Safety Evaluation of Chemical Insecticides to Tetrastichus howardi (Hymenoptera: Eulophidae), a Pupal Parasitoid of Spodoptera frugiperda (Lepidoptera: Noctuidae) Using Three Exposure Routes

Abstract

Spodoptera frugiperda has become a major pest in many crops worldwide. The main control strategies are biological and chemical controls. However, pesticides have varying degrees of toxicity to parasitic wasps in the field. To integrate chemical and biological controls, we evaluated the safety of insecticides to Tetrastichus howardi, an important pupal parasitoid of S. frugiperda. This study assessed the toxicity of six major control insecticides (emamectin benzoate, chlorfenapyr, indoxacarb, chlorantraniliprole, bisultap, and lufenuron) to T. howardi based on risk quotient. The results showed that indoxacarb had the lowest risk quotient (RQ = 7.43). Then the side effects of three sublethal concentrations (LC20, LC30, LC40) of indoxacarb were tested using three methods (1. Adult exposure to pesticide residues on the glass tube; 2. Adult exposure to pesticide residues on the host; 3. Larval exposure to pesticides through host exposure). Overall, T. howardi had a lower parasitism rate and emergence rate with the higher pesticide concentrations. Furthermore, among three methods, the adult exposure to pesticide residues on the glass tube was the most efficient in inhibiting the parasitism rate, and impairing the emergence rate and the offspring female/male ratio. This study guides a more scientific and comprehensive application of pesticides and releases natural enemies in the field.

Selectivity of Insecticides to a Pupal Parasitoid, Trichospilus diatraeae (Hymenoptera: Eulophidae), of Soybean Caterpillars

“…The greater T. diatraeae female survival after 24 h of exposure confirms the safety of these insecticides for this parasitoid [ 32 ]. Botanical insecticides such as azadirachtin are considered safe for natural enemies, not causing significant mortality of the parasitoids Trichogramma nubilale Ertle & Davis, 1975 and Trichospilus pupivorus Ferrière, 1930 (Hymenoptera: Eulophidae) [ 33 , 34 ].…”

“…Even when Bt was ingested by chewing the chorion of the egg on which the insecticide was sprayed during parasitoid emergence, this did not cause mortality or reduce the survival of the parasitoid Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae) [ 8 ]. Lufenuron and teflubenzuron, from the benzoylurea group, are growth regulators in insects and do not affect the survival of adult natural enemies [ 32 ]. However, acephate is an organophosphate from a group of insecticides, generally with a broad spectrum and low selectivity, causing high mortality of parasitoids [ 35 ].…”

Residual Behavior and Dietary Risk Assessment of Chlorfenapyr and Its Metabolites in Radish

“…The irrational use of pesticides caused by the resistance of insect pests [ 7 , 8 , 9 ] leads to the increasingly serious residual contamination of chlorfenapyr [ 10 , 11 , 12 , 13 ] in vegetables and other agricultural products. This poses a potential threat to non-target organisms [ 14 , 15 ] and human health [ 16 , 17 ]. In addition, chlorfenapyr is also degraded and metabolized in plants to produce a product of toxicological significance, tralopyril.…”

Selection of insecticides, determitionof applying timing and times, and establishment of dynamic economic threshold on sweet corn for the invasive Spodoptera frugiperda in tropical Asia

“…The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an agricultural migratory pest of corn and is native to tropical and subtropical regions of America (Spark 1979;Liu et al 2022). After its rst detection in West Africa in 2016, FAW rapidly spread across the African continent (Goergen et al 2016;Cock et al 2017) and made its appearance in India in May 2018 (Ganiger et al 2018).…”