Assessment of Trap Crops for The Wheat Bug, Nysius huttoni Management: A Cage Study

The wheat bug, Nysius huttoni, is an endemic New Zealand insect pest. Its feeding can seriously reduce crop establishment in forage A cage study was conducted in Lincoln University, New Zealand to evaluate the pest’s host preferences on four plant species. Kale plants (Brassica oleracea) were used as a potentially susceptible control and other four trap plants were tested to evaluate as potential trap-plants. These were: Lobularia maritima (alyssum), Triticum aestivum (wheat), Coriandrum sativum (coriander) and Trifolium repens (white clover). The alyssum plant was more attractive to the wheat bug. The survival rate and preferences of the wheat bug was significantly better than other four plants. The deployment of such flowering trap crops can potentially trap the wheat bug and also provide multiple ecosystem services (ES) in an agro-ecosystem. The findings can be used to develop the wheat bug management protocol and also potentially provide ecosystem services in brassica fields.

The relationship between natural rain intensity and Ascochyta blight in chickpea development.

Ascochyta blight is one of the most devastating diseases of chickpea worldwide. In Australia, Ascochyta blight management strategy in a standing crop is solely based on applying protective fungicides before a forecast rainfall event. Despite this, studies on the likely interaction between variable natural rain amount, rain duration, environmental factors and Ascochyta blight development are rare. We used generalised linear mixed models to investigate the relationship between rain intensity, wind speed and Ascochyta blight development. Briefly, 7 g of infested chickpea residue were placed at the soil surface in a 1 m2 plot, and three pots (3 trap plants per pot) of a susceptible chickpea cultivar were randomly placed on each side of the 1 m2 plot (total 12 pots), preceding a forecast rainfall event. Trap plants were transferred to a controlled temperature room (20°C) for 48 h (100% humidity) after rain events. After a 48 h incubation period, trap plants were transferred to a glasshouse (20°C) to allow lesion development. The number of lesions on all plant parts were counted after two weeks. Lesions developed in rain amounts as low as 1.4 mm and rain durations as short as 0.7 h. The number of lesions significantly increased with increasing rain amount. There was positive effect of increasing rain duration and a negative effect of increasing wind speed. This study suggests that small rain amounts, shorter duration rains or a limited amount of primary inoculum are not barriers to conidial dispersal or infection.

Marigold (Tagete erecta): An Effective Meloidogyne incognita Trap Plant

Root-knot nematodes (Meloidogyne spp.) are soil-borne pathogens that can cause severe damage to agricultural production. The most common approaches to prevent root-knot nematode infections are based on crop rotation with non-host plants, use of chemical insecticides, biological control methods, and use of nematode-antagonistic or trap plants. Marigolds (Tagetes erecta) are used as nematode-killing plants, but there is controversy over the mechanism through which they control root-knot nematodes. This study confirmed that marigold root-exudates are lethal to root-knot nematodes, illustrated that marigolds act as trap plants for root-knot nematodes when planted close to nematode host plants such as tomato. We investigated the rates of infection and development of nematode larvae injected into the marigold root system to evaluate whether marigolds could act as a non-host plant for root-knot nematodes. We found that aqueous solutions of marigold root-exudates showed strong lethal and inhibitory effects on sec-stage juveniles and eggs of root-knot nematodes. Marigold roots secreted substances that attracted nematodes from the surrounding environment. Furthermore, marigold root cells contained substances that had a strong inhibitory effect on the development of root-knot nematodes, resulting in diapause in nematodes, and inhibition of further infection. Herein we report a preliminary exploration of the antagonistic mechanism in marigolds for controlling the growth and development of root-knot nematodes. Our research provides basis for promoting the use of marigold for the control of nematodes as an important part of sustainable cropping strategies that rely on biological pest control. © 2021 Friends Science Publishers

Evaluation of Brassicaceae Seedlings as Trap Plants for Bagrada Hilaris Burmeister in Caper Bush Cultivations

The caper bush, Capparis spinosa (Brassicales: Capparaceae), is intensively grown on Pantelleria Island (Trapani, Sicily, Sicilian channel) where it has been granted protected geographical indication (PGI) by the EU. On this island, Bagrada hilaris, a stink bug native of Asia and Africa, is the major pest of caper crops. Recent studies have shown the attraction of B. hilaris to volatiles of brassicaceous plants at the seedling stage. The objective of this study was to evaluate three cotyledon-stage seedlings of host plants, Brassica oleracea var. botrytis (cauliflower), Eruca sativa (rocket) and Brassica carinata (Abyssinian cabbage), as potential trap plants for B. hilaris. The relative preferences of these species were first evaluated in laboratory and field experiments, carried out during summer when the level of B. hilaris infestation was the highest. Behavioral bioassays in the laboratory conditions showed that adults of B. hilaris preferred to orient toward seedlings of B. oleracea and E. sativa over B. carinata. Field experiments confirmed these results. Then seedlings were tested in trap plant trials, by sowing them in artificial pots formed with aluminum trays and placing them in caper fields infested with B. hilaris. Results showed that E. sativa and B. oleracea diverted hundreds of B. hilaris individuals from the capers to these sources of attraction. Overall, these results suggest that B. oleracea and E. sativa seedlings used as lure inside traps or as trap plants may be a useful tool in the management of B. hilaris populations.

Native Arbuscular Mycorrhizal Fungi Characterization from Saline Lands in Arid Oases, Northwest China

Arbuscular mycorrhizal fungi (AMF) colonize land plants in almost every ecosystem, even in extreme conditions, such as saline soils. In the present work, we report the mycorrhizal capacity of rhizosphere soils collected in the dry desert region of the Minqin Oasis, located in the northwest of China (Gansu province), which is characterized by several halophytes. Lycium spp. and Peganum nigellastrum were used as trap plants in a greenhouse experiment to identify autochthonous AMF associated with the halophytes’ rhizospheres. Morphological observations showed the typical AMF structures inside roots. Twenty-six molecularly distinct AMF taxa were recovered from soil and root DNA. The taxonomical diversity mirrors the several AMF adapted to extreme environmental conditions, such as the saline soil of central China. Knowledge of the AMF associated with halophytes may contribute to select specific fungal isolates to set up agriculture strategies for protecting non-halophyte crop plants in saline soils.

The role of conidia in the dispersal of Ascochyta rabiei

Ascochyta rabiei asexual spores (conidia) were assumed to spread over short distances (∼10 m) in a combination of rain and strong wind. The potential distance of conidial spread was investigated in three rainfall and three sprinkler irrigation events. Chickpea trap plants were distributed at the distances of 0, 10, 25, 50 and 75 m from infected chickpea plots before scheduled irrigation and forecast rainfall events. Trap plants were transferred to a controlled temperature room (20 °C) for 48 h (100% humidity) after being exposed in the field for 2–6 days for rainfall events, and for one day for irrigation events. After a 48 h incubation period, trap plants were transferred to a glasshouse (20 °C) to allow lesion development. Lesions on all plant parts were counted after two weeks, which gave an estimate of the number of conidia released and the distance travelled. Trap plants at all distances were infected in all sprinkler irrigation and rainfall events. The highest number of lesions on trap plants were recorded closest to the infected plots – the numbers decreased as the distance from the infected plots increased. There was a positive relationship between the amount of rainfall and the number of lesions recorded. A generalised additive model was developed that efficiently described spatial patterns of conidial spread. With further development, the model can be used to predict the spread of A. rabiei. This is the first systematic study to show that conidia distribute A. rabiei over longer distances than previously reported.

VALIDATION OF TECHNOLOGY COMPONENTS FOR PEANUT POD BORER (Etiella zinckenellaTriet.) CONTROL

Peanut pod borer caused by Etiella zinckenella is one of the important pests of peanut in Indonesia. The symptoms of E. zinckenella attack are blackened pods and rotten seeds, causing yield loss up to 90%. The research aim was to validate the efficacy of various control technology components of peanut pod borer pests. The research was conducted at the Natar (Lampung) experimental station from April to August 2014. The research was arranged using a complete randomized design (CRD) method, the treatment consisted of six control technology components, and treatment was repeated four times. The results showed that the more larvae found in the pods, the greater the damage of the pods are crushed by larvae. Application of lambda cyhalothrin insecticide (P6) starting at 35–70 days after planting (DAP) was not able to suppress larval populations of E. zinckenella so that damaged pods were also larger and not significantly different from without control (P0). Lamda sihalotrin insecticide application also harms the survival of natural enemies (predators and parasitoids). Lamda cyhalothrin insecticides can be combined with other control components such as soybean trap plants, thiametoxam and carbofuran and parasitoid of Trichogramma bactrae-bactrae to control of peanut pod borer. Application of Lecanicillium lecanii biopesticide was combined with chemical insecticides thiametoxam or carbofuran can suppress E. zinckenella larvae and yield loses, beside it can safety against the survival of predators the order Araneida and Coleoptera and parasitoid of Hymenoptera and Diptera. Biopesticides of L. lecanii were combined with tiametoxam or carbofuran insecticides can be recommended for control agents of peanut pod borer E. zinckenella.