Search Results (11)

The extended application of pesticides has intensified the resistance problem in Liriomyza trifolii within Hainan Province. This study aimed to elucidate the underlying mechanisms contributing to the elevated resistance observed in this pest by employing Whole-Genome Re-sequencing (WGR) technology. Through the analysis and comparison of WGR data focusing on voltage-gated sodium channel (VGSC) from diverse regions and LT-S of L. trifolii in Hainan Province, we identified a total of six nonsynonymous single nucleotide polymorphisms (nsSNPs) and thirty-one synonymous single nucleotide polymorphisms (sSNPs) in five wild populations MY, TS, DA, TY, and JY. Among the six nsSNPs, three (PyR1: M918T, L1014F, and PyR2: T933I) have been confirmed as linked to pyrethroid resistance, while one (D IVS6: V1845I) was associated with resistance to indoxacarb. Moreover, the frequency of these four mutations generally increases with decreasing latitude. Additionally, under sustained pesticide selection pressure, L. trifolii exhibits an evolutionary pattern characterized by a dN/dS ratio (nsSNP/sSNP = 6/31 ≈ 0.19) of less than 1. Among the 31 sSNPs that held an absolute quantitative advantage, the highest occurrence frequency reached 94.44% (G2033: JY), and this sSNP occurred in all populations. In contrast, among a limited number of 6 nsSNPs, the highest occurrence frequency attained 100% (L1014F: all populations). This study substantiates that the elevated resistance observed in L. trifolii within Hainan Province can be ascribed to the presence of four nsSNPs-M922T, T933I, L1018F, and V1845I in their VGSC. Furthermore, the emergence of cross-resistance between pyrethroids and indoxacarb has been identified. This research offers a novel theoretical foundation for future investigations into the resistance mechanisms of L. trifolii. Full article

The recent incursions of three agromyzid leafminers (Liriomyza huidobrensis, L. sativae, and L. trifolii) into Australia pose a significant threat to horticultural production. Outbreaks of these polyphagous pests are consistently associated with the disruption of their parasitoids caused by the widespread use of non-selective insecticides and to increasing pesticide resistance in these agromyzids. An analysis of the international literature for records of parasitoids associated with L. huidobrensis, L. sativae, and L. trifolii revealed that they are attacked by a similar profile of parasitoid families: Eulophidae (63% of records), Braconidae (19%), Pteromalidae (9%), and Figitidae (8%). Diglyphus isaea, Neochrysocharis formosa and Hemiptarsenus varicornis (all already recorded in Australia) were the most commonly reported parasitoids worldwide. These species, along with Australia’s broader parasitoid fauna, will play an important role in managing invasive Liriomyza species, provided insecticide use does not disrupt their populations. However, key knowledge gaps remain, especially regarding the taxonomy of local parasitoids, their potential use in conservation biocontrol programs, and the local landscape features that support parasitoid populations. The use of various species in augmentative releases is considered, including constraints and opportunities related to strain selection and the potential use of thelytokous strains for mass-rearing. Full article

Global climate change has intensified temperature fluctuations, significantly impacting insect populations. Thermal tolerance has emerged as a critical determinant of species distribution and invasion potential. Liriomyza trifolii, an economically important invasive pest, has been rapidly expanding in southeastern coastal regions of China, gradually displacing its congeners L. sativae and L. huidobrensis. This competitive advantage is closely associated with its superior thermal adaptation strategies. Here, we first examine the temperature-mediated competitive dominance of L. trifolii, then systematically elucidate the physiological, biochemical, and molecular mechanisms underlying its temperature tolerance, revealing its survival strategies under extreme temperatures. Notably, L. trifolii exhibits a lower developmental threshold temperature and higher thermal constant, extending its damage period, while its significantly lower supercooling point confers exceptional overwintering capacity. Physiologically, rapid cold hardening (RCH) enhances cold tolerance through glycerol accumulation and increased fatty acid unsaturation, while heat acclimation improves thermotolerance via a trade-off between developmental processes and reproductive investment. Molecular analyses demonstrate that L. trifolii combines the low-temperature inducible characteristics of L. huidobrensis with the high-temperature responsive advantages of L. sativae in heat shock protein (Hsp) expression patterns. Transcriptomic studies further identify differential expressions of lipid metabolism and chaperone-related genes as key to thermal adaptation. Current research limitations include incomplete understanding of non-Hsp gene regulatory networks and laboratory–field adaptation discrepancies. Future studies should integrate multi-omics approaches with ecological modeling to predict L. trifolii’s expansion under climate change scenarios and develop temperature-based green control strategies. Full article

Liriomyza trifolii is a significant invasive pest that targets horticultural and vegetable crops, causing large-scale outbreaks characterized by pronounced thermotolerance and insecticide resistance. This study examined the impact of long-term selection for abamectin resistance during the larval stage of L. trifolii on its population dynamics and thermal tolerance. We conducted a comprehensive comparison between the abamectin-resistant strain (AB-R) and the susceptible strain (S), including age-stage, two-sex life table analysis, thermal preference (T_pref), critical thermal maximum (CT_max), heat knockdown times (HKDTs), eclosion and survival rates, and LtHsp expression under heat stress. Our results showed that while selection for abamectin resistance was detrimental to survival and reproduction, it activated self-defense mechanisms and rapid adaptive adjustments and conferred modest thermal tolerance, which suggests a dual nature of insecticide effects. The AB-R strain exhibited significantly higher thermal preference and CT_max values, along with a longer HKDT and improved survival. Additionally, there was a significant upregulation of LtHsp expression in the AB-R strain compared to the S strain. These findings indicate that the evolution of thermal adaptation was accompanied by abamectin resistance development, emphasizing the necessity of considering temperature effects when applying chemical control. Our study provides valuable insights into how physiological acclimation may help mitigate the toxic effects of insecticides and illustrate how insects respond to multiple environmental pressures. Full article

The composition and seasonal abundance of hymenopteran parasitoids of Liriomyza trifolii (Burgess) was investigated on snap bean (Phaseolus vulgaris L.), tomato (Solanum lycopersicum L.), and squash (Cucurbita pepo L. ‘Enterprise’) from 2010 to 2016 in South Florida in two studies. In the first study (2010–2016), 13 species of parasitoids were collected from the snap bean crop. Opius dissitus Muesebeck (Braconidae) was the most abundant parasitoid throughout the study period from September 2010 to February 2016. Diaulinopsis callichroma Crawford (Eulophidae) was the second most abundant parasitoid on bean in 2010, 2012, 2014, and 2016. Other parasitoids included Euopius sp. (Braconidae)., Diglyphus begini (Ashmead), D. intermedius (Girault), D. isaea (Walker), Neochrysocharis sp., Closterocerus sp., Chrysocharis sp., Zagrammosoma lineaticeps (Girault), Z. muitilineatum (Ashmead), Pnigalio sp. (all Eulophidae), and Halticoptera sp. (Pteromalidae). In the second study on the comparative abundance of parasitoids in three crops conducted in 2014 and 2016 using bean (Phaseolus vulgaris L., tomato (Solanum lycopersicum L.) and squash (Cucurbita pepo L.) arranged in a randomized complete block design, bean attracted more parasitoids than tomato and squash irrespective of parasitoid species and years. This information will help in devising a biocontrol-based integrated program for managing leafminers in beans and other vegetable crops. Full article

In recent years, novel strategies to control insects have been based on protease inhibitors (PIs). In this regard, molecular docking and molecular dynamics simulations have been extensively used to investigate insect gut proteases and the interactions of PIs for the development of resistance against insects. We, herein, report an in silico study of (disodium 5′-inosinate and petunidin 3-glucoside), (calcium 5′-guanylate and chlorogenic acid), chlorogenic acid alone, (kaempferol-3,7-di-O-glucoside with hyperoside and delphinidin 3-glucoside), and (myricetin 3′-glucoside and hyperoside) as potential inhibitors of acetylcholinesterase receptors, actin, α-tubulin, arginine kinase, and histone receptor III subtypes, respectively. The study demonstrated that the inhibitors are capable of forming stable complexes with the corresponding proteins while also showing great potential for inhibitory activity in the proposed protein-inhibitor combinations. Full article

Liriomyza trifolii is an important invasive pest that infects horticultural vegetables, displaying a strong competitive advantage and showing great potential for inflicting harm. Chitin synthase is one of the key enzymes in insect chitin metabolism and plays an important role in insect growth and development. In this study, a chitin synthase (CHS) transcript of L. trifolii was cloned, and the results showed that LtCHS belongs to the CHS2 family. The expression analysis indicated the presence of the highest abundance of LtCHS2 in the pupae at different developmental stages but showed no significant difference among different tissues in the adult. Furthermore, a dsRNA immersion method was developed for RNA interference (RNAi) in L. trifolii using LtCHS2 transcript. RNAi can significantly reduce the expression of LtCHS2 in pupae, and the emergence rate of the pupae was significantly lower than that of the control. The results provide a theoretical basis for exploring the role of chitin synthase gene in L. trifolii and proposing new pest control strategies. Full article

Rapid cold hardening (RCH) is a rapid and critical adaption of insects to sudden temperature changes but is often overlooked or underestimated as a component of survival. Thus, interspecific comparisons of RCH are needed to predict how phenotypes will adapt to temperature variability. RCH not only enhances cold survival but also protects against non-lethal cold injury by preserving essential functions such as locomotion, reproduction, and energy balance. This study investigated the difference in basal cold tolerance and RCH capacity of L. trifolii and L. sativae. In both species, the cold tolerance of pupae was significantly enhanced after short-term exposure to moderately cold temperatures. The effect of RCH last for 4 h in L. sativae but only 2 h in L. trifolii. Interestingly, L. trifolii adults had a RCH response but L. sativae adults failed to acclimate. Short-term acclimation also lowered the supercooling point significantly in the pupae of both species. Based on these results, we propose a hypothesis that these differences will eventually affect their competition in the context of climate change. This study also provides the basis for future metabolomic and transcriptomic studies that may ultimately uncover the underlying mechanisms of RCH and interspecific competition between L. trifolii and L. sativae. Full article

The leafminer fly, Liriomyza trifolii, is an invasive pest of vegetable and horticultural crops in China. In this study, a microinjection method based on dsRNA was developed for RNA interference (RNAi) in L. trifolii using genes encoding vacuolar-ATPase (V-ATPase). Expression analysis indicated that V-ATPase B and V-ATPase D were more highly expressed in L. trifolii adults than in larvae or pupae. Microinjection experiments with dsV-ATPase B and dsV-ATPase D were conducted to evaluate the efficacy of RNAi in L. trifolii adults. Expression analysis indicated that microinjection with 100 ng dsV-ATPase B or dsV-ATPase led to a significant reduction in V-ATPase transcripts as compared to that of the dsGFP control (dsRNA specific to green fluorescent protein). Furthermore, lower dsRNA concentrations were also effective in reducing the expression of target genes when delivered by microinjection. Mortality was significantly higher in dsV-ATPase B- and dsV-ATPase D-treated insects than in controls injected with dsGFP. The successful deployment of RNAi in L. trifolii will facilitate functional analyses of vital genes in this economically-important pest and may ultimately result in new control strategies. Full article

Auxins are commonly used for commercial propagation of chrysanthemums by stem cuttings. Recent studies imply that these root-promoting hormones also affect plant defense responses. The underlying motive of this study stems from the serendipitous observation that water dipping of auxin-coated cuttings beneficially affected thrips herbivory. Therefore, the primary objective of this investigation was to explore the role of indole-3-butyric acid (IBA) in relation to herbivore susceptibility in chrysanthemum. We observed contrasting findings concerning the physical presence of IBA and it’s role in promoting susceptibility of cuttings to thrips, which may in part be explained by the phenotypical variations of cuttings generated from mother plants. Nonetheless, we repeatedly demonstrated considerable protection, in some experiments up to 37%, against thrips and leaf miner upon water dipping of IBA-coated cuttings. Assessment of polyphenol oxidase activity (PPO), 14 days after dipping treatment, suggests that neither direct induction nor priming of plant defenses are involved. Future experiments aimed at understanding the early signaling events may help to explain the underlying mechanisms involved in conferring herbivore protection. We propose a dual role for auxins in early integrated pest management strategies to maximize plant development and minimize herbivory through feasible, cost-effective water dipping treatments. Full article

Small heat shock proteins (sHSPs) comprise numerous proteins with diverse structure and function. As molecular chaperones, they play essential roles in various biological processes, especially under thermal stresses. In this study, we identified three sHSP-encoding genes, LtHSP19.5, LtHSP20.8 and LtHSP21.7b from Liriomyza trifolii, an important insect pest of ornamental and vegetable crops worldwide. Putative proteins encoded by these genes all contain a conserved α-crystallin domain that is typical of the sHSP family. Their expression patterns during temperature stresses and at different insect development stages were studied by reverse-transcription quantitative PCR (RT-qPCR). In addition, the expression patterns were compared with those of LtHSP21.3 and LtHSP21.7, two previously published sHSPs. When pupae were exposed to temperatures ranging from −20 to 45 °C for 1 h, all LtsHSPs were strongly induced by either heat or cold stresses, but the magnitude was lower under the low temperature range than high temperatures. Developmentally regulated differential expression was also detected, with pupae and prepupae featuring the highest expression of sHSPs. Results suggest that LtsHSPs play a role in the development of the invasive leaf miner fly and may facilitate insect adaptation to climate change. Full article