RESUMO
To explore the relationship between larch caterpillar population and meteorological factors, a suite of linear regression models were developed. We used a stepwise regression approach to obtain the best model based on the Akaike information criterion (AIC). We also identified the key meteorological factors based on relative weight, and analyzed their marginal influences on larch ca-terpillar population. Our modeling results showed that meteorological conditions during the young larva stage and breeding stage played a key role in impacting larch caterpillar population. In contrast, meteorological conditions during the middle larva stage and old larva stage had a weaker effect. The mean daily relative humidity during young larva stage, the accumulated daily temperature less than -22 â during young larva's overwintering stage, and the total rainfall in breeding stage were the key meteorological factors affecting the population of larch caterpillar. With the increase of one standard deviation from the mean daily relative humidity during young larva stage and the total rainfall in breeding stage, the larch caterpillar population would be reduced by 62% and 35% of standard deviation, respectively. In contrast, one standard deviation increase of the accumulated daily temperature less than -22 â during young larva's overwintering stage would increase larch caterpillar population by 40% of standard deviation. Our study suggests that the larch caterpillar population in the future may explode in response to global warming, and its infestation could exhibit a new pattern. It is therefore very important to establish a long-term population monitoring system.
Assuntos
Umidade , Larix , Mariposas , Chuva , Temperatura , Animais , Larva , Modelos LinearesRESUMO
Taking the 4th-instar larval Propsilocerus akamusi as test object, this paper studied the acute toxicity of phenol, and the body mass, pupation rate, protective enzyme activities, and detoxifying enzyme activities of the larvae under exposure to phenol. The LC50 value of phenol to the larvae after exposure for 6, 24, 48, 72, and 96 h was 222.52, 134.86, 67.74, 47.39, and 35.76 mg x L(-1), respectively, and the dry mass, fresh mass, and pupation rate of the larvae decreased under the exposure of 0. 4, 4, and 40 mg phenol x L(-1). During 72 h exposure to phenol, the larval catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and carboxylesterase (CarE) activities responded to phenol in concentration- and time-dependent way, while the acid phosphatase (ACP) and alkaline phosphatase (ALP) activities responded slowly and were only inhibited significantly under the exposure to 40 mg x L(-1) of phenol for 48 and 72 h, respectively. It was suggested that the body mass, pupation rate, and CAT, SOD, GST, and CarE activities of 4th-instar larval P. akamusi could be used as the biological markers to monitor the phenol pollution of water body.
