Journal of Insect Science最新文献

The Colorado potato beetle (CPB, Leptinotarsa decemlineata (Say)) is the most important defoliator of solanaceous crops. Control of this pest is hindered by its ability to develop resistance to insecticides, including insecticidal proteins from Bacillus thuringiensis (Bt) Berliner. Therefore, it is important to find alternative tools that may be combined into an integrated pest management approach for CPB control. In this study, we evaluated the efficiency of the combined use of the Cry3Aa protein from Bt and Chrysoperla rufilabris (Burmeister) in controlling CPB. Control of CPB larval second instar at different densities by 3 larval instars of the predator was tested in potato leaves treated with an LC50 concentration of the Cry3Aa protein. Potato leaf damage was evaluated in experiments where CPB larvae were fed with leaves treated with Cry3Aa protein and exposed to predator larvae for 7 days or until all CPB larvae were dead. Results show that all 3 instars of the predator presented a type II functional response for all conditions evaluated. The first and second larval instars of C. rufilabris larvae attacked twice the number of prey (1.34-2.91 and 2.9-4.75, respectively) when CPB larvae were fed on leaves with the Cry3Aa protein. A complete reduction in the number of CPB larvae and lower levels of potato leaf damage was observed when the predator larvae were present. These results support the combined use of the Cry3Aa protein with C. rufilabris in increasing the efficiency of CPB control.

The polyphagous species of cotton bollworm, Helicoverpa armigera (Hübner), is one of the major constraints in sesame production. The present study aimed to explore the life history and life table parameters of H. armigera on several meridic diets based on various sesame cultivars (Barekat, Mohajer, Shevin, Chamran, Jiroft, Behbahan, Sistan, Dashtestan, Dezful, and Hamidieh). Furthermore, the antioxidant defense system of H. armigera was evaluated via measuring antioxidant enzyme activities, namely, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). According to the results, the development time of H. armigera was prolonged when fed on Jiroft, while it was shortened rearing on Mohajer and Barekat seed-based diets. The lowest fecundity of the pest was also observed on Jiroft seeds. Meanwhile, the highest value of either r or λ was on Barekat, whereas their lowest amounts were obtained on diets containing the seeds of Dashtestan, Behbahan, Dezful, and Jiroft. A significant upregulation of antioxidant enzymes of SOD, POD, and CAT was recorded on the meridic diets containing the seeds of Chamran or Jiroft. However, the level of POD was significantly decreased in larvae fed on Mohajer, Dashtestan, Barekat, and Sistan seed-based diets. The results of the cluster analysis revealed that Behbahan, Dezful, and Jiroft seeds were the most resistant to H. armigera attack. Our findings suggest that seed-based meridic diets can be effectively utilized for the rapid screening of sesame cultivars' resistance to pests, offering valuable insights for breeding programs focused on enhancing plant resistance.

Allochrony can be an important premating isolating mechanism in insects but its physiological basis has seldom been determined. It operates at a diurnal scale to differentiate mating times of some closely related tephritid taxa. For example, the sympatric sibling species Bactrocera tryoni (Froggatt) and Bactrocera neohumeralis (Hardy) mate at dusk and during the day, respectively. Rectal gland emissions of courting males function as sex pheromones in B. tryoni and recent evidence shows differences between the 2 species in many volatiles released from crushed rectal glands. Here we use gas chromatography-mass spectrometry to show that the head space compositions of whole male emissions of each species are generally but not invariably correlated with those of their respective rectal glands and they also differ between the species. Further, while the compositions of the whole male emissions do not vary diurnally in either species, the total amounts of the emissions do, in species-specific ways, with those of B. tryoni higher at dusk and night and those of B. neohumeralis higher during the day. Thus, the species differ substantially in their diurnal patterns of total whole fly emissions in a manner consistent with their allochrony, while the compositions of the emissions also differ substantially, which could also contribute to their premating isolation but is independent of their allochrony.

Phlebotomine sand flies stand out for their role in vector-borne diseases, having taxonomic priority in aspects of public health. Traditional identification based on morphology involves some limitations that have been corrected with the implementation of complementary methodologies such as cytochrome c oxidase subunit I barcoding and recently mass spectrometry. In Mexico, nearly 38% of sand fly species count with a molecular characterization, but additional information is still necessary for improving sand fly species delimitation. We carried out a molecular species delimitation study of sand flies distributed in the Mexican Transition Zone, between the Nearctic and Neotropical regions, with newly generated cytochrome c oxidase subunit I barcodes, and the first protein profiles created. Compelling evidence showed putative new taxa emerge from Micropygomyia aff. durani (Vargas & Diaz-Nájera) and Pintomyia Series serrana Barretto, and several cryptic species be contained within the genera Micropygomyia and Psathyromyia, which could be of biological and epidemiological interest. However, for some taxa an exhaustive taxonomic revision at the morphological and molecular levels is recommended, especially for sand flies of wide distribution in the New World.

Cockroaches live in diverse habitats around the world. In central Chile, wild cockroaches are commonly associated with native habitats in the Mediterranean-type temperate scrub and sclerophyll forest, contributing to several ecosystem functions. Cockroaches within this group share some characteristics of their external morphology, such as reddish-black color, both sexes with brachypterous wings, and similar size. This coincides with some of the characteristics reported in 1933 for the species Moluchia brevipennis (Saussure, 1864) (Blattellidae). However, the internal genital morphology suggests that these correspond to at least three species. Here, we studied these morphological features using classical dissection techniques and SEM. Based on this, we redescribed the male of M. brevipennis, the female, and the ootheca, which was previously unknown. In the same way, we assign a lectotype from Saussure's original material. In addition, we describe two new species: Moluchia akelarre Schapheer, Villagra, and Vera sp. nov. and Moluchia kuyen Schapheer, Villagra, and Vera sp. nov. Finally, we reconstruct the geographic distribution of the three species and their association with the plant strata of the Mediterranean climate zone of Chile. Based on this, we discuss the importance of the characters used, such as the tergal specializations in the tergite I, and the need to incorporate new characters that allow a correct determination. This work elucidates differences in the diversity of native cockroaches of Central Chile and contributes to the taxonomic knowledge of this lineage, laying the foundations for later studies that explain the diversification of native cockroaches of Central Chile.

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are small fungus-farming beetles that damage stressed nursery trees directly through tunneling and structural weakening, and indirectly by introducing pathogenic fungi. Stressed trees emit ethanol, which is the primary host-locating cue for ambrosia beetles. This study evaluated the efficacy of low-cost ethanol detectors as a solution for the early detection of flood-stressed trees susceptible to ambrosia beetle infestation. Experiments were conducted using 48 native dogwoods (Cornus florida L.) subjected to flooded or non-flooded conditions. The attacks of ambrosia beetles were significantly higher in flooded trees, indicating a clear preference and validating the use of flood stress as a reliable method for susceptibility assessment. Ethanol emitted from these trees was measured using low-cost alcohol saliva test strips and Dräger Pac 8000 personal gas detectors alongside a solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) for ethanol confirmation. In addition to stem tissue analysis for ethanol detection via SPME-GC-MS, we found that twig and root tissue samples can also be assessed effectively using low-cost detectors such as alcohol strips and Dräger devices. GC-MS, a reliable method for volatile compound identification and quantification, confirmed ethanol as the dominant volatile in flooded trees, with both low-cost detectors correlating positively with SPME-GC-MS results. These detectors could offer a rapid, cost-effective method for identifying trees at risk of ambrosia beetle attack. However, their accuracy can be limited by false positives, as some plant genera emit aromatic volatiles such as eugenol, which may interfere with ethanol detection. More work is needed to optimize these tools for use by nursery growers, consultants, and researchers as an early-warning system and aid in ambrosia beetle management decision-making.

Developing and establishing a permanent insect population under mass-rearing conditions is challenging, but it offers the opportunity to collect and compare life history, physiological, morphological, and behavioral traits in real-time and over multiple generations. Halyomorpha halys (Stål, 1855) (Hemiptera: Pentatomidae), a serious agricultural insect pest in northern Italy, was used to establish a permanent mass-rearing protocol under controlled abiotic conditions. The study aimed to evaluate the impact of permanent laboratory rearing on various life history and morphological traits over 8 generations. Development time and developmental success rate of the eggs and nymphal stages, fecundity, mortality rate and body size of the adults were documented. In general, a significant variability was observed in both developmental success rate and developmental time for eggs and juvenile stages, although without an obvious trend. In adults, on the other hand, a common trend in fecundity, number of egg masses and survival was observed. All 3 parameters exhibited a marked decline beginning in the second generation, followed by a significant recovery starting from the seventh generation, indicating potential laboratory adaptation. The body size, on the other hand, showed a slight decrease from the second generation that remained almost constant in subsequent generations. While the results demonstrate the clear success of a continuous H. halys mass-rearing, they also show the current challenges and limits of rearing this invasive insect species under laboratory conditions over several generations without the addition of new individuals.

The eggplant fruit and shoot borer (Leucinodes orbonalis Guenée) is a devastating lepidopteran pest of the eggplant (Solanum melongena L.), causing significant economic losses. Reference genomes aid in understanding insect pest biology and can guide pest management programs. For eggplant fruit and shoot borer, however, genomic resources are scarce; hence, this study presents an annotated genome assembly of the Philippine eggplant fruit and shoot borer genome using Illumina short reads. The 480,399,388 bp long assembly contained 31,568 contigs with an N50 of 204,698 bp and a BUSCO score of 96.5%. Annotation of repeat elements indicates that the eggplant fruit and shoot borer genome comprises 38.50% interspersed repeats, which are mostly unclassified repeats. Functional RNA annotation revealed 1,310 functional RNA genes consisting primarily of tRNAs, rRNAs, snRNAs, and miRNAs. Protein structural annotation predicted a total of 12,671 genes. Annotation using a Cluster of Orthologous groups indicates proteins belonging to group S (unknown), group T (signal transduction), group O (posttranslational modification), and group K (transcription). Of the proteins belonging to group S, PFAM analysis revealed proteins containing chitin, juvenile hormone, odorant and pheromone-binding protein domains, and zinc finger motifs. Further analysis of the predicted proteins indicates that the EFSB possesses conserved biochemical machineries in insect chemosensation, detoxification, and hormone biosynthesis and reception. Variation profiling, on the other hand, detected 11,103,848 SNPs and 3,031,155 indels possibly occurring in Philippine eggplant fruit and shoot borer. Overall, the genome assembly and annotation generated from this study contribute to establishing genome references, and may aid in understanding the EFSB through future studies aimed at its effective control.

A major challenge in studying the biology of the Melolonthidae has been the lack of a consistent supply of organisms with known characteristics. This study aimed to develop a methodology for mass-rearing a Cyclocephala barrerai Martínez (Coleoptera: Melolonthidae) colony over several laboratory generations. The mass-rearing was initiated with eggs from wild-collected adults; each developmental instar was reared under conditions suited to their environmental and nutritional needs. Insect survival, egg-adult cycle length, sex ratio, adult weight, and number of eggs laid by each female were recorded for each generation. The morphology of mass-rearing organisms was compared to that of the wild-collected specimens. A second cohort of organisms from the original generation was reared under identical conditions and their survival, duration, and morphometry of each larval instar were recorded weekly. These data were then compared to those from the original group to assess the impact of constant manipulation during the larval instar. The mass-rearing methodology proposed in this work successfully reared 3 generations of C. barrerai with an overall average egg-adult survival rate of 66.6%. The egg-adult cycle length, proportion of females and males, and average weight differed among generations. The F1 organisms presented similar morphometrics to those collected in the field. Manipulation significantly reduced insect survival. Mass-rearing of C. barrerai facilitates a comprehensive study of its biology and may establish the species as a model for the Melolonthidae. This methodology establishes the foundations for rearing congeneric species in the laboratory.

Colored sticky traps are used for management of many common agricultural insect pests. Several recent studies have shown that traps can be improved by systematically considering properties of color vision for the target species. In the current study, we extend this approach to spatial vision, using information about the interommatidial angle of an agriculturally important insect pest, western flower thrips Frankliniella occidentalis (Pergande), to predict spatial resolution capabilities for a yellow flower pattern across a range of viewing distances. We tested the hypothesis that pattern sizes matching the spatial resolution capabilities of western flower thrips at a given viewing distance would outperform traps with mismatched pattern sizes by measuring the number of western flower thrips caught on sticky traps containing differently sized flower patterns resolvable at 5, 10, or 20 cm. We found an interaction between pattern size and viewing distance, with significantly more western flower thrips caught on traps when the predicted resolvable distance of the pattern matched the distance traps were placed from a central release point. We further tested the range over which trap patterns are effective in more complex viewing environments using commercial polytunnels. In polytunnel trials, we found that increasing the resolvable distance of patterns increased western flower thrips capture up to approximately 26 cm, after which western flower thrips capture decreased up to the maximal visible range tested (50 cm) in the absence of additional sensory cues. Together, these results show the utility of considering spatial vision in improving trap performance and offers functional insights to improve pest management in visual trap design.