Seasonal Trap Captures Data of Stink and Leaf-Footed Bugs in a Northern Italian Ecosystem

Abstract

An essential first step to implement a control strategy against herbivorous insects is the monitoring of their populations. The efficacy of pheromone-based traps in capturing herbivorous insects can be enhanced by adding adjuvants and using slow-release dispensers to ensure long-lasting attractiveness. Here, we present datasets from a two-year field monitoring campaign of the invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), using clear sticky traps baited with its aggregation pheromone and a synergist, tested towards different dispensers and adjuvants. Bycatch data for native stink bugs (all Hemiptera: Pentatomidae) and leaf-footed bugs (Hemiptera: Coreidae) are also presented. The R code provided was used to organize data and generate weekly captures or weekly density of both H. halys and non-target species. The information provided in this article may contribute to the optimization of pest control strategies in agriculture.

Dataset: Available in the Supplementary Materials.

Dataset License: CC-BY 4.0

1. Summary

In the area where it has established, the brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), poses a significant threat to agriculture [1,2,3].

The need for sustainable and effective monitoring strategies for invasive and highly migratory insects, such as H. halys, is paramount [4]. Monitoring invasive pests is challenging because little is known about their ecology and behavior in recently introduced areas. While trap designs based on visual and vibrational stimuli can be used, e.g., [5,6], pheromone-based traps are the simplest and most commonly used method [7]. However, pheromones must be used with care as they degrade rapidly in the field. Several pheromone-baited trap features must be tested when the choice of the best attractant is under investigation [8]. Some examples of characteristics to consider are pheromone lure substrate, trap type, lure longevity, and field position [9]. It is essential that dispensers continuously release a small amount of pheromone over a prolonged period [10]. The attractivity of lures can be evaluated in the field by counting the number of insects captured over the season [11], and improving the dispenser design can optimize pest trapping [12]. Nowadays, the main attractant adopted to monitor H. halys populations is its two-component aggregation pheromone, (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol and (3R,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (both hereby referred as “PHER”), used in synergy with the aggregation pheromone of Plautia stalii (Scott) (Hemiptera: Pentatomidae), methyl (2E,4E,6Z)-2,4,6-decatrienoate (“MDT”) [13,14].

In the main article by Giannuzzi et al. [11], using sticky traps, the best combination of the pheromonal component with the synergist, the dispenser type, and the inclusion of different adjuvants was evaluated through a two-year field trial (2023 and 2024) in a natural reserve in Northern Italy. Trap captures of H. halys juveniles, adults, and non-target stink bugs (Hemiptera: Pentatomidae) and leaf-footed bugs (Hemiptera: Coreidae) were recorded weekly. At the same time, the density of H. halys individuals and non-target species around the traps was assessed. In fact, the combination of the aggregation pheromone and a synergist strengthens H. halys in the area surrounding the odor source [15].

The results of the analyses are fully reported in the main research article [11], which showed that the combination of higher doses of both pheromone and synergist with a dispenser consisting of a non-biodegradable polymer (NBP) that included the adjuvant, performed better in 2023 than the blister pack (BLS) and wax tablet (WXT) dispensers. In 2024, the bio-polymer (BIP) and blister pack (BLS) dispensers that were compared did not differ from each other, but both performed significantly better than the control. The addition of adjuvants and the presence of the two pheromone components on the same dispenser (single lure) or their loading in two different dispenser portions (dual lure) did not improve the attraction. The method reported here would be useful for future experiments aiming to evaluate the efficacy of newly designed pheromone traps in monitoring insect populations. Proper monitoring means are helpful for pest control purposes. For example, by identifying the period of early infestation, it is possible to apply sustainable treatments with natural products [16,17,18]. Also, the presence of physogastric adults may be related to the presence of freshly laid eggs on plants, and this could be the perfect time for egg parasitoid release, such as T. mitsukurii [19] or T. japonicus [20,21,22]. The graphical representation of trap catches and insect abundance makes it easy to understand the data, and the methodology used in this manuscript may be useful to other researchers.

2. Data Description

The 2023 and 2024 field data from [11] and the R v4.3.2 script used for their graphical representation are deposited in the Supplementary Materials.

In the same section, the geographic coordinates of the traps are provided in the file “coordinates.csv”, and the monitored area is illustrated in the PDF file “study_area.pdf”. The four files “2023 trap captures.csv”, “2023 abundance in the surrounding vegetation.csv”, “2024 trap captures.csv”, and “2024 abundance in the surrounding vegetation.csv” are used by the file “R_script_graphs.txt”. This file contains the R code used to represent the data (e.g., Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11 and Figure 12).

2.1. Captures

The file entitled “2023 trap captures.csv” corresponds to the trap captures of adults and juveniles of H. halys and non-target species during the 2023 field trial. Specifically, the first column, “Week”, corresponds to the day of the weekly trap monitoring. The second column, “Rep”, reports the replication number of the experiment (for details on the experiment set-up, please refer to the main manuscript [11]). The third column, “position”, describes the physical position of the trap, while the fourth column, “name”, denote the acronym of the dispenser type, followed by the PHER/MDT ratio, and the abbreviation of the adjuvant, when present. The columns from five to thirteen refer to the numbers of H. halys adults, juveniles, and other insect species caught in the trap.

For 2024, the file entitled “2024 trap captures.csv” corresponds to the trap captures of adults and juveniles of H. halys and non-target species during the 2024 field trial. The columns from one to four describe the same variables as in the previously mentioned files. Specifically for the column “name”, acronyms refer to the dispenser type, the loading mode of the two pheromones PHER/MDT (together SL or separately DL), and the adjuvants, when added. Columns from five to twenty regard the numbers of H. halys female and male adults, juveniles according to instar stage, and other adult and juvenile stink bug species present in the trap. The twenty-first column stands for the type of additive, with the abbreviation IP corresponding to FI, MP to FM, MW to ML, and MWM to MLM, as described in

Table 2. Summary of the treatments evaluated in 2024 field trial. “BLS” stands for blister pack, “BIP” for bio-polymer, “SL” for single lure, “DL” for dual lure, and “CNT” for control (no lure, no dispenser). Different adjuvants were added together with PHER/MDT (10 mg/125 mg): mineral oil (“MO”), a fatty acid isopropyl ester (“FI”), a fatty acid methyl ester (“FM”), and fatty acid methyl ester with lignocellulosic flour (“ML”). When no adjuvants were added, it was referred to as “00”. The dual lure BIP with PHER without adjuvants and MDT with ML was denoted as “BIP_DL_MLM”.

Treatment	Dispenser Type	Adjuvant
CNT	Control	-
BLS_SL_00	Blister Pack	None
BLS_SL_MO	Blister Pack	Mineral Oil
BLS_SL_FI	Blister Pack	Fatty acid Isopropyl ester
BLS_SL_FM	Blister Pack	Fatty acid Methyl ester
BLS_DL_00	Blister Pack	None
BLS_DL_MO	Blister Pack	Mineral Oil
BLS_DL_FI	Blister Pack	Fatty acid Isopropyl ester
BLS_DL_FM	Blister Pack	Fatty acid Methyl ester
BIP_SL_00	Bio-Polymer	None
BIP_SL_FM	Bio-Polymer	Fatty acid Methyl ester
BIP_SL_ML	Bio-Polymer	Fatty acid Methyl ester with Lignocellulosic Flour
BIP_DL_00	Bio-Polymer	None
BIP_DL_FM	Bio-Polymer	Fatty acid Methyl ester
BIP_DL_ML	Bio-Polymer	Fatty acid Methyl ester with Lignocellulosic Flour
BIP_DL_MLM	Bio-Polymer	Fatty acid Methyl ester with Lignocellulosic Flour (MDT)

of the main article [11]. Column twenty-second is the dispenser (bp is for the BLS, and ep is for BIP; detailed description in [11]). The last column, “quantity”, is a more explicative description of the pheromone loading mode. The data from the 2024 monitoring campaign indicate that even juveniles were captured in the traps.

2.2. Abundance in the Surrounding Vegetation

The file entitled “2023 abundance in the surrounding vegetation.csv” refers to the total of H. halys and other non-target species, both adults and juveniles, in the surrounding of the traps. The first four columns describe the same variables detailed in the trap capture file (e.g., “2023 trap captures.csv”), whereas the columns five to twenty-nine contain the number of insects collected around the trap.

For 2024, the file entitled “2024 abundance in the surrounding vegetation.csv” describes the abundance of H. halys individuals and other non-target species, both adults and juveniles, in the surrounding of the traps. The first four columns and the last three correspond to the same variables as those in the “2024 trap captures.csv” file, while columns five to thirty contain the number of insects collected from the surrounding vegetation.

3. Methods

3.1. Type of Dispenser

Depending on the year, different types of dispensers and PHER/MDT combinations were used in field experiments. In 2023, three types of dispensers were tested: the blister pack (BLS), wax tablet (WXT), and non-biodegradable polymer (NBP). Each dispenser was loaded with varying amounts of PHER and MDT.

For the 2024 field trial, only two types of dispensers were utilized: the blister pack (BLS), which included some modifications from the previous year, and a newly developed bio-degradable polymer (BIP). Unlike in 2023, only one PHER/MDT ratio was evaluated, as previous results indicated that this variable did not significantly influence insect attraction.

Table 1. Summary of the treatments evaluated in 2023 field trial. “BLS” stands for blister pack, “WXT” for wax tablet, and “NBP” for non-biodegradable polymer. In addition to control (CNT, no lure, no dispenser), four different combinations of PHER/MDT were evaluated: 10/125 mg (“1”), 15/125 mg (“2”), 20/200 mg (“3”), and 20/300 mg (“4”). The NBP dispenser included a fatty acid methyl ester (FM) as adjuvant, while no adjuvants were added to the others (“00”).

Treatment	Dispenser Type	PHER/MDT	Adjuvant
CNT	Control	-	-
BLS_1_00	Blister Pack	10 mg/125 mg	None
BLS_2_00	Blister Pack	15 mg/225 mg	None
BLS_3_00	Blister Pack	20 mg/200 mg	None
BLS_4_00	Blister Pack	20 mg/300mg	None
WXT_1_00	Wax Tablet	10 mg/125 mg	None
WXT_2_00	Wax Tablet	15 mg/225 mg	None
WXT_3_00	Wax Tablet	20 mg/200 mg	None
WXT_4_00	Wax Tablet	20 mg/300 mg	None
NBP_1_FM	Non-Biodegradable Polymer	10 mg/125 mg	Fatty acid Methyl ester
NBP_2_FM	Non-Biodegradable Polymer	15 mg/225 mg	Fatty acid Methyl ester
NBP_3_FM	Non-Biodegradable Polymer	20 mg/200 mg	Fatty acid Methyl ester
NBP_4_FM	Non-Biodegradable Polymer	20 mg/300 mg	Fatty acid Methyl ester

and Table 2 provide a detailed description of the various treatments evaluated over the two experimental years. All the dispenser and the formulation tested were provided by Russell IPM Ltd. (Deeside CH5 2NU, UK). For further details, please refer to the main article [11].

3.2. Study Site and Monitoring Data

Weekly monitoring data were collected in 2023 and 2024 in a natural area of approximately 100 hectares in Northern Italy (central coordinates 44°39′57.6″ N, 10°49′12.0″ E), using clear sticky traps (24.5 cm by 40 cm, Halys Trap, Serbios Srl, Badia Polesine, Italy). Traps were hung horizontally 1.5–2 m above the ground inside the tree canopy or shrubs. Unbaited traps were used as controls. They were placed along a walkway, 50 m apart, and checked once a week on the same weekday (Thursdays). Each treatment was repeated three times in a randomized block design. Every three weeks, the sticky panels were replaced, and the trap treatments were randomized within each block. The plant species of the area are part of the host range of H. halys [23,24] and are described in detail in the main article [11]. Stink bugs and leaf-footed bugs were identified using available keys [25,26,27]. No meteorological (e.g., temperature, rainfall) data were available for the study area. The 2023 experiment took place from August to November, for a total of 12 weeks. In 2024, the experiment ran from July to October, covering a period of 14 weeks.

Weekly monitoring involved both trap inspections and active searching in the surrounding area. The number of H. halys and other insects captured in the trap, as well as their abundance in the surrounding vegetation, were analyzed in relation to the adopted treatment type, and, where possible, the type of adjuvant and whether a single or dual lure was used. All the results of statistical analysis, including a correlation analysis between traps captures and density in the surrounding area, are detailed in the main article and in the supplementary materials available at the following link: https://www.mdpi.com/article/10.3390/insects16040341/s1 (accessed on 23 September 2025). Regarding graphical representation of insect monitoring data, the R script is provided. The following packages were used: “ggplot2” [28] and “dplyr” [29].