Katsuyuki Kohno

Comparison of the life history strategies of three Dysdercus true bugs (Heteroptera: Pyrrhocoridae), with special reference to their seasonal host plant use

The life history strategy and seasonal host plant use of three Dysdercus bugs (D. cingulatus, D. poecilus and D. decussatus) were compared based on 2 years of twice monthly observations on Ishigaki‐jima Island (24°N, 124°E) in the southernmost part of Japan. Dysdercus poecilus reproduced almost year round, exclusively on Sida rhombifolia, which bears fruit and/or seeds almost year round. Dysdercus cingulatus reproduced successively on various malvaceous and bombacaceous plant species, according to their seasonal fruiting cycles. Its robust reproduction was observed on Hibiscus makinoi during winter months and on Chorisia speciosa and Bombax ceiba in early summer, whereas small‐scale reproduction was observed on various malvaceous plant species during the summer and autumn months. Dysdercus decussatus reproduced on Hibiscus tiliaceus and Thespesia populnea during the summer months, when these host plants bear abundant fruit and/or seeds, and its adults formed conspicuous aggregations without copulation on the underside of the leaves of those plants from November to the subsequent May. Each Dysdercus species showed a species‐specific life history strategy according to the differences in the phenology of their host plants.

Seasonal fluctuations in offspring body size in the wolf spider, Pardosa astrigera (Araneae: Lycosidae)

Seasonal fluctuations in body sizes of mother spiders, spiderlings, and clutch size in the wolf spider, Pardosa astrigera (L. Koch) (Araneae: Lycosidae), were investigated. Cephalothorax and abdomen widths were measured in females with egg sacs collected in Tsu, Mie Prefecture, from May 2009 to October 2013. Spiderlings that emerged from the egg sacs were counted and those widths measured. In addition, abdomen–cephalothorax size ratio, which could be correlated with seasonal adaptation of spiderlings, was calculated. Means for cephalothorax size of mothers and offspring tended to decrease from March to October. Mean cephalothorax and abdomen sizes of the spiderlings in March, April, May, and October were significantly larger than in July and August. Abdomen–cephalothorax size ratios in March, April, May, and June were significantly larger than in July and August. Environmental temperature in Tsu increases steadily from March to August and drops toward October. Significant negative correlations were detected between temperature and cephalothorax and abdomen widths of spiderlings. These results suggest that body size and abdomen–cephalothorax size ratio of spiderlings change seasonally, and environmental temperature would affect body size. Furthermore, considering that body size would put a limit on the available prey, food conditions could also be an influence.

Attraction of Leuroperna sera (Lepidoptera: Plutellidae) to a synthetic sex pheromone lure for Helicoverpa armigera (Lepidoptera: Noctuidae, Heliothinae)

Leuroperna sera (Meyrick, 1889) adults were specifically captured at sticky traps using a synthetic sex pheromone lure for Helicoverpa armigera (Hubner, [1808]) as an attractant. Among the components of the lure for H. armigera, (Z)-9-hexadecenal is likely to be a key component for the attraction of L. sera. The lure will be useful for forecasting the occurrence of L. sera.