Steinernema taiwanensis n. sp. (Rhabditida: Steinernematidae), a new entomopathogenic nematode from Taiwan.

A new isolate of the entomopathogenic nematode, Steinernema taiwanensis n. sp., was isolated from soil in Pingtung County, Taiwan. This new species could be characterized and distinguished from other related species by its morphological characters, morphometrics, and phylogenetic analysis. The body length and distance from anterior end to nerve ring of infective juveniles is 1012 (983-1045) µm and 124 (120-127) µm, lateral field formula 2, 6, 7, 8, 2, and the tail length 90 (79-96) µm without dorsal constriction in tail region. The first generation males of S. taiwanensis n. sp. are characterized by spicule shape, smooth blade tip, 23 genital papillae (11 pairs and 1 single papilla), spicule length of 94 (89-99) µm and gubernaculum length of 68 (65-70) µm. Females from the first generation of S. taiwanensis n. sp. have no epiptygmata and a slightly developed post-anal swelling. Phylogenetic analysis of ITS and D2D3 regions of rDNA showed that S. taiwanensis n. sp. belongs to the Longicaudum-clade and comprises a monophyletic group with S. guangdongense and S. longicaudum. The new isolate is described as a novel species according to morphological and phylogenetic analyses.

Demography and Consumption of Spodoptera litura (Lepidoptera: Noctuidae) Reared on Cabbage and Taro.

Spodoptera litura (F.) causes considerable economic damage to multiple agro-crops annually in many countries. In this study, the demography of S. litura reared on cabbage and taro was investigated using the age-stage, two-sex life table at 25±1°C, 60±10% relative humidity, and a photoperiod of 12: 12 (L:D) h. Our results showed that the net reproductive rate, intrinsic rate, and finite rate of population increase on cabbage (1893.1 offspring, 0.2374 d(−1), and 1.2679 d(−1)) were all not significantly different from those on taro (1361.0 offspring, 0.2298 d(−1), and 1.2584 d(−1)). The net consumption rate on cabbage (439.1 cm2) was, however, three times higher than that on taro (141.7 cm2). According to the population parameters, both cabbage and taro are suitable host plants for S. litura. When both the population growth rate and the consumption rate were taken into consideration, the finite consumption rate on cabbage (ω=3.8054) was significantly higher than that on taro (ω=1.3184). In Taiwan, taro and cabbage are commonly planted in adjacent farm plots, with taro being grown from March to November and cabbage from October to April. Because of the overlapping growth periods of the two crops, S. litura can easily propagate throughout the year by switching between the adjacent crops during the overlap periods. Pest management strategies for controlling S. litura must be thoroughly reevaluated based on ecological characteristics, including its life table and consumption rate on its major host plants.

Life table and consumption capacity of corn earworm, Helicoverpa armigera, fed asparagus, Asparagus officinalis.

The life table and consumption rate of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) reared on asparagus, Asparagus officinalis L. (Asparagales: Asparagaceae) were studied under laboratory conditions to assess their interaction. Development, survival, fecundity, and consumption data were analyzed by the age-stage, twosex life table. This study indicated that asparagus is a natural host of H. armigera. However, the poor nutritional content in asparagus foliage and the poor fitness of H. armigera that fed on asparagus indicated that asparagus is a suboptimal host in comparison to hybrid sweet corn. The uncertainty associated with life table parameters was estimated by using jackknife and bootstrap techniques, and the results were compared for statistical inference. The intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and mean generation time (T) were estimated by the jackknife technique to be 0.0780 day(-1), 1.0811 day(-1), 67.4 offspring, and 54.8 days, respectively, while those estimated by the bootstrap technique were 0.0752 day(-1), 1.0781 day(-1), 68.0 offspring, and 55.3 days, respectively. The net consumption rate of H. armigera, as estimated by the jackknife and bootstrap technique, was 1183.02 and 1132.9 mg per individual, respectively. The frequency distribution of sample means obtained by the jackknife technique failed the normality test, while the bootstrap results fit the normal distribution well. By contrast, the relationship between the mean fecundity and the net reproductive rate, as estimated by the bootstrap technique, was slightly inconsistent with the relationship found by mathematical proof. The application of the jackknife and bootstrap techniques in estimating population parameters requires further examination.

Effects of green manure cover crops on Spodoptera litura (Lepidoptera: Noctuidae) populations.

Spodoptera litura (F.) is an important pest of numerous agro-economic crops, including green manure cover crops. In Taiwan, sesbania (Sesbanin roxburghii Merr.), sunn hemp (Crotalaria juncea L.), and rapeseed (Brassicae campestris L. variety chinensis) are the most popular green manure crops; sesbania and sunn hemp are commonly planted in warm seasons, whereas rapeseed is grown in the winter. In this study, life-table data for S. litura reared on these three green manures were collected to evaluate their roles as refuges of this pest. The net reproductive rate, intrinsic rate of increase, and finite rate of increase of S. litura were the highest when reared on sesbania (1428.1 offspring, 0.2327 d(-1), 1.2621 d(-1)), followed by sunn hemp (778.4 offspring, 0.2070 d(-1), 1.2300 d(-1)) and rapeseed (737.6 offspring, 0.2040 d(-1), 1.2263 d(-1)). The high growth rates on these green manure crops show that they can serve as potential breeding sites for S. litura. Population projection demonstrated the rapid growth of S. litura on sesbania, sunn hemp, and rapeseed as well. Because most growers have traditionally ignored pest management in green manure fields, the mass emergence of S. litura in these fields may cause unexpected infestations in nearby vegetable, corn, and peanut crops. This study shows that the use of green manures as sources of nutrients should be critically reassessed and an area-wide pest management program should be instituted by taking the population of S. litura in green manure fields into consideration.

A comparison of artificial diet and hybrid sweet corn for the rearing of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) based on life table characteristics.

The demographic characteristics of Helicoverpa armigera (Hübner) reared on hybrid sweet corn (Zea mays L. variety saccharata) (hybrid super sweet corn KY bright jean) and on an artificial diet were compared by using the age-stage, two-sex life table. Because the hatch rate of eggs varies with maternal age, age-specific fecundity was calculated based on the numbers of hatched eggs to reveal the biological characteristics of H. armigera accurately. The intrinsic rate of increase (r), finite rate (λ) and mean generation time (T) of H. armigera were 0.0853 d(-1), 1.0890 d(-1), and 46.6 d, respectively, on Z. mays and 0.1015 d(-1), 1.1068 d(-1), and 46.3 d, respectively, on the artificial diet. There were significant differences in the intrinsic rate of increase and finite rate between two treatments. The age-stage life expectancy and reproductive value also were calculated. The relationships among the net reproductive rate, the mean female fecundity, the number of emerged females, and the total number of individuals used in the life table study are consistent with theoretical expectations. We recommend the age-stage, two-sex life table for use in insect demographic studies to incorporate both sexes and the variation in developmental rate among individuals and to obtain accurate population parameters. The artificial diet is more suitable for the mass rearing of H. armigera.

The bacterium associated with the entomopathogenic nematode Steinernema abbasi (Nematoda: Steinernematidae) isolated from Taiwan.

A symbiotic bacterium of the entomopathogenic nematode, Steinernema abbasi, isolated from Taiwan, determined to be a species of Xenorhabdus based on its physiological and biochemical characteristics has been determined to be similar to Xenorhabdus indica of S. abbasi Oman isolate as based on sequence analyses of 16S rDNA.

Intestinal myiasis caused by larvae of Telmatoscopus albipunctatus in a Taiwanese man.

Here we reported the first case in Taiwan of human intestinal myiasis caused by larvae of Telmatoscopus albipunctatus. The 21-year-old male patient experienced gastroenteritis and anal itching. During the patient's first hospital visit the doctor suspected Enterobius infection. After treatment with anthelmintic mebendazole, 5 live larvae were passed out in the feces. Symptoms were resolved a few days later. The larvae were brown and slender, measuring approximately 10 mm in length. The worms were located in the intestine. Subsequent examination showed that the cause was an infestation of larvae of T. albipunctatus. The patient was likely infected by ingestion of eggs or early-stage larvae in contaminated food.