To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Larvae of the wheat midge, Sitodiplosis mosellana (Géhin), feed on developing seeds of common and durum wheats, Triticum aestivum L. and Triticum durum L. (Graminae). The trophic relationships between insect and plant were quantified as biomass gains or losses using plants infested artificially in the laboratory and naturally in plots and commercial fields. The biomass of seeds from different parts of a wheat spike varied, but seeds in all parts of a spike were infested, independently of their potential biomass. Most infested seeds had 1–3 larvae, but at least 11 larvae could mature on a single seed without reducing larval biomass. When larvae finished feeding and seeds attained about one third of their biomass, specific impact varied from 4.1 to 8.5 mg of seed biomass lost for each milligram of biomass gained by a larva, with the impact declining as the number of larvae per seed increased. Specific impact rose to 100 mg/mg as seeds of T. aestivum and a primitive wheat, Triticum monococcum L., matured, and higher still for T. durum. Wheat plants did not compensate for wheat midge damage, and no indirect damage to uninfested seeds was detected. The distribution of biomass for infested seeds was bimodal, with over 40% less than 8 mg when hand harvested, whereas infested seeds harvested mechanically had a unimodal distribution, with nearly all of the most severely damaged seeds removed during harvest. A visual rating system of six damage categories was related to the biomass of the seeds. The germination and early growth rate of infested seeds were reduced compared with those of uninfested seeds. Based on the biomass relationships for the insect–plant interaction and the visual rating of damage, high-protein number 1 grade common and durum wheat and number 1 grade durum wheat can tolerate up to 6% of the seeds being infested by larvae, before downgrading is likely. For other grades, the economic threshold is 10% of the seeds infested, based on yield loss. Seed growers can adopt the threshold for number 1 wheat (6% infestation) to prevent downgrading, which would also reduce the effects of infestation on seed germination to an acceptable level.
Over an order of magnitude reduction in dark current was observed for gas-source molecular beam epitaxially (GSMBE) grown, lattice-matched n- and p-type InGaAs/InP quantum-well infrared photodetectors (QWIPs). Peak spectral response at 8.93 and 4.55 μm for n- and p-type QWIPs, respectively, open the possibility of dual-band monolithic integration under identical GSMBE growth conditions.
Email your librarian or administrator to recommend adding this to your organisation's collection.