The effects of Bacillus thuringiensis (Bt) Cry1C toxin on the metabolic rate of Cry1C resistant and susceptible Spodoptera exigua (Hu¨bner) (Lepidoptera: Noctuidae) are investigated using closed-system respirometry. Mechanisms of resistance to the Bt toxin may be associated with an energetic cost that can be measured as an increase in metabolic rate compared with Bt-susceptible insects. This hypothesis is tested using third-and fifth-instar larvae and 1-7-day-old pupae. Metabolic rate is measured as the amount of O 2 consumed and CO 2 produced. _ V V O 2 and _ V V CO 2 (mL g À1 h À1 ) of third-instar Cry1C resistant larvae reared continuously on a diet containing 320 mg Cry1C toxin per g diet (CryonT) are significantly greater than third-instar Cry1C resistant larvae reared on toxin for 5 days and reared thereafter on untreated diet (Cry5dT), Cry1C resistant larvae reared on untreated diet (CryReg) and the susceptible parental strain (SeA) reared on untreated diet. There are no differences in _ V V O 2 and _ V V CO 2 (mL g À1 h À1 ) among treatment groups for fifth-instar larvae. CryonT larvae and pupae weigh significantly less than larvae and pupae receiving other treatments. Smaller body mass may be an important biological cost to individuals exposed continuously to Bt toxin. One-day-old pupae of all treatment groups exhibit a high _ V V O 2 (mean approximately 0.174 mL g À1 h À1 ) with CryonT having a significantly greater value than all other treatments; there are no differences among the other treatments. Pupal metabolic rates of all treatment groups decline to a minimum between days 2 and 4 then increase linearly between days 4 and 7 until adult emergence. These results demonstrate no difference in metabolic rates, and possibly fitness costs, between resistant (CryReg and Cry5dT) and susceptible (SeA) S. exigua except when larvae were reared continuously on toxin (CryonT).
The brown marmorated stink bug (BMSB),Halyomorpha halys(Stål) (Hemiptera: Pentatomidae) is non-native species that has rapidly expanded its range in the United States of America and Canada. This study was aimed at increasing our knowledge of the biology of BMSB and developing a rearing method. A laboratory culture maintained on 15 different foods (pear, peach, Granny Smith apple, red delicious apple, squash, tomato, carrot, green bean, grape, corn, leaves of princess tree, leaves of butterfly-bush, dry seeds of sunflower, cowpea, and peanut) had on average 26.0±2.1 eggs per egg mass, and an incubation period averaging 6.94±1.2 days. Developmental duration from second instar to adult averaged 28.2±0.9 days similar to second instars reared to adult on single diet of green beans, corn, sunflower, cowpea, and peanut seeds. Survival from egg to adult was 85.4% and a growth index (GI) of 2.2±0.2 for the laboratory culture comparable to ⩾2.0 GI and 80–90% reported nymphal development on a diet of dry sunflower, cowpea, and peanut seeds. We reared six generations of BMSB before the study was terminated. Our results indicate the foods that are better for BMSB growth, development, and survival.
Industrial hemp (Cannabis sativa), has been proposed as a new crop that might be of interest to organic farmers in the North Carolina and other states in the United States. However, little is known about how organic farmers view this crop. We conducted a survey among North Carolina certified organic growers to ascertain their knowledge of, and willingness to adopt, industrial hemp. Contact information was obtained from a database of certified organic farmers in North Carolina and the growers were contacted by email and directed to complete an online questionnaire. Growers were asked a wide range of questions about farm characteristics, technology adoption, interest toward industrial hemp, and policy issues regarding hemp adoption. A total of 245 farmers were contacted; 64 started the survey and 35 responded to all questions. Our results indicate that 85% of North Carolina organic growers are interested in growing hemp on their farms and the majority wanted to learn more about the crop production practices, adapted cultivars, and legality of growing it. Seventy-five percent expressed interest in being certified growers while 52% wanted to grow industrial hemp primarily for cannabidiol (CBD) oil. Most (65%) respondents indicate they aspired to be among the first farmers in their area to grow and sell hemp. Growers who have tried new crops or new farming technology in the last three years were more likely to adopt industrial hemp production. These findings will help decision-makers understand the critical concerns of growers who are willing to adopt industrial hemp as an alternative income-generating enterprise.
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