Journal of Insect Science最新文献

Cantharidin is a toxic defensive substance secreted by most blister beetles when attacked. It has been used to treat many complex diseases since ancient times and has recently regained popularity as an anticancer agent. However, the detailed mechanism of the cantharidin biosynthesis has not been completely addressed. In this study, we cloned McSTE24 (encoding STE24 endopeptidase) from terpenoid backbone pathway, McCYP305a1 (encoding cytochrome P450, family 305) and McJHEH [encoding subfamily A, polypeptide 1 and juvenile hormone (JH) epoxide hydrolase] associated to JH synthesis/degradation in the blister beetle Mylabris cichorii (Linnaeus, 1758, Coleoptera: Meloidae). Expression pattern analyses across developmental stages in adult males revealed that the expressions of 3 transcripts were closely linked to cantharidin titer exclusively during the peak period of cantharidin synthesis (20-25 days old). In contrast, at other stages, these genes may primarily regulate different biological processes. When RNA interference with double-stranded RNA suppressed the expressions of the 3 genes individually, significant reductions in cantharidin production were observed in males and also in females following McJHEH knockdown, indicating that these 3 genes might primarily contribute to cantharidin biosynthesis in males, but not in females, while females could self-synthesis a small amount of cantharidin. These findings support the previously hypothesized sexual dimorphism in cantharidin biosynthesis during the adult phase. McCYP305a1 collaborates with its upstream gene McSTE24 in cantharidin biosynthesis, while McJHEH independently regulates cantharidin biosynthesis in males.

The establishment of invasive species populations can threaten the ecological balance in naïve habitats and impact agricultural production practices. Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) (old-world bollworm, OWBW) and Helicoverpa zea (corn earworm, CEW) were geographically separated prior to the 2013 report of OWBW invasion into South America. Introgression of OWBW-specific cytochrome P450 337B3 (CYP337B3) gene into CEW was repeatedly detected across South America and the Caribbean. Two hybrids were documented from Texas in 2019. In this study, screening insects collected in Olathe, CO, USA, where a failure of pyrethroids to control CEW damage to conventional sweetcorn in 2023 detected 28.6% of insects with the OWBW-specific CYP337B3 marker. Nucleotide sequencing of the CYP337B3 gene identified 73.1% and 26.9% of insects carried CYP337B3v2 and CYP337B3v6 alleles, respectively, and 0.15 overall frequency of CYP337B3 alleles. Based on prior data for distinct phylogeographic origins of CYP337B3v2 and v6 alleles, our results indicate Olathe samples were derived from 2 different introductions: An uncertain source of the v6 allele that was initially reported in West Africa and possibly South American or Caribbean origin of the globally distributed v2 allele. One of the 1618 individuals screened also carried a ribosomal RNA internal transcribed spacer 1 derived from OWBW. Local selection pressures at the Olathe location imposed by repeated pyrethroid exposures are likely attributed to the prevalence of CYP337B3, where control practices hasten the accumulation of phenotypic resistance by adaptive introgression. Pyrethroid and other resistance factors carried by invasive OWBW may continue to impact CEW management tactics across the Americas.

The potential role of the juvenile hormone receptor gene (methoprene-tolerant, Met) in reproduction of Coccinella septempunctata L. (Coleoptera: Coccinellidae)(Coleoptera: Coccinellidae), was investigated by cloning, analyzing expression profiles by quantitative real-time PCR, and via RNA interference (RNAi). CsMet encoded a 1518-bp open reading frames with a predicted protein product of 505 amino acids; the latter contained 2 Per-Arnt-Sim repeat profile at amino acid residues 30-83 and 102-175. CsMet was expressed in different C. septempunctata larvae developmental stages and was most highly expressed in third instar. CsMet expression in female adults gradually increased from 20 to 30 d, and expression levels at 25 and 30 d were significantly higher than levels at 1-15 d. CsMet expression in 20-d-old male adults was significantly higher than in males aged 1-15 d. CsMet expression levels in fat body tissues of male and female adults were significantly higher than expression in the head, thorax, and reproductive system. At 5 and 10 d after CsMet-dsRNA injection, CsMet expression was significantly lower than the controls by 75.05% and 58.38%, respectively. Ovary development and vitellogenesis in C. septempunctata injected with CsMet-dsRNA were significantly delayed and fewer mature eggs were produced. This study provides valuable information for the large-scale rearing of C. septempunctata.

The Canary Islands is a Macaronesian volcanic archipelago with a depauperate community of three species of Kalotermitidae, including Kalotermes dispar. A total of 54 Kalotermes colonies were collected from Gran Canaria, Tenerife, La Gomera, La Palma, and El Hierro islands. Soldiers and imagos were morphologically examined and sequenced for four mitochondrial markers. Although morphological differences could not be detected, phylogenetic analysis of both cox1/tRNA/cox2 and rrnL markers revealed two distinct clades of K. dispar, suggesting cryptic diversity. The diversification within the Canary Kalotermes lineage most likely occurred around 7.5 Mya, while the divergence within the two clades was reconstructed at about 3.6 Mya and 1.9 Mya. Kalotermes approximatus from the southeastern Nearctic constitutes a sister to the Canary Kalotermes, while the Palearctic K. flavicollis, K. italicus, and K. phoenicae form a separate clade. It is hypothesized that a faunal exchange of Kalotermes from the Nearctic to the Canary Islands occurred via transoceanic rafting during the mid-Miocene.

Tephritis angustipennis (Diptera: Tephritidae) and Campiglossa loewiana (Diptera: Tephritidae) are phytophagous pests in China. Their damage has significantly impacted the collection and cultivation of germplasm resources of native Asteraceae plants. However, the genetic characteristics and structure of their population are unclear. This study focused on the highly damaging species of T. angustipennis and C. loewiana collected from the three-river source region (TRSR). We amplified the mitochondrial cytochrome C oxidase subunit I (mtCOI) gene sequences of these pests collected from this area and compared them with COI sequences from GenBank. We also analyzed their genetic diversity and structure. In T. angustipennis, 5 haplotypes were identified from 5 geographic locations; the genetic differentiation between France population FRPY (from Nylandia, Uusimaa) and China populations GLJZ (from Dehe Longwa Village, Maqin County), GLDR (from Zhique Village, Dari County), and GLMQ (from Rijin Village, Maqin County) was the strongest. GLJZ exhibited strong genetic differentiation from GLDR and GLMQ, with relatively low gene flow. For C. loewiana, 11 haplotypes were identified from 5 geographic locations; the genetic differentiation between the Chinese population GLMQ-YY (from Yangyu Forest Farm, Maqin County) and Finnish population FDNL (from Nylandia, Uusimaa) was the strongest, with relatively low gene flow, possibly due to geographical barriers in the Qinghai-Tibet plateau. Only 1 haplotype was identified across GLDR, GLMQ, and GLBM. High gene flow between distant locations indicates that human activities or wind dispersal may facilitate the dispersal of fruit flies and across different geographic. Geostatistical analysis suggested a recent population expansion of these 2 species in TRSR. Our findings provide technical references for identifying pests in the TRSR region and theoretical support for managing resistance, monitoring pest occurrences, analyzing environmental adaptability, and formulating biological control strategies for Tephritidae pests on Asteraceae plants.

Bemisia tabaci New World (NW) (Gennadius) (Hemiptera: Aleyrodidae), a whitefly in the B. tabaci species complex, is polyphagous on many plant species. Yet, it has been displaced, albeit not entirely, by other whitefly species. Potential causes could include issues with adaptation, feeding, and the colonization of new-hosts; however, insights that would help clarify these possibilities are lacking. Here, we sought to address these gaps by performing electropenetrography (EPG) recordings of NW whiteflies, designated "Napus" and "Rapa," reared on 2 colony hosts, Brassica napus and B. rapa, respectively. Analysis of 17 probing and pathway (pw) phase-related EPG variables revealed that the whiteflies exhibited unique probing behaviors on their respective colony hosts, with some deterrence being encountered on B. rapa. Upon switching to B. rapa and B. napus, the probing patterns of Napus and Rapa whiteflies, respectively, adapted quickly to these new-hosts to resemble that of whiteflies feeding on their colony hosts. Results for 3 of the EPG variables suggested that B. rapa's deterrence against Napus whitefly was significant prior to the phloem phase. This also suggested that adaptation by Rapa whitefly improved its pw probing on B. rapa. Based on analysis of 24 phloem phase-related EPG variables, Napus and Rapa whiteflies performed equally well once they entered phloem phase and exhibited comparable phloem acceptability on both the colony- and new-hosts. These findings demonstrate that NW whiteflies reared on a colony host are highly adaptable to feeding on a new host despite encountering some deterrence during the nonphloem phases in B. rapa plant.

Ascogaster mimetica Viereck is an egg-larval parasitoid that targets Sparganothis sulfureana Clemens, a major cranberry pest in North America. While previous studies have shown that other Ascogaster species respond to cues from their hosts' eggs, it remains unknown whether A. mimetica utilizes these cues to recognize S. sulfureana. We hypothesized that female A. mimetica recognizes S. sulfureana from another cranberry pest, Choristoneura parallela Robinson, based on the presence of surface cues on eggs. To test this, we observed female A. mimetica behavior when exposed to eggs from its host, S. sulfureana; a nonhost, C. parallela; and eggs of S. sulfureana that were washed clean with hexane. Additionally, we tracked parasitism rates in each group. Our results revealed that A. mimetica spent 9.5 times longer walking when exposed to C. parallela eggs and 6 times longer when exposed to hexane-washed S. sulfureana eggs compared to unwashed S. sulfureana eggs. Also, A. mimetica spent 3 times longer grooming when exposed to hexane-washed than unwashed S. sulfureana eggs. In contrast, females spent 6 and 18 times longer drumming and probing/ovipositing on unwashed S. sulfureana eggs than on C. parallela eggs and 5 times longer probing/ovipositing on unwashed S. sulfureana eggs than on hexane-washed S. sulfureana eggs. Higher parasitism rates were observed from unwashed S. sulfureana eggs compared to those from C. parallela eggs and hexane-washed S. sulfureana eggs. Our findings suggest that the presence of egg surface cues, like scales, of S. sulfureana likely plays a crucial role in host acceptance and parasitism success for A. mimetica.

Pairs of adult male crickets, Gryllus bimaculatus, fight and immediately determine winner and loser statuses. The winner male repeatedly produces an aggressive (rival) song by rubbing his forewings together. In this study, I removed the plectrum, a sound-producing structure in the forewing, from male crickets and measured their brain serotonin (5-hydroxytryptamine: 5-HT) levels immediately after a 10-min aggressive interaction. Pairs of plectrum-removed males fought and established clear winner-loser relationships, like the case of intact males. The plectrum-removed winner males frequently rubbed their forewings together, but were unable to produce song. Aggressive interaction reduced significantly brain 5-HT levels in the plectrum-removed males, regardless of their winner and loser statuses. Furthermore, the reduction of brain 5-HT was detected primarily in the central body, a group of neuropils spanning the midline of the brain. In contrast, in pairs of intact males, aggressive interaction reduced brain 5-HT levels in the loser males, but not in the winner males. Plectrum removal alone did not affect the brain's 5-HT levels. These results suggest that aggressive song emitted by the winner male cricket prevents the reduction of 5-HT levels in his own brain, especially in the central body.

The Entomological Society of America (ESA) Student Debates is an annual student competition at the ESA Annual Meeting organized by Student Debates Subcommittee (SDS) members of the ESA Student Affairs Committee. In conjunction with the 2023 ESA Annual Meeting theme, 'Insects and influence: Advancing entomology's impact on people and policy', the theme of this year's student debate was 'Addressing emerging issues in entomology'. With the aid of ESA membership, the SDS selected the following debate topics: (1) Should disclosure of artificial intelligence large language models in scientific writing always be required? and (2) Is it more important to prioritize honey bee or native pollinator health for long-term food security within North America? Four student teams from across the nation, composed of 3-5 student members and a professional advisor, were assigned a topic and stance. Over the course of 5 months, all team members researched and prepared for their assigned topic before debating live with an opposing team at the 2023 ESA Annual Meeting in National Harbor, Maryland. SDS members additionally prepared and presented introductions for each debate topic to provide unbiased backgrounds to the judges and audience for context in assessing teams' arguments. The result was an engaging discussion between our teams, judges, and audience members on emerging issues facing entomology and its impact on people and policy, such as scientific communication and food security, that brought attention to the complexities involved when debating topics concerning insects and influence.