Piperitone (p-Menth-1-En-3-One): A New Repellent for Tea Shot Hole Borer (Coleoptera: Curculionidae) in Florida Avocado Groves.

The tea shot hole borer, Euwallacea perbrevis, has been recently established in Florida, USA, where it vectors fungal pathogens that cause Fusarium dieback in avocado. Pest monitoring uses a two-component lure containing quercivorol and α-copaene. Incorporation of a repellent into IPM programs may reduce the incidence of dieback in avocado groves, particularly if combined with lures in a push-pull system. This study evaluated piperitone and α-farnesene as potential repellents for E. perbrevis, comparing their efficacy to that of verbenone. Replicate 12-week field tests were conducted in commercial avocado groves. Each test compared beetle captures in traps baited with two-component lures versus captures in traps containing lures plus repellent. To complement field trials, Super-Q collections followed by GC analyses were performed to quantify emissions from repellent dispensers field-aged for 12 weeks. Electroantennography (EAG) was also used to measure beetle olfactory response to each repellent. Results indicated that α-farnesene was ineffective; however, piperitone and verbenone were comparable in repellency, achieving 50-70% reduction in captures, with longevity of 10-12 weeks. EAG responses to piperitone and verbenone were equivalent, and significantly greater than response to α-farnesene. Since piperitone is less expensive than verbenone, this study identifies a potential new E. perbrevis repellent.

Volatile Emissions and Relative Attraction of the Fungal Symbionts of Tea Shot Hole Borer (Coleoptera: Curculionidae).

Euwallacea perbrevis is an ambrosia beetle that vectors fungal pathogens causing Fusarium dieback in Florida avocado trees. Current monitoring lures contain quercivorol, a fungus-produced volatile, but the exact attractant is unknown since lures contain a mixture of p-menth-2-en-1-ol isomers and both α- and ß-phellandrene. This study used pure cultures of six symbiotic fungi isolated from E. perbrevis to document volatile emissions and determine the relative attraction of symbionts in binary choice assays. In a comparative test, headspace solid-phase microextraction followed by gas chromatography-mass spectroscopy was used to identify and quantify emissions from 3-week-old cultures. In a temporal study, Super-Q collection followed by gas chromatography-flame ionization detection was used to measure cis- and trans-p-menth-2-en-1-ol emissions for three months. A total of 15 compounds were detected, with monoterpene hydrocarbons and oxygenated monoterpenoids predominating. Only trans-p-menth-2-en-1-ol was common to all six symbionts. Peak levels of both isomers were observed at day 7, then gradually declined over a 90 day period. In choice tests, avocado sawdust disks inoculated with Fusarium sp. nov. were the most attractive. This symbiont produced only two volatiles, trans-p-menth-2-en-1-ol and limonene. The combined results indicate that trans-p-menth-2-en-1-ol is the primary female attractant emitted from symbiotic fungi, but limonene may be a secondary attractant of E. perbrevis.

Effectiveness of Hot-Water Immersion Against Brevipalpus yothersi (Acari: Tenuipalpidae) as a Postharvest Treatment for Lemons.

Citrus leprosis is a destructive disease of citrus caused by several viruses (CiLVs) that are quarantine pests in the United States. Brevipalpus yothersi Baker (Acari: Tenuipalpidae) vectors the most virulent strain of CiLV. This mite is present in the United States and could facilitate the spread of the disease if CiLV reaches the country. Postharvest treatments could mitigate B. yothersi on imported commodities from areas where CiLV exists. The current study explores the effectiveness of hot-water immersion as a postharvest treatment against B. yothersi. Lemons were immersed in water at 21, 48, 53, or 63°C for 5, 10, and 15 min. Immersions at 53 and 63°C for all time schedules dislodged over 99% of adult mites. Lemon fruit quality and B. yothersi egg viability after hot-water immersion were also evaluated. Fruit quality significantly decreased in lemons treated at 63°C resulting in decay (grade 3, rejection), while at 53°C there was a quality reduction (grade 2, minimum acceptable market level) compared to lemons immersed at 21°C or nontreated controls (grade 1). None of the eggs hatched when the lemons were immersed in water at 63°C and an average of 1.5% hatched at 53°C for all time schedules. Immersion in water at 53°C for 5 min dislodged 99.71% and 57.14% of adult and immature mites, respectively, and resulted in 98.11% unhatched eggs without significant fruit quality reduction. Hot-water immersion could be a key component in a systems approach to control B. yothersi on imported citrus fruits from countries where citrus leprosis is present.

Development and reproduction of Amblyseius largoensis (Acari: Phytoseiidae) feeding on pollen, Raoiella indica (Acari: Tenuipalpidae), and other microarthropods inhabiting coconuts in Florida, USA.

The red palm mite, Raoiella indica (Acari: Tenuipalpidae), is an important pest of palms (Arecaceae) and other species within the Zingiberaceae, Musaceae and Strelitziaceae families. Raoiella indica was discovered in the USA (Palm Beach and Broward counties, Florida) late in 2007, and it subsequently spread to other Florida counties. The predatory mite Amblyseius largoensis (Acari: Phytoseiidae) has been found associated with R. indica in Florida. In order to verify whether A. largoensis can develop and reproduce when feeding exclusively on R. indica, the biology of this predator was evaluated on various food sources, including R. indica. Five diets [R. indica, Tetranychus gloveri Aonidiella orientalis, Nipaecocus nipae, oak (Quercus virginiana) pollen] and a no-food control were tested to determine the predators' development, survivorship, oviposition rate, sex ratio and longevity at 26.5 +/- 1 degrees C, 70 +/- 5% RH and a 12:12 L:D photophase. Amblyseius largoensis was able to complete its life cycle and reproduce when fed exclusively on R. indica. The development of immature stages of A. largoensis was faster and fecundity and survivorship were higher when fed on R. indica or T. gloveri compared to the other food sources. The intrinsic rate of natural increase of A. largoensis was significantly higher when fed on R. indica than on other diets. These results suggest that, despite earlier assessments, A. largoensis can play a role in controlling R. indica.