Bulletin of Entomological Research最新文献

The Asian corn borer, Ostrinia furnacalis (Guenée), emerges as a significant threat to maize cultivation, inflicting substantial damage upon the crops. Particularly, its larval stage represents a critical point characterised by significant economic consequences on maize yield. To manage the infestation of this pest effectively, timely and precise identification of its larval stages is required. Currently, the absence of techniques capable of addressing this urgent need poses a formidable challenge to agricultural practitioners. To mitigate this issue, the current study aims to establish models conducive to the identification of larval stages. Furthermore, this study aims to devise predictive models for estimating larval weights, thereby enhancing the precision and efficacy of pest management strategies. For this, 9 classification and 11 regression models were established using four feature datasets based on the following features geometry, colour, and texture. Effectiveness of the models was determined by comparing metrics such as accuracy, precision, recall, F1-score, coefficient of determination, root mean squared error, mean absolute error, and mean absolute percentage error. Furthermore, Shapley Additive exPlanations analysis was employed to analyse the importance of features. Our results revealed that for instar identification, the DecisionTreeClassifier model exhibited the best performance with an accuracy of 84%. For larval weight, the SupportVectorRegressor model performed best with R² of 0.9742. Overall, these findings present a novel and accurate approach to identify instar and predict the weight of O. furnacalis larvae, offering valuable insights for the implementation of management strategies against this key pest.

Significant differences in life-history traits between the southern population (S) and northern (N) population of the cabbage beetle Colaphellus bowringi make it an excellent model for studying inheritance in this insect. In the present study, we observed the life-history traits of pure strains, F₁, reciprocal backcross and reciprocal F₂ progeny under a photoperiod of L:D 15:9 h at 22 °C. The S population had shorter larval development time, longer pupal time, higher body weight, growth rate and weight loss compared with the N population. In the F₁ testing, the larval development time and body weight in hybrid populations were intermediate between the parents, and the paternal parents played a greater role in determining the larval development time, while the maternal parents exhibited a greater role in determining the body weight. The pupal time of hybrid populations was significantly shorter than that of the parents. In the reciprocal backcross testing, both father and grandfather affected the larval development time, while both mother and grandmother affected the body weight. Consistently, in the reciprocal F₂ cross testing, the grandfather was more influential in determining the larval development time, and grandmother was more important in determining the body weight. In all tested populations, females had greater body weight, higher growth rate and weight loss than males. Hybridization pattern did not affect sex dimorphism and sex ratio. Overall, these findings suggest that different pathways (maternal or paternal effects) were involved in the inheritance of various life-history traits in C. bowringi.

Insect odorant-binding proteins (OBPs) are the key proteins in insect olfactory perception and play an important role in the perception and discrimination of insects. Frankliniella occidentalis is a polyphagous pest and seriously harms the quality and yield of fruits, flowers and crops worldwide. Therefore, the discovery of OBPs has greatly improved the understanding of behavioural response that mediates the chemoreception of F. occidentalis. To identify the OBP gene of F. occidentalis and its sequence and expression, rapid amplification cDNA ends (RACE) and qRT-PCR reaction system were performed. The results showed that the sequence of FoccOBP9 gene was 846 bp and the reading frame was 558 bp, encoding 185 amino acid residues, a 3' non-coding region of 195 bp and a 5' non-coding region of 93 bp.The molecular weight of the protein was about 20.08 kDa, and the isoelectric point was 8.89. FoccOBP9 was similar to AtumGOBP and CnipOBP2 (30%), followed by BdorGOBP, DficGOBP, DsuzGOBP, AalbOBP38, CmarOBP6 and SexiOBP. Phylogenetic analysis of the FoccOBP9 demonstrated that the FoccOBP9 had a relatively close evolutionary relationship with SgreOBP1, AtumGOBP, HeleOBP3, CbowOBP17, CnipOBP2 and CpalOBP2. The prediction of secondary structure showed that FoccOBP9 protein contained 135 amino acid residues forming α-helix, 91 amino acid residues forming β-sheets and 24 amino acid residues forming β-turning. However, three-dimensional structure prediction showed that the FoccOBP9 protein skeleton was composed of six α-helices and the loops connecting these helices. Dynamic observation of the three-dimensional structure revealed that five α-helices (α1, α2, α4, α5, α6) were found in the structure. The expression profiles analysis revealed that FoccOBP9 are highly abundant in antenna significantly, followed by the head and belly, and almost no expression in the chest and foot. Therefore, the identification and analysis of OBP may be useful for monitoring and limiting the damage of F. occidentalis.

Multiple mating is a behaviour observed across various polyandrous insect species. It is suggested that, in ladybirds, this strategy of multiple copulations is used to enhance fecundity and fertility through sperm replenishment. Studies on sperm depletion need to correlate fertility with the presence of spermatozoa in the spermatheca. This study investigates the role of sperm replenishment in the ladybird Cryptolaemus montrouzieri. We hypothesised that females of this species exhibit fecundity and fertility rates proportional to the number of sperm replenishment opportunities (constant, periodic or absent). We observed oviposition behaviour and hatching rates over 30 days, and simultaneously tested for sperm depletion in females that copulated once. We dissected the spermathecae at four post-copulation moments to count spermatozoa under a microscope. Our results indicate that a single copulation suffices to maintain fertility for at least 30 days. Females with constant replenishment opportunities exhibited higher fecundity but lower fertility and increased mortality, suggesting a reproductive cost associated with frequent mating. Females with no replenishment during the experiment, exhibited the highest hatchability rate and lowest oviposition. Periodic copulation resulted in optimal female mating rate, with average fertility and fecundity. A plausible hypothesis would be that paired females choose to fertilise fewer eggs from a single male but are unable to control the effects of the oviposition stimulus induced by the male's presence. These findings have implications for the management and rearing of C. montrouzieri in biological control programmes, optimizing mating strategies for mass production.

The Asian corn borer (ACB), Ostrinia furnacalis (Guenée, 1854), is a serious pest of several crops, particularly a destructive pest of maize and other cereals throughout most of Asia, including China, the Philippines, Indonesia, Malaysia, Thailand, Sri Lanka, India, Bangladesh, Japan, Korea, Vietnam, Laos, Myanmar, Afghanistan, Pakistan and Cambodia. It has long been known as a pest in South-east Asia and has invaded other parts of Asia, Solomon Islands, parts of Africa and certain regions of Australia and Russia. Consequently, worldwide efforts have been increased to ensure new control strategies for O. furnacalis management. In this article, we provide a comprehensive review of the ACB covering its (i) distribution (geographic range and seasonal variations), (ii) morphology and ecology (taxonomy, life-history, host plants and economic importance) and (iii) management strategies (which include agroecological approaches, mating disruption, integrated genetic approaches, chemical as well as biological control). Furthermore, we conclude this review with recommendations to provide some suggestions for improving eco-friendly pest management strategies to enhance the sustainable management of ACB in infested areas.

Parasitoids employ diverse oviposition strategies to enhance offspring survival and maximise fitness gains from hosts. Ladybird parasitoids, significant natural enemies of ladybirds, have the potential to disrupt biocontrol efforts, yet their biology and ecology remain poorly understood. This study investigated the host-parasitoid interaction among three sympatric larval endoparasitoids of Cheilomenes sexmaculata (Coleoptera: Coccinellidae): Homalotylus hemipterinus (Hymenoptera: Encyrtidae), Nothoserphus mirabilis (Hymenoptera: Proctotrupidae) and Oomyzus scaposus (Hymenoptera: Eulophidae). Our objective was to understand host instar preferences from five perspectives related to host profitability, handling difficulty or parasitism decision-making, and to examine the occupation rates of each parasitoid in different host instars. Host profitability was determined by development time, adult offspring dry mass, sex ratio, brood size, parasitism success rate and host handling time. Host handling difficulty was evaluated through host defensive behaviour and handling time. Parasitism decision-making was evaluated through acceptance rate and preference score that considered the first reaction of female wasp to the host. Results showed that each parasitoid responded differently to the host from various perspectives. However, the first two suitable hosts of these parasitoids overlap on the third instar host, with first to third instar hosts being ideal for H. hemipterinus, and third to fourth instar hosts being ideal for N. mirabilis and O. scaposus. In the field, the occupation rate of each parasitoid in third instar host was influenced by the population of N. mirabilis, implying its superior competitiveness. This study reveals the host instar preferences of ladybird parasitoids and highlights the potential for interspecific competition.

The canopy of forests as the 'last biotic frontier' has often been neglected in insect biodiversity studies because it is harder to access compared to the understorey, even in relatively well-known temperate ecosystems. We investigated the diversity, abundance, and body size patterns of macromoths (Lepidoptera) in the canopy and understorey in a central European deciduous forest. We collected moths at two sites during 19 trapping nights and three lunar phases between July and September 2021 using a weak ultraviolet light emitting diode (LED) lamp (LepiLED mini). Overall, we captured 4368 individuals (165 species) from 11 families. Based on a number of metrics, richness and diversity was significantly lower in the canopy than in the understorey. Non-metric multidimensional scaling ordinations show that communities largely overlap, but the proportion of species that only occur in the understorey was higher. While Noctuidae and Erebidae species were abundant in both strata, Geometridae species were most frequently observed in the understorey. We identified 16 indicator species for the understorey but only three for the canopy. Forewing length of moths in the canopy was on average 1.7 mm longer than of those in the understorey. Overall, the understorey is far more important for moths than the canopy in a temperate forest. The canopy is dominated by fewer and larger species and probably has a higher proportion of dispersers.

Mosquitoes, particularly Aedes aegypti, pose significant public health risks by transmitting diseases like dengue, zika and chikungunya. Bacillus thuringiensis var. israelensis (BTI) is a crucial larvicide targeting mosquitoes while sparing other organisms and the environment. This study evaluated the effects of sublethal BTI doses on Ae. aegypti larvae regarding mortality, development, adult emergence and size, using a wide-area spray application in an urban neighbourhood. Laboratory experiments with four BTI concentrations (0, 0.008, 0.02 and 0.04 ppm) assessed compensatory and over compensatory responses. The spray achieved over 90% larval mortality within 48 h, but accumulating sublethal doses could trigger compensatory and over compensatory effects, enhancing the fitness of survivors. A dose-response relationship was evident, with higher BTI concentrations leading to increased mortality, reduced longevity and fewer pupae. BTI exposure also skewed the sex ratio towards males and altered adult sizes, potentially affecting population dynamics and vectorial capacity. These findings highlight the effectiveness of BTI in Ae. aegypti control and the importance of understanding compensation, overcompensation and density-dependent effects. While wide-area BTI applications can reach inaccessible breeding sites and offer potent mosquito control, careful consideration of ecological and evolutionary consequences is crucial.

Juvenile hormone (JH) regulates multiple physiological functions in insects including growth, metamorphosis, and reproduction. Juvenile hormone epoxide hydrolase (JHEH) and juvenile hormone esterase (JHE) are degradative enzymes that metabolise JH, and JH receptor (methoprene-tolerant, Met) functions in the regulation of female reproduction and vitellogenesis. In this study, JH titres in Coccinella septempunctata adult females were determined using ultra high-performance liquid chromatography and tandem mass spectrometry; the JH titres ranged from 0.03 to 0.16 ng g^-1 in 5- to 30-day-old female adults. JHEH, JHE, and Met expression were studied in different reproductive stages of C. septempunctata females by quantitative real-time PCR. JHEH transcription levels were highest in 25-day-old female adults and were 1.93-fold higher than expression levels in 5-day-old adults. JHEH and JHE expression levels were inhibited by the addition of JH to the artificial diet. Met expression in C. septempunctata supplied with 3 μl JH in artificial diet was similar to Met transcription in females supplied with an aphid diet, and the results showed that supplementation with 3 μl JH in 582.2 g of artificial diet was the most suitable for reproductive regulation of C. septempunctata. The results of this study provide important insights for the improvement of C. septempunctata artificial diets.

We evaluated the lethal and sublethal effects of two novel Betaproteobacteria-based insecticides (Burkholderia spp. strain A396 as Venerate® XC; Chromobacterium subtsugae strain PRAA4-1 as Grandevo® WDG) and two neem-based insecticides (1.2% azadirachtin A and B as Azatrol and 3% azadiractin as Molt-X) on the cotton aphid, Aphis gossypii, and its natural enemy, Coccinella septempunctata. Aphids were given both residual and direct treatments, i.e. exposed to residues applied by leaf dipping, or by spraying the insects and foliage, while the predator was treated directly with insecticides. Well-established spirotetramat (Movento® 240 SC) was used as standard due to its effectiveness against a wide range of pests, its unique mode of action, and its systemic properties. All insecticides were effective against aphid mostly in concentration-dependent manner, as do exposure time, but at different magnitudes. Spirotetramat and Azatrol induced the highest toxicity to adult aphids, while spirotetramat and Molt-X were more noxious to aphid nymphs. C. subtsugae and Burkholderia were less effective, inducing only moderate levels of aphid mortality. Azatrol and spirotetramat were more detrimental to the fecundity of aphid compared to other products. Insecticides significantly increased the development time of nymphs surviving exposure to insecticides, except Burkholderia. Azatrol were more destructive to eggs, larvae and adult of Coccinella septempunctata, together with spirotetramat for young larvae and adults, relative to other treatment. The development time of predator larvae remained unaffected by treatment. New Betaproteobacteria- and neem-based insecticides except Azatrol seem to be a promising tool to suppress population of Aphis gossypii and integrate pest management programmes.