Preference ofZeugodacus cucurbitae(Coquillett) for three commercial fruit vegetable hosts in natural and semi natural conditions

Abstract

Introduction. Host preference of Zeugodacus cucurbitae in three vegetables was determined under choice and no-choice experiments. Materials and methods. The experiments were conducted in both semi-natural (under cage) and natural (no cage) field conditions. The trials were run for three seasons between March 2013 and July 2014 in Morogoro Region, Tanzania. In each season, two sets of plots of watermelon Citrullus lanatus, cucumber Cucumis sativus and pumpkin Cucurbita sp., were established in mono and mixed cropping systems. A set of plots was placed under individual cages and another set of plots was left open. Colonies of Z. cucurbitae were regularly established from wild cucurbits and the emerging adults were maintained on artificial diets. The adults were released into cages once in a cropping season, at a sex ratio ratio of 1:1. A total of 60 and 180 adults were released into choice (4×4 m) and no choice (4 × 12 m) plots respectively. Open fields were infested naturally. Released adults were between 21 and 30 days old post emergence. Flies were released between six and eight weeks after sowing the vegetables. Fruits were harvested a week after release of flies into cages. Trials were also conducted to determine the dominant cucurbit infester in cucumber. Infestation rates and incidences were determined and used to indicate preference of Z. cucurbitae among the three vegetables. Results and discussion. Highest infestation rate of Z. cucurbitae was recorded in watermelon while lowest in pumpkin. Infestation rates were significantly high in fruits grown under no choice compared to choice plots. More flies emerged from fruits grown in no choice plots. However, infestation rates were not significantly different among fruits from natural and semi-natural conditions. Other cucurbit infesters, Dacus bivittatus, D. frontalis, D. vertebratus and D. ciliatus emerged from fruits grown in open (no cage) field plots. Further results show that Z. cucurbitae dominated Dacus bivittatus and D. frontalis in cucumber. Conclusion. Watermelon is the most preferred host of the dominant cucurbit infester Z. cucurbitae.

Performance of Three Isolates of Metarhizium anisopliae and Their Virulence against Zeugodacus cucurbitae under Different Temperature Regimes, with Global Extrapolation of Their Efficiency

“…In Africa, member of the genus Dacus (native to Africa) have been the most dominant and damaging fruit flies resulting in significant yield losses [11]. However, the problem was further compounded by the widespread invasion of the alien invasive species Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae) (formerly known as Bactrocera cucurbitae ), very often leading to total crop failure [12,13] due to the pest’s is high fecundity [13] and the lack of natural enemies on the continent. Moreover, Z. cucurbitae is highly polyphagous posing a serious threat for production of non-cucurbitaeous crops [14].…”

Bioefficacy of Isolates of Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) (Ascomycota: Hypocreales) as field Protectants of Citrullus lanatus (Thunb.) Matsum. and Nakai against Fruit Flies

“…Young fruits of watermelon were highly infested during monitoring. The cucurbit fruit fly favored early stages of fruits, and the infested fruits failed to develop properly and dropped-off from the plant . Earlier studies on fruit flies have also reported that the adult females preferred unopened flowers and young fruits for egg laying. ,, Infestation rate recorded after fruits harvesting and incubation showed variation among treatments and seasons.…”

“…Zeugodacus cucurbitae prefers watermelon, pumpkin and cucumber and can cause up to 100% loss in an unprotected crop . On cucurbit plants, an average yield loss of 53% due to damage by native species was recorded on pumpkin ( Cucurbita pepo L.) and tomatoes ( Solanum lycopersicum L. ). , Depending on the environmental conditions, susceptibility of the crop species, and the geographic location, the extent of losses varies between 30 to 100%. − …”

Larval host plant influences male body size and mating success in a tephritid fruit fly

“…Studies of oviposition preference have been conducted on Z . cucurbitae (Sarwar et al., ; Mwatawala et al., ), but rigorous tests of the preference–performance hypothesis are not yet available for this species — but see Akol et al. (), Joachim‐Bravo & Zucoloto (), Joachim‐Bravo et al.…”

“…In fact, whereas various insect studies (reviewed in Gripenberg et al, 2010) support the preference-performance hypothesisi.e., oviposition preferences have evolved to maximize offspring growth and survival; also known as the 'mother knows best' principle; Valladares & Lawton, 1991)other studies do not (e.g., Marchioro & Foerster, 2014;Hufnagel et al, 2017). Studies of oviposition preference have been conducted on Z. cucurbitae (Sarwar et al, 2013;Mwatawala et al, 2015), but rigorous tests of the preference-performance hypothesis are not yet available for this speciesbut see Akol et al (2013), Joachim-Bravo & Zucoloto (1997, Joachim-Bravo et al (2001), and Muthuthantri & Clarke (2012) for data on other tephritid species. In short, the present study demonstrates a host plant-mediated effect on a crucial parameter of adult fitness (male mating success) in the laboratory but similarly demonstrating this pattern in the field will be difficult, given the many ecological factors that may influence this relationship.…”