Bruchid a Serious Pest on Pulse Crops: Its Control Measures and Breeding Advancements: A Review

Bruchid (Callosobruchus spp.) are the most destructive, notorious storage pest of pulses in the tropical and sub-tropical region. The yield losses are higher than half of the expected yield with in the short period of time. Bruchid initial infestation started in the field and shortly builds up during storage time and cause severe seed damage up to 100 per cent. Bruchid infestation ranges from 60 to 100% within two to three months of storage period. Among the different bruchid species, cowpea weevils (C. maculatus F.) and azuki bean weevils (Callosobruchus chinensis L.) are the most destructive storage pest of pulses. Though several options are now available to identify the elite genotypes against bruchid infestation, still the development of genotypes with sufficient level of host plant resistance is not achieved. In this pursuit, the present article has given a detailed review of the major species of bruchid, insect life style, management practices, screening technique, sources of resistance, novel breeding strategies and recent advancements including use of molecular markers in marker aided selection and QTL studies for bruchid resistance.

Assessing the optimal frequency of early parasitoid releases in an apple orchard to control Dysaphis plantaginea: a proof of concept study

Alternative measures to pesticides to control the rosy apple aphid Dysaphis plantaginea are being developed. Naturally occurring predators and parasitoids often fail to reduce aphid abundance below the economic threshold in orchards, because they are active too late after the aphid first infestation. We tested the efficiency of mass release of two parasitoid species, Aphidius matricariae and Ephedrus cerasicola, early in the season to match the presence of aphid fundatrix (sensitive stages). In this trial focusing on an organic apple orchard, three releases were done either every week or every two weeks to test the effect of the release frequency, during two consecutive years. The number of aphid colonies and aphid number per tree were monitored from late March to late May. Degree-days necessary for parasitoid emergence in the field after release were calculated. We show that a sufficient level of aphid control by parasitoids is reached during the first month of the survey, but control mostly fails during the second part of the monitoring session, for both release treatments, and compared to the neem oil control treatment. The relative effects of release frequencies were different between years probably because of interannual differences in aphid population dynamics and initial infestation in orchards. The field survey and the degree-day model suggest that parasitoid releases, at either frequency, are promising candidates for biological control of the rosy aphid, although the method still needs proper calibration. This conclusion needs to be reinforced by repeating the study in more orchards, but our case study lays the first empirical basis that will help to develop future control methods of aphids by parasitoid releases in apple orchards. We argue that releases should be done one to two weeks before first aphid detection to account for long development times of parasitoids at relatively low temperatures.

Evaluation of Early Bark Beetle Infestation Localization by Drone-Based Monoterpene Detection

The project PROTECTFOREST deals with improvements in early bark beetle (e.g., Ips typographus and Pityogenes chalcographus) detection to allow for fast and effective response to initial infestation. The removal of trees in the early infestation stage can prohibit bark beetle population gradation and successive timber price decrease. A semiconductor gas sensor array was tested in the lab and attached to a drone under artificial and real-life field conditions. The sensor array was able to differentiate between α-pinene amounts and between different temperatures under lab conditions. In the field, the sensor responded to a strong artificial α-pinene source. The real-life field trial above a spruce forest showed preliminary results, as technical and environmental conditions compromised a proof of principle. Further research will evaluate the detection rate of infested trees for the new proposed sensor concept.

Early Detection of Bark Beetle Infestation by Drone-Based Monoterpene Detection

The project PROTECTFOREST deals with the improvement of early bark beetle detection to allow a fast and effective response to initial infestation. The removal of trees in the early infestation stage can prohibit bark beetle population gradation and successive timber price decrease. A semi-conductor gas sensor array was tested in the lab and attached to a drone under artificial and real-life field conditions. The sensor array was able to differentiate between α-pinene amounts and between different temperatures under lab conditions. In the field, the sensor responded to a strong artificial α-pinene source. The real-life field trial showed preliminary results, as technical and environmental conditions did compromise proof of principle. Further research will evaluate the detection rate of infested trees with the new proposed sensor concept.

Spatial Distribution of Frankliniella schultzei (Thysanoptera: Thripidae) in Open-Field Yellow Melon, With Emphasis on the Role of Surrounding Vegetation as a Source of Initial Infestation

Frankliniella schultzei (Trybom) is a serious pest of melon crops and is commonly found in the main producing areas of melon in Brazil (North and Northeast regions). This pest causes significant losses, damaging plants through feeding and tospovirus vectoring. Thus, the proper management of F. schultzei is crucial to prevent economic losses, and knowledge of the within-field distribution patterns of F. schultzei can be used to improve this pest management. This study aimed to determine the within-field distribution (through semivariogram modeling and kriging interpolation) and the factors associated with F. schultzei abundance in open-field yellow melon crops. We surveyed four yellow melon fields located in Formoso do Araguaia (Tocantins state, North Brazil) for thrips abundance in various crop stages (vegetative, flowering, and fruiting) in 2015 and 2016. Twelve models were fitted and it was determined that F. schultzei counts were strongly aggregated. The median spatial dependence was 4.79 m (range 3.55 to 8.02 m). The surface maps generated by kriging depicted an edge effect in fields 3 and 4. In addition, correlation analyses indicated that air temperature and presence of surrounding cucurbits are positively associated with F. schultzei abundance in yellow melon fields. Altogether, these insights can be combined for spatially based pest management, especially when the conditions (cucurbits in the surroundings and warmer periods) are favorable to F. schultzei.

Onion thrips Thrips tabaci [Thysanoptera: Thripidae] reduces yields and THC in indoor grown cannabis

ABSTRACTCannabis (Cannabis sativa L. [Rosales: Cannabaceae]) is a newly legalized crop and requires deeper insights on its pest communities. In this preliminary study, we identified a thrips species affecting indoor grown cannabis in Canada and tested its impact on plant yield. We used three levels of initial infestation (zero, one, and five thrips) on individual plants grown in two growing mediums: normal substrate or substrate containing the biostimulant Bacillus pumilus, Meyer and Gottheil [Bacillales: Bacillaceae]. We found that the onion thrips, Thrips tabaci (Lindeman) [Thysanoptera: Thripidae] is proliferating in indoor grown cannabis. Furthermore, our results showed that fresh yields were higher for the plants that initially received zero thrips compared to those that initially received five thrips. Moreover, the biostimulant did not help reduce the impact of thrips. We highlight the importance for growers to carefully monitor thrips infestations in indoor grown cannabis. Finally, we emphasize the need for more research related to the impact of pests on cannabis yields and safe means of pest control for this strictly regulated crop.

Economic Savings from Invasive Plant Prevention

Prevention programs are often assumed to be the most cost-effective method for managing invasive plants. However, there is very little information available about economic and biological factors that determine the forage benefits resulting from prevention programs. We developed an easy to use economic model to assess potential savings in livestock forage that might result from implementing prevention programs. The model can be used to determine potential loss in forage production caused by invasive plants and to estimate potential income savings by preventing invasive plant infestations. The model compares a prediction of populations with and without a prevention program using a logistic growth function. Animal unit month (AUM) price and interest rates are the primary economic input variables. The primary biological input variables are amount of invasive plant utilization, size of the initial infestation, and the spread rate with and without prevention. Our model suggests that as the AUM price increases and/or the interest rate decreases, the total savings increases for each AUM that was protected through a prevention program. The model also shows savings per AUM increases as the size of the initial infestation decreases, suggesting that prevention should focus on eliminating seed sources and seed production early in the program. Using our model inputs, the savings per AUM was about $9.20 for each percent reduction in spread rate over 100 yr.

Biochemical responses of cucumber to Tetranychus urticae Koch (Acari: Tetranychidae) mediated biotic stress

The effect of two spotted spider mite (Tetranychus urticae Koch) feeding on leaf level physiological characteristics of cucumber (Cucumis sativus Linnaeus) was investigated. Young cucumber plants were artificially infested with different densities of T. urticae (5, 10, 15 and 20 mites/ grown up leaf) while uninfested plants acted as control. Post infestation, the plants differed in their support to mite density in accordance with initial infestation density and observation period. Highly significant negative correlation of -0.92, -0.93, -0.95 and -0.92 for total chlorophyll, chlorophyll a, chlorophyll b and carotenoids, respectively, at the highest infestation level) was recorded between mite density and photosynthetic pigments in infested leaves as compared to uninfested ones. There was a significant decrease (P= 0.05) in the level of (a progressive decline from 2.82, 0.36 and 2.17% dry weight in control to the maximum of 2.09, 0.26 and 1.87% dry weight for N, P and K, respectively, at highest infestation level) in the infested leaves in response to mite infestation. Interaction between initial infestation level and observation period also suggested a significant impact of T. urticae infestation on the leaf phytochemicals of cucumber (P= 0.05).