Insecticidal Cry proteins from Bacillus thuringiensis (Bt) can be transferred from genetically engineered crops to herbivores to natural enemies. For the lady beetle Harmonia axyridis, we investigated potential uptake of Cry proteins from the gut to the body and intergenerational transfer. Third and fourth instar H. axyridis fed with pollen or spider mites from SmartStax maize contained substantial amounts of Cry1A.105, Cry1F, Cry2Ab2, Cry3Bb1, and Cry34Ab1. Cry protein concentrations in lady beetle larvae were typically one order of magnitude lower than in the food. When H. axyridis larvae were fed Bt maize pollen, median amounts of Cry protein in the non-feeding pupae were below the limit of detection except for small amounts of Cry34Ab1. No Cry protein was detected in pupae when spider mites were used as food. Cry protein concentrations decreased quickly after H. axyridis larvae were transferred from pollen or spider mites to Bt-free food. Aphids contained very low or no detectable Cry protein, and no Cry protein was found in H. axyridis larvae fed with aphids, and in pupae. When H. axyridis adults were fed with Bt maize pollen (mixed with Ephestia kuehniella eggs), the median concentrations of Cry proteins in lady beetle eggs were below the limit of detection except for Cry34Ab1 in eggs laid later in adult life. No Bt protein was detected in eggs laid by H. axyridis females fed with aphids from Bt maize. Our results confirm previous observations that Cry proteins are degraded and excreted quickly in the arthropod food web without evidence for bioaccumulation. Despite the fact that small amounts of Cry proteins were detected in some samples of the non-feeding pupal stage of H. axyridis as well as in eggs, we conclude that this route of exposure is unlikely to be significant for predators or parasitoids in a Bt maize field.

The present study aimed to analyze the chemical composition of five species of the genus Piper (P. aduncum L.; P. crassinervium Kunth.; P. malacophyllum Prels.; P. gaudichaudianum Kunth.; P. marginatum L.), and assess their toxicity to the adults of Drosophila suzukii (Diptera: Drosophilidae) and the pupal parasitoid Trichopria anastrephae Lima (Hymenoptera: Diapriidae). The major compounds were monoterpene hydrocarbons (5.3–60.9%); oxygenated monoterpenes (13.3%); sesquiterpenes hydrocarbons (8.3–45.3%), oxygenated sesquiterpenes (5.2–58.8%); and arylpropanoids (15.2–29.6%). In bioassays of ingestion and topical application, essential oils (EOs) from P. aduncum, P. gaudichaudianum, and P. marginatum killed approximately 100% of adults of D. suzukii, similarly to the insecticide based on spinetoram (75 mg L⁻¹) (96.2% of mortality). Besides, the dry residues from P. aduncum, P. gaudichaudianum, and P. marginatum provided a repellent effect on oviposition (≅ 7 eggs/fruits) and negative effects on egg viability (≅ 2 larvae/fruits) of D. suzukii on artificial fruits. Based on the estimate of the lethal concentration required to kill 90% of exposed flies, EOs from P. aduncum, P. crassinervium, P. gaudichaudianum, P. malacophyllum, and P. marginatum provided low toxicity to the parasitoid T. anastrephae in a bioassay of ingestion and topical application (mortality < 20%), similarly to the water treatment (≅ 5% of mortality). EOs of Piper species tested in this work showed to be promising plant insecticides for the management of D. suzukii.

The cotton mealybug, Phenacoccus solenopsis Tinsley (Sternorrhyncha: Pseudococcidae) is a serious pest of various cultivated plants in Pakistan. Recent reports show that the parasitoid Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae) is a good biocontrol agent of the pest. Compatibleness is important in any IPM programme, and the insecticide used must have little or no effects on the biological control agent. This study investigated the compatibility of neem treatments and a commercial insecticide, imidacloprid on A. bambawalei. Bioassays were laid out in a completely randomized design (CRD) under laboratory conditions. Results showed that the adult stage of the parasitoid was more susceptible to the commercial insecticide imidacloprid than the concealed pupal stage. Moreover, on the basis of the International Organization for Biological Control (IOBC) toxicity categories of the commercial insecticide, imidacloprid was moderately toxic throughout the study period (Ex >80%) while neem was slightly toxic after 24 h of use (Ex <80%). Results also suggest that A. bambawalei release should be delayed for at least 1 week after neem treatments. Because imidacloprid destroys A. bambawalei, it might cause resurgence of P. solenopsis; thus, farmers should avoid integrating the insecticide in the control of P. solenopsis.

The negative impact of conventional pesticides on the environment is already extensively discussed worldwide. Although the use of chemical agents for controlling agricultural pests remains as first-line strategy for pest control, novel biorational active insecticides, such as spirotetramat, have appeared in the pesticide market during recent years in Argentina. The aim of this study was to assess the toxicity of spirotetramat on two developmental stages of a Neotropical strain of Eretmocerus mundus, with the conventional insecticide cypermethrin as a positive control, and to determine spirotetramat’s side effects on parasitoid demographic parameters. Lethal effects of both insecticides on pupae and adults were evaluated by adult emergency and survival, respectively; whereas sublethal effects on both development stages were assessed by adult longevity, reproduction capacity, sex ratio, and longevity of the first progeny. Spirotetramat proved less harmful than cypermethrin at both developmental stages studied, corroborating once more the high toxicity of this pyrethroid to natural enemies. Although spirotetramat did not affect the emergence and reproductive capacity of adults surviving pupal exposure, the longevity of the first progeny was reduced as was adult survival and longevity after exposure to residues. Spirotetramat also reduced all demographic parameters in the population evaluation. This work is the first report of spirotetramat toxicity at the population level and demonstrates the need to assess the total effect of pesticides on natural enemies.

The ectoparasitoid Tamarixia triozae is a promising biological control agent of the tomato psyllid, Bactericera cockerelli, based on its high parasitism rates on different crops. The parasitism, host feeding, and transgenerational effects (in terms of sex ratio) of T. triozae females exposed to three insecticides (soybean oil, imidacloprid, and abamectin) as eggs, larvae, and pupae were evaluated when a mixture of second, third, fourth, and fifth instars of the host B. cockerelli was offered. The concentrations bioassayed of each insecticide corresponded to the minimum field-registered concentration [MiFRC] and one-half the MiFRC. No parasitism of B. cockerelli second instars was recorded when parasitoid’s females were exposed in any of the three immature stages to any of the insecticides. In contrast, in some cases, parasitism of T. triozae females treated as eggs, larvae, or pupae with soybean oil and imidacloprid was reduced in third, fourth, or fifth instar. In most cases, the host feeding was reduced in second and third instar of the host B. cockerelli when T. triozae females were treated as eggs, larvae, or pupae. Any insecticide modified the sex ratio in the F2 generation. In conclusion, both parasitism and host feeding were affected by the insecticides depending on the concentration and on the nymphal instar of the host B. cockerelli offered.