Effect of a Neem (Azidirachta indica) -Based Insecticide on Oviposition Deterrence, Survival, Behavior and Reproduction of Adult Western Cherry Fruit Fly (Diptera: Tephritidae)

Bait spray for control of European cherry fruit fly: an appraisal based on semi‐field and field studies

“…As described above, the principal mode of action of neem is inhibition or disruption of ovarian and egg development, and consequently of oviposition. This has been described by several authors for other tephritid species and proven for R cerasi in own laboratory studies as well as in semi‐field trials considering persistence, i.e. effect of fresh and aged residues (Vogt H, unpublished).…”

“…Although a statistical comparison with trials of previous years is not possible, the results indicate strongly that early ingestion and on‐going provision of neem is most important for an effective control of R. cerasi . A stronger impact of neem on young females compared to older ones has been described by Van Randen and Roitberg for R. indifferens . In own laboratory tests we achieved complete inhibition of ovarian development in R. cerasi when females had access to neem bait (NAT‐norm) for a week from day two after emergence onwards.…”

“…The earlier tests with older females may therefore be a ‘worst case scenario’, and with adequate treatments under field conditions the females should encounter the bait immediately after emergence. Furthermore, neem negatively affects longevity of tephritid flies, a further factor contributing to the efficacy of neem, with young females being more susceptible according to our laboratory investigations (Koeppler K & Vogt H, unpublished).…”

“…Our field trial in Hiltpoltstein was particularly susceptible to immigration effects due to an experimental design of relatively small blocks of numerous cherry varieties (early to late). If neem is used for control purposes, immigrating mature females may not be affected fast enough and thus may successfully infest fruit . The success of field trials that incorporated a chemical barrier (Dossenheim, 2011, 2012) confirms the importance of preventing immigration when using neem.…”

“…Exposure in intervals (considering degradation and washing off during field application) revealed that young females should have access to the bait within a week for at least two days continuously and bait free gaps should not be longer than five days (Vogt H, unpublished). Probably the generally higher fruit infestation that was observed in bait treatments in semi‐field trials prior to 2011 was caused by females having more advanced ovarian development, on which any effect resulting from neem uptake is too slow so as to impede egg laying sufficiently . The earlier tests with older females may therefore be a ‘worst case scenario’, and with adequate treatments under field conditions the females should encounter the bait immediately after emergence.…”