Greenhouses In Japan Research Articles

Daily progeny production and thermal influence on development and adult longevity of the leafminer parasitoid, Gronotoma micromorpha (Hym., Eucoilidae)

Abstract: To evaluate the potential of the parasitoid Gronotoma micromorpha (Perkins) as a biological control agent for the serpentine leafminer Liriomyza trifolii (Burgess) in greenhouses, we determined daily progeny production and thermal influence on both total development (oviposition to adult emergence) and adult longevity of this wasp in the laboratory in the host L. trifolii. The mean total number of progeny produced was 75.6 per female at 25°C under a 15‐h light/9‐h dark (15L : 9D) photoregime. The developmental rate of G. micromorpha significantly correlated with constant temperature between 18 and 30°C. The lower thermal threshold and thermal constant for total development of this wasp were 11.7°C and 333.3 heat degree‐days, respectively. The results indicate that adult female G. micromorpha do not oviposit at 15°C and that the lower threshold for oviposition is approximately 18°C. In heated greenhouses in Japan, leafminers and their parasitoids are exposed to both high temperatures and a short photoregime from late autumn to winter, but these conditions (25°C, 10L : 14D) did not significantly affect the total development of G. micromorpha. When wasps were not exposed to hosts, the mean adult longevity at 15 or 20°C was significantly longer than that at 25°C. When wasps were allowed to oviposit into hosts at 25°C, the mean adult longevity was significantly longer than when wasps were not exposed to hosts. As adult female G. micromorpha do not feed on hosts and are pro‐ovigenic, suppression of oviposition probably decreased adult longevity. The biological traits of G. micromorpha elucidated by this and previous studies indicate that this wasp is suitable as a biological control agent for L. trifolii in greenhouses.

Respiration Properties of Tree-ripe Mango Fruit under CA Condition

Tree-ripe 'Irwin' mango fruit grown under the green houses in Japan have excellent quality. Unfortunately, their harvesting period is very limited and storability is very less. Therefore, a method for preserving the fruit quality is highly needed. Temperature and the gas composition are the most important factors affecting the rate of respiration and ultimately the fruit quality attributes. Respiration rate is the necessary parameter for designing the storage conditions. In the present investigation, the effects of storage temperature (5, 15, 25°C) and gas composition on the O2 consumption and the CO2 production have been studied by using the flow through system. The ratios of the respiration rate under controlled atmosphere conditions (1.6 to 20.7% O2, 0. 2 to 10.2% CO2, balanced with N2) were calculated against the values under normal air condition. The results obtained on the respiration rate and the respiration quotient suggest that low temperature in combination with CA gas composition of carbon dioxide around 10% will be effective to suppress the respiration rate of tree-ripe 'Irwin' mango fruit, and oxygen should be higher than 5 % to avoid the anaerobic respiration.

Effect of temperature on development and survival of Wollastoniella rotunda (Heteroptera: Anthocoridae), a predator of Thrips palmi (Thysanoptera: Thripidae).

To assess the possibility of using Wollastoniella rotunda as a biological-control agent against Thrips palmi in greenhouses in Japan, the effect of temperature on development and survival of W. rotunda was investigated. Developmental times and survival rates of W. rotunda eggs and nymphs when reared on T. palmi were measured at eight constant temperatures: 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0 and 32.5°C. At these temperatures, the developmental times of W. rotunda eggs and nymphs ranged from 6.6 to 29.9 days and 14.0 to 47.6 days, respectively. The developmental zero (T0) and the thermal constant (K) were calculated to be 11.5°C and 106.4 degree-days for eggs, 9.6°C and 257.7 degree-days for male nymphs, and 9.2°C and 268.8 degree-days for female nymphs. More than 50% of the eggs died at 15.0°C and 32.5°C, while more than 70% of the eggs hatched at temperatures from 17.5 to 30.0°C. Nymphal survival rates reached 70% or more for all the temperatures tested. These results suggest that W. rotunda can survive and develop in Japanese greenhouses during the winter season.