THRESHOLD TEMPERATURE AND THERMAL CONSTANT FOR EGG DEVELOPMENT OF NORTHERN CORN ROOTWORM, DIABROTICA LONGICORNIS (COLEOPTERA: CHRYSOMELIDAE)

1983 ◽  
Vol 115 (8) ◽  
pp. 1051-1052 ◽  
Author(s):  
C. R. Dominique ◽  
W. N. Yule

The northern corn rootworm, Diabrotica longicornis (Say), is a recent pest of corn in southern Québec (Guibord 1976). Little is known of local quantitative temperature relationships, although such information could have important practical applications in developing a pest management program.The object of this study was to determine the threshold temperature and thermal constant for egg development and eclosion, and to relate soil and air temperatures to the phenology of egg hatch in the field under Qutbec corn-growing conditions.

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Man P. Huynh ◽  
Chad Nielson ◽  
B. Wade French ◽  
Dalton C. Ludwick ◽  
Ryan W. Geisert ◽  
...  

AbstractThe northern corn rootworm, Diabrotica barberi Smith & Lawrence, has a univoltine life cycle that typically produces one generation a year. When rearing the northern corn rootworm in the laboratory, in order to break diapause, it is necessary to expose eggs to a five month cold period before raising the temperature. By selective breeding of the small fraction of eggs that hatched without cold within 19–32 days post oviposition, we were able to develop a non-diapausing colony of the northern corn rootworm within five generations of selection. Through selection, the percentages of adult emergence from egg hatch without exposure to cold treatment significantly increased from 0.52% ± 0.07 at generation zero to 29.0% ± 2.47 at generation eight. During this process, we developed an improved method for laboratory rearing of both the newly developed non-diapausing strain as well as the diapausing strain. The development of the non-diapausing colony along with the improvements to the rearing system will allow researchers to produce up to six generations of the northern corn rootworm per year, which would facilitate research and advance our knowledge of this pest at an accelerated rate.


1986 ◽  
Vol 118 (8) ◽  
pp. 781-787 ◽  
Author(s):  
R.M. Trimble

AbstractThe threshold temperature (t0) for both oviposition and egg development and the thermal constant (K) for egg development were determined using linear regression analysis for an Ontario population of the spotted tentiform leafminer, Phyllonorycter blancardella (Fabr.). Fecundity was highly variable, ranging from 1 to 152 eggs, and was not significantly affected by temperature. Calculation of the daily oviposition rates for the first 4 days of the experiment and for the period from the beginning of the experiment until the day on which the last egg was laid resulted in estimates of the oviposition threshold of 9.1 and 8.9°C, respectively. The threshold temperature for egg development was estimated as 2.5°C and the thermal constant for egg development as 172.5 degree-days.


2020 ◽  
Vol 45 (1) ◽  
Author(s):  
Jordan D Reinders ◽  
Zachary D Rystrom ◽  
Emily E Reinders ◽  
Timothy B Dang ◽  
Lance J Meinke

2019 ◽  
Vol 49 (2) ◽  
pp. 27-33
Author(s):  
S. I. Anosov ◽  
A. S. Surnachev ◽  
K. K. Musinov

The object of the research was to study the influence of sowing dates on sugar accumulation in different varieties of soft winter wheat. Less winterhardy variety of soft winter wheat Novosibirskaya 2 was compared with more winter-hardy ones Novosibirskaya 3, Novosibirskaya 40 and Krasnoobskaya ozimaya. The research was carried out in 2016-2018 inthe established experimental plot in the foreststeppe of Priobye, theObregion. The predecessor was bare fallow. The planting dates were August 20, September 1, September 10. Weather conditions of the autumn growing season, during which the accumulation of sugars occurs, differed significantly depending on the year of study and the sowing dates. The warmest conditions were in 2018, whereas the coolest – in 2017. The amount of accumulated sugars varied depending on the growing conditions and genotypic characteristics of varieties. The highest amount of sugars was accumulated by all varieties during the third term of planting, the lowest amount – during the second term. Lower air temperatures contributed to the increase in the amount of sugars, even when the duration of their accumulation period was shortened, which can be explained by a change in carbohydrate balance in crops when the accumulation of sugars is greater than their consumption for crop respiration. The genotype plays an important role in the carbohydrate metabolism of plants. In more winter-hardy varieties (Novosibirskaya 40, Novosibirskaya 3), the change in the amount of accumulated sugars in contrasting conditions ranged insignificantly (the coefficient of variation was 9.1 and 8.7%, respectively). At the same time, plants of the less winter-hardy variety of Novosibirskaya 2 showed a significantly greater variation in the sugar content under similar conditions (the coefficient of variation 24.7%). Cooler conditions of a later term of sowing contributed to the greatest amount of accumulated sugars. Varietal differences also determined changes in carbohydrate balance.


2017 ◽  
Vol 90 (2) ◽  
pp. 94-99
Author(s):  
Dalton C. Ludwick ◽  
Anthony Zukoff ◽  
Matt Higdon ◽  
Bruce E. Hibbard

2013 ◽  
Vol 49 (No. 2) ◽  
pp. 89-97
Author(s):  
T. Středa ◽  
O. Vahala ◽  
H. Středová

The sum of effective temperatures (SET) of adult western corn rootworm (WCR) occurrence was determined based on several criteria. The risk of WCR occurrence was mapped, and the areas of continuous reproduction of WCR in the Czech Republic were identified. The daily soil SET was observed until the initial adult WCR occurrence, and it ranged from 414 degree days (DD) when the lower threshold temperature (LTT) was 12.5°C at 0.02 m depth to 719 DD (LTT of 10°C at a depth of 0.05 m). The daily air SET ranged from 415 DD (LTT 12.5°C at a height of 2 m) to 726 DD (LTT of 10°C at a height of 0.05 m).  


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