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Thermal acclimation in the grain mite Acarus siro (Acari: Acaridae)
Abstract
Grain mites reared on wheat germ at 21±1°C and 85% r.h. were treated (acclimated) as adults at 0, 14, 28 or 33°C for 1 or 4 days. Fecundity, longevity and numbers of F1 females and males produced were compared. A treatment of 1 day was enough to acclimateAcarus siro and change the studied developmental parameters. Acclimation always lowered fecundity but the magnitude of the effect was dependent upon the temperature regime. The number of males and females emerging differed greatly among various temperature regimes; however, the sex ratio of emerged adults remained in most instances quite constant.
... During the thermal acclimation, mites adapt to ambient temperatures (Davis and Boczek 1988). Sinha (1964) found that a population of A. siro reared at 6ЊC survived for longer at Ϫ18ЊC than specimens reared at 21ЊC. ...
The thermal preferences in a grain mass and respiration at various temperatures in mites (Acari: Acarididae) of medical and economical importance [Acarus siro (L. 1758), Dermatophagoides farinae Hughes 1961, Lepidoglyphus destructor (Schrank 1871), and Tyrophagus putrescentiae (Schrank 1781)] were studied under laboratory conditions. Based on the distribution of mites in wheat, Triticum aestivum L., grain along a thermal gradient from 10 to 40 degrees C, L. destructor, D. farinae, and A. siro were classified as eurythermic and T. putrescentiae as stenothermic. The lowest preferred temperature was found for D. farinae (28 degrees C), followed by A. siro (28.5 degrees C), L. destructor (29.5 degrees C), and T. putrescentiae (31.5 degrees C). The relationship between the respiration rate and the temperature was similar for all four mite species. The highest respiration was found in the range from 31 to 33 degrees C. This is approximately 2 degrees C higher than the preferred temperature of these species. The lower temperature threshold of respiration ranged from 1 to 5 degrees C and the upper threshold ranged from 45 to 48 degrees C. Acclimatization of A. siro to temperature regimes of 5, 15, and 35 degrees C resulted in thermal preferences between 9 and 12 degrees C, 9 and 20 degrees C, and 28 and 35 degrees C, respectively. The respiration rate of acclimatized specimens increased with the temperature, reaching a maximum at 29.0 degrees C for mites acclimatized at 5 and 15 degrees C and a maximum at 33.7 degrees C for those acclimatized at 30 degrees C.
A thorough review of the literature has identified the key factors and interactions that affect the growth of mite pests on stored grain commodities. Although many factors influence mite growth, the change and combinations of the physical conditions (temperature, relative humidity and/or moisture content) during the storage period are likely to have the greatest impact, with biological factors (e.g. predators and commodity) playing an important role. There is limited information on the effects of climate change, light, species interactions, local density dependant factors, spread of mycotoxins and action thresholds for mites. A greater understanding of these factors may identify alternative control techniques. The ability to predict mite population dynamics over a range of environmental conditions, both physical and biological, is essential in providing an early warning of mite infestations, advising when appropriate control measures are required and for evaluating control measures. This information may provide a useful aid in predicting and preventing mite population development as part of a risk based decision support system.
The chill-coma temperatures, oxygen consumption at several constant temperatures, and fresh weights of adults of Cryptolestes ferrugineus (Steph.), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.) and Tribolium castaneum (Hbst.) were determined before and after acclimation for 14 days at 15 deg C in the laboratory in Australia. Acclimation lowered the mean chill-coma temperatures of all species, but most in O. surinamensis. The oxygen consumption of insects that were free to move and of insects restrained during respirometry was reduced by acclimation. The curves relating respiration rate and temperature were shifted downwards by cold acclimation, but its effect on their slopes (i.e. on temperature sensitivity) varied between and within species. Similarly, the relative proportions of the change in the consumption rates of free insects acclimated at 15 deg C that were attributable to locomotor activity or to resting metabolism varied considerably. The weights of C. ferrugineus and R. dominica were increased by cold acclimation, but those of the other 2 species were not.
The oxygen consumption of adult Sitophilus oryzae (L.). S. granarius (L.) and S. zeamais Motsch, that were acclimated at 27 or 15°C was measured at constant temperatures of from 10 to 30°C and relative humidities of 94, 70 or 50%. Warm-acclimated weevils that were free to move within the respirometers used significantly more oxygen than cold-acclimated weevils in almost all measurement regimens. In general, oxygen uptake was greatest at 70% r.h., intermediate at 94% and lowest at 50%. High oxygen consumption in certain regimens suggested an interaction between the effects of humidity and measurement temperature in S. oryzae and, to a lesser extent, in S. granarius. An interaction between humidity and acclimation temperature was indicated in S. granarius by the finding that the Q10s of warm-acclimated weevils increased as humidity decreased whereas the Q10s of cold-acclimated weevils did not change. The relationships between the logarithm of oxygen consumption and measurement temperature were described in all three species by quadratic functions. The oxygen consumption of S. oryzae closely restrained within the respirometers was not affected by relative humidity. Such weevils consumed more oxygen at 15 and 20°C when warm-acclimated than they did when cold-acclimated; there was no significant difference, however, between the oxygen consumption of warm- and cold-acclimated weevils at either 25 or 30°C.
We studied low temperature acclimation by 4 immature age groups (21–24, 14–17, 7–10 or 0–3 days after oviposition), by adults from laboratory-cultured strains, and by a field strain of each of 3 species: Sitophilus oryzae (L.), rice weevil; Sitophilus granarius (L.), granary weevil; and Rhyzopertha dominica (F.), lesser grain borer. Insects were acclimated for 3 days at 21.1, 7 days at 15.5 and 7 days at 10.0°C, then placed in 4.4°C 2, 4, or 6 weeks. Non-acclimated samples were placed directly in 4.4°C.
Prior acclimation increased survival of all insects at 4.4°C. The most cold-tolerant rice weevils and granary weevils were those of 14–17 days development, and most tolerant lesser grain borers, of 21–24 days. More granary weevil adults from the field strain than from the laboratory strain survived. Granary weevil adults (field or lab) were more cold-tolerant than adults of the other 2 species. The least cold-tolerant stages of all species were 0–3 days development (eggs).
The effect of thermal acclimatization on the resting metabolism of adult grain weevils was examined by closely restraining the weevils during respirometry. Sitophilus oryzae (L.) acclimatized to 15°C consumed less oxygen over 11–23°C than 27°C‐acclimatized weevils but like amounts over 25–35°C. Similar results were observed with S. granarius (L.).
Respiration R–T curves of unrestrained S. oryzae and S. granarius showed no evidence of rotation at temperatures close to their chill‐coma thresholds but warm‐ and cold‐acclimatized weevils consumed similar amounts of oxygen when both categories of weevils were in chillcoma.
Acclimatizing S. oryzae from 27 to 13.5°C through four, weekly 4.5°C step‐transfers lowered the median chill‐coma thresholds of the weevils from 8.9 to 6.2°C, increased their life span at 9°C, an unfavourable temperature for this species, from 2 to 8 weeks and lowered their oxygen uptake at 9°C by 19%.
S. granarius and S. oryzae were exposed to 32° and 35° for 2, 7 and 14 days and 1, 2 and 7 days, respectively, and mortality tested at 40°. Under these conditions maximum acclimation of S. granarius was achieved after 14 days at 32° and 2 days at 35°, while S. oryzae maximum acclimation occurred after 2 days at 32° and 1 day at 35°. Longer exposure at 32° for S. oryzae and for both species at 35°, appeared to reverse the process. Rearing S. granarius for three and five generations at 30°, raised its tolerance to the test temperature. Rearing S. oryzae for three generations at 30° did not have any significant effect on that species.
ZUSAMMENFASSUNG
EMPFINDLICHKEIT GEGENÜBER EINER HOHEN TEMPERATUR BEI SITOPHILUS GRANARIUS UND S. ORYZAE (COLEOPTERA: CURCULIONIDAE) NACH EXPOSITION IN SUPRAOPTIMALEN TEMPERATUREN
Imagines von S. granarius und S. oryzae wurden physiologisch bei 32° und 35° für 2, 7 und 14 Tage, oder für 1, 2 und 7 Tage akklimatisiert und ihre Sterblichkeit bei 40° geprüft. Unter diesen Bedingungen wurde die maximale Akklimatisierung bei S. granarius nach 14 Tagen bei 32° und nach 2 Tagen bei 35° erreicht, während bei S. oryzae die maximale Akklimatisierung nach 2 Tagen bei 32° und 1 Tag bei 35° erreicht wurde. Längere Akklimatisierungs‐Perioden bei 32° für S. oryzae und für beide Arten bei 35° schienen den Prozess umzukehren. Die Züchtung von S. granarius für drei und fünf Generationen, und von S. oryzae für drei Generationen bei 30° vergrösserte die Toleranz von S. granarius gegen die experimentelle Temperatur, hatte aber keinen bedeutsamen Effekt bei S. oryzae.
Die Daten beweisen die Fähigkeit von S. granarius und S. oryzae , sich an höhere Temperaturen zu akklimatisieren, wobei der Grad der vergrösserten Toleranz bei den zwei Arten verschieden war. Es zeigte sich auch, dass in diesen zwei Arten der physiologische Akklimatisierungsprozess bei stufenweisem Wechsel zu einer höheren Temperatur effektiver war als der Prozess der Akklimatisierung bei Dauerzucht in einer erhöhten Temperatur. Die gegenwärtigen Daten beziehen sich nur auf die veränderte Empfindlichkeit hinsichtlich der Mortalität bei den akklimatisierten Insekten in hoher Temperatur.
A table is presented giving the minimum temperature and humidity at which 43 species of beetle, 9 species of moth and one mite can multiply sufficiently to become pests, and the range of temperature most favourable for each. An estimate of the maximum rate of increase for each species is also given.
SAS User's Guide: Statistics, Version 5 Edition
- Anon
Anon., 1985. SAS User's Guide: Statistics, Version 5 Edition. SAS Institute Inc., Cary, NC, 956 pp. Boczek, J., 1954. A rearing method for small insects and mites under controlled conditions. Ekol. Pol., 2: 473-476.
A rearing method for small insects and mites under controlled conditions
- J Boczek
- J. Boczek