Parasitism of Aganaspis daci against Ceratitis capitata under Mediterranean climate conditions

Abstract

The effect of environmental factors is essential to the success of parasitoids as biological control agents, as it determines their foraging activity, development, and survival. The larval-pupal parasitoid wasp Aganaspis daci (Weld) (Hymenoptera: Figitidae) is known to have a very low fertility (i.e., offspring production) in the field in certain Mediterranean areas, probably due to its inability to efficiently oviposit under such climatic conditions. In this study, the percentage of parasitism and induced mortality (mortality of host pupae attributed to parasitoids, from which adults do not emerge) caused by this wasp to the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), was assessed under field conditions across 1 year, using medfly-infested apples and parasitoid-confined release in a lemon orchard of southeastern Spain. As A. daci is known to have very few emergences in the field, fertility was assessed in the laboratory from parasitized pupae recovered from the field. We found average parasitism rates of 27% and high induced mortality rates of 66% under field conditions. Consequently, medfly population reduction (total mortality of C. capitata caused by A. daci, i.e., induced mortality + % parasitism) was, on average, 87%. Parasitism and induced mortality varied throughout the year, depending on the average temperature and relative humidity. The interaction of these factors resulted in the highest parasitism rates at low mean temperature and humidity values; likewise, the highest percentages of induced mortality were obtained with a combination of high mean temperature and low mean humidity values. In conclusion, A. daci may exert a strong impact on medfly populations, being a good candidate for inundative field releases for the management of C. capitata in the Mediterranean Basin.

Combined use of the larvo‐pupal parasitoids Diachasmimorpha longicaudata and Aganaspis daci for biological control of the medfly

“…Indeed, superparasitism is one of the main factors that may lead to high‐induced mortality, as previously reported for both A. daci (de Pedro et al, , ,b, ) and D. longicaudata (Montoya et al, ). Our work concurred with these studies with regards to higher induced mortality at lower host density (when superparasitism is also higher) and under greenhouse conditions.…”

“…Furthermore, temperature (among other environmental factors) could also explain the high fertility and parasitism values observed for A. daci in the present study under greenhouse conditions, because climatic conditions when the trials were carried out (June to July 2013) were very similar to those observed when this species was first recorded in Greece (Papadopoulos & Katsoyannos, ) and Spain (Verdú et al, ). These conditions are regarded as optimal for its development and parasitic activity (de Pedro, Beitia, Sabater‐Muñoz, et al, ). At other times of the year, A. daci development appears to be negatively affected by environmental conditions, whilst D. longicaudata seems to be more resistant to extreme climatic conditions (Harbi et al, ; Meirelles, Redaelli, & Ourique, ).…”

Abiotic factors affecting Diachasmimorpha longicaudata (Hymenoptera: Braconidae) activity as a natural enemy of Ceratitis capitata (Diptera: Tephritidae) under semi‐natural conditions in the Mediterranean region

“…The effects of temperature and RH were previously investigated and demonstrated on several biological and behavioural parameters of D. longicaudata and other parasitoids including parasitism rate, host searching, immature development and flight activity (de Pedro et al., ; Duale, ; Hebert, Cloutier, & Regniere, ). For example, in the braconid Fopius arisanus (Sonan), flight and parasitic activities increased with temperature and decreased with relative humidity (Rousse et al., ).…”

Effect of the olive fruit size on the parasitism rates ofBactocera oleae(Diptera: Tephritidae) by the figitid waspAganaspis daci(Hymenoptera: Figitidae), and first field releases of adult parasitoids in olive grove

“…Although A. daci can successfully parasitize infested olive fruit in laboratory conditions, our results support no activity of A. daci in fi eld conditions, despite of the prevailing optimal conditions for the fi eld released wasps in terms of host availability. In general, fi eld studies have so far revealed very low fertility rates and high immature mortality of A. daci, driven mainly by low (<20 o C) or high (>30-35 o C) temperatures (de Pedro et al, 2016;2017), even though exceptions exist (Papadopoulos and Katsoyannos, 2003;Ali et al, 2016). Nevertheless, parasitism rates under low temperatures are expected to be high only under low humidity levels, while warm and wet conditions favor parasitism rates of A. daci during summer, suggesting that both temperature and relative humidity aff ect parasitism rates of A. daci in the Mediterranean basin (de Pedro et al, 2017).…”

“…In general, fi eld studies have so far revealed very low fertility rates and high immature mortality of A. daci, driven mainly by low (<20 o C) or high (>30-35 o C) temperatures (de Pedro et al, 2016;2017), even though exceptions exist (Papadopoulos and Katsoyannos, 2003;Ali et al, 2016). Nevertheless, parasitism rates under low temperatures are expected to be high only under low humidity levels, while warm and wet conditions favor parasitism rates of A. daci during summer, suggesting that both temperature and relative humidity aff ect parasitism rates of A. daci in the Mediterranean basin (de Pedro et al, 2017). For instance, in the coastal area of Syria, fi eld parasitism of A. daci was recorded from May to September with a peak during June and August, when temperatures ranged from 22 o C to 26 o C (Ali et al, 2016).…”