Bulletin of Entomological Research最新文献

The olive black scale, Saissetia oleae (Olivier), is a significant pest of olive crops worldwide. The developmental, reproductive, and population growth parameters of S. oleae were evaluated under five constant temperature conditions (18°C to 33°C). Developmental durations significantly decreased with increasing temperatures. Female lifespan decreased from 161.6 days at 18°C to 104.3 days at 33°C, while male lifespan decreased from 96.8 days at 18°C to 49.4 days at 33°C. The highest sex ratio (proportion of females) of 0.35 was observed at 30°C, with pre-adult survival rates of 63%, while survival rates dropped to 28% at 18°C. Parthenogenesis was not observed in females. The total pre-oviposition and post-oviposition periods decreased with increasing temperature, with the longest oviposition period at 33°C (49.6 days). Maximum fecundity was recorded at 33°C (379.0 eggs/female), followed by 30°C (298.6 eggs/female), and decreased sharply at 18°C (90.1 eggs/female). The intrinsic rate of increase (r) was highest at 30 and 33°C (0.038 d⁻¹), while the net reproductive rate (R₀) peaked at 30°C (104.5 offspring/female). The predicted fecundity of the next generation showed significant potential growth at 27 and 30°C, with the population increasing 65.3 times at 30°C and 39.4 times at 27°C. The developmental threshold for S. oleae was highest for first-instar nymphs (7.58°C), while second-instar nymphs had lower thresholds (1.09-1.65°C), with total pre-adult development requiring 1250 degree-days for both males and females. These findings underscore the significant impact of temperature on the development and reproduction of S. oleae, with implications for pest management in olive orchards.

Aphids are important pests of cereal crops and cause economically significant damage through direct feeding and the transmission of plant viruses. In Europe, the aphid species of greatest concern are the grain aphid (Sitobion avenae Fabricius) and the bird cherry-oat aphid, (Rhopalosiphum padi Linnaeus). Often, cereal crops are dominated by a small number of prolific clonal populations and these populations can differ in phenotypic traits of agricultural importance. There are two heritable factors that influence aphid phenotype: aphid genetic diversity and the presence of endosymbionts.Here, multiple cereal aphid populations are used to determine how heritable factors influence aphid phenotype. Several agriculturally important phenotypic traits are examined, and both endosymbiont- and genotype-derived phenotypes are identified. For S. avenae, aphid genotype influences all phenotypic traits assessed, and association with the facultative endosymbiont Regiella insecticola influences alate morph production with co-infection of R. insecticola and Fukatsuia symbiotica increasing reproductive output. For R. padi, adult aphid morph (apterous or alate) is the key driver behind reproductive output, with a genotype × morph effect also found to influence development time.Overall, these results provide insight into the biological drivers behind phenotypic diversity in agriculturally important aphid species. Being able to associate heritable factors with key phenotypes can generate biological insights into the processes underpinning the dominance of specific aphid clones and can be used to develop pest and disease management strategies based around the phenotypic risk of the aphid populations present.

Eotetranychus kankitus is an important pest on several agricultural crops, and its resistance to pesticides has promoted the exploration of biological control strategies. Beauveria bassiana and Neoseiulus barkeri have been identified as potential agents for suppressing spider mites. This study aimed to investigate the pathogenicity of B. bassiana on E. kankitus and its compatibility with N. barkeri. Results showed that among the five tested strains of B. bassiana, Bb025 exhibited the highest level of pathogenicity on E. kankitus. Higher application rates (1 × 10⁸ conidia/mL) of Bb025 led to a higher mortality rate of E. kankitus (90.402%), but also resulted in a 15.036% mortality of N. barkeri. Furthermore, preference response tests indicated that both E. kankitus and N. barkeri actively avoided plants sprayed with Bb025 compared to the control group that was sprayed with Tween-80. In a no-choice test, we observed that N. barkeri actively attacked Bb025-treated E. kankitus with no adverse effect on its predatory capacities. Furthermore, N. barkeri laid more eggs when fed on Bb025-treated E. kankitus compared to Tween-80-treated E. kankitus, but the subsequent generation of surviving individuals fed on Bb025-treated E. kankitus was reduced. These findings demonstrate that the Bb025 strain of B. bassiana is highly virulent against E. kankitus while causing less harm to N. barkeri. Consequently, a promising strategy for controlling E. kankitus could involve the sequential utilisation of Bb025 and N. barkeri at appropriate intervals.

Coccygidium luteum (Hymenoptera: Braconidae), a solitary larval parasitoid, is associated with the fall armyworm (FAW), in Africa. However, there is very limited information on reproductive biology, and other biological parameters that influence its life strategies. We conducted laboratory experiments to gain new insights into the biology of C. luteum reared on FAW as the host. Host age preference, reproductive biology, lifetime fecundity, life cycle, and adult longevity were studied under laboratory conditions of 28 ± 1°C and 70 ± 3% relative humidity. This study revealed that C. luteum prefer early (1st-3rd) instars of FAW for oviposition. The maximum parasitism rate was 80% at second instar larvae. A mean pre-oviposition period of 0.38 ± 0.51 days, oviposition period of 5.13 ± 0.64 days, and no post-oviposition period were observed. The mean lifetime parasitism rate of FAW larvae by female C. luteum was 49 ± 24. Longevity of unmated C. luteum was 14.44 ± 1.43 days for males and 12.83 ± 1.12 days for females. Mated ovipositing females lived for 7 days. Mean female and male progenies per adult female C. luteum was 28.11 ± 8.18 and 39.89 ± 4.76 respectively, with an overall sex ratio of 1.42 at 28 ± 1°C using second instar larvae. Total life cycle from oviposition to adult emergence was 23 ± 1 days. This study provides the basic information about C. luteum that could be utilised for mass rearing of this parasitoid under an augmentative biological control of FAW programme.

Rachiplusia nu (Guenée) (Lepidoptera: Noctuidae) is a significant agricultural pest in South America infesting several crops, including soybeans. Bacillus thuringiensis (Berliner) (Bt) soybean, expressing Cry1Ac protein, is widely planted as a control method for numerous lepidopteran pests. However, insect resistance to Bt proteins poses a threat to its sustainability. Recent field reports from Argentina, Uruguay, and Brazil have documented unexpected injury to Bt soybean caused by R. nu populations, which may indicate the development of resistance to Cry1Ac in this species. This study aimed to evaluate the biological performance, reproductive parameters, and reproductive compatibility of two R. nu strains, one susceptible (SS) and the other exhibiting reduced susceptibility to Bt toxin (RR), when reared on Bt and non-Bt soybean. Reproductive compatibility between strains was investigated through parental and hybrid crosses, evaluating fecundity, fertility, and mating success. SS larvae fed with Bt soybean failed to complete their life cycle, whereas RR larvae exhibited higher survival rates. Egg and larval stages of RR larvae were longer when reared on Bt soybean. Pupal mass was lower for Bt-fed resistant strain, although this did not reflect on fecundity and longevity. Results on parental crosses revealed that Bt-fed RR strain displayed reduced mating success, fecundity, and fertility, compared to the non-Bt treatment. Hybrid crosses showed evidence for prezygotic and postzygotic incompatibility. These results suggest a shift in susceptibility of R. nu to Cry1Ac protein and highlight the importance of implementing robust insect resistance management strategies to maintain the effectiveness of Bt crops.

The whitefly, Bemisia tabaci is a cryptic species complex in which one member, Middle East-Asia Minor 1 (MEAM1) has invaded globally. After invading large countries like Australia, China, and the USA, MEAM1 spread rapidly across each country. In contrast, our analysis of MEAM1 in India showed a very different pattern. Despite the detection of MEAM1 being contemporaneous with invasions in Australia, the USA, and China, MEAM1 has not spread widely and instead remains restricted to the southern regions. An assessment of Indian MEAM1 genetic diversity showed a level of diversity equivalent to that found in its presumed home range and significantly higher than that expected across the invaded range. The high level of diversity and restricted distribution raises the prospect that its home range extends into India. Similarly, while the levels of diversity in Australia and the USA conformed to that expected for the invaded range, China did not. It suggests that China may also be part of its home range. We also observed that diversity across the invaded range was primarily accounted for by a single haplotype, Hap1, which accounted for 79.8% of all records. It was only the invasion of Hap1 that enabled outbreaks to occur and MEAM1's discovery.

The relationships between the Japanese beetle (JB) Popillia japonica Newman, 1841 and the grapevine agroecosystem were investigated in Piedmont in 2020 and 2021, to assess the impact of the species and its distribution within vineyards in relation to the proximity of environmental risk factors. Grubs were sampled by soil coring in the inter-rows of vineyards, whereas both adult beetles and defoliation were counted directly on grapevine plants. The presence of spatial autocorrelation was assessed and the influence of environmental variables (distance from woodlands, meadows and the margin of the vineyard, soil parameters, year of sampling, and year of first detection of the JB) was evaluated through generalized linear mixed models. Beetles and defoliation were more clustered at the edges of vineyards, whereas grubs were localized in few hot spots, generally close to meadows. Spatial autocorrelation was weaker for grubs with respect to adults and defoliation. Grub density depended on distance from meadows, and partially on soil features. Adults abundance was influenced by the proximity to meadows, woodlands, and their presence was clustered at the margin of vineyards. The JBs seem to rely on grapevine mainly as a food source rather than a reproductive site, preferring meadows for egg-laying: therefore, pest management in vineyards should be more focused on adult beetles rather than larvae in the vineyard inter-rows.

The present study describes the feeding effects of Neoseiulus cucumeris Athias-Henriot (Acari: Phytoseiidae) on western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae). In addition, daily and total predation capacity, preference, and prey switching potential of this predator were studied on both pest species. WFT had a boosting effect on the biological parameters of N. cucumeris, primarily resulting in shorter developmental time, higher fecundity, and higher population growth potential than TSSM. Although immatures and males of N. cucumeris consumed significantly more TSSM than WFT, there was no significant difference in net predation rate, stable and finite predation rates of the predator between two prey species. We found an average of 10.58 and 7.93 TSSM and WFT are required to produce a single predator egg, respectively. WFT is preferred over TSSM by the predator. Negative switching behaviour was seen in N. cucumeris as it switched from the abundant prey to the rare prey. Both prey species were suitable for N. cucumeris, being able to develop successfully on them. The predator performed optimally on WFT compared with TSSM owing to its enhanced biological parameters as well as its preference, indicating that thrips are a more relevant resource than spider mites.

Rhopalosiphum padi is an important grain pest, causing severe losses during crop production. As a systemic insecticide, flonicamid can control piercing-sucking pests efficiently. In our study, the lethal effects of flonicamid on the biological traits of R. padi were investigated via a life table approach. Flonicamid is highly efficiently toxic to R. padi, with an LC₅₀ of 9.068 mg L^-1. The adult longevity and fecundity of the R. padi F₀ generation were markedly reduced under the LC₂₅ and LC₅₀ concentrations of flonicamid exposure. In addition, negative transgenerational effects on R. padi were observed under exposure to lethal concentrations of flonicamid, with noticeable decreases in the reproductive period, adult longevity, total longevity, and total fecundity of the F₁ generation under the LC₂₅ concentration of flonicamid. Furthermore, the third nymph stage (N3), preadult stage, duration of the adult pre-reproductive period, duration of the total pre-reproductive period, reproductive period, adult longevity, total longevity, and total fecundity of the F₁ generation were significantly lower under treatment with the LC₅₀ concentration of flonicamid. The life table parameters were subsequently analysed, revealing that the intrinsic rate of increase (r_m) and the net reproductive rate (R₀) were significantly lower but that the finite rate of increase (λ) and the mean generation time (T) were not significantly different under the LC₂₅ and LC₅₀ concentrations of flonicamid. These data are beneficial for grain aphid control and are critical for exploring the role of flonicamid in the integrated management of this key pest.

Mango is a delicious tropical fruit with high economic value worldwide. The Forest-Savanna Transition zone of Ghana contributes significantly to the production of mangoes for both local and international markets. The zone is plagued with the fruit fly 'menace' like all mango-producing areas in Ghana. Not much has been done in terms of species monitoring. A 24- month fruit fly monitoring survey was conducted in eight mango orchards, to assess the composition of fruit flies associated with Mango and their damage levels. Four para-pheromone attractants (Methyl Eugenol, Terpinyl Acetate, Trimedlure, and Cuelure) were used to monitor fruit flies. Eight improvised water bottle traps (two per lure) were purposefully deployed in each orchard. A total of 18 tephritid species belonging to five genera were recorded. Bactrocera (one species), Ceratitis (six species), Dacus (eight species), Zeugodacus (one species) and Xanthaciura (two species). Bactrocera dorsalis was the most abundant species (90% of the collected samples), while the native mango fly, C. cosyra constituted 0.5%. Dacus fuscovittatus and Dacus pleuralis were for the first time captured and identified in Ghana. Dacus langi, Dacus carnesi, Dacus (diastatus?), Ceratitis silvestrii and C. quinaria were recorded for the first time in the zone. The zone recorded a diversity index of 0.41. Damage levels ranged from 41-91%. Ten out of the 18 species, are of economic importance on mango and must be watched. Periodic updates on seasonal fluctuations, species composition and new arrivals are key to the successful implementation of any management strategy.