Codling Moth Wing Morphology Changes Due to Insecticide Resistance

Resistance to deltamethrin in Triatoma infestans (Hemiptera: Reduviidae): does it influence the phenotype of antennae, wings, and heads?

In vector control terms, insecticide resistance is the development of the capacity, of an insect population, to tolerate doses of an insecticide that are lethal to most individuals in a typical population of the same species. The genetic changes that determine resistance may have adaptive costs in the resistant phenotype or, conversely, may result in an adaptive advantage when compared to susceptible insects in the environment without insecticides. Triatoma infestans is one of the main vectors of Trypanosoma cruzi in the southern cone of South America. High insecticide resistance in T. infestans was detected in Argentina in Salta and Chaco provinces. The objective of this study was to determine the possible morphometric changes in wings, heads, and the antennal phenotype of deltamethrin-resistant T. infestans (RR) males and females compared to susceptible insects (SS), evaluating its implication in adaptive processes such as olfactory capacity, dispersion, and probability of colonizing new habitats, among others. Nine type I landmarks were marked on wings, 5 type II landmarks on heads, and 10 antennal sensilla were counted on 106 adults of both sexes (resistant and susceptible from first and second laboratory generations). Morphological divergence was observed between the two groups (RR and SS). The RR insects showed smaller sizes of wings and heads and shape compatible with lower dispersal potential and different active dispersal behaviors. Antennae also revealed sensory simplification in RR and divergence between RR and SS, although more marked in females. This study characterizes for the first time T. infestans RR and SS through wings, heads, and antennae. The results suggest a lower dispersive potential in resistant insects and the differences described lay the foundations for the identification of a resistance biomarker in triatomines.

Organic Control Strategies for Use in IPM of Invertebrate Pests in Apple and Pear Orchards

Growers of organic tree fruit face challenges in controlling some pests more easily suppressed by broad-spectrum insecticides in conventionally managed orchards. In recent decades, there has been a move towards organically growing varieties normally reliant on synthetic chemical pesticides (e.g., Gala), often to meet retailer/consumer demands. This inevitably makes crop protection in organic orchards more challenging, as modern varieties can be less tolerant to pests. In addition, there have been substantial reductions in plant protection product (PPP) approvals, resulting in fewer chemical options available for integrated pest management (IPM)-maintained orchards. Conversely, the organic management of fruit tree pests involves many practices that could be successfully implemented in conventionally grown crops, but which are currently not. These practices could also be more widely used in IPM-maintained orchards, alleviating the reliance on broad-spectrum PPP. In this review, we evaluate organic practices, with a focus on those that could be incorporated into conventional apple and pear production. The topics cover cultural control, biological control, physical and pest modifications. While the pests discussed mainly affect European species, many of the methods could be used to target other global pests for more environmentally sustainable practices.

Exploratory Analysis of Color Forms' Variability in the Invasive Asian Lady Beetle Harmonia axyridis (Pallas 1773)

The Asian ladybird (Harmonia axyridis Pallas), native to Asia, is one of the 100 most invasive species in the world and has spread worldwide. This study aimed to characterize color forms of H. axyridis in Croatia and to analyze the variability of wing shape between populations and indicated forms. Geometric morphometric methods were used to analyze a total of 129 left and right wings in males and 126 left and right wings in females of H. axyridis collected from four different sites in Croatia. The results show a significant difference in wing shapes between the studied forms. Each form had its own specific morphotype that likely originated under the influence of genetic changes in the species. This study demonstrates that the use of geometric morphometric analysis is effective in studying the variability in H. axyridis populations. As this study is the first of its kind, for further clarity, it is necessary to conduct additional studies on a larger number of sites and an equal number of individuals of all forms.