Adjustment of fecundity and sex ratio in response to social environments in a haplodiploid mite

Animals can adjust reproductive strategies in favour of corporation or competition in response to local population size and density, the two key factors of social environments. However, previous studies usually focus on either population size or density but ignore their interactions. Using a haplodiploid spider mite, Tetranychus ludeni Zacher, we carried out a factorial experiment in the laboratory to examine how ovipositing females adjust their fecundity and offspring sex ratio during their early reproductive life under various population size and density. We reveal that females laid significantly more eggs with increasing population size and significantly fewer eggs with increasing population density. This suggests that large populations favour cooperation between individuals and dense populations increase competition. We demonstrate a significant negative interaction of population size and density that resulted in significantly fewer eggs laid in the large and dense populations. Furthermore, we show that females significantly skewed the offspring sex ratio towards female-biased in small populations to reduce the local mate competition among their sons. However, population density incurred no significant impact on offspring sex ratio, while the significant positive interaction of population size and density significantly increased the proportion of female offspring in the large and dense populations, which will minimise food or space competition as females usually disperse after mating at crowded conditions. These results also suggest that population density affecting sex allocation in T. ludeni is intercorrelated with population size. This study provides evidence that animals can manipulate their reproductive output and adjust offspring sex ratio in response to various social environments, and the interactions of different socio-environmental factors may play significant roles.

A new species and a new combination for the subfamily Cunaxinae (Acari: Cunaxidae)

A new species of Cunaxidae, namely Cunaxa bagualensis Wurlitzer & Ferla sp. nov., is described and illustrated based on females and males collected in soil and leaf litter in the Atlantic rainforest biome in a rural forest fragment in Mormaço county, Rio Grande do Sul state, Brazil. Additionally, Armascirus livingstoni Laniecka & Kazmierski, 2021 is transferred to Dactyloscirus based on some observations.

The mitochondrial genome and phylogenetic analysis of the tick Haemaphysalis qinghaiensis Teng, 1980 (Acari:Ixodidae)

Haemaphysalis qinghaiensis is an endemic species and mainly inhabiting in the northwestern plateau of China, which can transmit many zoonotic pathogens and cause great harm to animals. In this study, the complete mitochondrial genome (mitogenome) of H. qinghaiensis was assembled through the Illumina HiSeq platform. The mitogenome was 14,533 bp in length, consisting of 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes and 3 noncoding regions (NCRs). The bias towards a high A+T content with 77.65% in mitogenome of H. qinghaiensis. The rearrangement of mitochondrial genes in H. qinghaiensis was consistent with other hard ticks. The phylogenetic analysis based on the concatenation of 13 PCGs from 65 tick mitogenomes showed that the H. qinghaiensis was clustered into a well-supported clade within the Haemaphysalis genus. This is the first complete mitogenome sequence of H. qinghaiensis, which provides a useful reference for understanding of the taxonomic and genetics of ticks.

Spatial distribution and fluctuating populations of predatory mites (Mesostigmata: Phytoseiidae), phytophagous mites (Acari: Eriophyidae, Tetranychidae) and their relationships with wild chili pepper phenological stages in two Natural Protected Areas of Mexico

Ecological interactions between mites (predatory and phytophagous) and wild plants growing in undisturbed environments play a crucial role to understand their natural settlement, development and dispersion patterns. Pequin chili pepper, Capsicum annuum L. var. glabriusculum, is a low-cost natural resource for local communities living inside Natural Protected Areas (ANP) of Tamaulipas State in Mexico. The aims of this research work were: 1) determine the spatial distribution pattern of predatory and phytophagous mites, 2) determine the spatiotemporal association between predatory and phytophagous mites, and 3) determine the association among different mite species and some phenological stages of Pequin chili pepper. The most abundant phytophagous mites were Tetranychus merganser and Aculops lycpoersici, and the predatory species were Amblyseius similoides, Euseius mesembrinus and Metaseiulus (Metaseiulus) negundinis. Most mite species showed an aggregated distribution pattern according to the plant phenological stages. However, the distribution of mite species throughout time showed different types of aggregation. On the other hand, we found positive associations among A. lycopersici and T. merganser phytophagous mites with A. similoides, E. mesembrinus and M. (M.) negundinis predators mites. The association between plants and mite species were influenced by the phenological stages of Pequin chili pepper. This is an indication of the complexity among trophic-chain interactions that depend largely on the available resources and competition. These two factors serve as foundations for settlement, development and dispersion patterns of certain species.

Impact of citrus species on the biological characteristics and life table parameters of Eutetranychus orientalis (Klein) (Acari: Tetranychidae)

Biological characteristics and life table parameters of Eutetranychus orientalis (Klein) were revealed on four different citrus species: grapefruit (Citrus paradisi Macf. cv. Star Ruby), lemon (C. limon (L.) Burm. f. cv. Meyer), mandarin (C. reticulata Blanco cv. Okitsu) and orange (C. sinensis L. cv. Washington Navel) under laboratory conditions. Results show that oviposition period, fecundity, and life table parameters varied significantly depending on the host plant species. Furthermore, host plant species had little effect on immature development, except for the teleiochrysalis and total developmental period, which was significantly shorter on lemon (13.77 days for females, 12.67 days for males). Total mean numbers of eggs laid by E. orientalis was 15.92 on mandarin and 29.78 on lemon. In addition, intrinsic rate of increase (rm), net reproductive rate (R0), finite rate of increase (λ) and doubling time (DT) are 0.12 day–1, 10.41 ♀/♀, 1.13 day–1 and 5.59 days for lemon, 0.17 day–1, 22.36 ♀/♀, 1.19 day–1 and 4.04 days for grapefruit, respectively. However, shortest and longest mean generation times (To) were obtained at 18.26 days on orange and 19.37 days on grapefruit. Our results demonstrate that intergeneric differences of Citrus should be considered when determining E. orientalis population abundance and dynamics in field conditions.

Tolerance and functional response of Neoseiulus californicus (McGregaor) to starvation stress

The ability to endure starvation is important for predatory mite survival and its effectiveness as biological control agent. We studied the longevity and functional response of the prodator mite Neoseiulus californicus (McGregaor) under starvation stress. N. californicus individuals were treated as three groups: the mites were provided with nothing (group I), with fresh bean leaves (group II), and with water (group III) to the larvae, protonymphs, deutonymphs, adult males and females. Functional response of N. californicus to Tetranychus urticae Koch eggs was evaluated after starvation for 0 h, 24 h, 48 h, and 72 h. Results showed that all life stages of N. californicus in group III had the longest survival time among the three groups. Adult females had the strongest ability to endure starvation with a mean survival time of 8.16 d. Females had the ability to lay eggs, but the number of eggs laid was less than a mean of 1.2 eggs per female in the three starvation groups. N. californicus exhibited a Holling’s Type II functional response at all hunger levels. The handling time (Th) and attack rate (α) of the predator were not significantly different in all hunger levels. Predation rate of starved 0 h to 72 h initially increased and then decreased. The highest predation rate was recorded when the predators were starved for 24 h.

Morphological and molecular analysis of Ornithodoros hasei and Ornithodoros sp. cf. O. mimon (Acari: Argasidae) from northeastern Argentina

In this study two species of soft ticks belonging to the genus Ornithodoros were recorded in three areas in the province of Corrientes, Argentina. Four larvae were identified as Ornithodoros hasei (Schulze, 1935) on Molossus molossus (Molossidae) in Paraje Tres Cerros (Department of San Martín), while 56 larvae were identified as Ornithodoros sp. cf. O. mimon Kohls, Clifford & Jones, 1969 on Eptesicus furinalis and Myotis levis (Vespertilionidae) in Paraje Galarza (Department of Santo Tomé) and Colonia Carlos Pellegrini (Department of San Martín). These last two locations are found within the Esteros del Iberá eco-region. The known distribution range of O. hasei and O. cf. O. mimon is expanded to include the province of Corrientes. Two new ectoparasite-host associations were recorded for Argentina between O. hasei on M. molossus and O. cf. O. mimon on M. levis. The morphological differences together with the results of the phylogenetic analysis show that O. hasei presents genetic similarity with specimens from Brazil, and in Argentina, with ticks from Santa Fe. Instead, Ornithodoros sp. cf. O. mimon recorded in Corrientes and Uruguay belong to a different taxon than the O. mimon recorded in Brazil and Santa Fe, Argentina. Based on this, O. mimon should be considered a complex of species in which the specimens from Corrientes are provisionally considered as Ornithodoros sp. cf. O. mimon until their taxonomic status can be determined.

A new species of Meriadenogamasus Athias-Henriot (Parasitiformes: Parasitidae) from China, with a key to world species of the genus

The diagnosis of the genus Meriadenogamasus Athias-Henriot is updated based on the description of a new species, Meriadenogamasus longisetus Yao & Jin sp. nov., from south of China. This is the first described male mite for the genus. A key to the known species of the genus is provided.

Biological parameters and host preference of Tyrophagus putrescentiae (Schrank) on different Pleurotus ostreatus cultivars

Tyrophagus putrescentiae (Acari: Acaridae) is a destructive pest of edible fungi. Different species of edible fungi have variable effects on the growth, development and fecundity of T. putrescentiae, but it is unclear whether these effects exist in the same species. We used nine cultivars of the oyster mushroom (Pleurotus ostreatus) to evaluate the development and reproduction parameters of T. putrescentiae at 26 ± 1°C and 80 ± 5% humidity. Different P. ostreatus cultivars had significant effects on the immature stages, female fertility, and reproductive lifespan. Total egg-to-adult development time ranged from 10.0 ± 1.2 d (on Po389 cultivar) to 12.5 ± 1.0 d (on Po62 cultivar). Mite mortality ranged from 54.3 ± 4.2% (on Po86 cultivar) to 100.0 ± 0.0% (on Po62 cultivar). The number of eggs laid per female ranged from 3.2 ± 0.4 (on Po45 cultivar) to 9.1 ± 1.1 (on Po86 cultivar). The average lifespan of females ranged from 3.0 ± 0.5 d (on Po45 cultivar) to 16.3 ± 1.7 d (on Po86 cultivar). Host preference of the mite was significantly different among the nine cultivars with a preference for cultivars Po65, Po80, Po389, and Po86. These results indicate that P. ostreatus cultivars significantly affect the biology of T. putrescentiae and the relationship between mite damage and mushroom yield.