Summary
Laboratory studies were conducted to assess impacts of temperature and humidity regimes on the development of Nezara​ viridula (L.) (Hemiptera: Pentatomidae) from inland and coastal populations in NSW, Australia. Four temperature regimes, 25±2ºC, 30±2ºC, 33±2ºC, and 36±2ºC and two humidity regimes, 40±10% and 80±10% RH were applied in the experiment with a constant photoperiod of 14:10 h (L:D). The developmental time of the nymphal stage of N. viridula significantly decreased with increasing temperature. Percentage nymphal survival significantly decreased with increasing temperature or high humidity (80% RH) regimes. Longevity of N. viridula adults declined with increasing temperature or high humidity regimes and femalelongevity was longer than males. High temperatures (30, 33 and 36ºC) or high humidity significantly reduced reproductive performance and capacity of N. viridula compared to low temperature (25ºC) or low humidity (40% RH). However, high humidity significantly increased egg hatchability of N. viridula compared with a low humidity regime. Interactions of temperature and humidity regimes significantly changed incubation period, adult longevity, mating frequency, pre-mating period, egg-mass size and egg hatchability of N. viridula. Interactions of population location (coastal or inland), temperature andhumidity regimes significantly changed incubation period and pre-oviposition period of N. viridula. Temperature and humidity are important environmental factors for the development and reproduction of N. viridula. Higher temperatures shorten the length of nymphal duration, but reduce nymphal survival. The optimum temperature for the development and reproduction of N.viridula was 25ºC with 40 ± 10% RH. No differences in nymphal duration, nymphal survival, adult longevity or reproduction performance between inland and coastal N. viridula populations were found under different climate conditions. We show the importance of assessing all life-stages in the response to varying temperature and humidity regimes, especially in terms of assessing responses to climate change.

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Rice (Oryza sativa L.) is one of the most important staple food crops in Southeast Asia, a region that is also partic- ularly vulnerable to climate change. We introduced a multi-scale crop modeling approach to assess the impacts of climate change on future rice yields in Southeast Asia. National- and farmer-level adaptation strategies may be developed by combining the advantages from regional- and field-scale crop models. Climate variables collected from the COordinated Regional climate Downscaling EXperiment (CORDEX)-East Asia were used as inputs to run the GLAM-Rice and CERES-Rice crop models. Simulations produced by the GLAM-Rice model identified Cambodia as the country in Southeast Asia where the reduction in rice yields under climate change will be the largest (a decrease of approximately 45% in the 2080s under RCP 8.5, relative to the baseline period 1991– 2000) without adequate adaptation. The results of the model simulations considering the CO2 fertilization effect showed that improved irrigation will largely increase rice yields (up to 8.2–42.7%, with the greatest increases in yields in Cambodia and Thailand) in the 2080s under RCP 8.5 compared to a scenario without irrigation. In addi- tion, the grid cell that will benefit the most (12.6 °N and 103.8 °E) was identified through further investigation of the spatial distribution of the effects of irrigation for Cambodia. For this grid cell, the CERES-Rice model was used to develop the best combination of adaptation measures. The results show that while a doubled application rate of nitrogen fertilizer (100 kg N ha−¹ ) will increase rice yields by 3.9% in the 2080s under the RCP 4.5 scenario for the Sen Pidao cultivar, a decrease in rice yield was projected for the Phka Rumduol cultivar under RCP 4.5. For both cultivars, the results show that additional adaptation strategies besides the 100 kg N ha−¹ fertilizer applica- tion rate and planting adjustment should be applied in order to offset all of the negative projected impacts of cli- mate change on rice yields in the 2080s under RCP 8.5. It is concluded that this study can be useful to enhance food security in Southeast Asia by providing informed recommendations for efficacious adaptation strategies.

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In rice-based lowland areas in the Mekong region, the lack of full irrigation water availability for post-rice legume crops and the poor soil physical and chemical conditions are major constraints for development of sound rice/legume double cropping system. In order to improve legume productivity, use of rice straw mulch and various crop establishment methods were examined in two series of mungbean experiments in Cambodia where soils were coarse and strongly compacted. In one set of experiments conducted at four locations in the first year the effect of straw mulch, planting method (manual vs seed drill) and tillage method (conventional vs no-till) was examined. Another set of experiments were conducted in the second year at three locations with four levels of mulch under two planting densities. On average in year 1, mulching of rice straw at 1.5 t/ha increased mungbean crop establishment from 72 to 83%, reduced weed biomass from 164 to 123 kg/ha and increased yield from 228 to 332 kg/ha. Mulch was effective in conserving soil moisture, and even at maturity the mulched area had on average 1% higher soil moisture content. The amount of mulch between 1 and 2 t/ha did not show consistent effects in year 2, partly because some mulch treatments resulted in excessive soil moisture content and were not effective. Rice straw mulch had a significant effect on mungbean yield in 6 out of the 7 experiments conducted in two years, and mean yield increase was 35%. This yield advantage was attributed to better crop establishment, improved growth and reduced weed pressure, but in some cases only one or two of these factors were effective. On the other hand, planting method, tillage method and planting density had only small effects on mungbean yield in most experiments. Only in one location out of four tested, the no-till treatment produced significantly higher yield than the conventional method. Seed drill produced similar mungbean establishment and grain yield to the manual planting suggesting that the planter can be used to save the labour cost which is increasing rapidly in the Mekong region. Maximum root depth varied little with mulch or planting density, and was shallow (<20 cm) in all three locations where this character was determined. It is concluded that while rice straw mulch increased yield of mungbean following rice, the inability of mungbean roots to penetrate the hard pan is a major constraint for development of a sound rice/mungbean cropping system in the lowlands with compacted soils.

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