Trap Capture Rates Research Articles

Box thorn, key early season host of the Mediterranean fruit fly

Abstract In the Mediterranean region, from November to early June, Mediterranean fruit fly or medfly (Ceratitis capitata Wiedemann) populations decrease drastically and in some places disappear. For area‐wide control or eradication programmes, it is important to know on which wild hosts a medfly population can establish itself and subsequently cause later in the season important losses in commercial crops. Trapping of medfly in a box thorn (Lycium europaeum L.) hedge of the oasis of Tozeur, Tunisia, indicates that despite this plant being largely neglected by medfly later in the year, it is a principal early‐spring host of the pest. Fruit infestation rate in May was c. 292 pupae/kg of fresh fruits and an average of two larvae per infested fruit. The trap capture rate was c. 26 flies/trap/h. The importance of this non‐commercial key‐host in the development and distribution of medfly population during the early season when no other host is available is discussed. The diurnal bimodal flight activity rhythm o...

Apple maggot fly response to red sphere traps in relation to fly age and experience

AbstractResponses of the apple maggot fly, Rhagoletis pomonella (Walsh), to 8 cm red sticky sphere traps, baited with the synthetic fruit odor butyl hexanoate, were investigated in field‐caged apple trees containing green or red Gravenstein apples. Trap capture rate and the probability of oviposition in apples before capture generally increased with female age and number of mature eggs in ovaries. Two days of pre‐test exposure of mature females to red hawthorns, green Red Delicious apples or green Gravenstein apples had no significant effect on the likelihood of a fly finding a red sphere. However, before capture on a sphere or departing a tree, hawthorn‐exposed females found significantly fewer apples and laid significantly fewer eggs than females exposed to Gravenstein apples. Variation in duration of pre‐test exposure (1–4 days) of flies to Gravenstein apples had no detectable influence on female response to apples or to a red sphere in a test tree. The relevance of these findings to effectiveness of sphere traps for R. pomonella control in commercial orchards is discussed.

Identification of the Primary Female Sex Pheromone Component of the Mimosa Webworm (Lepidoptera: Plutellidae)

E 11-tetradecenyl acetate ( E 11-14:Ac) was identified as the primary female sex pheromone component of the mimosa webworm, Homadaula anisocentra Meyrick. Chemical analyses by gas chromatography and gas chromatography/mass spectrometry of virgin female sex pheromone gland extracts indicated the presence of E 11-14:Ac, E 11-14: OH, and 14:Ac, whereas sex pheromone gland volatiles contained only E 11-14:Ac and 14: Ac (at approximately 1% of E 11-14:Ac). Gas chromatography-electroantennogram detector analyses indicated male antennal responsiveness to a component in pheromone gland extracts and volatiles that had an elution time coincident with E 11-14:Ac. In field-trapping studies, E 11-14:Ac elicited trap capture rates not different ( P > 0.05) from those in traps baited with virgin females. Addition of either E 11-14:OH or Z11-14:Ac reduced trap capture rates, whereas E - and Z11-14:Ald appeared to have no effect on trap capture rates.

Current-Voltage Characteristics-What Do Experiments Really Tell Us?

ABSTRACTExperimentally measured current-voltage measurements in amorphous silicon hydride pin diodes have been fit to computer simulations by Hack and den Boer [1] using relatively small values for the neutral and charged trap capture rates. Silver and Cannella [2] have proposed larger values for the capture rates, accompanied by larger electron and hole band mobilities. We discuss here the possible reasons for expecting the larger values for the capture rates, and their influence on current voltage measurements both with and without the higher mobilities. It is found that the simulated I-V results using only the larger capture rates are much smaller than those for Hack and den Boer's parameters. However, when the large values are used for both the capture rates and the mobilities, the I-V relationship is quite similar to that for the smaller capture rates and mobilities. We also show the differences in the simulated transient currents for the different sets of parameters, and we discuss the causes of these differences.

Effects of Dissolved Oxygen Concentration and Light Intensity on Activity Cycles of Fishes Inhabiting Warm Springs

The cycles of killifishes of the genus Crenichthys were studied, using trap capture rates and sound volumes as indices of activ- ity. When other factors are optimal, the fish are less active in the dark than in the light, regardless of clock time. A variety of environmental parameters could probably alter the cycles when any one factor is un- favorable. Low concentrations of dissolved oxygen result in reduced activity. Such reduction can be effected at one site where dissolved oxygen is limited, while nearby populations are active in localities that have more dissolved oxygen. Apparently at 32 C activities are adverse- ly affected by oxygen supplies below 2 ppm. cyprinodont fishes inhabiting springs and the adjacent distrilbutaries in eastern Nevada. Each of the springs inhabited by these small fishes is exceedingly clear, has a relatively constant temperature, usually a slightly alkaline pH, and a relatively low dissolved oxygen concentration at the outflow (Hubbs and Hettler, 1964). The exceedingly constant environmental temperature contrasts sharp,ly with the highly variable temperatures recorded by Barlow (1958) in his analysis of diurnal activity patterns of another desert cyprinodont, Cyprinodon macularius, near the Salton Sea. This paper will discuss activity cycles similar to those discussed by Barlow; yet the thermal stimulus is not a likely causal factor.