Broad-scale suppression of cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae), associated with Bt cotton crops in Northern New South Wales, Australia

2016 ◽  
Vol 107 (2) ◽  
pp. 188-199 ◽  
Author(s):  
G.H. Baker ◽  
C.R. Tann
Keyword(s):  
Host Plant ◽  
Helicoverpa Armigera ◽  
Cotton Bollworm ◽  
Bt Cotton ◽  
Cotton Production ◽  
Bt Toxin ◽  
Pheromone Trapping ◽  
Eastern Australia ◽  
Helicoverpa Armígera ◽  
Broad Scale

AbstractThe cotton bollworm, Helicoverpa armigera, is a major pest of many agricultural crops in several countries, including Australia. Transgenic cotton, expressing a single Bt toxin, was first used in the 1990s to control H. armigera and other lepidopteran pests. Landscape scale or greater pest suppression has been reported in some countries using this technology. However, a long-term, broad-scale pheromone trapping program for H. armigera in a mixed cropping region in eastern Australia caught more moths during the deployment of single Bt toxin cotton (Ingard®) (1996–2004) than in previous years. This response can be attributed, at least in part, to (1) a precautionary cap (30% of total cotton grown, by area) being applied to Ingard® to restrict the development of Bt resistance in the pest, and (2) during the Ingard® era, cotton production greatly increased (as did that of another host plant, sorghum) and H. armigera (in particular the 3rd and older generations) responded in concert with this increase in host plant availability. However, with the replacement of Ingard® with Bollgard II® cotton (containing two different Bt toxins) in 2005, and recovery of the cotton industry from prevailing drought, H. armigera failed to track increased host-plant supply and moth numbers decreased. Greater toxicity of the two gene product, introduction of no cap on Bt cotton proportion, and an increase in natural enemy abundance are suggested as the most likely mechanisms responsible for the suppression observed.

Mating of Helicoverpa armigera (Lepidoptera: Noctuidae) moths and their host plant origins as larvae within Australian cotton farming systems

2012 ◽  
Vol 103 (2) ◽  
pp. 171-181 ◽  
Author(s):  
G.H. Baker ◽  
C.R. Tann
Keyword(s):  
Host Plant ◽  
Helicoverpa Armigera ◽  
Stable Carbon Isotopes ◽  
Production Systems ◽  
Farming Systems ◽  
C4 Plants ◽  
C3 Plants ◽  
Bt Cotton ◽  
Cotton Production ◽  
Helicoverpa Armígera

AbstractTransgenic (Bt) cotton dominates Australian cotton production systems. It is grown to control feeding damage by lepidopteran pests such as Helicoverpa armigera. The possibility that these moths might become resistant to Bt remains a threat. Consequently, refuge crops (with no Bt) must be grown with Bt cotton to produce large numbers of Bt-susceptible moths to reduce the risk of resistance developing. A key assumption of the refuge strategy, that moths from different host plant origins mate at random, remains untested. During the period of the study reported here, refuge crops included pigeon pea, conventional cotton (C3 plants), sorghum or maize (C4 plants). To identify the relative contributions made by these (and perhaps other) C3 and C4 plants to populations of H. armigera in cotton landscapes, we measured stable carbon isotopes (δ13C) within individual moths captured in the field. Overall, 53% of the moths were of C4 origin. In addition, we demonstrated, by comparing the stable isotope signatures of mating pairs of moths, that mating is indeed random amongst moths of different plant origins (i.e. C3 and C4). Stable nitrogen isotope signatures (δ15N) were recorded to further discriminate amongst host plant origins (e.g. legumes from non-legumes), but such measurements proved generally unsuitable. Since 2010, maize and sorghum are no longer used as dedicated refuges in Australia. However, these plants remain very common crops in cotton production regions, so their roles as ‘unstructured’ refuges seem likely to be significant.

Increasing tolerance to Cry1Ac cotton from cotton bollworm, Helicoverpa armigera, was confirmed in Bt cotton farming area of China

2007 ◽  
Vol 32 (4) ◽  
pp. 366-375 ◽  
Author(s):  
GUO-PING LI ◽  
KONG-MING WU ◽  
FRED GOULD ◽  
JIAN-KANG WANG ◽  
JIN MIAO ◽  
...  
Keyword(s):  
Helicoverpa Armigera ◽  
Cotton Bollworm ◽  
Bt Cotton ◽  
Farming Area ◽  
Helicoverpa Armígera

scholarly journals Oviposition site selection and survival of susceptible and resistant larvae of Helicoverpa armigera (Lepidoptera: Noctuidae) on Bt and non-Bt cotton

2016 ◽  
Vol 106 (6) ◽  
pp. 710-717 ◽  
Author(s):  
T.T.A. Luong ◽  
S.J. Downes ◽  
B. Cribb ◽  
L.E. Perkins ◽  
M.P. Zalucki
Keyword(s):  
Helicoverpa Armigera ◽  
Site Selection ◽  
Oviposition Preference ◽  
Resistance Management ◽  
Oviposition Site ◽  
Bt Cotton ◽  
Oviposition Site Selection ◽  
Bt Toxin ◽  
Cotton Plants ◽  
Helicoverpa Armígera

AbstractIn Australia Bt cotton has been planted since 1996, and has greatly improved the control of its key target Helicoverpa armigera (Hübner). There is no strong evidence that genetically modified cotton has been selected for significant physiological resistance to Bt toxin in field populations. There are many possible explanations for the lack of apparent selection that range from high compliance with the resistance management strategy for this technology to a lack of behavioral preference in key traits such as oviposition that could favor survival. To date most experiments that test oviposition of H. armigera on Bt cotton vs. conventional cotton have been done with susceptible moths. We determine the oviposition preference of a field isolated Bt resistant line of H. armigera and a susceptible counterpart when given a choice of non-Bt cotton and Bt-cotton with the same genetic background, and test whether there is any relationship between oviposition site selection (different plant structures) and the survival of the first instar larvae. Within cotton plants, our experiments consistently showed that both resistant and susceptible moths did not choose plants or plant parts that were less toxic in terms of Bt toxin on which to lay eggs. There was one exception in that susceptible moths were more likely to lay eggs on squares of Bt cotton plants than squares of non-Bt cotton. As expected, the mortality of susceptible H. armigera neonates was significantly higher on structures of Bt cotton plants than on those structures of conventional cotton, and survival was greater on flowers than on other structures of Bt cotton. This confirms opportunities for selection for resistance, and demonstrates no advantage in this respect to carrying resistance genes that might overcome the Bt toxins.

scholarly journals Expressing Double-Stranded RNAs of Insect Hormone-Related Genes Enhances Baculovirus Insecticidal Activity

2019 ◽  
Vol 20 (2) ◽  
pp. 419 ◽  
Author(s):  
Zheming Liu ◽  
Xiaofang Wang ◽  
Yan Dai ◽  
Xiaoli Wei ◽  
Mi Ni ◽  
...  
Keyword(s):  
Helicoverpa Armigera ◽  
Insecticidal Activity ◽  
Target Genes ◽  
Receptor Gene ◽  
Mrna Level ◽  
Recombinant Baculovirus ◽  
Cotton Bollworm ◽  
Cotton Production ◽  
Control Value ◽  
Helicoverpa Armígera

Baculoviruses have already been used for insect pest control, but the slow killing speed limits their further promotion and application. Here we provide a strategy for improving baculovirus insecticidal activity using Helicoverpa armigera nucleopolyhedrovirus (HearNPV) to express double-stranded RNAs (dsRNAs) targeting cotton bollworm (Helicoverpa armigera) juvenile hormone (JH)-related genes. Droplet-feeding bioassays show that the 50% lethal concentration (LC50) values of recombinant baculoviruses expressing the dsRNA of JH acid methyl transferase gene (HaJHAMT) and the JH acid binding protein gene (HaJHBP) were 1.24 × 104 polyhedral inclusion bodies (PIB)/mL and 2.26 × 104 PIB/mL, respectively. Both were much lower than the control value (8.12 × 104 PIB/mL). Meanwhile, the LT50 of recombinant baculovirus expressing dsRNA of HaJHBP was only 54.2% of the control value, which means that larval death was accelerated. Furthermore, the mRNA level of target genes was reduced in recombinant baculovirus-treated cotton bollworm larvae. Transcription of several key genes involved in hormone signaling pathways—for example, ecdysone receptor gene (HaEcR)—was also altered. This study establishes a new strategy for pest management by interfering with insect hormone-related gene expression via baculoviruses, and the engineered baculoviruses have great potential application in cotton production.

scholarly journals Evaluating Cross-Resistance to Cry and Vip Toxins in Four Strains of Helicoverpa armigera With Different Genetic Mechanisms of Resistance to Bt Toxin Cry1Ac

2021 ◽  
Vol 12 ◽  
Author(s):  
Liangxuan Qi ◽  
Hanyang Dai ◽  
Zeng Jin ◽  
Huiwen Shen ◽  
Fang Guan ◽  
...  
Keyword(s):  
Helicoverpa Armigera ◽  
Genetic Basis ◽  
Cross Resistance ◽  
Bt Cotton ◽  
Bt Toxin ◽  
Field Control ◽  
Helicoverpa Armígera ◽  
Genetic Mechanisms ◽  
Evolution Of Resistance ◽  
Control Failures

Evolution of resistance by pests has diminished the efficacy of transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt). In China, where transgenic cotton producing Bt toxin Cry1Ac has been planted since 1997, field control failures have not been reported but the frequency of resistance to Cry1Ac has increased in the cotton bollworm, Helicoverpa armigera. This provides incentive to switch to multi-toxin Bt cotton, which is grown in many other countries. Previous work created four laboratory strains of H. armigera with >100-fold resistance to Cry1Ac, with the genetic basis of resistance known in all but the LF256 strain. Here, we analyzed the genetic basis of resistance in Cry1Ac in LF256 and evaluated cross-resistance of all four strains to three toxins produced by widely planted multi-toxin Bt cotton: Cry1Fa, Cry2Ab, and Vip3Aa. DNA sequencing revealed that LF256 lacked the mutations in three genes (HaTSPAN1, HaABCC2, and HaABCC3) that confer resistance to Cry1Ac in two other strains of H. armigera we analyzed. Together with previous results, the data reported here show that each of the four strains examined has a different genetic basis of resistance to Cry1Ac. Significant positive cross-resistance occurred to Cry1Fa in three of the four strains tested but not to Cry2Ab or Vip3Aa in any strain. Thus, Cry2Ab and Vip3Aa are likely to be especially valuable for increasing the efficacy and durability of Bt cotton against H. armigera populations that have some resistance to Cry1Ac.

Sign in / Sign up

Export Citation Format

Share Document