Larval Sampling and Instar Determination in Field Populations of Northern and Western Corn Rootworm (Coleoptera: Chrysomelidae)

Hammack, Leslie; Ellsbury, M. M.; Roehrdanz, Richard L.; Pikul, J. L.

doi:10.1603/0022-0493-96.4.1153

Cited by 59 publications

(47 citation statements)

References 21 publications

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“…Preliminary experiments indicated 17 days at 24°C would allow larvae on isoline to develop to third instar (final instar) but not progress to pre-pupal or pupal stages. Larvae recovered from each Berlese were counted, and head capsule widths were measured using an ocular micrometer on a stereo microscope (Bausch and Lomb Stereo â , San Diego, CA) to determine the larval instar (George and Hintz 1966;Hammack et al 2003). The combined fresh weight (larvae were removed from 70% ethyl alcohol and air-dried for 3 min on Kimwipes â , Kimberly-Clark, Atlanta, GA before weighing) of surviving larvae per replication was measured using a pan balance (Mettler-Toledo, Columbus, OH; precision: 0.01), and average fresh weight per larva was determined by dividing the weight by the number of larvae per replication.…”

Section: On-plant Bioassaysmentioning

confidence: 99%

Effects of adult emergence timing on susceptibility and fitness of Cry3Bb1‐resistant western corn rootworms

Wangila

Meinke

2016

J Applied Entomology

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Field‐evolved resistance by the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte to the Cry3Bb1 trait expressed in maize, has been documented in areas of Nebraska USA. Currently, only limited information is available on life‐history traits of Cry3Bb1‐resistant field populations. Therefore, the Gassmann on‐plant bioassay was used to investigate the potential variability among four Cry3Bb1‐resistant WCR field collections made in 2011–2012 by focusing on the key parameters: larval survival, developmental stage and weight with specific emphasis on the impact of adult emergence timing on these parameters in subsequent progeny. Key results: In three of four collections, the susceptibility of larval progeny from adults that emerged early or late within a generation from Cry3Bb1 plants was similar. Each of the three collections exhibited complete resistance; that is, survival on Cry3Bb1 plants was greater or equal to survival on non‐Bt isoline plants. Bioassays from an additional field collection from one site 2 years (2013) after the original collection (2011) (both from Cry3Bb1 maize) indicated that resistance to Cry3Bb1 was maintained over time at the site despite Bt trait rotation in 2012. In general, comparative WCR life‐history parameter data from Cry3Bb1 and isoline maize indicate that fitness of field collections exhibiting complete resistance was similar on each hybrid. The mean proportion of larvae in third instar and mean weight of larvae recovered in bioassays from progeny of early‐ and late‐emerged adults was not significantly affected by emergence period. This suggests that delays in development and associated mean adult emergence commonly observed in populations that are susceptible to Cry3Bb1 may become smaller as populations become resistant to Cry3Bb1. Results from this article will inform Cry3Bb1 resistance mitigation efforts and contribute to the development of sustainable WCR management programmes.

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Section: On-plant Bioassaysmentioning

confidence: 99%

Effects of adult emergence timing on susceptibility and fitness of Cry3Bb1‐resistant western corn rootworms

Wangila

Meinke

2016

J Applied Entomology

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“…The total number of larvae recovered from each bioassay container was counted. For all larvae, we used a microscope (Leica MZ6) with digital camera and image analysis software (Motic Images Inc.) to measure width of larval head capsules and then determined larval instar based on the scale of Hammack et al 51 To ensure that larvae were not pupating in bioassay cups, we carefully inspected the soil of three bioassay cups for each of the four maize hybrids evaluated (DCK 6169, DCK 6172, 2T777 and 2T789) for three of 2010…”

Section: Disclosure Of Potential Conflicts Of Interestmentioning

confidence: 99%

Western corn rootworm and Bt maize

et al. 2012

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“…The larvae extracted from each plant were counted and classified into larval stages (L1, L2, and L3) by measuring head capsule width as described by Hammack et al (2003). The WCR root feeding was evaluated based on the root fresh weight of four plant replicates for each treatment.…”

Section: Methodsmentioning

confidence: 99%

Multitrophic interactions among Western Corn Rootworm, Glomus intraradices and microbial communities in the rhizosphere and endorhiza of maize

et al. 2013

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The complex interactions among the maize pest Western Corn Rootworm (WCR), Glomus intraradices (GI—recently renamed Rhizophagus intraradices) and the microbial communities in both rhizosphere and endorhiza of maize have been investigated in view of new pest control strategies. In a greenhouse experiment, different maize treatments were established: C (control plants), W (plants inoculated with WCR), G (plants inoculated with GI), GW (plants inoculated with GI and WCR). After 20 days of WCR root feeding, larval fitness was measured. Dominant arbuscular mycorrhizal fungi (AMF) in soil and maize endorhiza were analyzed by cloning of 18S rRNA gene fragments of AMF, restriction fragment length polymorphism and sequencing. Bacterial and fungal communities in the rhizosphere and endorhiza were investigated by denaturing gradient gel electrophoresis of 16S rRNA gene and ITS fragments, PCR amplified from total community DNA, respectively. GI reduced significantly WCR larval development and affected the naturally occurring endorhiza AMF and bacteria. WCR root feeding influenced the endorhiza bacteria as well. GI can be used in integrated pest management programs, rendering WCR larvae more susceptible to predation by natural enemies. The mechanisms behind the interaction between GI and WCR remain unknown. However, our data suggested that GI might act indirectly via plant-mediated mechanisms influencing the endorhiza microbial communities.

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Larval Sampling and Instar Determination in Field Populations of Northern and Western Corn Rootworm (Coleoptera: Chrysomelidae)

Cited by 59 publications

References 21 publications

Effects of adult emergence timing on susceptibility and fitness of Cry3Bb1‐resistant western corn rootworms

Effects of adult emergence timing on susceptibility and fitness of Cry3Bb1‐resistant western corn rootworms

Western corn rootworm and Bt maize

Multitrophic interactions among Western Corn Rootworm, Glomus intraradices and microbial communities in the rhizosphere and endorhiza of maize

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