Search

The insect chemosensory system plays an important role in many aspects of insects’ behaviors necessary for their survival. Despite the complexity of this system, an increasing number of studies have begun to understand its structure and function in different insect species. Nonetheless, the chemosensory system in the orange spiny whitefly Aleurocanthus spiniferus, as one of the most destructive insect pests of citrus in tropical Asia, has not been investigated yet. In this study, the sensillum types, morphologies and distributions of the male and female antennae of A. spiniferus were characterized using scanning electron microscopy. In both sexes, six different sensilla types were observed: trichodea sensilla, chaetica sensilla, microtrichia sensilla, coeloconic sensilla, basiconic sensilla, and finger-like sensilla. Moreover, we identified a total of 48 chemosensory genes, including 5 odorant-binding proteins (OBPs), 12 chemosensory proteins (CSPs), 3 sensory neuron membrane proteins (SNMPs), 6 odorant receptors (ORs), 8 gustatory receptors (GRs), and 14 ionotropic receptors (IRs) using transcriptome data analysis. Tissue-specific transcriptome analysis of these genes showed predominantly expression in the head (including antennae), whereas CSPs were broadly expressed in both head (including the antennae) and body tissue of adult A. spiniferus. In addition, the expression profiling of selected chemosensory genes at different developmental stages was examined by quantitative real time-PCR which was mapped to the transcriptome. We found that the majority of these genes were highly expressed in adults, while AspiORco, AspiGR1, AspiGR2, and AspiIR4 genes were only detected in the pupal stage. Together, this study provides a basis for future chemosensory and genomic studies in A. spiniferus and closely related species. Furthermore, this study not only provides insights for further research on the molecular mechanisms of A. spiniferus-plant interactions but also provides extensive potential targets for pest control.

The aphid parasitoid Aphelinus asychis Walker is an important biological control agent against many aphid species. In this study, we examined whether the rearing host aphid species (the pea aphid, Acyrthosiphon pisum and the grain aphid, Sitobion avenae) affect the performance of A. asychis. We found that A. pisum-reared A. asychis showed a significantly larger body size (body length and hind tibia length) and shorter developmental time than S. avenae-reared A. asychis. There was no difference in the sex ratio between them. The longevity of A. pisum-reared A. asychis was also significantly longer than that of S. aveane-reared A. asychis. Furthermore, A. pisum-reared A. asychis presented stronger parasitic capacity and starvation resistance than S. aveane-reared A. asychi. In addition, host aphid alteration experiments showed that A. asychis only takes two generations to adapt to its new host. Taken together, these results revealed that A. pisum is a better alternative host aphid for mass-rearing and releasing of A. asychis. The body size plasticity of A. asychis is also discussed.

In insects, neuropeptides and their receptors not only play a critical role in insect physiology and behavior but also are the potential targets for novel pesticide discoveries. Aphidius gifuensis is one of the most important and widespread aphid parasitoids, and has been successfully used to control aphid. In the present work, we systematically identified neuropeptides and their receptors from the genome and head transcriptome of A. gifuensis. A total of 35 neuropeptide precursors and 49 corresponding receptors were identified. The phylogenetic analyses demonstrated that 35 of these receptors belong to family-A, four belong to family-B, two belong to leucine-rich repeat-containing GPCRs, four belong to receptor guanylyl cyclases, and four belong to receptor tyrosine kinases. Oral ingestion of imidacloprid significantly up-regulated five neuropeptide precursors and four receptors whereas three neuropeptide precursors and eight receptors were significantly down-regulated, which indicated that these neuropeptides and their receptors are potential targets of some commercial insecticides. The RT-qPCR results showed that dopamine receptor 1, dopamine receptor 2, octopamine receptor, allatostatin-A receptor, neuropeptides capa receptor, SIFamide receptor, FMRFamide receptor, tyramine receptor and short neuropeptide F predominantly were expressed in the head whilst the expression of ion transport peptide showed widespread distribution in various tissues. The high expression levels of these genes suggest their important roles in the central nervous system. Taken together, our study provides fundamental information that may further our understanding of neuropeptidergic signaling systems in the regulation of the physiology and behavior of solitary wasps. Furthermore, this information could also aid in the design and discovery of specific and environment-friendly insecticides.

This paper reviews and introduces innovative research pertaining to the age-stage, two-sex life table. The main topics discussed are: (1) Analysis of data involving group-reared life table studies. We address the rationale behind the data analysis used when constructing a group-reared life table. Proper analysis of grouped-reared life table data enables the collection of realistic and applicable data for ecological studies, devising efficient mass-rearing programs and formulating pest management routines using time- and labor-saving group-rearing methods. (2) The bootstrap-match technique. This novel technique is applicable to those instances when constructing a complete life table involves collecting the immature independently from the adult data. (3) Application of the set theory in life table research. This procedure enables a mathematical description of the population structure and bootstrap samples. (4) Application of the multinomial theorem. Using the multinomial theorem enables calculation of the exact probability of bootstrap samples. (5) Inclusion of infertile bootstrap samples. Because it is impossible to calculate the intrinsic rates of increase for infertile samples, they are normally omitted in life table analysis. Inclusion of these infertile bootstrap samples produces an unbiased life table analysis. (6) The Cartesian product. The Cartesian product of two sets produces the complete coverage of all possible differences. We compared the paired bootstrap test, the Cartesian paired test based on bootstrap results, and the Cartesian paired test based on the multinomial theorem. (7) Integration of life table data with predation data. This procedure, which is especially relevant to biological control programs, enables a comprehensive study of the predator-prey relationship. (8) Computer simulation based on life tables. Population projection based on the age-stage, two-sex life table not only provides the means to predict the dynamics of stage structures of a given pest population, but also provides an insight into the dynamics of predation capacity of the predator population. (9) Problems in life table research. Each of the subjects discussed is crucial for the theoretical advancement and practical applications of scientific demographic research. [ABSTRACT FROM AUTHOR]

We developed an innovative bootstrap-match technique for use in life table construction. This technique should be considered when any of the following four situations occur: 1) It is necessary to collect the immature and adult life table data separately due to obligatory diapause of one of the life stages. 2) It is necessary to collect the immature and adult life table data separately due to the difficulties in mating the adults under controlled laboratory conditions. 3) A large cohort is used for collecting immature data but a much smaller cohort is used for the adult data. 4) The life table data for the immatures were collected using individually reared insects while the adult data was obtained using group-reared insects. In order to demonstrate the applicability and reliability of this technique, we split twelve life tables of various insect species from previously published papers into two distinct components as if they were collected separately and then reunited them using the bootstrap-match technique. The population parameters of the bootstrap-match life tables were all highly consistent with the original life tables. We applied this technique to the Sunn pest, Eurygaster integriceps Puton, which has one generation per year and goes through an extended dormancy period averaging ~300 days (includes aestivation and overwintering). We demonstrated that ignoring the overwinter duration will result in unrealistic overestimation of population parameters. Conversely, bootstrap-match life tables that included the overwintering duration generated more realistic population parameters. Population projections using bootstrap-match life tables were also shown to generate realistic predictions of the population growth. [ABSTRACT FROM AUTHOR]

Antheraea pernyi Guérin-Méneville eggs have become an important host for rearing Trichogramma and are the preferred host for mass production of Trichogramma dendrolimi Mausumura, a widely used natural enemy in pest control practices. However, the effects of fertilization of host eggs on their mass production remains unclear. In this study, we evaluated parasitism and biological parameters for T. dendrolimi reared on A. pernyi eggs with five different treatments under the laboratory conditions. The five treatments were manually-extracted unfertilized washed eggs (MUW), naturallylaid unfertilized washed eggs (NUW) and unwashed (NUUW) eggs, naturally-laid fertilized washed eggs (NFW) and unwashed (NFUW) eggs. Our results showed that T. dendrolimi preferred MUW eggs to other treatments, although all treated A. pernyi eggs were accepted by T. dendrolimi. Generally, T. dendrolimi parasitized more washed eggs than unwashed eggs, and a greater number of unfertilized than fertilized eggs. On MUW eggs, the highest number of adults emerged per egg coupled with the shortest pre-emergence time and longest longevity of offspring. Those T. dendrolimi adults emerging from unfertilized eggs exhibited a higher number per egg, shorter pre-emergence time and longer adult longevity than those from fertilized eggs. There was no significant difference in percentage of female progeny, time to adult death, hind tibia length and egg load across all treatments. Our results demonstrate that MUW eggs of A. pernyi are most suitable for mass production of T. dendrolimi. [ABSTRACT FROM AUTHOR]

The life table is a type of research tool that is frequently used in many studies involving population and community ecology. They are the basis for many comprehensive studies in pest management, pesticide resistance, predator-prey relationships, biological control, mass-rearing and harvesting of insects, plant resistance, etc. Because the morphology, physiology, survival, fecundity, and predation/consumption rate of most arthropods will vary significantly depending on their developmental stage and sex, precise description of stage differentiation and inclusion of both sexes are critical for attaining realistic and accurate life table analyses and correctly evaluating the overall fitness of populations. Since traditional female age-specific life tables ignore the male individuals in a population and are incapable of describing the unique and important feature of stage differentiation (i.e., metamorphosis) that is a defining characteristic of insects and mites, their application to data analysis involving these groups will inevitably result in miscalculations and limit the practical application of these life tables. On the other hand, the age-stage, two-sex life table (hereafter referred to as the two-sex life table whenever appropriate), can precisely delineate stage differentiation and includes both sexes in data analysis, description, and interpretation, and in practical applications. In this review, the problems of female age-specific life tables are examined, followed by a discussion of the advantages of using the two-sex life table. Finally, applications of the two-sex life table in various types of entomological research are discussed and accompanied by examples. [ABSTRACT FROM AUTHOR]

The life table of the green lacewing, Chrysopa pallens (Rambur), was studied at 22°C, a photoperiod of 15:9 (L:D) h, and 80% relative humidity in the laboratory. The raw data were analyzed using the age-stage, two-sex life table. The intrinsic rate of increase (r), the finite rate of increase (λ), the net reproduction rate (R0), and the mean generation time (T) of CH. pallens were 0.1258 d-1, 1.1340 d-1, 241.4 offspring and 43.6 d, respectively. For the estimation of the means, variances, and SEs of the population parameters, we compared the jackknife and bootstrap techniques. Although similar values of the means and SEs were obtained with both techniques, significant differences were observed in the frequency distribution and variances of all parameters. The jackknife technique will result in a zero net reproductive rate upon the omission of a male, an immature death, or a nonreproductive female. This result represents, however, a contradiction because an intrinsic rate of increase exists in this situation. Therefore, we suggest that the jackknife technique should not be used for the estimation of population parameters. In predator-prey interactions, the nonpredatory egg and pupal stages of the predator are time refuges for the prey, and the pest population can grow during these times. In this study, a population projection based on the age-stage, two-sex life table is used to determine the optimal interval between releases to fill the predation gaps and maintain the predatory capacity of the control agent. [ABSTRACT FROM AUTHOR]

Effects of eight insecticides on Diadegma insulare (Cresson), a parasitoid of the diamondback moth, Plutella xylostella L., were evaluated under the laboratory conditions. The insecticides were three azadirachtin-based products (Ecozin, Agroneem and Neemix), two Bacillus thuringiensis (Bt) products (Xentari and Crymax), indoxacarb, spinosad, and λ-cyhalothrin. When D . insulare pupae were treated, none of the insecticide treatments except λ-cyhalothrin significantly reduced adult emergence, with 76-90% adults emerged from the treated pupae. In the λ-cyhalothrin treatment, only 10% D . insulare pupae produced adult wasps. Indoxacarb, spinosad, and λ-cyhalothrin caused 100% D . insulare adult mortality in 24 h in Petri dishes sprayed with insecticides in the contact bioassays, and 95.8, 100 and 95.8% adult mortality in 24 h in the ingestion bioassays, respectively. In contrast, all three azadirachtin-based insecticides and the two Bt-insecticides caused only 0-10.4% mortality of D . insulare adults after ingestion. The surviving D . insulare from ingestion treatments with Bt- and azadirachtin-insecticides parasitized 50.8-67.6% of P. xylostella larvae, respectively, compare to 72.1% for the water control. After ingesting indoxacarb, spinosad and λ-cyhalothrin mixed in honey-water, both the females and the males lived significantly shorter than those ingesting Bt- and azadirachtin-insecticides and the non-insecticide honey-water. Effects of leaf residues of indoxacarb, spinosad and λ-cyhalothrin varied significantly. The leaf residues of spinosad had the least effects on D . insulare adults, and 7- and 10-day-old residue only caused 5.6 and 7.4% mortality in 24 h, whereas 10-day-old leaf residues of indoxacarb and λ-cyhalothrin caused 40.7 and 57.4% mortality in 24 h, respectively. [ABSTRACT FROM AUTHOR]