Egg-Associated Germs Induce Salicylate Defenses but Not Render Plant Against a Global Invasive Fruit Fly Effectively

Germs associated with insect eggs can profoundly mediate interactions between host plants and herbivores, with the potential to coordinate plant physiological reactions with cascading effects on insect fitness. An experimental system was established including the oriental fruit fly (OFF, Bactrocera dorsalis) and tomato to examine the functions of egg-associated germs in mediating plant–herbivore interactions. OFF feeding resulted in significantly increased tannins, flavonoids, amino acids, and salicylic acid in the host tomato. These defensive responses of tomato were induced by the egg-associated germs, including Lactococcus sp., Brevundimonas sp., and Vagococcus sp. Tannins and flavonoids had no significant feedback effects on the pupal weight of OFF, while pupal biomass was significantly decreased by tannins and flavonoids in the germ-free treatment. Metabolome analysis showed that OFF mainly induced metabolic changes in carboxylic acid derivatives. Phenylalanine significantly induced downstream metabolic changes associated with phenylpropanoid accumulation. Finally, we conclude that the effects of egg-associated germs played an important role in facilitating OFF population adaptation and growth by mediating plant defenses, which provides a new paradigm for exploring the interaction of plant–pest and implementing effective pest biocontrol

Additional file 1 of Population mixing mediates the intestinal flora composition and facilitates invasiveness in a globally invasive fruit fly

Additional file 1: Supplementary Information for results. Supplementary Information Fig. 1. Differences in invasiveness between the original (Fujian and Hainan) and mixed outbred populations (invasive population) of B. dorsalis. A, pupal weight; B, ovary size at 15 d after emergence; C, number of eggs laid per female per day; D, hatching rate. Supplementary Information Fig. 2. The effects of amino acid and intestinal microbe on body weight of the oriental fruit fly. A, Cephalo-pharyngeal bone length in inbred and outbred populations of B. dorsalis. B, Food intake of B. dorsalis inbred population and outbred population. C, pupal weight of inbred populations supplemented with different amino acids. D, pupa weight after feed exchange between inbred and outbred populations. Supplementary Information Fig. 3. Phenotypic differences between inbred and outbred populations of B. dorsalis. A, pupal weight; B, ovary size at 15 d after adult emergence; C, survival fraction; D, fecundity. Asterisks indicate significant differences (*,p<0.05; **, p<0.01, ***, p<0.001), and ns indicates no significant differences. Supplementary Information Fig. 4. Species compositions of the microbiomes of the intestinal flora and oviposition fluids in F populations of B. dorsalis. A, bacterial composition and relative abundance; B, fungal composition and relative abundance. The inner circle represents the oviposition fluids, and the outer circle represents the intestinal flora. Supplementary Information Fig. 5. Species compositions of the microbiomes of the intestinal flora in the inbred F and the outbred F♀×H♂ populations of B. dorsalis. A, bacterial composition and relative abundance; B, fungal composition and relative abundance. The inner circle represents the inbred F population, and the outer circle represents the outbred F♀×H♂ population. LEfSe diagram of intestinal bacteria (C) and fungi (D) between inbred F and outbred F♀×H♂ populations. Supplementary Information Fig. 6. Species compositions of the microbiomes of the intestinal flora in the inbred H and the outbred H♀×F♂ populations of B. dorsalis. A, bacterial composition and relative abundance; B, fungal composition and relative abundance. The inner circle represents the inbred H population, and the outer circle represents the outbred H♀×F♂ population. LEfSe diagram of intestinal bacteria (C) and fungi (D) between inbred H and outbred H♀×F♂ populations. Supplementary Information Table 1. The artificial diet of Bactrocera dorsalis. Supplementary Information Table 2. Life table parameters of the inbred and the outbred populations ofB. dorsalis. Supplementary Information for methods. Microbiome determination and analysis: DNA extraction and sequencing. Analysis of microbiome data. Diet exchange experiments

Data_Sheet_1_Including Host Availability and Climate Change Impacts on the Global Risk Area of Carpomya pardalina (Diptera: Tephritidae).docx

Fruit flies are a well-known invasive species, and climate-based risk modeling is used to inform risk analysis of these pests. However, such research tends to focus on already well-known invasive species. This paper illustrates that appropriate risk modeling can also provide valuable insights for flies which are not yet “on the radar.” Carpomya pardalina is a locally important cucurbit-infesting fruit fly of western and central Asia, but it may present a risk to other temperate countries where melons are grown. MaxEnt models were used to map the risk area for this species under historical and future climate conditions averaged from three global climate models under two shared socio-economic pathways in 2030 and 2070 from higher climate sensitivity models based on the upcoming 2021 IPCC sixth assessment report. The results showed that a total of 47.64% of the world’s land mass is climatically suitable for the fly; it could establish widely around the globe both under current and future climates with host availability. Our MaxEnt modeling highlights particularly that Western China, Russia, and other European countries should pay attention to this currently lesser-known melon fly and the melons exported from the present countries. The current and expanding melon trade could offer direct invasion pathways to those regions. While this study offers specific risk information on C. pardalina, it also illustrates the value of applying climate-based distribution modeling to species with limited geographic distributions.</p

Estimated proportion of diet for <i>P. japonica</i> adults originating from C₃-based resources and/or C₄-based resources in the field from 2008–2010.^a

a<p>Proportions of diet for <i>P. japonica</i> adults were estimated based on the carbon isotope ratio linear equation and δ¹³C value of <i>P. japonica</i> adults collected in field.</p

Carbon isotope ratios of <i>P. japonica</i> adults in laboratory.

<p>(<b>A</b>) Carbon isotope ratios of plant and insect species used in dietary switching experiment. Carbon isotope ratios (mean δ¹³±SD) of plants (cotton and maize), aphids from cotton and maize, and <i>P. japonica</i> adults. Adult (C3) was raised on cotton aphids. Adult (C4) was raised on maize aphids. MV, middle δ¹³C values of <i>P. japonica</i> adults was −16.71‰ as the proportion of aphids from a C₃-based resource and a C₄ -based resource was 50%. Error bars indicate the SD. (<b>B</b>) Carbon isotope ratios of <i>P. japonica</i> adults in dietary switching experiment. Carbon isotope ratios (mean δ¹³±SD) of laboratory-reared <i>P. japonica</i> adults (▴) before and after a shift in diet from a C₃-based resource (cotton aphids reared on cotton) to one based on C₄ plants (maize aphids reared on maize). (<b>C</b>) Relationship of δ¹³C values of <i>P. japonica</i> and proportions of aphids form C₃ and C₄-based resource. Aphids were from a C₃-based resource and a C₄ -based resource on which they were grown in the laboratory. The ladybird beetles were grown from eggs to adults on five food mixtures consisting of, respectively, 100% cotton aphids/0% maize aphids, 75% cotton aphids/25% maize aphids, 50% cotton aphids/50% maize aphids, 25% cotton aphids/75% maize aphids and 0% cotton aphids/100% maize aphids. Linear equation Y = 0.120X-22.723 (<i>F</i> = 57.08, <i>P</i> = 0.005, <i>R</i>² = 0.95): where Y is δ¹³ values of <i>P. japonica</i>, X is proportion of aphids from a C₃-based resource and a C₄-based resource.</p

Relationship between <i>P. japonica</i> eggs, larva and adults and and aphids in landscape plots during 2008, 2009 and 2010.^a

a<p>x is the aphid density data, which was log-transformed (ln(n+1)) for analysis. y is density of <i>P. japonica</i> eggs, larva and adults.</p

Dynamics of <i>P. japonica</i> larvae.

<p>Densities of <i>P. japonica</i> larvae in cotton patches (black triangle) and maize patches (red circle) in field landscape plots in 2008 (<b>A</b>), 2009 (<b>B</b>), and 2010 (<b>C</b>). *Significant differences between densities of <i>P. japonica</i> larvae in cotton patches and maize patches at p<0.05. **Significant differences between densities of <i>P. japonica</i> larvae in cotton patches and maize patches at p<0.01. Densities of accumulative <i>P. japonica</i> larvae in cotton patches and maize patches at all sample dates of field landscape plots in 2008 (<b>D</b>), 2009 (<b>E</b>) or 2010 (<b>F</b>). Different lowercases above the bars indicate significant differences in densities of accumulative <i>P. japonica</i> larvae in cotton patches and maize patches at p<0.05. Data are presented as adults per square meter of crop plants (mean±SE) with separate field landscape plots used as replicates. Sample size of cotton patch and maize patch are both 20. N indicates the size of samples tested.</p

Dynamics of aphid density.

<p>Aphid density in cotton patches (black triangle) and maize patches (red circle) in field landscape plots in 2008 (<b>A</b>), 2009 (<b>B</b>), and 2010 (<b>C</b>). The data for aphid density were log-transformed (ln(n+1)). *Significant differences between densities of aphid in cotton patches and maize patches at p<0.05. **Significant differences between densities of aphid in cotton patches and maize patches at p<0.01. Densities of accumulative aphid in cotton patches and maize patches at all sample dates of field landscape plots in 2008 (<b>D</b>), 2009 (<b>E</b>) or 2010 (<b>F</b>). Different lowercases above the bars indicate significant differences in densities of accumulative aphid in cotton patches and maize patches at p<0.05. Data are presented per square meter of crop plants (mean±SE) with separate field landscape plots used as replicates. Sample size of cotton patch and maize patch are both 20. N indicates the size of samples tested.</p

Linear regression between densities of <i>P. japonica</i> adults on maize and landscape shape index of plot.^a

a<p>x is the landscape shape index of plot, y is the densities of <i>P. japonica</i> adults on maize patches of plot.</p>b<p>the densities of <i>P. japonica</i> adults on maize patches in each plot were accumulated in all sample dates in 2008, 2009 or 2010.</p

DataSheet_1_Impacts of climate change on climatically suitable regions of two invasive Erigeron weeds in China.docx

IntroductionErigeron philadelphicus and Erigeron annuus are two ecologically destructive invasive plants from the Asteraceae family. Predicting the potential distribution pattern of two invasive alien Erigeron weeds can provide a scientific basis for prevent the further spread of these two weeds in China under climate change.MethodsBased on historical occurrence datasets and environmental variables, we optimized a MaxEnt model to predict the potential suitable habitats of E. philadelphicus and E. annuus. We also analyzed the shifts of distribution centroids and patterns under climate change scenarios.ResultsThe key variables that affect the potential geographical distribution of E. annuus and E. philadelphicus, respectively, are temperature seasonality and precipitation of the driest month. Moreover, topsoil sodicity and topsoil salinity also influence the distribution of E. philadelphicus. Under climate change, the overall suitable habitats for both invasive alien Erigeron weeds are expected to expand. The potential geographical distribution of E. annuus exhibited the highest expansion under the SSP245 climate scenario (medium forcing scenarios), whereas E. philadelphicus had the highest expansion under the SSP126 climate scenario (lower forcing scenarios) globally. The future centroid of E. annuus is projected to shift to higher latitudes specifically from Hubei to Hebei, whereas E. philadelphicus remains concentrated primarily in Hubei Province. The overlapping suitable areas of the two invasive alien Erigeron plants mainly occur in Jiangsu, Zhejiang, Fujian, Jiangxi, Hunan, Guizhou, and Chongqing, within China.DiscussionClimate change will enable E. annuus to expand into northeastern region and invade Yunnan Province whereas E. philadelphicus was historically the only suitable species. E. annuus demonstrates a greater potential for invasion and expansion under climate change, as it exhibits higher environmental tolerance. The predictive results obtained in this study can serve as a valuable reference for early warning systems and management strategies aimed at controlling the spread of these two invasive plants.</p