Adaptation and induced response of Piezodorus Guildinii (Westwood, 1837) (Hemiptera: Pentatomidae) to seasonal variations

Effect of the photoperiod, temperature and food on the biology, physiology and phenology: Biological fixation and nitrous oxide emission: Doctoral thesis abstract

Abstract

Piezodorus guildinii (Westwood) is the hemipteran phytophagous that may cause major economic losses in the soybean crop in Uruguay, because it is the most abundant species, and causing major damage. To implement holistic pest management programs, it is necessary to understand how the biotic and abiotic factors influence on the seasonality of this insect. This research had as objective to evaluate the effects of photoperiod, temperature, and different foods in the biology and in the development of adaptations and induced responses of P. guildinii. Results allowed to establish that the food (availability and quality), and the photoperiod and temperature conditions are critical in regulating the seasonality of P. guildinii. Between 33 ° 55 'and 34 ° 17' S latitude, P. guildinii was recorded on 15 plants species and on five niches of hibernation. In forage legumes adults and nymphs were collected, while in perennial plantas and winterniches only adults were captured. In alfalfa adults were present almost the entire year. This insect fed on immature pods alfalfa had better performance (lower nymphs’ mortality, higher adult longevity, and ♀ with reproductive performance) than other forage legumes, demonstrating that alfalfa is an important host in life history. Laboratory results and field survey indicate that when photophase is ≤12 h and the temperature is below 20 °C, a high percentage of adult enters in reproductive diapause; they accumulate energy reserves, show immature reproductive organs and smaller body size, present less frequent food activity, and ♀ show clear coloration of the pronotum band and of the connexivum. Results suggest that alfalfa is the cropt on which efforts should be concentrated in order to develop efficient management tactics to be applied during spring; this should prevent the development of stink bug populations that will colonize the soybean.