In-Field Capable Loop-Mediated Isothermal Amplification Detection of Spodoptera frugiperda (Lepidoptera: Noctuidae) Larvae Using a Rapid and Simple Crude Extraction Technique.

Fall armyworm, Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), is an economically important pest worldwide and has recently been identified in Australia. Morphological identification of S. frugiperda at early larval stages can be difficult often requiring expert microscopy analysis. Rapid and accurate in-field diagnosis is vital for management decision support and there are no tools currently available for this purpose. In this study, a sensitive, specific, and in-field capable loop-mediated isothermal amplification (LAMP) assay was developed to detect S. frugiperda larvae. A primer set based on a highly conserved region of the S. frugiperda cytochrome oxidase subunit 1 (COX1) gene provided detection within 30 min from both total DNA and crude extractions. The crude extraction technique of crushing 10 mg of S. frugiperda material in 50 µl ddH2O and further diluting the homogenate in ddH2O is rapid, simple, and does not require heat blocks, centrifuges, or special buffers increasing its utility as a field-based technique. The primer set detected as little as 24 pg of S. frugiperda DNA and did not cross-react with any other of the lepidopteran species tested that are easily confused with S. frugiperda in Australia. Therefore, this assay could be used in-field to correctly identify the presence of S. frugiperda and thereby greatly assist with timely management decisions.

Removal and Burial of Weed Seeds by Ants (Hymenoptera: Formicidae) From the Soil Surface of a Cropped Area in Western Australia.

Although granivorous ants are known to collect weed seeds from cropping areas in Australia, the fate of these seeds has not been adequately investigated. Seeds of annual ryegrass (Lolium rigidum Gaud.) and wild radish (Raphanus raphanistrum L.) were placed around the nests of five native ant species (Iridomyrmex greensladei Shattuck, Rhytidoponera metallica Smith, Melophorus turneri Forel, Monomorium rothsteini Forel, and Pheidole hartmeyeri Forel) and tracked continuously over a 24-h period. Removal rates and seed preference of the ant species were evaluated. Ant nests were then excavated to determine the placement of seeds that were taken into each nest. Seed preference, seed removal efficiencies, activity, and seed storage all varied between the ant species. Annual ryegrass seed was collected by three species of ants and was removed from the soil surface more efficiently than wild radish seed. Most ant species stored seed below ground at a depth that is inhibitory to emergence, thereby potentially removing that portion of seed from the seed bank, but some seed was placed at germinable depths. Pheidole hartmeyeri was identified as a likely biological control agent for annual ryegrass seeds and wild radish, while Me. turneri and Mo. rothsteini have potential as biocontrol agents for annual ryegrass, but further research is needed.

Oviposition Preferences of Pickleworm (Lepidoptera: Crambidae) in Relation to a Potential Push-Pull Cropping Management Approach.

Pickleworm, Diaphania nitidalis Cramer (Lepidoptera: Crambidae), is a major pest of cucurbits. The current management approach for this pest is weekly insecticide applications. A push-pull cropping approach may be an alternative management practice and could reduce reliance on pesticides. One potential push-pull scenario is the use of squash (Cucurbita pepo L.) as a trap crop and watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai) as a deterrent intercrop to manage pickleworm on cantaloupe (Cucumis melo L.). This study investigated if the underlying mechanism required for the success of this management approach (a female oviposition preference or nonpreference among squash, cantaloupe, and watermelon) is present. A series of oviposition preference experiments was conducted to see how individual females responded when presented with different host plants for oviposition. Under laboratory conditions, when females had the choice of a leaf from squash, cantaloupe, and watermelon, they laid a higher proportion of their eggs on the cantaloupe leaf. However, under greenhouse conditions, when females were presented with whole plants of the three different species, they laid a higher percent of their eggs on the squash plant. Females laid a similar number of eggs on watermelon as compared with cantaloupe under greenhouse conditions, and appeared to not be averse to laying their eggs on watermelon. However, when presented with a noncucurbit, such as bean, females laid a low number of total eggs. Overall, it appears that squash may be more preferred as an oviposition substrate than cantaloupe or watermelon and may be a useful trap crop or pull. Further study to determine a suitable deterrent intercrop or push and evaluation of the proposed system under field conditions are needed.

Temperature-dependent development of the parasitoid Tachinaephagus zealandicus on five forensically important carrion fly species.

The influences of temperature and host species on the development of the forensically important parasitoid Tachinaephagus zealandicus Ashmead (Hymenoptera: Encyrtidae) were studied at six constant temperatures in the range of 15-30 degrees C. T. zealandicus completed development successfully between 15 degrees C and 27 degrees C on five species of Calliphoridae, Calliphora albifrontalis Malloch, Calliphora dubia Macquart, Lucilia sericata Meigen, Chrysomya rufifacies Macquart and Chrysomya megacephala Fabricius. No adult parasitoids emerged from any of the host species reared at 30 degrees C. Temperature and host species significantly influenced development time, emergence success and progeny size. Development was significantly longer on Ch. megacephala and Ch. rufifacies at 18-24 degrees C and significantly longer on Ch. rufifacies and C. albifrontalis at 15 degrees C and 27 degrees C. Parasitoid emergence success was greatest at 21 degrees C, declined at the temperature extremes (15 degrees C and 27 degrees C) and was significantly lower on Ch. megacephala and Ch. rufifacies than on the three other host species. Progeny numbers per host pupa were highest at 21-24 degrees C, declined on either side of this temperature range and were significantly lower on L. sericata, Ch. rufifacies and Ch. megacephala than on either C. dubia or C. albifrontalis. An effect of host species on sex ratio was only observed at 27 degrees C, at which a higher proportion of T. zealandicus females emerged from Ch. megacephala and Ch. rufifacies than from the other host species. The thermal requirements for development (developmental thresholds, thermal constant, optimum temperature) of T. zealandicus in each host species were estimated using linear and non-linear models. Upper and lower developmental thresholds ranged between 29.90 degrees C and 31.73 degrees C, and 9.73 degrees C and 10.08 degrees C, respectively. The optimum temperature for development was estimated at between 25.81 degrees C and 27.05 degrees C. Given the significant effect of host species on development time, the use of parasitoid-host-specific developmental data in forensic application is recommended.