Discrepancy Between Antennal and Behavioral Responses for Enantiomers of a-Pinene: Electrophysiology and Behavior of Helicoverpa Armigera (Lepidoptera)

The ability of adult cotton bollworm, Helicoverpa armigera (Hubner), to distinguish and respond to enantiomers of α-pinene was investigated with electrophysiological and behavioral methods. Electroantennogram recordings using mixtures of the enantiomers at saturating dose levels, and single unit electrophysiology, indicated that the two forms were detected by the same receptor neurons. The relative size of the electroantennogram response was higher for the (−) compared to the (+) form, indicating greater affinity for the (−) form at the level of the dendrites. Behavioral assays investigated the ability of moths to discriminate between, and respond to the (+) and (−) forms of α pinene. Moths with no odor conditioning showed an innate preference for (+)-α-pinene. This preference displayed by naıve moths was not significantly different from the preferences of moths conditioned on (+)-α-pinene. However, we found a significant difference in preference between moths conditioned on the (−) enantiomer compared to naıve moths and moths conditioned on (+)-α-pinene, showing that learning plays an important role in the behavioral response. Moths are less able to distinguish between enantiomers of α-pinene than different odors (e.g., phenylacetaldehyde versus (−)-α-pinene) in learning experiments. The relevance of receptor discrimination of enantiomers and learning ability of the moths in host plant choice is discussed.

Screening of new lines of cereal grains for inclusion in Near Infra Red Scan calibrations

The project will provide enough data for a reliable and robust NIRs. It will more fully develop the in vitro method to enable less costly assessment of grains in the future. It will also provide a reliable assessment for DE which is the most expensive component of pig feed.

Effect of physiological and experiential state of Bactrocera tryoni flies on intra-tree foraging behavior for food (bacteria) and host fruit

Using caged guava trees in Queensland, Australia, provided with food and oviposition sites, the foraging behaviour of females of the tephritid Bactrocera tryoni was investigated in relation to hunger for protein, the presence or absence of bacteria as a source of protein, the degree of prior experience with host fruit and quality of host fruit for oviposition. One aim was to evaluate whether it is immature or mature B. tryoni females that are responsible for initially inoculating host fruit surfaces with "fruit-fly-type" bacteria, the odour of which is known to attract B. tryoni females. Three-week-old immature females provided with sucrose but deprived of protein from eclosion had a much greater propensity than 3-week-old protein-fed mature females to visit vials containing fruit-fly-type bacteria, irrespective of whether vials were associated with adjacent host fruit or not. In the absence of associated bacteria in vials, immature females had a much lower propensity than mature females to visit host fruit. In the presence of bacteria in vials, however, propensity of immature and mature females to visit fruit was about equal. Mature (but not immature) females were more inclined to visit fruit that ranked higher for oviposition (nectarines) than fruit that ranked lower (sweet oranges). Mature females that attempted oviposition during a single 3-min exposure period to a nectarine prior to release were much more likely to find a nectarine than were mature females naive to fruit or immature females with or without prior contact with fruit. Exposure to a nectarine before release did not affect the propensity of either mature or immature females to alight on an odourless visual model of a nectarine, however. As judged by numbers of leaves visited, protein-deprived immature females were more active than protein-fed mature females, irrespective of the sorts of resources on a tree. It was concluded that: the 1st B. tryoni females to arrive on the fruit of a host tree and therefore inoculate the fruit with fruit-fly-type bacteria were unlikely to be sexually immature, but to be mature as a result of having earlier acquired protein elsewhere; the odour of colonies of fruit-fly-type bacteria when associated with host fruit attracted protein-hungry but not protein-fed females; and the odour of the fruit itself attracted mature females (especially experienced ones) but not immature females.

Host selection and parasitism behavior of lysiphlebus testaceipes: Role of plant, aphid species and instar

The aphid parasitoid Lysiphlebus testaceipes is a potentially valuable biological control agent of Aphis gossypii a major worldwide pest of cotton. One means of increasing the abundance of a biological control agent is to provide an alternative host habitat adjacent to cropping, from which they can provide pest control services in the crop. Host selection and parasitism rate of an alternative host aphid, Aphis craccivora by L. testaceipes were studied in a series of experiments that tested its host suitability relative to A. gossypii on cotton, hibiscus and mungbean. Host acceptance, as measured by number of ovipositions was much greater in A. craccivora compared to A. gossypii, while more host aphids were accepted on mungbean than cotton. When given a choice L. testaceipes attacks more 4th instar and adult stages (63% and 70%, respectively) of both hosts than 2nd instar nymphs (47%). In a switching (host choice) experiment, L. testaceipes preferentially attacked A. craccivora on mungbean over A. gossypii on cotton. Observations of parasitoid contact with A. gossypii cornicle secretion suggest it provides a useful deterrent against parasitoid attack. From these experiments it appears L. testaceipes has a preference for A. craccivora and mungbean compared to A. gossypii and cotton, in this respect using A. craccivora and mungbean as alternative habitat may not work as the parasitoid is unlikely to switch away from its preferred host. © 2012.

Effect of monensin inclusion in supplements for cattle consuming low quality tropical forage

A pen feeding study was carried out over 70 days to determine the effects of monensin (M) inclusion in two commercial supplements designed to provide different planes of nutrition to recently weaned steers. Thirty Bos indicus crossbred steers (191.4 +/- s.d. 7.1 kg) were individually fed a low quality pangola grass hay (57 g crude protein/kg DM; 497 g/kg DM digestibility) ad libitum (Control) with either a urea/molasses-based supplement of Rumevite Maxi-graze 60 Block (B), fed at 100 g/day, or grain-based Rumevite Weaner Pellets (WP), fed at 7.5 g/kg liveweight (W).day, both with and without M, viz. B, B+M, WP and WP+M, respectively. There were no significant interactions between supplement type and M inclusion for any measurement. Growth rates (main effects) averaged 0.17, 0.35 and 0.58 kg/day for the Control, B and WP supplements, respectively, with all means different (P < 0.05), while the response (P < 0.05) to M across supplement type was 0.11 kg/day. Hay DM intake was similar for the Control and B treatments (18.6 and 19.6 g/kg W.day) but was reduced (P < 0.05) with the WP supplement (16.8 g/kg W.day) while corresponding total DM intakes increased from 18.6 to 20.0 to 23.5 g/kg W.day (all differences P < 0.05), respectively. Monensin inclusion in the supplements did not affect supplement, hay or total DM intake. Inclusion of of M in supplements for grazing weaners in northern Australia may increase survival rates although the effect of M with cattle at liveweight maintenance or below requires further investigation.

Elevated CO2 affects the behavior of an ecologically and economically important coral reef fish

We tested the effect of near-future CO2 levels (a parts per thousand 490, 570, 700, and 960 mu atm CO2) on the olfactory responses and activity levels of juvenile coral trout, Plectropomus leopardus, a piscivorous reef fish that is also one of the most important fisheries species on the Great Barrier Reef, Australia. Juvenile coral trout reared for 4 weeks at 570 mu atm CO2 exhibited similar sensory responses and behaviors to juveniles reared at 490 mu atm CO2 (control). In contrast, juveniles reared at 700 and 960 mu atm CO2 exhibited dramatically altered sensory function and behaviors. At these higher CO2 concentrations, juveniles became attracted to the odor of potential predators, as has been observed in other reef fishes. They were more active, spent less time in shelter, ventured further from shelter, and were bolder than fish reared at 490 or 570 mu atm CO2. These results demonstrate that behavioral impairment of coral trout is unlikely if pCO(2) remains below 600 mu atm; however, at higher levels, there are significant impacts on juvenile performance that are likely to affect survival and energy budgets, with consequences for predator-prey interactions and commercial fisheries.

Controlled release of ethylene gas from the ethylene-α-cyclodextrin inclusion complex powder with deliquescent salts

Deliquescent calcium chloride (CaCl2) and magnesium chloride (MgCl2) were investigated for their practical application to release ethylene gas from an ethylene-α-cyclodextrin inclusion complexes (CD IC) powder at relative humidities (RHs) between 11.2 and 93.6 % at 18 °C. The IC powder and deliquescent salts were mixed at a ratio of 1:5, respectively. CaCl2 and MgCl2 started to deliquesce at 32.7 % RH. The IC powder dissolved in the concentrated salt solutions to release ethylene gas. Increasing the RH accelerated the release rate. Maximum release of ethylene gas was achieved after 24 h at 75.5 and 93.6 % RH for both IC powder-deliquescent salts mixture. The deliquescent salts proved to be a simple option for releasing ethylene gas from the IC powder.

Uses of an innovative ethylene-α-cyclodextrin inclusion complex powder for ripening of mango fruit

A novel ethylene-α-cyclodextrin (α-CD) inclusion complex (IC) powder was investigated to ripen Calypso mango fruit. Modulated release of ethylene gas from the IC powder was achieved by admixture with deliquescent salt CaCl2 at RHs of 75.5% and 93.6%. The IC powder was tested in the laboratory and for in-transit ripening of mango fruit over two seasons. In the laboratory experiment, ethylene gas started to release from the IC powder in 2 h and complete release was achieved in 24 h. Assessments of fruit colour and firmness showed that encapsulated ethylene and commercial grade ethylene from pressurised cylinder similarly shortened the ripening time to 9–10 days (after harvest) for treated fruit as compared with 15 days for untreated mango. Mango fruit treated in both ways with ethylene showed more uniform ripening than the control. For the in-transit ripening using the IC powder, ethylene was found to be between 4.9 and 10.5 μL L−1 in the headspace of the truck containers over 48 h. Mango fruit from the treated containers shortened the ripening time by 3–6 days as compared to the untreated control fruit. Thus, the safe and convenient IC powder has demonstrated promise for in-transit fruit ripening.