Journal of Economic Entomology

Xu, Wei; Lyu, Baoqian; Yan, Sanqiang; Song, Yaoyao; Tang, Jihong; Zhou, Xiaojuan; Wang, Chongtian

doi: 10.1093/jee/toae087pmid: 38700485

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Spodoptera litura (Fabricius) are the main pests on corn (Poaceae: Gramineae). The performance of the larval wasp, Microplitis pallidipes Szépligeti (Hymenoptera: Braconidae), was reported on S. frugiperda and S. litura. In this study, we evaluated host selectivity, constructed an age–stage, 2-sex life table, and assessed the pest control potential of M. pallidipes against these 2 pests under laboratory conditions. In a 2-choice host preference experiment, M. pallidipes exhibited a stronger preference for S. frugiperda over S. litura and a distinct preference for second instars. We also investigated the parasitism of females that were either unfed or fed with 10% honey–water solution under different host densities and found that the highest parasitism rate was observed when M. pallidipes were fed with honey–water solution on the first day after mating and a presented female wasp:host ratio of 1:90. In a nonselective assay, M. pallidipes successfully completed a full generation on both hosts. However, the parasitoids exhibited higher fitness and population growth potential when reared on S. frugiperda, with a net reproductive rate (R0) of 24.24, an intrinsic rate of increase (r) of 0.20 per day, a finite rate of increase (λ) of 1.23 per day, and a mean generation time (T) of 15.69 days. This study elucidates the performance of M. pallidipes on 2 Spodoptera host species and offers insights into its biological control potential on lepidopteran pests.

Kratz, Madlen; Manning, Robert; Dods, Kenneth; Baer, Boris; Blache, Dominique

doi: 10.1093/jee/toae045pmid: 38606526

Nutrition has been identified as a key driver of colony health and productivity. Yet, in honey bees, relatively little is known about how the vast variety of natural pollen sources impact larval development. The impact of the nutritional quality of 4 naturally occurring pollen sources, of importance to the Western Australian beekeeping industry, was tested on honey bee (Apis mellifera L.) development. Bee packages consisting of 800 g of bees and a mated sister queen were assigned to 40 nucleus hives and randomly allocated to one of the 4 feed treatments (10 colonies each) of marri (Corymbia calophylla Lindl.), jarrah (Eucalyptus marginata Sm.), clover (Trifolium repens L.), and canola (Brassica napus L.) pollen. Emerging bees were collected once the first bees started hatching on the assigned feed sources. Newly emerging bees were weighed individually, and body composition was measured in batches according to the feed treatment groups. Food consumption was recorded for the duration of the experiment. Nurse bees successfully raised young adult workers from the larval stage until emergence when fed with one of 4 pollen patties with different nutritional qualities. There was no difference in the body composition or weight of emerging bees fed on the different pollen types. However, the body weight of bees increased over time, most likely related to colony size and structure. With the type of pollen patties having little impact on larval development, the availability of pollen may be more important than its composition, providing bees have access to all essential nutrients.

Yang, Xinyu; Wang, Mei; Gu, Yifan; Han, Wensu; Li, Xiaoyu; Li, Xiang; Zhong, Yihai; Gao, Jinglin

doi: 10.1093/jee/toae051pmid: 38592125

Given the rapid spread and potential harm caused by the small hive beetle, Aethina tumida (Coleoptera: Nitidulidae) in China, it has become imperative to comprehend the developmental biology of this invasive species. Currently, there is limited knowledge regarding the impact of A. tumida female oviposition site preference on larval growth and development. To examine this, we investigated the ovipositional preference of adult female A. tumida on bee pupae, beebread, banana, and honey through a free choice test. Furthermore, we assessed the impact of these food resources on offspring performance, which included larval development time, survival, wandering larvae weight, emerged adult body mass, reproduction, and juvenile hormone titer. Our results showed that A. tumida females exhibited a strong preference for ovipositing on bee pupae compared to other diets, while showing reluctance toward honey. Moreover, A. tumida larvae that were fed on bee pupae displayed accelerated growth compared to those fed on other diets. Furthermore, A. tumida fed on bee pupae exhibited higher weights for wandering larvae, and emerged adult, increased pupation rates, enhanced fecundity and fertility, as well as a larger number of unilateral ovarioles during the larval stage when compared to those fed on other diets. Overall, the results indicate that the oviposition preferences of A. tumida females are adaptive, as their choices can enhance the fitness of their offspring. This finding aligns broadly with the hypothesis of oviposition preference and larval performance. This study can provide a foundation for the development of attractants aimed at promoting the oviposition of the A. tumida adults.

Xu, Jin; Zhang, Zhengyi; Guo, Yulong; Yang, Huipeng; Li, Xiaoying; Guo, Yueqin; Zeng, Huayan; Wu, Yueguo; Yao, Jun; Li, Jilian

doi: 10.1093/jee/toae053pmid: 38630485

Wild bumble bees (Hymenoptera: Apidae) play a vital role in agro-ecosystems as important pollinators. However, they are threatened by virus pathogens that are widespread in honey bees. Previous studies have reported that viruses were able to be transmitted across bee genera and caused potential danger to wild bumble bees. China is a global biodiversity hotspot for bumble bees. However, the impact of viruses on the wild bumble bee communities remains elusive. Black queen cell virus (BQCV) is one of the most common honey bee viruses. Here, a total of 72 wild bumble bee samples from 17 geographic regions of China were tested for BQCV. Thirteen positive samples were identified and sequence comparison of partial capsid genes demonstrated a genetic identity of 99.69% to 100%. A phylogenetic tree analysis also showed a close relationship between 13 BQCV isolates and others from a variety of recorded hosts in China. Meanwhile, a distinct evolutionary branch of China isolates was formed when clustering isolates from worldwide bumble bee species. A correlation between BQCV and their geographic locations were observed (P < 0.05). This study not only provides the first evidence of widespread BQCV in wild bumble bee communities in China but also detects a distinct set of genetically identical or closely related BQCV variants that circulate and evolutionarily differ from other countries.

Li, Qunchen; Wang, Yuhua; Qi, Guojun; Fan, Min; Ye, Tongen; Wang, Gang; Shi, Daxia; He, Yurong; Wang, Desen

doi: 10.1093/jee/toae067pmid: 38665095

Hot water mound drench treatment has broad application prospects in the control of the red imported fire ant (RIFA), Solenopsis invicta Buren (Hymenoptera: Formicidae). However, much work still needs to be carried out to provide a theoretical basis and technical support for the use of this method against RIFAs under field conditions. In this study, we monitored the temperature changes at different depths within RIFA nests during laboratory-simulated hot water mound drench experiments and evaluated the lethal effect of hot water treatment on RIFAs. Furthermore, the targeted removal effect of hot water mound drench treatment on RIFA nests under field conditions was evaluated. Results indicated that the temperature at depths of 5, 15, and 25 cm inside the simulated ant nests was higher than 51.1 °C within 30 min after treatment, resulting in a 100% mortality rate for RIFAs at all tested depths. Under field conditions, when nests were disturbed, the percentage of RIFAs crawling out of their nests gradually increased with time after disturbance, reached its maximum value at 25 or 30 s after the disturbance, and then gradually decreased. Single hot water mound drench treatment (each ant nest was treated with 17.8–21.6 liter of hot water at a temperature of 97–100 °C) can significantly reduce the RIFA population in ant nests and lead to a 72.7% reduction in the number of surviving ant nests. However, the safety, operability, and timelines of hot water mound drench treatment for RIFA field control still need further investigation.

Lennon, Kylie; Querejeta, Marina; Dutta, Bhabesh; Johnson, Caroll; Schmidt, Jason M

doi: 10.1093/jee/toae064pmid: 38597635

Weed management is challenging for vegetable crops that are highly sensitive to weed competition, such as onions. Thrips (Thysanoptera: Thripidae) are major insect pests of onions, causing damage through feeding, and vectoring bacterial pathogens causing bulb rot. Both thrips and their associated pathogens are known to survive on many weed species in onion growing regions. Combining weeding with biopesticides may synergistically manage thrips and reduce disease prevalence. However, disturbances from weeding may negatively impact natural enemies. We estimated the effects of organic weed management and biopesticides on weed density, thrips and natural enemy activity, disease severity, and yield. The experiment was a randomized complete block design, with 4 replications of each weeding (control, tine-weeded twice, tine-weeded 4 times, and hand-weeded) and biopesticide (control, OxiDate 2.0, Serenade) combination. Arthropods were monitored using yellow sticky cards, and weed counts, marketable yield, and bulb rot prevalence were estimated. Hand-weeding resulted in the lowest weed density and thrips abundance. Additionally, hand-weeding produced a 9× higher yield compared to all other treatments. Significant interactions were observed between tine-weeding and biopesticide treatments on the prevalence of bulb rot. Natural enemy abundance was slightly negatively impacted by weeding, dependent on the year. DNA metabarcoding results showed high parasitoid diversity in this onion system and high numbers of reads for multiple genera containing important known biological control agents. Our study suggests hand-weeding is necessary in the southeast for maximum onion yield. Future research should focus on exploring the impact of management on natural enemy communities in onion systems on a large scale.

Roldán, Erik L; Stelinski, Lukasz L; Pelz-Stelinski, Kirsten S

doi: 10.1093/jee/toae089pmid: 38701242

Wolbachia pipientis is a maternally inherited intracellular bacterium that infects a wide range of arthropods. Wolbachia can have a significant impact on host biology and development, often due to its effects on reproduction. We investigated Wolbachia-mediated effects in the Asian citrus psyllid, Diaphorina citri Kuwayama, which transmits Candidatus Liberibacter asiaticus (CLas), the causal agent of citrus greening disease. Diaphorina citri are naturally infected with Wolbachia; therefore, investigating Wolbachia-mediated effects on D. citri fitness and CLas transmission required artificial reduction of this endosymbiont with the application of doxycycline. Doxycycline treatment of psyllids reduced Wolbachia infection by approximately 60% in both male and female D. citri. Psyllids treated with doxycycline exhibited higher CLas acquisition in both adults and nymphs as compared with negative controls. In addition, doxycycline-treated psyllids exhibited decreased fitness as measured by reduced egg and nymph production as well as adult emergence as compared with control lines without the doxycycline treatment. Our results indicate that Wolbachia benefits D. citri by improving fitness and potentially competes with CLas by interfering with phytopathogen acquisition. Targeted manipulation of endosymbionts in this phytopathogen vector may yield disease management tools.

Cook, David F; Tufail, Muhammad Shoaib; Voss, Sasha C; Howse, Elliot T; Rogers, Ella K

doi: 10.1093/jee/toae043pmid: 38518379

This study determined a cost-effective larval diet for rearing Calliphora dubia Macquart for use as a potential managed pollinator in Australia. This fly has potential as a pollination species to support honey bees (Apis mellifera). Larvae of C. dubia were reared mostly in meat meals with varying amounts of either whole egg powder, whole eggs (+ shell), bran flakes, skimmed milk powder, brewer’s yeast, or poultry oil. This was done from an economic and production perspective to support commercial rearing. Several laboratory-based studies determined the growth and output from various ingredient combinations. Larvae fed 90% meat meal and 10% whole egg powder developed rapidly through to pupation with a high pupation rate, adult size, and percent adult emergence. Given the high cost and difficulty in sourcing whole egg powder, media comprising mostly meat meals with the addition of bran flakes and whole eggs also supported rapid larval development, pupation rate, and adult emergence. The ideal amount of media/larvae was 0.5 g/larvae to support high pupation rates and adult emergence. Adult eclosion occurred over 4–5 days, even when larvae were laid and fed within 1 h on ample media. Commercial mass rearing would then require daily cohorts of larvae to ensure peak adult fly emergence over 1–2 days for release into a crop. Mass-rearing C. dubia should use meat meal as the base ingredient with bran flakes and whole eggs added and fed at 0.5 g of media/larvae. Based on the current media ingredient costs, rearing 1-m adult C. dubia would cost just over $500 (US$342).

Liu, Qi; Chen, Li-Lin; Wang, Lin-Lin; Sun, Yue; Lai, Yu-Ying; Long, Na-Dang; Shi, Yi-Han; Quan, Li-Fei; Feng, Wan-Qiu; Liang, Gui-Mei; Zhao, Jia-Lin; Zhou, Zi-Qin

doi: 10.1093/jee/toae078

Pu, Shiqi; Fang, Yujia; Yang, Yuhang; Qu, Qingsheng; Liu, Mengjin; Lian, Jialin; Tang, Xudong; Shen, Zhongyuan; Qian, Ping

doi: 10.1093/jee/toae072pmid: 38691061

Microsporidia Nosema bombycis (Nb) is a cellular parasite responsible for pébrine disease in silkworms, significantly impacting the sericulture industry. Long non-coding RNAs (lncRNAs), which are RNA fragments longer than 200 nucleotides, are pivotal in a range of cellular and physiological functions. However, the potential role of silkworm lncRNAs in response to Nb infection remains unknown. This study conducted transcriptome sequencing on both larvae and Nb-infected midguts of silkworms, identifying 1,440 lncRNAs across all examined midgut samples. Within the Nb-infected group, 42 differentially expressed lncRNAs (DElncRNAs) and 305 differentially expressed mRNAs (DEmRNAs) were detected. Functional annotation and pathway analysis showed that these DEmRNAs are mostly involved in metabolism, apoptosis, autophagy, and other key pathways. The co-expression network of DEmRNAs and DElncRNAs illustrates that 1 gene could be regulated by multiple lncRNAs and 1 lncRNA may target multiple genes, indicating that the regulation of lncRNA is intricate and networked. In addition, the DElncRNA-miRNA-mRNA network showed that some DElncRNAs may be involved in the immune response and metabolism through miRNA. Notably, the study observed an increase in lncRNA MSTRG857.1 following Nb infection, which may promote Nb proliferation. These findings offer insights into the complex interplay between insects and microsporidia.