Journal of Applied Entomology最新文献

Spodoptera frugiperda, an invasive pest insect that targets maize and other crops, first arrived in Japan in the summer of 2019. This species occurs year-round in East Asian subtropical regions such as southern mainland China and the island of Taiwan, where the mean air temperature in the coldest month is above 10°C. Adults are similarly found throughout the year on the southwestern islands of Japan. Trap monitoring there showed continuous or intermittent S. frugiperda catches in the three winter seasons since 2019. However, it was difficult to distinguish between immigrants arriving from these neighbouring areas and local individuals occurring on each Japanese island. In this study, the possible natal origin of captured insects on five small islands (Yonagunijima, Taramajima, Okinawajima, Amamioshima and Tanegashima) was determined by investigating the strontium radiogenic isotope ratios (⁸⁷Sr/⁸⁶Sr) and comparing them with those of reference hosts and insects. Since trapping data and the ⁸⁷Sr/⁸⁶Sr values of trapped insects didn't support S. frugiperda's winter breeding on the northernmost island, Tanegashima, further analysis was limited to the four southern islands. The ⁸⁷Sr/⁸⁶Sr values of reference host plants and reared insects on the four islands ranged from 0.70929 to 0.71009, while those of catch insects ranged from 0.70885 to 0.71090. The ⁸⁷Sr/⁸⁶Sr values of the catch insects and the reference on the four islands did not differ significantly. In addition, the monthly averages of daily mean air temperature in January and February 2020–2022 were above 10°C, and the wind direction at the surface was mostly from the northeast or northwest. These pieces of evidence, together with winter host availability, suggested that S. frugiperda occurs year-round on the islands. In other words, the year-round occurrence area of S. frugiperda in East Asia extends to the Japanese southwestern islands below Amamioshima Island.

Phyllocnistis citrella Stainton, commonly known as the citrus leafminer, threatens global citrus production. This study focuses on elucidating the population dynamics and spatial distribution of P. citrella in lemon orchards located in Northern Portugal. From May to December, using delta traps with sexual pheromones, the levels of the adult population were monitored, and aggregation indices were calculated. Five distinct density peaks are observed, with the highest recorded in late July to early August. Spatial distribution consistently indicated an aggregated pattern. However, temporal variation in distribution was observed on specific dates. According to our results, it is suggested deploying two or three traps per hectare during peak density periods. This study significantly advances our understanding of P. citrella dynamics, emphasizing the need to consider spatial and temporal patterns for effective pest management. The outcomes underscore the importance of further exploration into factors influencing distribution patterns to refine control strategies. These insights are crucial for devising targeted and efficient measures to mitigate the impact of P. citrella on citrus orchards globally.

Measuring adverse effects on honey bees and their colonies requires a suitable methodology. For example, due to the large number of bees in a hive and the foraging activity, measuring the mortality of individuals is a difficult task that has not yet been adequately addressed. Knowing the natural daily mortality rate of a bee colony would be of great benefit in assessing whether and to what extent external influences and stress factors affect mortality. More precise mortality data could in turn help refining specific protection goals for regulatory purpose. The European Food Safety Authority recently published a document that estimated such mortality rates based on a systematic literature review, but none of these rates were assessed from continuous monitoring of colonies. Currently, bee mortality is routinely evaluated with various types of dead bee traps that prevent deceased bees from being removed from the colony. Both the literature review and the dead bee traps are relevant to regulatory risk assessment, but in our opinion are not describing the total mortality. Bee counters capable of precisely determining daily loss rates meet the above points and combine them with generating automated and continuous monitoring data. Lately, the field has gained a lot of importance in research and technological advances offer new possibilities in regulatory risk assessment. We will highlight these possibilities and discuss their future application in practice.

A previous comprehensive survey in the Mediterranean and Southeastern regions of Türkiye investigating the natural egg parasitism of lepidopteran maize pests, Sesamia spp, (Lepidoptera: Noctuidae) Ostrinia nubilalis Hbn. and Chilo partellus (Swinhoe; Lepidoptera: Crambidae) by Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) yielded successful establishment of laboratory cultures of six strains molecularly clustering into two main groups. In this study, the functional response and adult longevity of the strains reared and tested on a factitious host, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) were investigated to provide insights into their potential as candidate biocontrol agents under constant laboratory conditions. The functional response modelling process consisted of two main sequential steps: model selection using polynomial logistic regression and parameter estimation using an iterative maximum likelihood estimation method. The functional response of two strains showed negative linear parameters (type II): HAP068M and HAP268S. Although their attack rate did not differ, the handling time of HAP268S was longer than that of HAP068M. In contrast, four strains had positive linear and negative quadratic parameters (type III) in their functional response: HAP044S, HAP070S, HAP210S, and HAP258M. The strains exhibiting type III functional response did not differ in their handling time, while HAP044S had a higher attack coefficient than HAP070S, HAP210S, and HAP258M. The longevity of both female and male adults significantly differed between strains. More importantly, the females belonging to strains exhibiting type II functional response presented a shorter longevity, compared to those with type III functional response. Males also showed a similar trend in their longevity. This paper discusses the differences in functional response types and estimated parameters of the strains in relation to their relevance for biological control programs and reveals a link between their functional response and longevity as potential reciprocal predictors.

Controlling the worldwide invasive pest Drosophila suzukii remains a challenge. One promising biological method for managing this pest is the use of larval and pupal parasitoids. Unfortunately, most of the larval parasitoids fail to successfully parasitise D. suzukii larvae in laboratory experiments due to the high immunity of the pest. So far, only the summer phenotype (summer morph) of D. suzukii has been tested for parasitisation. However, the winter phenotype (winter morph) is the dominant form of D. suzukii throughout the year in the northern hemisphere. Therefore, this study investigates the immunity during parasitisation for both phenotypes using the larval parasitoid Asobara japonica and the pupal parasitoid Trichopria drosophilae. It is the first to compare across all life stages the immunity of the winter phenotype to the summer phenotype of not only D. suzukii but also D. melanogaster. Our results indicate differences in the immunity between the two phenotypes for larvae, pupae, and adults. However, the degree and direction of these differences were inconsistent across the different life stages of D. suzukii. The findings have important implications for the integrated pest management (IPM) of D. suzukii.

Voltinism and life-history traits of the invasive fall armyworm (FAW) Spodoptera frugiperda were investigated under semi-natural conditions for a period of 2 years. The FAW invaded the corn field in the suburbs of Nanchang (28°46′ N, 115°50′ E) in early summer and produced six complete generations. FAW had the characteristics of short developmental time, high survival rates and strong fecundity. The development time of female pupae was significantly faster than that of male pupae, resulting in the emergence of female pupae earlier than male pupae. Except for the sixth generation in 2021, there was no significant difference between female and male sex ratio, which was close to 1:1. FAW showed male-bias sexual size dimorphism with male pupae being significantly larger than female pupae. Unlike pupal weight, in most generations, male adult weighed significantly less than females, because the weight loss of male pupae during metamorphosis was significantly greater than that of female pupae. The temporal variation of pupal weight did not conform to the temperature–size rule. Compared with 22.8°C, the 29.2°C high temperature not only significantly reduced the development time of larvae but also significantly increased pupal weight. The adult fecundity feeding on fresh corn leaves was higher than that feeding on live corn plants in most generations. In most generations, pupal weight was positively correlated with larval development time and adult weight was positively correlated with fecundity. In conclusion, climate differences between generations and years have significant effects on developmental time, body weight, sexual size dimorphism and fecundity of the FAW. These results add to the understanding of the evolution of life-history traits in the FAW and may have important implications for predicting population dynamics of the FAW and optimising control strategies.

Advancements in agricultural production have seen the rapid adoption of protected cropping systems globally. Such systems have been optimized for plant growth and efficiency, with little understanding of the potential impacts to key insect pollinators. Here, we investigate the effect of bird netting and polythene rain covers on the health and performance of honey bees (Apis mellifera L.) during the pollination of sweet cherry crops. Over two consecutive seasons, 12 full-strength colonies were equipped with tagged bees and radio frequency identification (RFID) systems. The colonies were equally divided between open control, bird netted and polythene (semi-permanent VOEN in 2019 and retractable Cravo in 2020) groups. Over 1300 individual bees were monitored for the duration of the commercial pollination period to determine behavioural parameters such as foraging commencement age, number and duration of trips and overall survival. Bees began foraging within the optimum age range (mean 15.7–24.1 days) under all covering types, with little indication of prolonged stress or increased mortality during the short season. Polythene covers (VOEN & Cravo) were found to significantly increase the total time needed for bees to orientate successfully. Once orientated, bees placed under covers conducted up to 155% more foraging trips, with a longer cumulative duration. Covering type was found to significantly impact the amount and type of pollen collected, with the most restrictive system (VOEN) yielding the highest proportion of cherry pollen. Overall, we found little evidence to suggest that the tested protective covers have a detrimental impact to honey bee foraging in cherry crops.

The research conducted so far on the chemical mechanisms of trees' defence against foliophages has not uncovered the chemical compounds biosynthesized by plants that are essential for these mechanisms. The objective of this study was to identify a chemical indicator for the presence of the pine beauty moth in Pinus sylvestris stands. Fresh needled shoots were collected from the crowns of pine trees in stands where the pine beauty moth tends to occur in large numbers, as well as from control stands. Total phenolic contents, total flavonoids contents, total chlorophyll content, terpene compounds, phenolic compound concentration, LMWOAs, sugar content, and colour analysis were conducted. Chlorophyll content, the presence of Panolis flammea in forest stands, and the colour of pine needles were discovered to be related. Variable L* correlated positively with the concentrations of chlorophyll a and b. In pine needles that were not attacked by the pine beauty moth, significantly higher concentrations of 4-hydroxybenzoic acid, salicylic acid, chlorogenic acid, syringic acid, quercitin, and rutin were found, with the first compound having the most significant effect (4-hydroxybenzoic acid). Based on the study results, the connected compounds in pine needles make them susceptible to insect attack. In addition, insect repellent programmes were mentioned.

Rodents are important hosts for ectoparasites, such as fleas, ticks, and mites, which means they are also important intermediate hosts for many zoonotic diseases. As anthropogenic environments bring humans and rodents into closer contact, an understanding of host–ectoparasite ecology is essential to predict and manage disease spillover risks. We aimed to understand how disturbances in vegetation cover affect rodent ectoparasite diversity, prevalence, spatial segregation, host (i.e., sex, genus, size, and habitat domain), and environmental (i.e., vegetation structure, forest cover, and rainfall) variables in the state of Michoacan, Mexico. We investigated these relationships by trapping rodents in five paired disturbed (reduced vegetation cover and regular human activities) and undisturbed (no reduction in vegetation cover) sites in the summer and autumn of 2022. From 110 trapped rodents, we collected 138 ectoparasites on 38 individuals. We found no difference in rodent diversity, ectoparasite diversity, or ectoparasite prevalence between disturbed and undisturbed sites. However, arboreal and male rodents had a higher probability of carrying ectoparasites than ground-dwelling and female rodents. Rodents with ectoparasites were not spatially clustered; rather, they were randomly distributed across trapping grids. We also identified two rodent genera (Rattus and Sigmodon) that carry ectoparasites of medical importance and that are in close contact with humans. Our results highlight the necessity of constant monitoring of rodents, ectoparasites, and their associated transmittable diseases. Assessing these interactions and how they are affected by anthropogenic disturbance could better inform management decisions and support the need for rodent conservation programmes in the area.

Herbivorous arthropods can induce their host to form structures where they shelter during unfavourable periods. The boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), can spend the off-season inside cotton plant structures, known as dry bolls, protected from pesticides, natural enemies and heat and desiccation on the soil surface, thereby increasing its survival and preserving its reproductive capacity. However, the relationship between the boll weevil and dry boll formation is not fully understood and requires further study. The formation and external and internal characteristics of dry bolls on cotton plants infested with different densities of boll weevils, and the emergence and survival of this insect from these structures, were evaluated. Compared with non-infested control plants, plants infested with boll weevil formed almost twice as many dry bolls, which were 2.3 times heavier and with a diameter 1.7 times larger than those on non-infested plants. Boll weevil infestation reduces the number of bolls and commercial mass of fibre + seeds, reducing productivity and increasing cotton harvest contaminants. However, dry bolls on non-infested plants demonstrate that other factors are involved in their formation.