Lethal and Sublethal Effects of Pyriproxyfen on Apis and Non-Apis Bees

Pyriproxyfen is a juvenile hormone mimic used extensively worldwide to fight pests in agriculture and horticulture. It also has numerous applications as larvicide in vector control. The molecule disrupts metamorphosis and adult emergence in the target insects. The same types of adverse effects are expected on non-target insects. In this context, the objective of this study was to evaluate the existing information on the toxicity of pyriproxyfen on the honey bee (Apis mellifera) and non-Apis bees (bumble bees, solitary bees, and stingless bees). The goal was also to identify the gaps necessary to fill. Thus, whereas the acute and sublethal toxicity of pyriproxyfen against A. mellifera is well-documented, the information is almost lacking for the non-Apis bees. The direct and indirect routes of exposure of the non-Apis bees to pyriproxyfen also need to be identified and quantified. More generally, the impacts of pyriproxyfen on the reproductive success of the different bee species have to be evaluated as well as the potential adverse effects of its metabolites.

Deployment and Fact Analysis of the In2Care® Mosquito Trap, A Novel Tool for Controlling Invasive Aedes Species

ABSTRACT During April–October 2019, the West Valley Mosquito and Vector Control District (Ontario, CA) deployed large numbers of In2Care® mosquito traps in a preliminary study to evaluate the trap's potential effectiveness at controlling invasive Aedes aegypti (L.) and Ae. albopictus (Skuse) in 6 cities of San Bernardino County, CA. The trap was used to attract ovipositing females, expose them to the juvenile hormone mimic pyriproxyfen and the entomopathogenic fungus Beauveria bassiana, and autodisseminate pyriproxyfen to other water sources prior to their death from fungal infection. The trap attracted Ae. aegypti and Culex quinquefasciatus, with the latter species predominating at much higher larval densities in the trap reservoirs. Field-collected larvae and pupae from the trap reservoirs showed complete adult emergence inhibition. Furthermore, the trap reservoirs retained high levels of residual larvicidal, pupicidal, and emergence inhibition activity after they were retrieved from the field, as indicated by laboratory bioassays against laboratory colony of Cx. quinquefasciatus. Results of this study support more detailed quantitative local evaluations on trap efficacy to measure the impact of the In2Care mosquito trap on wild invasive Aedes and Culex populations in future mosquito control efforts.

E93 expression and links to the juvenile hormone in hemipteran mealybugs with insights on female neoteny

Insect metamorphosis generates reproductive adults and is commonly accompanied by the direct or indirect development of wings. In some winged insects, the imago is altered by life history changes. For instance, in scale insects and mealybugs, reproductive females retain juvenile features and are wingless. The transcription factor E93 triggers metamorphosis and plays in concert with the juvenile hormone pathway to guarantee the successful transition from juvenile to adult. We previously provided evidence of an atypical down-regulation of the juvenile hormone pathway during female adult development in the Japanese mealybug. Here, we further investigate how E93 is involved in the production of neotenic wingless females, by identifying its isoforms, assessing their expression patterns and evaluating the effect of exogenous juvenile hormone mimic treatment on E93. This study identifies three E93 isoforms on the 5’ end based on Japanese mealybug cDNA and shows that female development occurs with the near absence of E93 transcripts, as opposed to male metamorphosis. Additionally, while male development is typically affected by exogenous juvenile hormone mimic treatments, females seem to remain insensitive to the treatment, and up-regulation of the juvenile hormone signaling is not observed. Furthermore, juvenile hormone mimic treatment on female nymphs did not have obvious effect on E93 transcription, while treatment on male prepupae resulted in decreased E93 transcripts. In this study, we emphasize the importance of examining cases of atypical metamorphosis as complementary systems to provide a better understanding on the molecular mechanisms underlying insect metamorphosis. For instance, the factors regulating the expression of E93 are largely unclear. Investigating the regulatory mechanism of E93 transcription could provide clues towards identifying the factors that induce or suppress E93 transcription, in turn triggering male adult development or female neoteny.Graphical abstractHighlights- Neotenic female Planococcus kraunhiae (Japanese mealybug) develops with low E93 expression.- E93 expression pattern during male development is typical to other insects.- Juvenile hormone mimic treatment on male prepupae results in decreased E93 transcripts.- Juvenile hormone mimic treatment on female nymphs does not have obvious effects on E93 transcription.- Female mealybugs have low sensitivity to juvenile hormone mimic treatments compared to males and other insects.

Crystal structure of pyriproxyfen

In the title compound {systematic name: 4-phenoxyphenyl (RS)-2-[(pyridin-2-yl)oxy]propyl ether}, C20H19NO3, which is a juvenile hormone mimic and insecticide, the dihedral angles between the plane of the central benene ring and those of the pendant pyridine ring and phenyl ring are 78.09 (6) and 82.14 (8)°, respectively. The conformation of the O—C—C—O linkage isgauche[torsion angle = −75.0 (2)°]. In the crystal, weak aromatic π–π stacking interactions [centroid–centroid separation = 3.8436 (13) Å] and C—H...π interactions link adjacent molecules, forming a three-dimensional network.