Morphological phenotypic dispersion of garlic cultivars by cluster analysis and multidimensional scaling

Multivariate techniques have become a useful tool for studying the phenotypic diversity of Germplasm Bank accessions, since they make it possible to combine a variety of different information from these accessions. This study aimed to characterize the phenotypic dispersion of garlic (Allium sativum L.) using two multivariate techniques with different objective functions. Twenty accessions were morphologically characterized for bulb diameter, length, and weight; number of cloves per bulb; number of leaves per plant; and leaf area. Techniques based on generalized quadratic distance of Mahalanobis, UPGMA (Unweighted Pair Group Method with Arithmetic Mean) clustering, and nMDS (nonmetrric MultiDimensional Scaling) were applied and the relative importance of variables quantified. The two multivariate techniques were capable of identifying cultivars with different characteristics, mainly regarding their classification in subgroups of common garlic or noble garlic, according to the number of cloves per bulb. The representation of the phenotypic distance of cultivars by multidimensional scaling was slightly more effective than that with UPGMA clustering

Effects of Maternal Age and Egg Quality on Mass Rearing of Mediterranean Fruit Flies (Diptera: Tephritidae)

Tests were conducted to determine if age of mass reared adult female Mediterranean fruit flies, Ceratitis capitata (Wiedemann), affected the viability of their offspring. Samples of eggs (0.4 g each) were collected on five consecutive days (4 to 8 d past adult emergence) from individual 660-liter adult colony screen cages and were reared in separate trays containing 0.5 liter of artificial diet. The mean volume of pupae obtained declined steadily with the age of the parents from 297 ± 21 (S.E.) ml per liter of larval diet for day 1 eggs to 158 ± 24 ml/liter for day 5 eggs. Hatch of eggs varied little, indicating that the viability of larvae declined with maternal age. The yield of pupae also varied significantly among replicates (adult cages), ranging from 174 ± 24 to 258 ± 23 ml per liter of diet. In a second test, pupal yield again declined with maternal age, whereas giving females a “break” from oviposition by withholding egging substrates on various schedules had no discernable effect on the relationship between age. In a second test (but not the first), maternal age also had significant effects on a number of quality traits in the progeny, including percentages of hatch, adult emergence, and flight ability. The authors propose that the observed cross-generation effects on insect survival and quality are likely a maternal effect and discuss possible implications of the findings for mass rearing operations

May we improve trapping in mating disrupted vineyards? The effect of pheromone lure and MD technology

Pheromone traps baited with 1 mg of the main sex pheromone component of Lobesia botrana (E)-7,(Z)-9-dodecadienyl acetate (hereafter referred as standard) are used to monitor the moth flight. Moreover, the same traps are currently used to evaluate mating disruption (MD) efficacy with limited accuracy. Actually, zero capture in the traps is still considered a “necessary but insufficient” indicator of effective MD. In the present study we aimed at assessing if either overloaded standard pheromone lures or addition of minor components of the natural blend could improve the effectiveness of the pheromone traps as early and accurate warning tools. A field trial was set up in large plots (min. 4 ha) treated with either commercial (Isonet L plus - Shin Etsu CBC; Rak 2 Max - BASF) or experimental (Puffer Lb – Suterra; No Mate Lb – Syngenta; Hercon® disrupt EGVM - Hercon Environmental; Splat Lobesia - Isca Technologies) MD dispensers. The pheromone release rate ranged from 325 to 900 mg/ha per day approximately, depending on the pheromone formulation. Addition of minor components did not significantly increase the captures in MD-treated plots compared to the standard lure at the same dose. Male catches in MD-treated plots significantly increased when the pheromone load of the trap bait was increased to 10 mg. Overloaded traps were more prompt in detecting male flight than the standard in MD treated plots. Indeed, when the infestation level was low, overloaded traps generally captured males at least a week before the standard lur

QUANTITATIVE DESCRIPTION OF THE INFLUENCE OF FLUCTUATING TEMPERATURES ON THE REPRODUCTIVE BIOLOGY AND SURVIVAL OF THE WESTERN CORN ROOTWORM, <i>DIABROTICA VIRGIFERA VIRGIFERA</i> LECONTE (COLEOPTERA: CHRYSOMELIDAE)

AbstractAdult corn rootworm beetles, Diabrotica virgifera virgifera LeConte, were maintained at five fluctuating temperature regimens with daily average temperatures of 16.0, 19.5, 23.0, 26.5, and 30.0°C. The mean number of eggs laid per female was greatest (602) at 26.5°C and least (295) at 16.0°C. The median length of life decreased with increasing temperature from 13.8 weeks at 19.5°C to 7.9 weeks at 30.0°C. Parameters were estimated for nonlinear functions relating age-specific fecundity and age-specific survival to physiological age.</jats:p