Alfredo Jiménez-Pérez

Properties of Edible Films Based on Oxidized Starch and Zein

The objective of this work was to investigate the effect of zein and film formulation on mechanical and structural properties of native (FNS), and oxidized with 2.5% (FOSA) and 3.5% (FOSB) banana starch. The oxidized starch showed differences from native starch due to the oxidation process, showing a decrease in lipids, proteins, and amylose. The increase of the sodium hypochlorite increased the content of carbonyl and carboxyl groups in the ranges 0.015–0.028% and 0.022–0.031%, respectively. The film obtained from FOSB displayed the highest tensile strength (5.05 MPa) and satisfactory elongation value (27.1%). The zein addition caused a decrease in these mechanical properties, as well as a significant decrease in water vapour permeability (WVP). However, films from FOSA and FOSB showed higher permeability than that of the native starch. The addition of glycerol and the level of oxidation increased the films moisture. Micrographs showed that, during the oxidation process, impurities were largely eliminated from the starch granule, noting more homogeneous structures both in granules and films.

Spatial analysis of mass trapping: how close is close enough?

BACKGROUND The identification of new attractants can present opportunities for developing mass trapping, but standard screening methods are needed to expedite this. We have developed a simple approach based on quantifying trap interference in 4 × 4 trap arrays with different spacings. We discuss results from sex pheromones in Lepidoptera (light brown apple moth, Epiphyas postvittana), Diptera (apple leaf curling midge, Dasineura mali) and Homoptera (citrophilous mealybug, Pseudococcus calceolariae), compared with a kairomone for New Zealand flower thrips (Thrips obscuratus). RESULTS The ratio of catch in corner traps to catch in centre traps was 25:1 at 750 D. mali traps ha(-1) , and was still ∼5:1 at 16 traps ha(-1) , suggesting trap interference even at such low trap densities. Trap competition for sex pheromone lures at close spacing (<5 m) was evident in 16-trap arrays of P. calceolariae, but less so for E. postvittana. No trap competition was observed at 4 m spacings with the kairomone for T. obscuratus. CONCLUSIONS The ratio of catch in traps in the corner and centre of a 16-trap array at different spacings offers a rapid preliminary assessment method for determining the potential for mass trapping. Additional knowledge of vital rates and dispersal is needed for predicting population suppression. Our approach should have value in mass trapping development.

Spatial analysis of mass trapping

BACKGROUND The identification of new attractants can present opportunities for developing mass trapping, but standard screening methods are needed to expedite this. We have developed a simple approach based on quantifying trap interference in 4 × 4 trap arrays with different spacings. We discuss results from sex pheromones in Lepidoptera (light brown apple moth, Epiphyas postvittana), Diptera (apple leaf curling midge, Dasineura mali) and Homoptera (citrophilous mealybug, Pseudococcus calceolariae), compared with a kairomone for New Zealand flower thrips (Thrips obscuratus). RESULTS The ratio of catch in corner traps to catch in centre traps was 25:1 at 750 D. mali traps ha(-1) , and was still ∼5:1 at 16 traps ha(-1) , suggesting trap interference even at such low trap densities. Trap competition for sex pheromone lures at close spacing (<5 m) was evident in 16-trap arrays of P. calceolariae, but less so for E. postvittana. No trap competition was observed at 4 m spacings with the kairomone for T. obscuratus. CONCLUSIONS The ratio of catch in traps in the corner and centre of a 16-trap array at different spacings offers a rapid preliminary assessment method for determining the potential for mass trapping. Additional knowledge of vital rates and dispersal is needed for predicting population suppression. Our approach should have value in mass trapping development.

Extrusion and Characterization of Thermoplastic Starch Sheets from "Macho" Banana

UNLABELLED Starch isolated from macho banana was oxidized by using 2.5% and 3.5% (w/w) of sodium hypochlorite. Native and oxidized starches with glycerol were processed using a conical twin screw extruder to obtain thermoplastic laminates or sheets, which were partially characterized. Oxidized banana starches presented higher moisture and total starch but lower ash, protein, lipids, and apparent amylose content than the native starch. Micrographs of sheets from oxidized starches showed wrinkles and cavities presumably caused by the plasticizer, but with less free glycerol and unplasticized starch granules than those from native starch. Sheets from oxidized starch showed a notorious increase in all thermal parameters (To, Tp, and ΔH), mechanical properties (tensile strength, elongation at break, and elasticity), and solubility. Banana starch X-ray diffraction patterns corresponded to a mixture of the A- and B-type polymorphs, with apparently slightly higher crystallinity in oxidized specimens than in native starch. A similar trend was observed in the corresponding sheets. PRACTICAL APPLICATION Due to the pollution problem caused by the conventional plastics, there has been a renewed interest in biodegradable sheets, because they may have the potential to replace conventional packaging materials. Banana starch might be an interesting raw material to be used as edible sheet, coating or in food packaging, and preservation, because it is biodegradable, cheap, innocuous, and abundant.

SIZE, FECUNDITY, AND GONADIC MATURATION OF TOXOTRYPANA CURVICAUDA (DIPTERA: TEPHRITIDAE)

Abstract The papaya fruit fly, Toxotrypana curvicauda Gerstaecker, is an important pest of papaya. It is distributed from Florida, USA, to northern South America. We studied aspects of its biology on papaya, Carica papaya. Females and males emerged within a 3-d period with similar numbers emerging daily. Females are heavier than males but had similar longevity. Puparial length, puparial weight, and adult weight did not correlate with adult longevity. First chorionated eggs were recorded 4 d after emergence. Females 6 d old had an average of 44 ± 2.2 (sem) chorionated eggs. Heavier females have a reproductive advantage as they have more chorionated eggs than light females. More than 85% of females lived at least 6 d.

REPELLENCY OF HYDROETHANOLIC EXTRACTS OF RICINUS COMMUNIS (EUPHORBIACEAE) TO SCYPHOPHORUS ACUPUNCTATUS (COLEOPTERA: CURCULIONIDAE) IN THE LABORATORY

ABSTRACT The agave snout weevil Scyphophorus acupunctatus Gyllenhal (Coleoptera: Curculionidae) is an ubiquitous insect and the main pest of blue tequila agave, Agave tequilana Weber, and other agaves. This study reports the repellent effect of the hydroethanolic extract of the castor oil plant, Ricinus communis L. (Euphorbiaceae) wild and ‘Mirante’ cultivar on the adults behavior. Females and males visited untreated agave tissue more frequently than agave tissue treated with R. communis extracts. Insects visited agaves treated with seed extracts more frequently than those with leave extracts; therefore leaves of R. communis deserve a closer look to identify their properties and gauge their potential use as a repellent.

Effect of Age, Body Weight and Multiple Mating on Copitarsia decolora (Lepidoptera: Noctuidae) Reproductive Potential and Longevity

Successful behavioral-based control methods rely on the accurate knowledge of the mating dynamics of the target insect. Age at first mating affects reproductive potential and the chance of multiple mating. The cabbage moth, Copitarsia decolora (Guenée) is an important pest of a number of commodities. We investigated combinations of age, body size and mating history to determine how these variables affect insect reproductive capacity. Fecundity and fertility decreased as the age of mating pairs increased, heavy and average sized females laid more eggs than light females. Female multiple mating did not enhance fecundity nor fertility potential. Furthermore, spermatophore size did not determine female re-mating behavior. However, female fecundity and fertility was related to the male mating history. Our results show that SIT is a valuable tool for controlling this pest.

Fecundity and mating propensity of Toxotrypana curvicauda (Diptera: Tephritidae) on an alternative host, Jacaratia mexicana (Caricaceae).

ABSTRACT Adult reproductive biology, including fecundity and mating propensity, may be affected by larval host for insects such as the papaya fruit fly, Toxotrypana curvicauda that do not require protein to produce eggs. Although the reproductive biology of papaya fruit flies that were reared on papaya fruit Carica papaya L. is known, little is known of flies that develop on alternate host fruit such as Jacaratia mexicana (Caricaceae). Therefore, uninfested J. mexicana fruit were collected from the field and infested by exposing them to oviposition in the laboratory by papaya fruit flies that were obtained from field-infested papaya. Puparia of females were longer then puparia of males, but there was no difference in either puparial width or weight. Females 6 d old produced 26 eggs/ovary. There was a positive linear relationship between puparial weight and number of chorionated eggs in mature females (6–8 d old), but puparial weight was not correlated with adult longevity. Females produced 2.99 eggs per mg of weight of puparium. Adult females were larger and heavier than adult males. Papaya fruit flies reared on J. mexicana are smaller, lighter, and have fewer eggs than reported for flies reared on C. papaya.

Effects of Five Species of Chenopodiaceae on the Development and Reproductive Potential of Copitarsia decolora (Lepidoptera: Noctuidae)

Abstract Modern agriculture aims to reduce continuous applications of synthetic chemical pesticides for pest control because of issues such as pollution, loss of trade and disruption of biological control agents, potentially leading to pest outbreaks. Botanical insecticides are a good alternative to synthetic pesticides, as they have lower environmental hazard, are biodegradable and can be used shortly before harvesting. We tested the effect of essential oils (EOs) and aqueous extracts (AEs) of Chenopodiaceae plants (Dysphania ambrosioides (=Chenopodium ambrosioides), Chenopodium album, C. berlandieri subsp. nuttalliae, C. graveolens and Beta vulgaris), incorporated into the diet under lab conditions, on a widely distributed insect pest in America, the cabbage pest, Copitarsia decolora Guenée 1852 (Lepidoptera: Noctuidae). The EO of C. graveolens at 0.5% reduced the larvae and pupae weight by 30 and 15%, respectively; increased the larval period length by 17% and reduced fecundity and fertility by 80 and 85%, respectively related to the control. EOs of C. berlandieri and B. vulgaris at 0.5% increased larval and pupal period length by 22% and 38% and both reduced fecundity and fertility by 99% related to the control. None of the plant extracts tested caused immediate C. decolora mortality, but EOs reduced mean survival time and reproductive capacity of the insect. This is the first report of C. berlandieri EO effect against an insect pest. The EOs of C. graveolens, B. vulgaris and C. berlandieri have great potential as alternatives to synthetic chemicals for insect control and deserve further exploration.

With or without pheromone habituation: possible differences between insect orders?

BACKGROUND Habituation to sex pheromones is one of the key mechanisms in mating disruption, an insect control tactic. Male moths often show reduced sexual response after pre-exposure to female sex pheromone. Mating disruption is relatively rare in insect orders other than Lepidoptera. RESULTS As a positive control we confirmed habituation in a moth (Epiphyas postvittana) using 24 h pre-exposure to sex pheromone to reduce subsequent activation behaviour. We then tested the impact of pre-exposure to sex or trail pheromone on subsequent behavioural response with insects from three other orders. Similar pre-exposure for 24 h to either sex pheromone [Pseudococcus calceolariae (Homoptera) and apple leaf curling midge Dasineura mali (Diptera), or trail pheromone of Argentine ants (Linepithema humile (Hymenoptera)], followed by behavioural assay in clean air provided no evidence of habituation after pre-exposure in these latter cases. CONCLUSIONS The moths alone were affected by pre-exposure to pheromone. For pests without habituation, sustained attraction to a point source may make lure and kill more economical. Improved knowledge of behavioural processes should lead to better success in pest management and mechanisms should be investigated further to inform studies and practical efforts generally enhancing effectiveness of pheromone-based management.