Laboratory and field evaluation of acetic acid-based lures for male Asian citrus psyllid, Diaphorina citri.

The Asian citrus psyllid (ACP) is a vector of a pathogen associated with greening and thus a major problem in citriculture worldwide. Lures are much needed for improving ACP trapping systems for monitoring populations and surveillance. Previously, we have identified acetic acid as a putative sex pheromone and measured formic acid- and propionic acid-elicited robust electroantennographic responses. We have now thoroughly examined in indoor behavioral assays (4-way olfactometer) and field tests the feasibility of these three semiochemicals as potential lures for trapping ACP. Formic acid, acetic acid, and propionic acid at appropriate doses are male-specific attractants and suitable lures for ACP traps, but they do not act synergistically. An acetic acid-based homemade lure, prepared by impregnating the attractant in a polymer, was active for a day. A newly developed slow-release formulation had equal performance but lasted longer, thus leading to an important improvement in ACP trap capture at low population densities

Modeling and validation of a parabolic solar collector with a heat pipe absorber

Cylindrical parabolic solar concentrators of small concentration ratio are attractive options for working temperatures around 120 degrees C. The heat gained can be utilized in many applications such as air conditioning, space heating, heating water and many others. These collectors can be easily manufactured and do not need to track the sun continuously. Using a heat pipe as a solar absorber makes the system more compact and easy to install. This study is devoted to modeling a system of cylindrical parabolic solar concentrators of small concentration ratio (around 5) fitted with a heat pipe absorber with a porous wick. The heat pipe is surrounded by evacuated glass tube to reduce thermal losses from the heat pipe. The liquid and vapor flow equations, energy equation, the internal and external boundary conditions were taken into consideration. The system of equations was solved and the numerical results were validated against available experimental and numerical results. The validated heat pipe model was inserted in an evacuated transparent glass tube as the absorber of the cylindrical parabolic collector. A calculation procedure was developed for the system, a computer program was developed and tested and numerical simulations were realized for the whole system. An experimental solar collector of small concentration, fitted with evacuated tube heat pipe absorber was constructed and instrumented. Experiments were realized with the concentrator axis along the E-W direction. Results of the instantaneous efficiency and heat gain were compared with numerical simulations realized under the same conditions and reasonably good agreement was found44299323CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESsem informaçã

Putative sex pheromone of the Asian citrus psyllid, Diaphorina citri, breaks down into an attractant

Abstract Under laboratory conditions, mating activity in Asian citrus psyllid (ACP) started 4 days after emergence, peaked at day 7, and showed a clear window of activity starting 8 h into the photophase and extending through the first hour of the scotophase. We confirmed that ACP males are attracted to emanations from conspecific females. Traps loaded with a candidate compound enriched with female extract, lignoceryl acetate (24Ac), at various doses were active only after being deployed for several weeks in the field, suggesting that a degradation product, not the test compound, was the active ingredient(s). Lignocerol, a possible product of 24Ac degradation, was not active, whereas acetic acid, another possible degradation product, was found in the airborne volatile collections from lures matured under field conditions and detected in higher amounts in volatiles collected from females at the peak of mating activity than in male samples. Acetic acid elicited dose-dependent electroantennographic responses and attracted ACP males, but not females, in Y-type and 4-way olfactometers. Field tests showed that acetic acid-baited traps captured significantly more males than control traps. Surprisingly, captures of females in acetic acid-baited traps were also higher than in control traps, possibly because of physical stimuli emitted by captured males