Apis mellifera is infected by more than 24 virus species worldwide, mainly positive-sense, single-stranded RNA viruses of the Dicistroviridae and Iflaviridae families. Among the viruses that infect honey bees, Deformed wing virus is the most prevalent and is present as three master variants DWV-A, B, and C. Given that the ectoparasitic mite Varroa destructor vectors these virus variants, recombination events between them are expected, and variants and their recombinants can co-exist in mites and honeybees at the same time. In this study, we detect, through RT-qPCR, the presence of DWV-A and B in the same samples of adult bees from colonies of Argentina. Total RNA was extracted from pools of ten adult bees from 45 apiaries distributed across the main beekeeping Provinces of Argentina (Buenos Aires, Santa Fe, Córdoba, Santiago del Estero, Río Negro, and Mendoza); then RT-qPCR reactions were performed to detect DWV-A and B, with specific primer pairs. After the amplifications, PCR products (204 and 660 bp amplicons for DWV-B, and ~250 bp for DWV-A) were purified and sequenced to verify that they corresponded to reported sequences, analyzing them using the Blast software. Of the 45 samples analyzed by RT-qPCR, over 90% were infected with DWV-A and 47% were also positive for DWV-B, where it was found in high prevalence specifically in colonies of A. mellifera of the Buenos Aires Province. Future studies will determine the impact of this type of the virus and its ability to recombine with the other DWV types in the apiaries of our country.

Tenuisvalvae notata (Mulsant) (Coccinellidae) is a predatory ladybird beetle native to South America. It specializes in mealybugs prey (Pseudococcidae), but relatively little is known about its ecology. In contrast, the ladybird beetle Cryptolaemus montrouzieri Mulsant (Coccinellidae) is indigenous to Australia and has been introduced to many countries worldwide including Brazil for biological control of mealybugs. The potential impacts of these introductions to native coccinellids have rarely been considered. The software CLIMEX estimated the climate suitability for both species as reflected in the Ecoclimatic Index (EI). Much of South America, Africa, and Australia can be considered climatically suitable for both species, but in most cases, the climate is considerably more favorable for C. montrouzieri than T. notata, especially in South America. The CLIMEX model also suggests seasonal differences in growth conditions (e.g. rainfall and temperature) that could affect the phenology of both species. These models suggest that few locations in South America would be expected to provide T. notata climatic refugia from C. montrouzieri. Although other ecological factors will also be important, such as prey availability, this analysis suggests a strong potential for displacement of a native coccinellid throughout most of its range as a consequence of the invasion by an alien competitor.

The small tomato borer, Neoleucinodes elegantalis (Guenée, 1854) is a multivoltine pest of tomato and other cultivated solanaceous plants. The knowledge on how N. elegantalis respond to temperature may help in the development of pest management strategies, and in the understanding of the effects of climate change on its voltinism. In this context, this study aimed to select models to describe the temperature-dependent development rate of N. elegantalis and apply the best models to evaluate the impacts of climate change on pest voltinism. Voltinism was estimated with the best fit non-linear model and the degree-day approach using future climate change scenarios representing intermediary and high greenhouse gas emission rates. Two out of the six models assessed showed a good fit to the observed data and accurately estimated the thermal thresholds of N. elegantalis. The degree-day and the non-linear model estimated more generations in the warmer regions and fewer generations in the colder areas, but differences of up to 41% between models were recorded mainly in the warmer regions. In general, both models predicted an increase in the voltinism of N. elegantalis in most of the study area, and this increase was more pronounced in the scenarios with high emission of greenhouse gases. The mathematical model (74.8%) and the location (9.8%) were the factors that mostly contributed to the observed variation in pest voltinism. Our findings highlight the impact of climate change on the voltinism of N. elegantalis and indicate that an increase in its population growth is expected in most regions of the study area.

Since its arrival in 2004, the non-native Harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae) has rapidly spread throughout Britain, and it is now the most common coccinellid in England. There have since been concerns about the detrimental effects it may have on native coccinellids because there is a strong correlation between the arrival of H. axyridis and the decline in native species, including the two-spot ladybird, Adalia bipunctata. However, there have been few studies of the behavioural interactions between these two species, which occupy a high-niche overlap. This study investigated if the presence of H. axyridis impacts the feeding behaviour of A. bipunctata through direct competition for aphid prey. Foraging and interactive behaviour of A. bipunctata and H. axyridis were investigated within microcosms. Adalia bipuncata exhibited a similar consumption rate and time in the presence of H. axridis, yet H. axyridis consumed 3.5 times more prey items and were seven times faster compared to A. bipuncata. Observations showed that H. axyridis does not directly disrupt the feeding behaviour of A. bipunctata, but rather indirectly excludes the native species through being a superior competitor for prey items. Results indicate that the decline in native coccinellid species may be a consequence of H. axyridis competitive advantage, but that the concept of coexistence should not be dismissed.

Monochamus alternatus Hope (Coleoptera: Cerambycidae) warrants attention as a dominant transmission vector of the pinewood nematode, and it exhibits tolerance to high temperature. Heat shock protein 70 (HSP70) family members, including inducible HSP70 and heat shock cognate protein 70 (HSC70), are major contributors to the molecular chaperone networks of insects under heat stress. In this regard, we specifically cloned and characterized three MaltHSP70s and three MaltHSC70s. Bioinformatics analysis on the deduced amino acid sequences showed these genes, having close genetic relationships with HSP70s of Coleopteran species, collectively shared conserved signature structures and ATPase domains. Subcellular localization prediction revealed the HSP70s of M. alternatus were located not only in the cytoplasm and endoplasmic reticulum but also in the nucleus and mitochondria. The transcript levels of MaltHSP70s and MaltHSC70s in each state were significantly upregulated by exposure to 35–50°C for early 3 h, while MaltHSP70s reached a peak after exposure to 45°C for 2–3 h in contrast to less-upregulated MaltHSC70s. In terms of MaltHSP70s, the expression threshold in females was lower than that in males. Also, both fat bodies and Malpighian tubules were the tissues most sensitive to heat stress in M. alternatus larvae. Lastly, the ATPase activity of recombinant MaltHSP70-2 in vitro remained stable at 25–40°C, and this recombinant availably enhanced the thermotolerance of Escherichia coli. Overall, our findings unraveled HSP70s might be the intrinsic mediators of the strong heat tolerance of M. alternatus due to their stabilized structure and bioactivity.

Tuta absoluta (Meyrick) is considered as a major pest of tomato worldwide that causes significant losses in the crop production. This study aimed to evaluate integration of two effective and environmentally safe methods (host plant resistant and biological control) for sustainable management of the pest under greenhouse conditions. The experiment was conducted based on the factorial design with ten replicates under greenhouse conditions (22 ± 3°C, 50 ± 10 RH and 14 L:10 D photoperiod). Infestation to T. absoluta was conducted at the first-flowering stage of the plants by introducing a pair of newly emerged adults (one female and one male) per plant. Ten days later, the biological agent, Trichogramma brassicae, was released on the treatments by hanging a card contained 50 parasitized eggs in each replicate. Observation was performed weekly on ratio of infested leaves per plant (%), number of larvae/plant, number of mines/leaf and ratio of infested fruits/plant (%). Results indicated that the susceptible variety alone (Izmir) supported the highest ratio of infested leaves (42.92 ± 1.95%), number of larvae/plant (12.86 ± 0.71), number of mines/leaf (1.29 ± 0.07) and infested fruits/plant (18.8 ± 1.10%), whereas the lowest (6.12 ± 0.42%, 1.85 ± 0.13, 0.18 ± 0.02 and 0.12 ± 0.06%, respectively) were observed in combined resistant variety (Cherry) and parasitoid released treatment. Integration of these methods not only decreases damage caused on tomato leaflets and fruits, but also reduces insecticide applications which are adversely impact human health and environment.

Many parasitoid species discriminate already parasitized hosts, thus avoiding larval competition. However, females incur in superparasitism under certain circumstances. Superparasitism is commonly observed in the artificial rearing of the parasitoid Diachasmimorpha longicaudata, yet host discrimination has been previously suggested in this species. Here, we addressed host discrimination in virgin D. longicaudata females in a comprehensive way by means of direct and indirect methods, using Ceratitis capitata and Anastrepha fraterculus which are major fruit fly pests in South America. Direct methods relied on the description of the foraging behaviour of females in arenas with parasitized and non-parasitized host larvae. In the indirect methods, healthy larvae were offered to single females and the egg distributions were compared to a random distribution. We found that D. longicaudata was able to recognize parasitized host from both host species, taking 24 h since a first parasitization for A. fraterculus and 48 h for C. capitata. Indirect methods showed females with different behaviours for both host species: complete discrimination, non-random (with superparasitism), and random distributions. A larger percentage of females reared and tested on A. fraterculus incurred in superparasitism, probably associated with higher fecundity. In sum, we found strong evidence of host discrimination in D. longicaudata, detecting behavioural variability associated with the host species, the time since the first parasitization and the fecundity of the females.

The short-lived polygamous moth Grapholita molesta (Busck) is an important fruit pest worldwide. Trapping males by synthetic female sex pheromones is not an effective reproductive control strategy. It is important to improve this technology by understanding the mating system of G. molesta. This study investigated mating opportunities and fertile egg production by altering the operational sex ratio, mating age, and male mating history in repeated single mating and multiple mating in the two sexes. Our results showed that the mating and reproductive parameters of virgin males were affected by the number and age of virgin females. Males preferred a female number ≤three-fifths of the male number or ≤2-day-old females, while they discriminated against a female number ≥three times of the male number or ≥5-day-old females. On the other hand, the mating and reproductive parameters of virgin females were affected by repeated single mating and especially multiple mating under different male mating histories. Females preferred once-mated males and discriminated against virgin males. These results indicated that mating systems including more and older virgin females for virgin males and different virgin males for virgin females may be suitable for suppressing G. molesta populations. Hence, these results revealed that preventing mating of virgin adults by synthetic female sex pheromones should be most effective in controlling G. molesta.

The water hyacinth grasshopper Cornops aquaticum (Bruner 1906) constitutes an appropriate model to assess phenotypic and karyotypic variability in the context of differentiation and adaptation of insect populations because it occurs over a wide latitudinal range. This study represents a general analysis of phenotype, karyotype and molecular variation in native populations of C. aquaticum in South America. This is also relevant because this insect is considered a promising biological control agent of water hyacinth, a native South American aquatic plant but a pest in South Africa. Along Paraná and Uruguay River Basins, body size correlated negatively with latitude, and positively so with temperature and rainfall in both sexes. To test whether the chromosomal and phenotypic patterns were adaptive, we compared them with neutral microsatellite loci variation in populations from the medium and lower course of the Paraná River. Firstly, the lack of pairwise association between karyotype and phenotype distance matrixes with that of neutral loci suggested non-neutrality. Secondly, phenotypic differentiation for all morphometric traits (PST) was significantly larger than molecular differentiation (FST), indicating a prevailing divergence selection effect on the observed phenotypic patterns. Finally, the phenotypic and genotypic spatial structures – inferred from Bayesian approaches – were discordant: neutral genetic structure clustered together most populations except for the two southernmost, downstream ones, whereas phenotypic spatial structure groups together all the deltaic populations and singles out the two northernmost ones. The results suggest directional selection leading to higher centric fusion frequencies in the downstream populations and favouring morphometric optimal differences in relation to the environment.

Andrena camellia Wu is one of the primary pollinators of Camellia oleifera A. in China. In this paper, the essential number of individuals for efficient pollination by this species was calculated via two criteria, based on various indicators including counts of pollen grains in provisions, from single visits, and from single foraging trips overall; single flower visit duration; single flight period duration; number of eggs laid by a single female over their lifetime; and the average number of flowers per plant. Based on the number of pollen grains collected per flower visit, the essential number of females necessary is 2107 in a 1-ha Camellia oleifera garden with 1800 plants, while only 1998 female individuals are essentially needed when estimated based on the mean number of pollen grains collected in a single flight period. We argue that the essential number estimated by the former method is more reasonable and accurate for practical applications.

Mexican beetle, Zygogramma bicolorata Pallister (Coleptera: Chrysomelidae) is a potential weed control biocontrol agent in Australia, India and other countries. Its grubs and adults feed on the leaves of parthenium weed, Parthenium hysterophorus and check the further growth of the plant. Experiments were conducted to understand host plant-mediated effects of elevated temperature and elevated CO2 on biocontrol agent Z. bicolorata. Food consumption, utilization, ecological efficiency and life-table parameters of Z. bicolorata were studied in grubs and adults stage up to diapause. Reduction of leaf nitrogen in parthenium weed foliage with a significant increase in carbon and C:N ratio was recorded at elevated CO2. Elevated CO2 and temperature had no effect on adult longevity before diapausing. Duration of egg's hatching, specific stages of grub and pupa of Z. bicolorata were significantly longer when beetles fed on leaves grown under elevated CO2 but these parameters decreased significantly on leaves grown under elevated temperature. Significantly high consumption rates with low growth and digestion conversions were observed under elevated CO2 and/or in coupled with elevated temperature. Elevated CO2 and temperature-grown parthenium weed foliage also had a significant effect on Z. bicolorata intrinsic rate of increase (R), finite rate of increase (λ), mean generation time (T), and gross reproductive rate. Changed quality of parthenium weed leaves in elevated CO2 and temperature levels resulted in the increase of consumption, slower food conversion rates, increase in developmental period with reduced reproduction efficiency of Z. bicolorata. Our results indicate that the reproduction efficiency of Z. bicolorata is likely to be reduced as the climate changes, despite increased feeding rates exhibited by grubs and adult beetles on parthenium weed foliage.

The oriental armyworm, Mythimna separata (Walker) is a serious pest of agriculture that does particular damage to Gramineae crops in Asia, Europe, and Oceania. Metamorphosis is a key developmental stage in insects, although the genes underlying the metamorphic transition in M. separata remain largely unknown. Here, we sequenced the transcriptomes of five stages; mature larvae (ML), wandering (W), and pupation (1, 5, and 10 days after pupation, designated P1, P5, and P10) to identify transition-associated genes. Four libraries were generated, with 22,884, 23,534, 26,643, and 33,238 differentially expressed genes (DEGs) for the ML-vs-W, W-vs-P1, P1-vs-P5, and P5-vs-P10, respectively. Gene ontology enrichment analysis of DEGs showed that genes regulating the biosynthesis of the membrane and integral components of the membrane, which includes the cuticular protein (CP), 20-hydroxyecdysone (20E), and juvenile hormone (JH) biosynthesis, were enriched. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that DEGs were enriched in the metabolic pathways. Of these DEGs, thirty CP, seventeen 20E, and seven JH genes were differentially expressed across the developmental stages. For transcriptome validation, ten CP, 20E, and JH-related genes were selected and verified by real-time PCR quantitative. Collectively, our results provided a basis for further studies of the molecular mechanism of metamorphosis in M. separata.

Much progress has been made in understanding the environmental and hormonal systems regulating winter diapause. However, transcriptional regulation of summer diapause is still largely unknown, making it difficult to understand an all-around regulation profile of seasonal adaptation. To bridge this gap, comparison RNA-seq to profile the transcriptome and to examine differential gene expression profiles between non-diapause, summer diapause, and winter diapause groups were performed. A total number of 113 million reads were generated and assembled into 79,117 unigenes, with 37,492 unigenes categorized into 58 functional gene ontology groups, 25 clusters of orthologous group categories, and 256 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. KEGG analysis mapped 2108 differentially expressed genes to 48 and 67 pathways for summer and winter diapauses, respectively. Enrichment statistics showed that 11 identical pathways similarly overlapped in the top 20 enriched functional groups both related to summer and winter diapauses. We also identified 35 key candidate genes for universal and differential functions related to summer and winter diapause preparation. Furthermore, we identified some genes involved in the signaling and metabolic pathways that may be the key drivers to integrate environmental signals into the summer and winter diapause preparation. The current study provided valuable insights into global molecular mechanisms underpinning diapause preparation.

With the purpose of broadening knowledge on the evolution of life history strategies and behaviour of fruit flies within the tribe Carpomyini, the natural history and mating behaviour of the poorly known species Rhagoletotrypeta pastranai Aczél, are described for the first time. Larvae of R. pastranai were recovered from infested Celtis tala Gillies ex Planch and Celtis iguanaea (Jacq.) Sarg. during a 2-month fruiting period. Adults emerged from the recovered pupae after an average of 144.9 ± 3.9 days for females and 143.2 ± 3.38 days for males, suggesting that most individuals became dormant. Results of a variable winter length study suggested that environmental factors other than winter length may regulate dormancy/diapause duration in this subtropical species. Under laboratory conditions, R. pastranai adults lived an average of 51.13 ± 3.06 days in case of females and 48.08 ± 3.76 days in case of males, and required 5–15 days to reach sexual maturity. Behavioural observations under confinement revealed scarce sexual activity but sufficed to determine that, as in other members of the tribe Carpomyini, R. pastranai exhibits a male resource defence mating system. We discuss our findings emphasizing the importance of documenting the natural history and behaviour of unknown species of family Tephritidae and additionally, we highlight the necessity of future research to understand factors regulating dormancy/diapause and the evolution of life history strategies and sexual behaviour of subtropical species.

The performance of six grain storage technologies for the control of insect pests in maize was evaluated over a 36-week (9-month) storage period. The six technologies used were: two ZeroFly® hermetic bag brands (laminated and non-laminated); Purdue Improved Crop Storage (PICS) bag; non-hermetic ZeroFly® bag; woven polypropylene (PP) bag containing maize grain treated with Actellic Gold® Dust (pirimiphos-methyl 1.6% + thiamethoxam 0.3%) and woven PP bag containing untreated grain. Each bag was filled with 50 kg maize grain and four replicates of each were set up. With the exception of the non-hermetic ZeroFly® bag, 50 live adults of the larger grain borer Prostephanus truncatus and of the maize weevil Sitophilus zeamais, were introduced into all the bags. Insects were not introduced into the non-hermetic ZeroFly® bag to assess its effectiveness in repelling infestation from outside. Parameters recorded were gas composition (oxygen and carbon dioxide) levels inside the bags; weight of flour generated by insect feeding activities; grain moisture level; live adult insect counts; grain damage and weight loss; grain germination rate and aflatoxin level. At termination, the plastic liners of the hermetic bags were examined for perforations. Results show that oxygen depletion and carbon dioxide evolution were faster in ZeroFly® hermetic compared to PICS bags. Throughout the 36-week storage trial, grain damage remained below 4% and weight loss below 3% in all the treatments except in the untreated PP bags in which it increased to 81.1 and 25.5%, respectively. The hermetic PICS, ZeroFly® and Actellic Gold dust-treated PP bags maintained grain germination at 60%, which was lower than the initial 90%, while in untreated control, it reduced to 4.7%. The mean aflatoxin levels fluctuated between 0.39 and 3.56 parts per billion (ppb) during 24 weeks of storage in all the technologies tested, which is below the acceptable maximum level of 10 ppb in maize. Based on the evaluation results, it can be concluded that hermetic PICS and ZeroFly® bags and woven PP bag with Actellic Gold dust-treated grain effectively protected stored maize grain from insect attack and weight losses. Appropriate strategies and mechanisms for the effective and efficient adoption of hermetic storage bag technology at scale would contribute towards global food security.

The cotton whitefly, Bemisia tabaci Gen. (Hem., Aleyrodidae), is a key pest of many vegetables. Entomopathogenic fungi are promising microbial control agents against B. tabaci, but limited information is available concerning indigenous Iranian isolates. In this study, three isolates of Akanthomyces lecanii (PAL6, PAL7, and PAL8) and one isolate of A. muscarius (AGM5) were obtained from citrus hemipteran pests, Pulvinaria aurantii Cock. and Aphis gossypii Glover, in Mazandaran province, northern Iran. The isolates were then morphologically and molecularly identified. The efficacies of five different agar media for vegetative growth and conidiation of each isolate were determined. Potato dextrose agar was the medium on which the fungal mycelia developed at a relatively high rate. However, the highest rate of conidiation was found on Sabouraud dextrose agar. To determine the effects of the isolates on B. tabaci, a dose–response bioassay was carried out to estimate lethal concentration (LC50) and lethal time (LT50) values of each fungal isolate to second instar nymphs. The mean LC50 values of A. lecanii isolates ranged from 4.22 × 106 to 7.35 × 1013 conidia ml−1 at 5 to 7 days after the treatment. For A. muscarius, the values varied from 9.2 × 104 to 8.7 × 1010 conidia ml−1 at 5 to 7 days after the treatment. The lowest and the highest mean LC50 values were observed for A. mucarius (AGM5) and A. lecanii (isolate PAL6), respectively. The mean LT50 values of A. lecanii and A. muscarius isolates were 7.1–9.0 and 4.9–7.2 days, respectively. The LT50 values of A. muscarius were significantly lower than the other isolates. Overall, all isolates, especially A. muscarius (AGM5), exhibited appropriate potential as a biological control agent against B. tabaci.

Cold winter temperatures significantly affect the biological control effort against water hyacinth, Pontederia ( = Eichhornia) crassipes Mart. (Pontederiaceae), in more temperate regions around the world. The population dynamics of the planthopper Megamelus scutellaris Berg. (Hemiptera: Delphacidae), a newly released biological control agent of water hyacinth, were recorded on the Kubusi River in the Eastern Cape Province (South Africa) over 15 months to determine the population recovery post-winter. Megamelus scutellaris incurred a severe population decline at the onset of winter when the water hyacinth plants became frost damaged. The combined effect of a population bottleneck and low minimum winter temperatures (6.12°C) below the agent's lower developmental threshold (11.46°C) caused a post-winter lag in agent density increase. Subsequently, the maximum agent population density was only reached at the end of the following summer growing season which allowed the water hyacinth population to recover in the absence of any significant biological control immediately post-winter. Supplementary releases of agents from mass-reared cultures at the beginning of the growing season (spring) is suggested as a potential method of reducing the lag-period in field populations in colder areas where natural population recovery of agents is slower.

Myzus persicae is a cosmopolitan aphid that is highly polyphagous and an important agricultural pest. The subspecies M. persicae nicotianae has been described for highly specialized phenotypes adapted to tobacco (Nicotiana tabacum). In Chile, the population of M. persicae nicotianae was originally composed of a single red genotype that did not possess insecticide resistance mutations. However, in the last decade, variation in the colour of tobacco aphids has been observed in the field. To determine whether this variation stems from the presence of new genotypes, sampling was carried out across the entire distribution of tobacco cultivation regions in Chile. The aphids collected were genotyped, and the frequency of kdr (L1014F), super-kdr (M918T), modification of acetylcholinesterase (MACE) and nicotinic acetylcholine receptor β subunit (nAChRβ) mutations associated with insecticide resistance was determined. A total of 16 new genotypes of M. persicae nicotianae were detected in Chile: four of them possessed the MACE mutation, and none of them possessed the kdr, super-kdr or nAChRβ mutation. The previously described red genotype was not detected in any of the sampled fields over two seasons. These results raise questions about the mechanisms underlying changes in the genetic structure of M. persicae nicotianae populations in Chile. Future research aimed at addressing these questions could provide new insight into aphid evolution and agricultural practices.

The meadow spittlebug, Philaenus spumarius (L.) (Hemiptera: Aphrophoridae), is the main vector in Europe of the recently detected plant pathogen bacterium Xylella fastidiosa Wells et al. (Xanthomonadales: Xanthomonadaceae). While the ecology of continental populations is well documented, nothing is known about the insular populations of P. spumarius, such as in Corsica, where the bacterium was detected in 2015. Hence, in an epidemiological context, the ecology of P. spumarius has been studied in a maquis landscape in the Ajaccio region between 2017 and 2019. Adults and nymphs were almost exclusively collected on Cistus monspeliensis L. (Cistaceae). However, very few specimens were collected in summer, suggesting a movement of the adults to sheltered habitats. Unfortunately, despite several trapping methods used, the location of adult summer habitat remains unknown for the studied population. It might be tempting to destroy the central plant host of P. spumarius populations. However, as spittlebug nymphs are highly polyphagous on low-growing plant species and as the females can lay eggs in any dead plant tissues, such practice could have limited the impact. Instead, the strong relationship between P. spumarius and C. monspeliensis could be used to monitor spittlebug populations, to limit/concentrate the means of insect control, or in an agronomic context to lure insects away from crops. Maintaining natural arboreal vegetation around agronomic systems could help decrease insect abundance – and potentially, pathogen load – on cultivated species. Such hypotheses need to be further studied by landscape experiments.