Western flower thrip, Frankliniella occidentalis (Pergande), is among the most economically important agricultural pests globally, attacking a wide range of vegetable and horticultural crops. In addition to causing extensive crop damage, the species is notorious for vectoring destructive plant viruses, mainly belonging to the genera Orthotospovirus, Ilarvirus, Alphacarmovirus and Machlomovirus. Once infected by orthotospoviruses, thrips can remain virulent throughout their lifespan and continue transmitting viruses to host plants when and wherever they feed. These irruptive viral outbreaks in crops will permanently disrupt functional integrated pest management systems, and typically require a remedial treatment involving insecticides, contributing to further development of insecticide resistance. To mitigate against this continuing cycle, the most effective management is early and comprehensive surveillance of the pest species and recognition of plant viruses in the field. This review provides information on the pest status of F. occidentalis, discusses the current global status of the viruses vectored by this thrip species, examines the mechanisms involved in transmitting virus‐induced diseases by thrips, and reviews different management strategies, highlighting the potential management tactics developed for various cropping systems. The early surveillance and the utilization of potential methods for control of both F. occidentalis and viruses are proposed.
Companion planting is a well-known strategy to manage insect pests and support a natural enemy population through vegetative diversification. Trap cropping is one such type of special companion planting strategy that is traditionally used for insect pest management through vegetative diversification used to attract insect pests away from the main crops during a critical time period by providing them an alternative preferred choice. Trap crops not only attract the insects for feeding and oviposition, but also act as a sink for any pathogen that may be a vector. Considerable research has been conducted on different trap crops as companion plant species to develop improved pest management strategies. Despite this, little consensus exists regarding optimal trap cropping systems for diverse pest management situations. An advantage of trap cropping over an artificially released natural enemy-based biological control could be an attractive remedy for natural enemies in cropping systems. Besides, many trap crop species can conserve natural enemies. This secondary effect of attracting natural enemies may be an advantage compared to the conventional means of pest control. However, this additional consideration requires a more knowledge-intensive background to designing an effective trap cropping system. We have provided information based on different trap crops as companion plant, their functions and an updated list of trap cropping applications to attract insect pests and natural enemies that should be proven as helpful in future trap cropping endeavors.
25 October 2016 in Experimental and Applied Acarology
Plant trichomes often function as physical barriers in preventing arthropod feeding and oviposition. Even though insects are frequently reported being entrapped and killed by trichome traps, the actual trapping behavior has not yet been described in detail. Capture experiments showed that capture efficiency during the plant's vegetative stage was considerably higher than in the fruiting and cotyledon stages. The ventral surface of the leaf was more effective in trapping flies than other parts of the plant. Capture-events monitoring showed that the mouthparts, legs, and ovipositor of Liriomyza trifolii adults are the body parts involved in entrapment by surface trichomes on Phaseolus vulgaris plants, and subsequently, deter their ability to feed, walk, and oviposit. Of the three main body parts normally affected, mouthparts was found to be the body part most susceptible to the trichomes. Entrapments were most often caused by landing, followed by puncturing or feeding, and occasionally by walking or fighting. Using scanning electron microscopy (SEM) and optical microscopy, we determined the susceptible positions of each body part and found that the flies were all trapped by hooked trichomes. This study revealed the process by which leafminer flies are entrapped by surface trichomes of the host plant and evaluated the capture efficiency. The results will contribute to our understanding of physical defenses against herbivores.