Lethal and sublethal effects of an emulsion based on Pogostemon cablin (Lamiaceae) essential oil on the coffee berry borer, Hypothenemus hampei.

The global search for eco-friendly and human-safe pesticides has intensified, and research on essential oils (EOs) has expanded due to their remarkable insecticidal activities and apparent human-safe. Despite this, most of the literature focuses on short-term and simplified efforts to understand lethal effects, with only a few comprehensive studies addressing sublethal exposures. To fill this shortcoming, we explore the lethal and sublethal effects of Pogostemon cablin (Lamiaceae) EO and an EO-based emulsion (18%) using the coffee berry borer Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae) as a model. First, we determine the toxicity of EO and EO-based emulsion using dose-mortality curves and lethal times. Second, we subjected adult females of H. hampei to sublethal doses to assess whether they affected their behavior, reproductive output, and histological features. Our findings reveal that patchoulol (43.05%), α-Guaiene (16.06%), and α-Bulnesene (13.69%) were the main components of the EO. Furthermore, the EO and its emulsion had similar toxicity, with dose-mortality curves and lethal times overlapping 95% confidence intervals. We also observed that sublethal exposure of females of H. hampei reduces reproduction and feeding, increases walking activity, and causes histopathological changes in the midgut. This study advances the knowledge of the lethal and sublethal effects of an eco-friendly substance on insects.Responsible Editor: Giovanni Benelli.

Citrus Mealybug Performance and Plant Strata Preference on Different Coffee Varieties.

The optimal defense theory stipulates that a plant prioritizes the defense of young tissue against herbivory, which may affect the spatial distribution of the attacking insect and its impact on plant performance. In this study, we evaluated the feeding and oviposition site preferences of the citrus mealybug, Planococcus citri (Risso, 1813) (Hemiptera: Pseudococcidae), when comparing different parts of the canopy of two coffee varieties as well as its fertility and life history parameters. We evaluated the feeding preference, oviposition site choice, and the distribution of different development stages of P. citri on different strata (apical, median, base, and trunk regions) of two coffee varieties, Coffea arabica and Coffea canephora, as well as the associated variations in life history parameters and fertility. The citrus mealybug preferred to feed and oviposit on young leaves despite the presence of high levels of defense compounds. On average, more than 38% of P. citri preferred the apical leaves of cv. Coffea arabica compared to the other parts of the plant. However, in cv. C. canephora, the proportion that preferred the apical leaves was greater than 55%. The net reproduction rate (R0) and the intrinsic rate of increase (rm) of P. citri reared on C. canephora were significantly higher than those seen on C. arabica. The generation time (T) of P. citri reared on C. arabica was significantly longer than that observed on C. canephora. The estimated population growth rate of mealybugs on C. canephora varieties over 15 generations was more than twice that of the population on C. arabica. The dispersion ability and choice of the most nutritious plant strata by nymphs and adults on coffee plants are fundamental to the fitness of these mealybugs. Mealybugs showed a distinct preference for C. canephora.

Seasonal Abundance, Defoliation, and Parasitism of Japanese Beetle (Coleoptera: Scarabaeidae) in Two Apple Cultivars.

The Japanese beetle, Popillia japonica Newman, is an invasive insect to the United States that feeds on turfgrass roots as a larva and the foliage, flowers, and fruit of many major ornamental and agricultural crops, such as apple, as an adult. Despite its generalist feeding behavior, P. japonica shows preferences for certain plant species and cultivars. Classical biological control for P. japonica, including release of Istocheta aldrichi (Mensil), has been pursued in Minnesota. This study was conducted to assess the effects of apple cultivar on season-long abundance of adult P. japonica and their defoliation; and to assess effects of apple cultivar and P. japonica abundance and sex on parasitism of P. japonica by I. aldrichi. Sampling occurred during the summers of 2017 and 2018 on Zestar! and Honeycrisp cultivars in four different apple orchards. Abundance and defoliation of P. japonica was higher on Honeycrisp than Zestar!. Parasitism of P. japonica by I. aldrichi was higher for females than for males. In 2018, the relationship between parasitism of P. japonica and host density varied by cultivar. These findings may help growers determine which apple cultivars should be prioritized for scouting and management efforts and may provide an estimate of potential biological control by I. aldrichi in agricultural areas in the Midwest.

Wet and warm conditions contribute to the occurrence of the neotropical butterfly Ascia monuste orseis Godart (Lepidoptera: Pieridae) on Brassica crops.

Ascia monuste orseis Godart (Lepidoptera: Pieridae) is a neotropical butterfly distributed in South America. During the larval stage, this insect causes economic losses on Brassica crops. Wet and warm conditions are known to increase subspecies occurrence, but it remains unclear why these conditions are more suitable. In this study, we have shown that both conditions are highly favourable for A. monuste orseis. We determined the thermal requirements for immature development and then created models for A. monuste orseis occurrence using Climex algorithm. Two models were built: one for the year-round presence and other for seasonal suitability. We validated the models using subspecies occurrence records and monitoring in two Brazilian regions (Northeast and Southeast). The minimum, optimum and maximum temperature for immature development were estimated at 16.37, 29.16 and 34.95 °C, respectively. The model for year-round presence indicated tropical areas as highly suitable for A. monuste orseis occurrence (with 88% of accuracy) and the seasonal models showed unsuitable areas in some parts of South America during cold and dry periods. Such predictions were observed in the monitored areas where A. monuste orseis was not found. These results can be associated with the mortality caused by low temperature to immature stages and drought conditions that may induce adult migration to moist habitats. Thus, we suggest that A. monuste orseis occurs mainly during wet and warm seasons on Brassica crops due to deleterious effects caused by cold and dry conditions. This information can be used to improve A. monuste orseis management in Brassica crops.