Search

Anaphothrips obscurus is a cosmopolitan pest feeding on cereals and other grasses. The effects of constant temperatures on the biology of A. obscurus are not well known. Laboratory studies were conducted to assess the effects of temperature on the development, survival, longevity, fecundity and population parameter of A. obscurus at six constant temperatures (15, 20, 25, 30, 32, 35 °C). The hatchability was the lowest at 15 °C, the highest at 25 °C and no eggs hatched at 35 °C. Developmental rates increased linearly as the temperature increased. The lower developmental threshold temperature was 10.6 °C and 200 degree-days were required to complete development from egg to adult. Adult longevity decreased with increasing temperature, and ranged from 68.87 d at 15 °C to 16.41 d at 32 °C. The highest total fecundity occurred at 20 °C with 162 eggs per female. The temperature-dependent total fecundity, age-specific oviposition rate, and age-specific survival rate models were described. The intrinsic rate of increase (rm) was significantly higher at 30 and 32 °C (0.239 and 0.250) than at other temperatures. This study suggests that optimal developmental and reproductive temperatures for A. obscurus ranges between 25 and 30 °C and this may help this species adapt to warmer areas and widen its distribution and potential for damage in response to global warming. These findings will also be useful in developing monitoring programs, population dynamic models, and timing of control measures for A. obscurus.

Anaphothrips obscurus (Muller) is a cosmopolitan pest feeding on cereal crops and grasses. This species exhibits wing polyphenism. Differences in the life history traits of female macropterous and brachypterous A. obscurus were compared in the laboratory for this study. Experiments were performed in climate chambers set at 20 and 25 ± 1 °C, 60 ± 10% RH under a 16 L:8D photoperiod. The duration of total pre-adult stage, adult pre-oviposition period and total pre-oviposition period of macropterous morphs were significantly longer than in the brachypterous morphs both at 20 and 25 °C. No significant differences were found in adult longevity, survival rate or total fecundity between the two wing morphs, while early fecundity was significantly higher for brachypterous females compared with that for macropterous females at two temperatures.

Post-mating, sexual interactions of opposite sexes differ considerably in different organisms. Post-mating interactions such as re-mating behavior and male harassment can affect the fitness of both sexes. Echinothrips americanus is a new insect pest in Mainland China, and little is known about its post-mating interactions. In this study, we observed re-mating frequency and male harassment frequency and their effects on fitness parameters and offspring sex ratios of E. americanus females. Furthermore, we tested the impact of mating and post-mating interactions on fitness parameters of males. Our results revealed that the re-mating frequency in female adults was extremely low during a 30-day period. However, post-mating interactions between females and males, consisting mainly of male harassment and female resistance, did occur and significantly reduced female longevity and fecundity. Interestingly, increased access to males did not affect the ratio of female offspring. For males, mating dramatically reduced their longevity. However, post-mating interactions with females had no effects on the longevity of mated males. These results enrich our basic knowledge about female and male mating and post-mating behaviors in this species and provide important information about factors that may influence population regulation of this important pest species.

Echinothrips americanus Morgan, an invasive pest on various ornamentals and greenhouse crops, was introduced into mainland China recently, posing a potential threat to ornamentals and greenhouse crops. It exhibits two different reproductive modes: arrhenotokous parthenogenesis and sexual reproduction. Laboratory studies were conducted to compare the developmental and reproductive biology of E. americanus in these two reproductive modes. Results showed that the oviposition period, and longevity of female adults using sexual reproduction were longer than those using parthenogenesis. Furthermore, sexual female adults had higher fecundity and survival rates. However, no significant differences were found among immature stages in the durations of first and second instars, prepupae, and pupae between the two reproductive modes, with the exception of the duration of the egg stadium. The survival rates for eggs and first and second instars were higher in sexual E. americanus whereas there were no survival differences for prepupae and pupae. These results provide valuable insights into the mechanisms of parthenogenesis and sex determination in Thysanoptera.