricinine, and a- Terthienyl). In five applications, there were no significant differences between treatments (Table 4), with < 12 individuals per plant.

Figure 1 Thrips mortality percentage. * Means with the same letter are statistically equal according to Tukey (p = 0.05). *AP: application.