The Biology and Thermal Requirements of the Fennel Aphid Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae)

Abstract

The relationship between the insect development rate and temperature was established very early and represents an important ecological variable for modeling the population dynamics of insects. The accurate determination of thermal constant values and the lower and upper developmental thresholds of Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae) on fennel (Foeniculum vulgare Miller (Apiales: Apiaceae)) crops would obviously benefit the effective application of control measures. This paper is a study of the biology and thermal requirements of H. foeniculi. Winged insects were collected from fennel crops at the Embrapa Algodão in Campina Grande, Paraíba. Nymphs (age ≤24 h) produced by winged insects were subjected to constant temperatures of 15, 20, 25, 28, 30 or 33°C, a photophase of 12 h and a relative humidity of 70±10%. The results of the study showed that at temperatures between 15 and 30°C, H. foeniculi nymphs were able to develop normally. The four instars were found at all temperatures tested. However, temperatures of 3 and 33°C were lethal to the nymphs. The nymph stage development time varied from 5 (30°C) to 19 (15°C) days. The influence of temperature on the development time is dependent on the instar. The base temperature (Tb) and the thermal constant (K) for the nymph stage were estimated at 11.2°C and 107.5 degree-days, respectively. The shortest nymph development stage was observed at 30°C, and the highest nymph viability (85.0%) was observed at 28°C. This information can be used for developing phenological models based on the temperature and development rate relationships so that outbreaks of H. foeniculi in the fennel crop can be predicted, therefore improving the application of control programs targeting this fennel pest.

Temperature-Dependent Fecundity and Life Table of the Fennel Aphid Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae)

“…Alate aphids did not survive temperatures of 15 and 30°C. These results confirm the sensitivity of this aphid species to high and low constant temperatures in the laboratory [ 22 , 32 ]. At all other temperatures (15–30°C), all apterous adults were capable of reproducing.…”

“…However, we have little detailed understanding of stability and change in field populations of fennel aphids, but certain features of applied population dynamics have been revealed. Extraordinary weather conditions, particularly temperatures, can have a marked effect on fennel aphid numbers [ 22 ]. Natural enemies can influence the rate of buildup of fennel aphids [ 22 ] and by interacting with other factors can shape the dynamics of this fennel pest [ 3 ].…”

“…The biological responses of H . foeniculi to different temperatures and its thermal requirements under laboratory conditions were reported by Malaquias et al [ 22 ]. However, quantitative information on life table parameters, such as intrinsic rate of increase ( r m ), net reproductive rate ( R 0 ), finite rate of increase ( λ ), mean generation time ( GT ), and population doubling time ( DT ) were not published in their studies.…”