Although many reports suggested the economic importance of the red imported fire ant, Solenopsis invicta Buren, few attempts to test the hypothesis that the red imported fire ant-aphid mutualism enhances the occurrence of red imported fire ant on crops, thereby interfering with their flowering and fruiting and affecting their output. To address this problem, we compare the effects of red imported fire ant on the flowering and fruiting of self-pollinating and cross-pollinating crops by field investigations and indoor experiments. In the field, our results revealed that regardless of the aphid interaction, red imported fire ant preferred flowering mungbean plants, and their activities decreased the yields of single plants, total pod number, kernel number, and kernel weight. The interaction of red imported fire ant and aphids generated unfavorable effects on rapeseed yields per plant, total pod number, grain number, grain weight, and thousand-kernel weight and stimulated an elevated proportion of malformed seeds. However, the differences were not significant if only red imported fire ant was present. In the laboratory, although red imported fire ant display no apparent preference toward the seedlings of mungbean or rapeseed, the ants clearly favor the flowering plants of mungbeans. Therefore, this study indicated that one of the main mechanisms whereby red imported fire ants affect the crop yield is by compromising the reproduction processes.

The six species of the genus Andraca Walker hitherto known from China are reviewed, and a new species, A. gongshanensis, sp. n., described from Yunnan Province,

Bactrocera dorsalis is a highly invasive and destructive pest distributed worldwide. Chemical insecticides remain the primary measure for their control; however, this species has already developed resistance to several insecticides. In recent years, there have been several reports of monitoring B. dorsalis resistance in China, but continuous monitoring results are lacking and do not even span a decade. In this study, we monitored the dynamics of resistance to seven insecticides among 11 geographically distinct Chinese populations of B. dorsalis (2010–2013; follow-up in 2023). The 11 populations were found to adapt rapidly to antibiotic insecticides (spinosad, emamectin benzoate, and avermectin), reaching high levels of insecticide resistance in several areas. Overall, a decreasing trend in resistance to organophosphorus insecticides (chlorpyrifos and trichlorfon) was observed, whereas pyrethroid (beta-cypermethrin and cyhalothrin) resistance trends were observed to both increase and decrease. The monitoring of field resistance among different B. dorsalis populations over the duration of this study is important for improving the efficiency and sustainability of agricultural pest management, and the results provide a scientific basis for the development of more effective resistance management strategies.

Predation by red imported fire ants, Solenopsis invicta on oriental fruit fly, Bactrocera dorsalis puparia was evaluated. No significant olfactory response of the workers was observed at 0, 2 and 4 days after fly pupation, whereas the workers were significantly attracted by the 6th day old puparia. We found S. invicta that predated on puparia of B. dorsalis in the field. The predation rate was negatively correlated with the depth of puparia in the soil. The predation rate was 70% at 4 cm depth; whereas, zero predation rate was observed at 6 cm depth. The predation rate was also significantly affected by soil moisture. The predation rate was 66.5% and 72.1% at soil moisture values of 40% and 80%, respectively, and no predation occurred at soil moisture value of 0%.

Geographic isolation is an important factor that limit species dispersal and thereby affects genetic diversity. Because islands are often small and surrounded by a natural water barrier to dispersal, they generally form discrete isolated habitats. Therefore, islands may play a key role in the distribution of the genetic diversity of insects, including flies. To characterize the genetic structure of island populations of Bactrocera dorsalis, we analyzed a dataset containing both microsatellite and mtDNA loci of B. dorsalis samples collected from six offshore islands in Southern China. The microsatellite data revealed a high level of genetic diversity among these six island populations based on observed heterozygosity (Ho), expected heterozygosity (HE), Nei’s standard genetic distance (D), genetic identity (I) and the percentage of polymorphic loci (PIC). These island populations had low F ST values (F ST = 0.04161), and only 4.16 % of the total genetic variation in the species was found on these islands, as determined by an analysis of molecular variance. Based on the mtDNA COI data, high nucleotide diversity (0.9655) and haplotype diversity (0.00680) were observed in all six island populations. F-statistics showed that the six island populations exhibited low or medium levels of genetic differentiation among some island populations. To investigate the population differentiation between the sampled locations, a factorial correspondence analysis and both the unweighted pair-group method with arithmetic mean and Bayesian clustering methods were used to analyze the microsatellite data. The results showed that Hebao Island, Weizhou Island and Dong’ao Island were grouped together in one clade. Another clade consisted of Shangchuan Island and Naozhou Island, and a final, separate clade contained only the Wailingding Island population. Phylogenetic analysis of the mtDNA COI sequences revealed that the populations on each of these six islands were closely related to different populations on mainland China. Our study suggests that these island populations have high genetic diversity, experience frequent gene flow and exhibit low or medium levels of genetic differentiation among some island populations. Therefore, the geographic isolation of the six islands does not appear to be a major dispersal barrier to B. dorsalis. Such knowledge is helpful for a better understanding of evolutionary processes of the species of island populations.