Toxic effects of cotton pest insecticides on the parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae)

Efeitos tóxicos de inseticidas contra pragas do algodão no parasitóide Palmistichus elaeisis (Hymenoptera: Eulophidae)

Abstract

The conservation of natural enemies, such as the parasitoid Palmistichus elaeisis, is essential to ensure its survival and functionality in agroecosystems. Preliminary studies evaluating the impacts of insecticides are crucial to support the inclusion of this species in future biological control programs targeting cotton pests. In this study, adult females of P. elaeisis were exposed to dry residues of the insecticides acephate, cartap, chlorfenapyr, deltamethrin, and malathion on cotton leaves at concentrations of 10, 25, 50, and 100% of the recommended field dose, with distilled water serving as the control. Mortality was assessed 24 hours after exposure. The natural mortality of the parasitoid was below 5%, and the insecticides exhibited wide variation in toxicity. Cartap caused minimal mortality (0–3.3%) and was classified as non-toxic (IOBC Class 1), indicating it was the least harmful compound. Deltamethrin caused low mortality at reduced doses (0–10%), classified as non-toxic to slightly harmful (IOBC Classes 1–2); however, it reached 100% mortality at the field dose, becoming highly toxic (Class 4). Acephate and chlorfenapyr caused high mortality (75–100%), classified as moderately to highly toxic (Classes 3–4), with relative toxicities 20 and 48.6 times higher than cartap, respectively. Malathion caused 100% mortality at all concentrations, being highly toxic (Class 4). Toxicity was strongly dose-dependent, and even at sublethal levels, acephate, chlorfenapyr, and malathion remained harmful. These results indicate that cartap is the most suitable option for integrated pest management in cotton due to its low toxicity to the parasitoid. In contrast, the other insecticides pose significant risks to its conservation.

Keywords:
endoparasitoid; integrated pest management; lepidoptera pests; toxicity

Resumo

A conservação de inimigos naturais, como o parasitoide Palmistichus elaeisis, é fundamental para garantir sua sobrevivência e funcionalidade nos agroecossistemas. Estudos preliminares que avaliem os impactos de inseticidas são essenciais para subsidiar a inclusão dessa espécie em futuros programas de controle biológico de insetos-praga do algodoeiro. Neste estudo, fêmeas adultas de P. elaeisis foram expostas a resíduos secos dos inseticidas acefato, cartap, clorfenapir, deltametrina e malationa em folhas de algodoeiro, nas concentrações de 10, 25, 50 e 100% da dose de campo, utilizando água destilada como controle. A mortalidade foi avaliada 24 horas após a exposição. A mortalidade natural do parasitoide foi inferior a 5%, e os inseticidas diferiram amplamente em toxicidade. Cartap causou mortalidade mínima (0–3,3%) e foi classificado como não tóxico (IOBC Classe 1), sendo o composto menos prejudicial. Deltametrina apresentou mortalidade baixa nas doses reduzidas (0–10%), sendo não tóxica a levemente tóxica (IOBC Classes 1–2), mas atingiu 100% de mortalidade na dose de campo, tornando-se altamente tóxica (Classe 4). Acefato e clorfenapir causaram mortalidade elevada (75–100%), classificando-se como moderadamente a altamente tóxicos (Classes 3–4), com toxicidades relativas 20 e 48,6 vezes maiores que a de cartap. Malationa causou 100% de mortalidade em todas as concentrações, sendo altamente tóxico (Classe 4). A toxicidade foi fortemente dependente da dose, e mesmo em níveis subletais, acefato, clorfenapir e malatona permaneceram prejudiciais. Os resultados indicam que cartap é a opção mais adequada para manejo integrado de pragas no algodoeiro, devido à sua baixa toxicidade ao parasitoide, enquanto os outros inseticidas representam riscos significativos à sua conservação.

Palavras-chave:
endoparasitoide; manejo integrado de pragas; lepidópteros-praga; toxicidade

1. Introduction

The diverse pest fauna, with varying feeding habits, behaviors, and ecologies, pose significant challenges for integrated pest management (IPM) in the cotton agroecosystem. Cotton plants are estimated to host 1,326 arthropod species, of which 58 can reach economically damaging levels, particularly lepidopteran pests (Matthews and Turnstall, 1994; Sahito et al., 2017). Most of the others are occasional visitors or pollinators (Allen et al., 2018; Rajendran et al., 2018).

Chemical control remains widely used in cotton, with insecticides such as the organophosphate acephate targeting aphids, beetles, lepidopterans, thrips, and other pests (Hari and Mahal, 2008; Fernandes et al., 2016). Acephate is a broad-spectrum neurotoxicant with variable toxicity to natural enemies (Bacci et al., 2009b; Preetha et al., 2009). The nereistoxin derivative cartap exhibits selective toxicity, affecting predatory wasps of Plutella xylostella (Lepidoptera: Plutellidae) (Bacci et al., 2009a) and immature stages of Chrysoperla externa (Neuroptera: Chrysopidae) (Soares and Carvalho, 2018), but with minimal effects on natural enemies of Bemisia tabaci (Hemiptera: Aleyrodidae) (Bacci et al., 2007). The pyrazole chlorfenapyr, used against lepidopterans and mites (Potin et al., 2022), is highly toxic to parasitoids and predators in cotton (Barros et al., 2018; Kim et al., 2018), while the pyrethroid deltamethrin is strongly toxic to larvae and adults of Adalia bipunctata (Coleoptera: Coccinellidae) and Chrysoperla carnea (Neuroptera: Chrysopidae) (Garzón et al., 2015).

Biological control is one of the pillars of IPM, with natural enemies contributing to the suppression of insect pests. The effectiveness of the pupal parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae) against lepidopteran pests of soybean and eucalyptus in Brazil, as well as its compatibility with insecticides used in these crops, has already been demonstrated (Aguiar et al., 2025). However, there is still no information regarding the performance of this parasitoid against lepidopteran pests of cotton, nor about its compatibility with insecticides commonly applied in cotton production, which may compromise the integration of chemical and biological control. Physiologically selective insecticides, which are more toxic to pests than to natural enemies, represent a key strategy for conserving beneficial insects (Ndakidemi et al., 2016; Pereira et al., 2023). Therefore, this study provides an essential preliminary assessment to identify potential impacts and support the inclusion of this parasitoid species in future biological control programs targeting cotton-associated insect pests.

This study aimed to evaluate the toxicity of acephate, cartap, chlorfenapyr, deltamethrin, and malathion, commonly used in cotton pest management, on the pupal parasitoid P. elaeisis.

2. Materials and Methods

2.1. Insects and plants

Adults of P. elaeisis and pupae of its host, T. molitor, were obtained from colonies of the Laboratory for the Biological Control of Insects (LCBI) at the Federal University of Viçosa (UFV) in Viçosa, Minas Gerais state, Brazil. Each pupa was exposed for 24 h to six mated females of P. elaeisis, aged 72 h (Pereira et al., 2008), with droplets of a 50% aqueous solution of honey placed on the inner wall of the tubes to provide food for the parasitoid. The tubes were sealed with hydrophilic cotton and kept in an acclimatized room at 22 ± 2ºC, 75 ± 5% RH and 12 h photophase.

Cotton leaves were collected from plants of the BRS 286 cultivar, grown at a spacing of 0.90 x 0.10 m with one plant per hole after thinning, in an experimental area of 50 m² (5 x 10 m) in the UFV Agronomy Valley.

2.2. Insecticides

Five commercial insecticides (acephate, cartap, chlorfenapyr, deltamethrin, and malathion) were evaluated (Table 1). These insecticides are frequently used in cotton pest control in the Brazilian Cerrado, but their effects on beneficial organisms, such as parasitoids, require further study.

Table 1
Insecticides/formulation, chemical class (Class), manufacture (Man.), toxicological classification (TC), and target pests, used in bioassays to evaluate toxicity to Palmistichus elaeisis (Hymenoptera: Eulophidae).

Insecticide/formulation	Class	Man.	TC	Target pests*
Acephate 750 g⋅kg–1 SP	Organophosphate	ALB	IV	1, 3, 4, 5, 6, 7, 8, 9, 14
Cartap 500 g⋅kg– SP	Nereistoxin	SCB	III	1, 6
Chlorfenapyr 240 g⋅L–1 SC	Pyrroles	Basf	III	8, 9, 12, 13, 14
Deltamethrin 25 g⋅L–1 EC	Pyrethroid	MA	I	1, 2, 9, 10, 11
Malathion 1000 g L–1 EC	Organophosphate	FMC	IV	1,2,3

• ^*
  ALB - Arysta Lifescience of Brazil, SCB - Sumitomo Chemical of Brazil, Basf - Basf SA, MA - Milenia Agrosciences, FMC - FMC Chemical of Brazil Ltda.
• Alabama argillacea⁽¹⁾, Anthonomus grandis⁽²⁾, Aphis gossypii⁽³⁾, Caliothrips brasiliensis⁽⁴⁾, Dysdercus ruficollis⁽⁵⁾, Eutinobothrus brasiliensis⁽⁶⁾, Frankliniella schultzei⁽⁷⁾, Helicoverpa armigera⁽⁸⁾, Heliothis virescens⁽⁹⁾, Horcia nobilellus⁽¹⁰⁾, Pectinophora gossypiella⁽¹¹⁾, Polyphagotarsonemus latus⁽¹²⁾, Spodoptera frugiperda⁽¹³⁾, Tetranychus urticae⁽¹⁴⁾. TC: Toxicological classification.

2.3. Lethal Concentration (LC₅₀) and mortality of Palmistichus elaeisis

The lethal concentration (LC₅₀) required to cause 50% mortality of P. elaeisis populations, as well as the effectiveness of the insecticides according to the manufacturer’s recommended dose to control target arthropod pests, were determined (Table 1). The experiment was arranged in a randomized block design, in a 5 × 4 factorial scheme (five insecticides × four doses), plus an additional control (distilled water) used for mortality correction by Abbott’s formula, and six replications.

Lethal concentration bioassays were conducted using Petri dishes (9.0 cm in diameter) covered with PVC plastic film. Cotton leaves collected from the apical part of the plants were treated on both surfaces with the insecticides and placed inside the dishes. Each leaf was trimmed to be slightly less than the diameter of the dish, ensuring continuous contact and exposure of the parasitoids to the treated surface.. Ten newly emerged adult P. elaeisis females (≤24 h old) were introduced into each Petri dish per concentration (replications) using a mouth aspirator. The parasitoids were provided with a food source of honey diluted in distilled water (50%), applied as small drops to the inner surface of the PVC cover using a syringe. The PVC film was perforated with a fine pin to facilitate gas exchange and minimize condensation resulting from leaf transpiration, following procedure described (Williams III and Price, 2004).

Cotton leaves treated with insecticides simulated parasitoid exposure in the field (Williams III and Price, 2004). A blank test was conducted on a flat surface of newspaper (50 × 50 cm), sprayed with distilled water and adhesive spreader (10 µL of Wil Fix spreader/100 mL of water) three times to calculate the concentrations of each insecticide mixture for use in the manual sprayer. This confirmed the volume of water needed to cover the marked surface.

The recommended dose per hectare for each insecticide was converted to the test area in proportion to the quantity of each insecticide (maximum dose) and the volume of 6 mL of water, using 100 mL of spraying solution. Sub-doses were applied by reducing the maximum dose by 10, 25, 50, and 100%, and a control treatment with distilled water. The soluble powder formulations of acephate and cartap, as well as the liquid formulations of chlorfenapyr, deltamethrin, malathion, and the adhesive spreader, were measured using a precision scale and a micropipette, respectively. The paper was changed after each spraying, and the cotton leaves were left to dry for 2 h in the shade (Bacci et al., 2007). After drying, a piece of cotton was wrapped around the petiole of each leaf and moistened with distilled water to delay dehydration. The Petri dishes were kept for 72 h in climatized chambers (BOD) at 25 ± 0.5ºC, relative humidity of 70 ± 5% and 12-h photophase.

Toxicity was assessed based on the mortality of P. elaeisis after 24 h of exposure to cotton leaves treated with the highest doses of the insecticides. Parasitoids touched with a pin after 5 min and without movements were considered dead.

2.4. Data analysis

The lethal concentrations (LC₅₀) and their respective 95% confidence intervals (CI₉₅) for the four insecticides were estimated using Probit mortality regression analysis (Finney, 1971), with the number of P. elaeisis adults plotted against the log₁₀-transformed doses. LC₅₀ values were considered significantly different when their CI₉₅ did not overlap. Mortality observed in the insecticide treatments was corrected for natural (control) mortality using Abbott’s formula (Abbott, 1925), considering that control, mortality below 10% was acceptable for the validity of the bioassays (OECD, 2017). The goodness of fit of the Probit model was evaluated using Pearson’s chi-square (χ²) test, and model fit was considered adequate when the χ² probability exceeded 0.05 (p > 0.05). Relative toxicity (RT₅₀) was calculated as the ratio between the highest LC₅₀ value (least toxic compound) and the lowest LC₅₀ value (most toxic compound) (Bacci et al., 2007). All mortality–concentration analyses were performed using SAS Proc PROBIT, version 9.0 (SAS Institute, 2006).

The normality of the P. elaeisis mortality data was verified using the Shapiro–Wilk test (p > 0.05), and homogeneity of variances was assessed using Bartlett’s test (p > 0.05). When the assumptions of normality and homoscedasticity were met, data were subjected to two-way ANOVA, and treatment means were compared using Tukey’s test at a 5% probability level (p ≤ 0.05) with SAS Proc GLM (SAS Institute, 2006).

3. Results

3.1. Lethal concentration (LC₅₀) and relative toxicity of insecticides (RT₅₀)

The natural mortality of P. elaeisis in the control group was below 5%, and this value was used to correct mortality in the insecticide treatments. Among the tested compounds, cartap caused the lowest corrected mortality (1%), followed by deltamethrin (2.1%). In contrast, chlorfenapyr, acephate, and malathion resulted in substantially higher mortality levels.

The estimated LC₅₀ values (Table 2) revealed apparent differences in the relative toxicity (RT₅₀) among the insecticides. Cartap was the least toxic compound and was therefore used as the reference for RT₅₀ comparisons. Chlorfenapyr and acephate were 48.6-fold and 20-fold more toxic, respectively, than cartap (Table 2). According to IOBC toxicity categories, cartap and deltamethrin fall within the “harmless” to “slightly harmful” range (≤30% effect). At the same time, chlorfenapyr and acephate are classified as “moderately harmful” to “harmful” based on their considerably lower LC₅₀ values and high RT₅₀ ratios. Malathion caused 100% mortality at all tested concentrations, preventing the estimation of its LC₅₀ and CI₉₅; thus, it is categorized as “highly harmful” (IOBC Class 4) to P. elaeisis.

Table 2
Estimative of lethal concentration to cause 50% population mortality (LC₅₀) and relative toxicity of five insecticides on Palmistichus elaeisis (Hymenoptera: Eulophidae).

Insecticide	N	Slope	LC50 (CI95)	χ2	RT50
Acephate	60	-1.98	6.7 (5.1–8.5)	25.9	20.0
Cartap	60	-2.83	134.7 (94.0–231.3)	62.9	1.0
Chlorfenapyr	60	0.49	2.8 (1.5–5.4)	24.0	48.6
Deltamethrin	60	-4.25	65.8 (56.4–79.5)	105.2	2.1
Malathion	60	-	-	-	-

• N= Total number of insects tested in six replications.
• ^a
  Probit analysis (Chi-square, α= 0.05).
• Pearson's chi-square test (χ2) to test the goodness of fit to the Probit model. RT₅₀ (relative toxicity): higher LC₅₀ value of insecticide/lower LC₅₀ value of other insecticide. CI₉₅: 95% confidence intervals. – it was not calculated due to 100% mortality with this insecticide.

3.2. Rate mortality at different subletal doses

A significant interaction was detected between insecticide treatment and concentration on the mortality of P. elaeisis (Table 3), indicating that the effect of each insecticide varied with dose. No independent main effect was observed for insecticides when concentration was not considered, reinforcing that toxicity was dose-dependent.

Table 3
Summary of the two-way analysis of variance (ANOVA) model for the effects of treatment (insecticides) and concentration of insecticides on the percentage of mortality of Palmistichus elaeisis (Hymenoptera: Eulophidae).

Source of variation	DF	Mean Square	F	P
Treatment (T)	4	59769.580	567.433	> 0.05
Concentration (C)	3	1036.667	9.842	< 0.01
T x C	12	354.028	3.361	< 0.01
Residue	100	105.333	-	-

Exposure to dry residues of chlorfenapyr and malathion resulted in consistently high mortality (91.6–100%) across all tested concentrations, placing both compounds in the IOBC “highly harmful” category. Acephate also caused high mortality (>95%) at 100%, 50%, and 25% of the recommended field dose. Only at 10% of the field dose did acephate show a reduction in mortality (75%), although it was still classified as “harmful” (IOBC Class 3).

Cartap resulted in the lowest mortality levels (0–3.3%), classifying it as IOBC “harmless” (Class 1) across all tested doses. Deltamethrin produced slightly higher mortality (0–10%) at 50%, 25%, and 10% of the recommended dose, remaining within the “harmless to slightly harmful” range (IOBC Class 1–2). However, at the full field dose, deltamethrin caused 100% mortality, approximately 30% higher than cartap (Table 4), and therefore falls into the “highly harmful” category (Class 4) under field-rate exposure.

Table 4
Mortality of Palmistichus elaeisis (Hymenoptera: Eulophidae) after 24 hours of exposure to the insecticides Acephate, Cartap, Chlorfenapyr, Deltamethrin, and Malathion at 100, 50, 25 and 10% of the field dose (FD) commonly used to control cotton pests.

Insecticide	Mortality (%)1
	100 FD	50 FD	25 FD	10 FD
Acephate	100.0± 0 aA	100.0 ± 0 aA	95.0 ± 0 aA	75.0 ± 0 bB
Cartap	3.3 ± 0 aC	1.7 ± 0 aB	0.0 ± 0 aB	0.0 ± 0 aC
Chlorfenapyr	100.0 ± 0 aA	100.0 ± 0 aA	100.0 ± 0 aA	91.7 ± 0 aA
Deltamethrin	33.3 ± 0 aB	10.0 ± 0 bB	0.0 ± 0 bB	0.0 ± 0 bC
Malathion	100.0 ± 0 aA	100.0 ± 0 aA	100.0 ± 0 aA	100.0 ± 0 aA

• ¹
  Means followed by the same lower-case letter per row or the same upper-case letter per column do not differ by the Tukey's test at 5% probability.

4. Discussion

Determining the toxicity of insecticides to natural enemies is fundamental to integrating biological and chemical control in IPM programs (Martínez et al., 2018; Torres and Bueno, 2018). The high mortality of P. elaeisis due to the insecticides used reinforces that exposure of natural enemies to non-selective chemicals can severely compromise biological control efficiency and ecological balance (Bueno et al., 2017; Ramos et al., 2018). This highlights the importance of selecting selective insecticides when combining chemical and biological control strategies, ensuring they are not applied during peak activity periods of parasitoids or predators (Desneux et al., 2007).

The lower toxicity of cartap and deltamethrin to P. elaeisis, compared with acephate, chlorfenapyr, and malathion, indicates that these compounds are less harmful to this parasitoid. This observation is consistent with the fact that LC₅₀ values of more toxic compounds are lower and require smaller doses to induce mortality (Raj et al., 2013). Cartap and deltamethrin could be integrated into IPM programs with minimal disruption to P. elaeisis populations.

The high relative toxicity of chlorfenapyr and acephate confirms that these insecticides are not selective to P. elaeisis, both under laboratory conditions (LC₅₀) and at recommended field doses. This supports reports that these insecticides target essential enzymatic systems (Alcántara-de-la Cruz et al. 2017). Chlorfenapyr, a pro-insecticide, acts as a mitochondrial oxidative phosphorylation uncoupler (Huang et al., 2023) after bioactivation by P450-dependent monooxygenases (Hunt and Treacy, 1998). Acephate, an acetylcholinesterase inhibitor, also disrupts neural transmission and causes hyperexcitation and death. The sublethal behavioral effects of acephate, such as reduced host-searching efficiency and impaired foraging (Pereira et al., 2023), highlight that non-lethal exposures also compromise biological control by reducing the effectiveness of natural enemies. These sublethal impacts are critical factors in IPM, affecting longevity, reproduction, and functional response of beneficial insects (Desneux et al., 2007; Gomes et al., 2020; Zilnik et al., 2023).

The interaction between the concentration and insecticide type on P. elaeisis mortality contrasts with the biphasic (hormetic) response reported for this parasitoid exposed to neem oil (Caldeira et al., 2022) and for Trichogramma japonicum (Hymenoptera: Trichogrammatidae) to sublethal doses of chlorantraniliprole (Wang et al., 2022). These discrepancies likely reflect differences in chemical nature, as botanical insecticides and diamides can induce stimulatory effects at low doses, unlike the neurotoxic compounds tested in this study. Understanding these differential responses is crucial for IPM programs combining selective insecticides with natural enemies, as hormetic or sublethal effects may transiently enhance biological control activity or, conversely, impair it (Caldeira et al., 2022).

The highest mortality rates associated with the organophosphates acephate and malathion are consistent with studies identifying these compounds as broad-spectrum and highly toxic to natural enemies (Yu, 2014; Hill et al., 2017). These findings are also similar to the high mortality of Oomyzus sokolowskii (Hymenoptera: Eulophidae) exposed to acephate-treated hosts (Cordero et al., 2007) and the over 90% mortality of predators and parasitoids exposed to acephate in Brassica crops (Bacci et al., 2007). Similarly, the high toxicity of malathion to Solenopsis saevissima (Hymenoptera: Formicidae) (Araújo et al., 2017) and to predatory species such as Chrysoperla externa (ORDEM: FAMILIA) and Coleomegilla quadrifasciata (Coleoptera: Coccinellidae) (Rugno et al., 2018) supports its broad non-selectivity and explains the total mortality observed for P. elaeisis. Mitigation strategies such as carefully selecting the timing of application, using reduced doses, and adopting formulations that minimize drift are recommended to reduce impacts on non-target organisms (Desneux et al., 2007).

The high toxicity of chlorfenapyr to P. elaeisis is also similar to reported for other parasitoid wasps, including Trichogramma nr. brassicae and Trichogramma chilonis (Hymenoptera: Trichogrammatidae) (Hewa-Kapuge et al., 2003; Wang et al., 2012). Chlorfenapyr is a pro-insecticide activated by oxidases and its mechanism of action depends on the same metabolic pathways for its detoxification. This dual dependence may explain its enhanced toxicity to P. elaeisis, which has been suggested to be due to the role of oxidases in the activation and metabolism of xenobiotics in parasitoids (Zhang et al., 2022; Yunta et al., 2023). Such findings reinforce the need to select insecticides favoring compounds with lower activation in non-target species.

The low toxicity of cartap corroborates findings for predatory wasps (Brachygastra lecheguana, Protonectarina sylveirae, and Polybia scutellaris (Hymenoptera: Vespidae)) and the predator Lasiochilus sp. (Hemiptera: Anthocoridae) (Bacci et al., 2009c, 2018). However, these results diverge from the high toxicity of cartap to Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae) and Diadegma semiclausum (Hymenoptera: Ichneumonidae) (Haseeb et al., 2000; Takada et al., 2001). Such interspecific differences likely arise from variations in cuticle structure and chemical composition, affecting insecticide penetration (Watson et al., 2017). Parasitoids with thinner or more lipophilic cuticles may absorb insecticides more rapidly (Bacci et al., 2009b; Balabanidou et al., 2018). Additionally, enhanced metabolic detoxification or alterations at the target site may contribute to the lower sensitivity of P. elaeisis to cartap (Bacci et al., 2018). These physiological traits should be considered when designing integrated strategies that incorporate selective insecticides and natural enemies, taking into account sublethal effects on the reproduction and foraging efficiency of natural enemies (Desneux et al., 2007; Zilnik et al., 2023).

The moderate toxicity of deltamethrin to P. elaeisis is consistent with reports that microsomal oxidases and esterases, which degrade pyrethroids, or changes in sodium channel sensitivity, explain it (Li et al., 2015). Reduced activity of Na⁺-, K⁺-ATPase and Mg²⁺-ATPase enzymes may further limit neurotoxic effects of this insecticide group (Bacci et al., 2018). These characteristics highlight the potential of pyrethroids for selective use, provided adequate application timing and methods to minimize exposure to non-target organisms. These findings underscore the need for careful selection of insecticides based on their lethal and sublethal effects, mode of action, and species-specific susceptibility, in order to integrate chemical and biological control in IPMs. Employing selective insecticides, adjusting application timing, reducing doses, and monitoring non-target effects are essential strategies to preserve natural enemy populations while maintaining effective pest suppression (Desneux et al., 2007; Gomes et al., 2020; Zilnik et al., 2023).

5. Conclusion

The low toxicity of the insecticide cartap to P. elaeisis at the commercial dose used in cotton crop suggests that it may be selective for this parasitoid. In contrast, the high toxicity of acephate, chlorfenapyr, and malathion indicates a strong potential to harm this and other natural enemies, while deltamethrin was moderately toxic. Careful management of these insecticides is essential to ensure effective pest control while minimizing adverse effects on P. elaeisis and other beneficial arthropods.

Acknowledgements

To “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)” and “Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)” for financial support.

Data Availability Statement

Data is available upon request.

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Edited by

• Editor:
  Takako Matsumura Tundisi

Publication Dates

• Publication in this collection
  27 Feb 2026
• Date of issue
  2026

History

• Received
  02 Oct 2025
• Accepted
  29 Dec 2025