Neotropical Entomology最新文献

Understanding the complex interplay between environmental factors and mosquito populations is crucial for effective vector-borne disease control. In this study, we investigated the combined effects of temperature and Ateleia glazioviana toxicity on the development and survival of Aedes aegypti, utilizing artificial microcosms. The first experiment used A. aegypti eggs, with microcosms varying by room temperature (18 °C and 25 °C) and exposure to A. glazioviana leaves, either without prior incubation or with a 14-day pre-incubation period. The second experimental design involved introducing larvae, with microcosms varying by room temperature (18 °C and 25 °C) and exposure to A. glazioviana leaves after a 14-day incubation period. For both experiments, we used only ultra-pure water and food for the control. Our results demonstrate that plant leachate toxicity had a more pronounced effect than temperature, with increased toxicity levels driving higher larval mortality rates. This reduction in competition among surviving larvae led to the development of larger individuals, consistent with the temperature-size rule. Notably, the impact of leachate toxicity was most significant when A. aegypti was exposed during the egg stage. Additionally, we observed that elevated temperatures were linked to increased wing asymmetry and reduced body size, suggesting heightened developmental instability under environmental stress. These findings have important implications for biological control strategies, emphasizing the need for pre-emptive measures before oviposition. Moreover, they challenge the commonly held assumption that temperature alone is the dominant factor shaping A. aegypti populations in Neotropical regions, highlighting the complex role of other ecological stressors.

This research aimed to study the feeding behavior of Nezara viridula (L.) adults on canola stems and siliques using the electropenetrography (EPG) technique. Three distinct phases were identified: non-feeding (waveform Np), pathway (waveform Nv1-which was divided into three subtypes Nv1a, Nv1b and Nv1w), and feeding (waveforms Nv2 and Nv3), which follow previously identified waveforms for this species on soybean. The Nv3 waveform was divided into two subtypes (Nv3a and Nv3b). Biological meanings of the waveforms were proposed by correlating them with visual observations and histological studies. The waveform Np was correlated with insect resting/walking on plant surface; Nv1a with initial stylet insertion and secretion of gelling saliva to create a salivary sheath; Nv1b with deep stylet penetration plus secretion of more gelling saliva; Nv1w with stylet withdrawal, and Nv2 with xylem ingestion, as previously observed for N. viridula nymphs on soybean. Nv3a was correlated with laceration/maceration activities; and Nv3b with ingestion of the lacerated/macerated tissue. Regarding comparative analysis, the initial penetration and stylet withdrawal were both significantly longer on stems. Xylem ingestion did not differ significantly between substrates. Feeding events were more common on siliques, and overall duration of ingestion was greater on this substrate. Although no difference in overall duration of laceration/maceration (cell-rupture feeding strategy) was observed between stems and siliques, the average duration of each laceration/maceration event was greater on stems. Significantly more time was spent on non-feeding activities on siliques compared with stems.

Insects and mammals share a similar innate immune system. Galleria mellonella (L.), a beekeeping pest, is an alternative model organism for human health studies due to its immune response similarity and ability to be maintained at 37 °C. While oxidative stress and genotoxicity cause diseases, antioxidant enzymes and epigenetic mechanisms are effective in immunological response processes. Although parasitoid venoms are potential candidates for pharmacological applications such as anticoagulant, antibiotic, painkiller, antiviral and anticancer agents, the information pool is scarce to reflect their effects in humans. In an attempt to reveal the pharmaceutical significance of parasitoid venoms and their potential effects on human health, different venom doses of Pimpla turionellae (L.), the solitary endoparasitoid of G. mellonella, were injected into the host. Then, the levels of protein content, advanced oxidised protein products, lipid peroxidation, antioxidant power and glutathione in host haemolymph, and the amounts of methylation marker 5-methyldeoxycytidine monophosphate and strand breakage rates under neutral and alkaline conditions in host DNA were analysed. Principal component analysis was performed to determine the number of components that oxidative parameters depend on, and multivariate correlation analysis was applied to evaluate the effects of the parameters on each other. It was concluded that P. turionellae venom appeared to be one of the most effective pharmaceutical agents among parasitoid venoms. Also, the 0.01 venom reservoir equivalent dose qualified as immunotherapeutic dose.

Insects, due to their unrestricted reproduction, have been a long-known nuisance causing significant damage to various crops. Besides the synthetic chemical pesticides, the bioactive compounds derived from medicinal plants also make a positive contribution against the control of pests. In this concern, the present study investigated the biological activity of essential oil and isolated sesquiterpene alcohols, τ-cadinol and β-bisabolol, from Clausena indica leaves against three insect pests, Spodoptera litura, Helicoverpa armigera, and Tribolium castaneum. Four different concentrations (25, 50, 75, and 100 g L^-1) of oil, τ-cadinol, and β-bisabolol in both normal and microencapsulated forms were tested for their efficacy in the field trial. Among all the compounds, τ-cadinol exhibited strong toxicity (LD₅₀ = 35.93-52.94 µg larva^-1), antifeedant activity (DC₅₀ = 52.51-75.93 µg cm^-2), and oviposition deterrent activity (OD₅₀ = 56.73-67.18 µg cm^-2) against all the tested pests followed by β-bisabolol and leaf essential oil. Additionally, both the compounds demonstrated noteworthy acetylcholinesterase inhibitory activity with IC₅₀ values of 24.53-30.98 μg mL^-1 and 32.15-40.41 μg mL^-1 respectively comparable to the positive control, galantamine. Moreover, both τ-cadinol and β-bisabolol exhibited the strongest cytotoxicity against Sf9 cells lines with IC₅₀ of 15.27 and 17.82 µg mL^-1 respectively while IC₅₀ of 5.02 µg mL^-1 was shown by azadirachtin on the same cell line. Results of the field trial reveal that all tested compounds showed considerable mortality of S. litura and H. armigera. Although the treatments showed good insecticidal activity in the field trial, but modifications are required for the concentration of active ingredients in the formulation or even in the formulation to enhance the effect. The results obtained lay a foundation for future field applications of oil and isolated compounds as crop protectants.

Diamondback moth, Plutella xylostella (L.), is a major pest of cruciferous crops, whereas Aphis craccivora is a major sucking pest of leguminous crops. Indiscriminate use of synthetic insecticides for the control of insect pests leads to insecticide resistance, harmful to natural enemies of pests, pollinators, the environment, and consumers' health. Therefore, it is necessary to screen/identify alternate strategies to control the target pests. Steroidal saponins, a group of specialized amphiphilic metabolites, are known for their various biological properties. There are a few reports on insecticidal activities of steroidal saponins. In the present study, insecticidal activities of nine diverse steroidal saponins isolated from Trillium govanianum were evaluated against Plutella xylostella and Aphis craccivora. Among the molecules, govanoside E (3) was found more effective against Plutella xylostella (LD₅₀ = 0.91 µL/insect) after 96 h of treatment followed by govanosides D and F (1.44 and 1.56 µL/insect, respectively). Similarly, govanoside E was also found effective against Aphis craccivora (LD₅₀ = 1.04 µL/insect) followed by dehydroxy-diosgenin and pennogenin-triglycoside (1.19 and 1.36 µL/insect, respectively). Furthermore, govanoside E (3) showed promising repellency (RC₅₀ = 1043.20 µL/L) against Plutella xylostella. The molecules also showed a dose-dependent relationship with inhibitory effects on the reproduction of Aphis craccivora. In vitro enzyme inhibition/mechanism study confirmed that govanoside E (3) inhibited glutathione-S-transferase (GST) and carboxylesterase (CES1) in test insects. The present study suggested the potential utilization of steroidal saponins for the control of target pests based on field bio-efficacy results.

The genus Chrysomela includes several species known to be pests of willow (Salix spp.) and poplar (Populus spp.) trees, primarily distributed across North America. However, these species are expanding beyond their natural range. This study presents the first record of C. scripta in Colombia where it feeds and reproduces on Salix humboldtiana; additionally, this species is also recorded for the first time from Ecuador and Peru based on participative science records; furthermore, another species, C. texana, is also recorded from Colombia. The introduction of these species raises concerns for timber-producing regions, particularly in Argentina and Chile, and on the existing pressures on Salix humboldtiana, the only native species of this genus in the region.

Introgressive hybridization involves the integration of genetic material from one population into another genetically distinct population. Despite its widespread occurrence in nature, the mechanisms and consequences of introgression remain poorly understood. In this study, we examine the hypothesis that the mitochondrial gene COI from Drosophila antonietae has been introgressed into the gene pool of a specific population of D. gouveai. Additionally, we extended our analysis to include other genes associated with the COX complex, such as mitochondrial (COII) and nuclear genes (CoVa, CG9603, and levy), across various populations of both species from different locations. We estimated indices of genetic diversity, constructed haplotype networks in both mitochondrial and nuclear genes, and performed selection tests to assess the evolutionary dynamics of mitochondrial genes. Our results confirm the hypothesis of a historical secondary contact between D. gouveai and D. antonietae in the region of Analândia, SP, showing asymmetric unidirectional introgression, with signs of positive selection in the mitochondrial genes.

Here, we studied Askola specimens sampled from streams in the Caatinga and Atlantic Forest ecoregions of Brazil. We associate nymphs and adults of A. mucuge using molecular tools (COI sequences). The nymph of this species can be differentiated from the two other known nymphs of the genus by the internal denticle medially located at the external incisor of the left mandible and by abdominal terga without marks. In addition, Automatic Barcode Gap Discovery revealed the possibility of cryptic species under the name of Askola froehlichi, suggesting three independent lineages. Our results reduce the Haeckelian and Linnean shortfalls for Askola, since we describe the third nymph of the genus and shed light on the possibility that the most widely distributed Askola species includes putative cryptic species.

Tetranychus urticae Koch is a major pest in cotton crops; in Brazil, the predatory mite Neoseiulus californicus (McGregor) is used for its biological control. Although the standard recommendation for controlling T. urticae is to release around 20,000 individuals per hectare, this is a general guideline and may not be suitable for cotton crops. The present study examined the effect of N. californicus on T. urticae populations in semi-field conditions to identify the predator density needed to reduce pest infestation and the percentage of infested plants. We tested predator-to-prey ratios of 0:50, 3:50, 5:50, and 10:50 on cotton plants maintained in a greenhouse. Tetranychus urticae individuals and the proportion of infested plants were counted daily for the first 5 days, then every 3 days until day 29. All tested densities of N. californicus reduced T. urticae infestation; however, only the release of 5 or 10 predators per 50 T. urticae individuals resulted in infestation levels below the economic threshold level (ETL) recommended for controlling the two-spotted spider mite in cotton crops.

Commercially available in Brazil since the 2013/2014 crop season, the adoption of Bt soybean rapidly increased to > 80% after only eight crop seasons (2020/2021). The widespread use of Bt soybean has achieved regional suppression of key lepidopteran pests and reduced insecticide use, providing economic and environmental benefits for all in Brazilian agriculture. Due to the high efficacy of Bt soybean in controlling key soybean lepidopteran pests and the simplicity of its use, most soybean farmers have adopted Bt soybean in extensive areas, reaching 94% adoption in the 2023/2024 crop season. However, the high adoption of Bt soybean associated with low refuge compliance has led to the first cases of pest resistance to Cry1Ac (Crocidosema sp. and Rachiplusia nu) in Brazil, representing major challenges to the future of this technology. Unfortunately, farmers wrongly believe that non-Bt soybean cultivars cannot be as profitable and productive as Bt soybean cultivars. Therefore, more than 10 years after Bt soybean adoption in Brazil, this review discusses the most important benefits and challenges of Bt soybean use and what can be expected for the next decade of this technology.