Determining the Effect of Temperature on the Growth and Reproduction of Lasioderma serricorne Using Two-Sex Life Table Analysis.

The cigarette beetle Lasioderma serricorne (Fabricius) is a major pest of stored products worldwide, especially tobacco and foods, causing huge economic losses. This study aimed to experimentally investigate the population dynamics of this pest at different temperatures and provide theoretical input for its control. Populations of L. serricorne were established under laboratory conditions at five temperatures (21 °C, 24 °C, 27 °C, 30 °C, and 33 °C). Results showed that an increasing temperature significantly affected the developmental time, longevity, oviposition period, and fecundity of L. serricorne. Both the longevity and fecundity of adult beetles were significantly reduced as the temperature increased. High temperatures significantly reduced the total duration of the preoviposition period but prolonged the oviposition period of L. serricorne. Increasing the temperatures from 21 °C to 33 °C significantly influenced the life table parameters of L. serricorne. The intrinsic increase rate (r), finite increase rate (λ), and gross reproductive rate (GRR) all increased with a greater rearing temperature, but mean generation time (T) was significantly shortened. To our best knowledge, this is the first report to detail the entire life history of the cigarette beetle in response to different temperatures when reared on tobacco dry leaves. This finding may provide basic information on the occurrence of L. serricorne in a warehouse setting and its mass rearing.

Whitefly-induced tomato volatiles mediate host habitat location of the parasitic wasp Encarsia formosa, and enhance its efficacy as a bio-control agent.

BACKGROUND: Whitefly Bemisia tabaci is a phloem-feeding insect and causes extensive agricultural damage around the world. Although the parasitic wasp Encarsia formosa is widely used to control B. tabaci on glasshouse tomatoes, low efficiency and discontinuity are frequently recorded. It has been well-documented that herbivore-induced plant volatiles (HIPVs) are important cues in the foraging behavior of the natural enemies of herbivores. However, the volatiles emitted from tomatoes infested by different developmental stages of B. tabaci (nymphs versus adults) have not been compared in terms of their effects on E. formosa attraction. RESULTS: Olfactometer assays with four tomato cultivars revealed that the E. formosa wasps showed a significant attraction to the volatiles from adult-infested plants (except for cv. Castlemart), but not to those from nymph-infested plants. In a close-range habitat, however, the wasps appeared to use visual or tactile cues derived from nymphs for host location. Volatile analyses and behavioral assays showed that wasp attraction was correlated with enhanced ß-myrcene and ß-caryophyllene emissions from adult-infested plants. Furthermore, the use of B. tabaci adult-induced plant cues under glasshouse conditions resulted in a higher parasitism rate by this parasitoid. CONCLUSION: Our findings confirm that E. formosa uses the HIPVs resulting from feeding of B. tabaci adults to locate host habitat. Release of ß-myrcene and ß-caryophyllene from dispensers may enhance the efficacy of E. formosa as a biological control agent against B. tabaci in glasshouse production systems.

Characterization of the complete mitochondrial genome of Lymantria sugii from China and its phylogenetic analysis.

The complete mitochondrial genome (mitogenome) of Lymantria sugii (Diptera: Tephritidae: Dacinae) was sequenced and annotated. The mitochondrial genome is 15,614 bp (GenBank No. MT265380), containing 80.4% A + T (A 39.1%, C 7.3%, G 12.2%, and T 41.3%), that is heavily biased toward A and T nucleotides. All PCGs were started with ATN (ATA/ATG/ATT/ATC) and were terminated with TAR (TAA/TAG) excepting ND4, which ended with single T. Additionally, the phylogenetic tree confirmed that L. sugii clustered with L. umbrosa, L. dispar and Lymantria sp. The current study would be enrich the mitogenomes of the Lymantriinae.

Complete mitochondrial genome of Dacus trimacula (Diptera: Tephritidae) using next-generation sequencing from China.

The complete mitochondrial genome (mitogenome) of the fruit fly species Dacus trimacula (Diptera: Tephritidae: Dacinae) are sequenced and annotated. The mitochondrial genome is 15,851 bp (GenBank No. MK940811) has an A + T content of 72.8% (A 39.2%; C 17.0%; G 10.2%, and T 33.6%), which is the classical structure for insect mitogenome. All PCGs started with ATN and stopped with TAN. The phylogenetic tree confirms that D. trimacula clustered with D. longicornis as the sister group to Zeugodacus. This study enriches the mitogenomes of the fruit flies.

Parasitism and Suitability of Fertilized and Nonfertilized Eggs of the Rice Striped Stem Borer, Chilo suppressalis (Lepidoptera: Crambidae), for Trichogramma Parasitoids.

Trichogramma spp. are egg parasitoids largely used worldwide for biological control of lepidopteran pests. Host quality (related to host size and age, host species, etc.) can influence parasitism preference and fitness of the parasitoid offspring. However, few studies have documented the performance of Trichogramma parasitoids when they parasitize nonfertilized eggs of their lepidopteran hosts. In the present study, we investigated the performance of three indigenous Trichogramma species ( Trichogramma japonicum Ashmead, Trichogramma dendrolimi Matsumura, and Trichogramma chilonis Ishii) on fertilized and nonfertilized eggs of their native host, Chilo suppressalis (Walker). The results showed that the three Trichogramma species tested could recognize fertilized and nonfertilized eggs of C. suppressalis . The different fertilization status eggs of C. suppressalis were all accepted by T. japonicum , T. chilonis , and T. dendrolimi with a clear tendency that they preferred to parasitize fertilized eggs whether under no-choice or choice conditions. All Trichogramma species successfully completed development in parasitized eggs of C. suppressalis regardless if the host eggs were fertilized or not. There was similar adult emergence rate, development time, and female progeny between fertilized and nonfertilized eggs for all Trichogramma species with an exception of development for T. chilonis . Trichogramma chilonis had shorter developmental time in fertilized eggs than in nonfertilized ones. Whether in fertilized or nonfertilized eggs, T. dendrolimi had longer development time than other two Trichogramma species. However, T. dendrolimi had the largest percentage of female progeny on fertilized eggs, followed by T. japonicum , and T. chilonis had the least percentage of female progeny. The present study indicates that Trichogramma parasitoids (i) can distinguish fertilized vs. nonfertilized host eggs, and (ii) could use nonfertilized host eggs for successful offspring development (despite showing lower preference for such eggs) [corrected].

Experience-induced habituation and preference towards non-host plant odors in ovipositing females of a moth.

In phytophagous insects, experience can increase positive responses towards non-host plant extracts or induce oviposition on non-host plants, but the underlying chemical and behavioral mechanisms are poorly understood. By using the diamondback moth, Plutella xylostella, its host plant Chinese cabbage, and a non-host plant Chrysanthemum morifolium, as a model system, we observed the experience-altered olfactory responses of ovipositing females towards volatiles of the non-host plant, volatiles of pure chemicals (p-cymene and alpha-terpinene) found in the non-host plant, and volatiles of host plants treated with these chemicals. We assessed the experience-altered oviposition preference towards host plants treated with p-cymene. Naive females showed aversion to the odors of the non-host plant, the pure chemicals, and the pure chemical-treated host plants. In contrast, experienced females either became attracted by these non-host odors or were no longer repelled by these odors. Similarly, naive females laid a significantly lower proportion of eggs on pure chemical-treated host plants than on untreated host plants, but experienced females laid a similar or higher proportion of eggs on pure chemical-treated host plants compared to untreated host plants. Chemical analysis indicated that application of the non-host pure chemicals on Chinese cabbage induced emissions of volatiles by this host plant. We conclude that induced preference for previously repellent compounds is a major mechanism that leads to behavioral changes of this moth towards non-host plants or their extracts.

Application of least squares vector machines in modelling water vapor and carbon dioxide fluxes over a cropland.

Least squares support vector machines (LS-SVMs), a nonlinear kemel based machine was introduced to investigate the prospects of application of this approach in modelling water vapor and carbon dioxide fluxes above a summer maize field using the dataset obtained in the North China Plain with eddy covariance technique. The performances of the LS-SVMs were compared to the corresponding models obtained with radial basis function (RBF) neural networks. The results indicated the trained LS-SVMs with a radial basis function kernel had satisfactory performance in modelling surface fluxes; its excellent approximation and generalization property shed new light on the study on complex processes in ecosystem.