Plant training for induced defense against insect pests: a promising tool for integrated pest management in cotton.

Enhancing cotton pest management using plant natural defenses has been described as a promising way to improve the management of crop pests. We here reviewed various studies on cotton growing systems to illustrate how an ancient technique called plant training, which includes plant topping and pruning, may contribute to this goal. Using examples from cotton crops, we show how trained plants can be brought to a state of enhanced defense that causes faster and more robust activation of their defense responses. We revisit the agricultural benefits associated with this technique in cotton crops, with a focus on its potential as a supplementary tool for integrated pest management (IPM). In particular, we examine its role in mediating plant interactions with conspecific neighboring plants, pests and associated natural enemies. We propose a new IPM tool, plant training for induced defense, which involves inducing plant defense through artificial injury. Experimental evidence from various studies shows that cotton training is a promising technique, particularly for smallholders, which can be used as part of an IPM program to significantly reduce insecticide use and to improve productivity in cotton farming. © 2018 Society of Chemical Industry.

Encounters with aphid predators or their residues impede searching and oviposition by the aphid parasitoid Aphidius ervi (Hymenoptera: Aphidiinae).

Intraguild predation (IGP) can be an important factor influencing the effectiveness of aphid natural enemies in biological control. In particular, aphid parasitoid foraging could be influenced by the presence of predators. This study investigated the effect of larvae of the predatory hoverfly Episyrphus balteatus DeGeer (Diptera: Syrphidae) and the multicolored Asian ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae) on the foraging behavior of the aphid parasitoid, Aphidius ervi Haliday (Hymenoptera: Aphidiidae) in choice experiments using a leaf disc bioassay. Wasp response to chemical tracks left by those predator larvae was also tested. Parasitoid behavior was recorded using the Observer (Noldus Information Technology, version 5.0, Wageningen, the Netherlands). The experiments were conducted under controlled environmental conditions using leaves of the broad bean plant, Vicia faba L. (Fabaceae) with Myzus persicae Sulzer (Homoptera: Aphididae) as the host complex. A. ervi females avoided aphid patches when larvae of either predator were present. A similar avoidance response was shown by A. ervi to aphid patches with E. balteatus larval tracks, whereas no significant response was observed to tracks left by H. axyridis larvae. It was concluded that IG predator avoidance shown by the aphid parasitoid A. ervi may be a factor affecting their distribution among host patches.

How does the age of hoverfly females affect their reproduction?

In the present study, we observed the effect of age of Episyrphus balteatus DeGeer (Diptera, Syrphidae) females on their fecundity and fertility (number and percentage of fertile eggs). Eight newborn E. batteatus couples were placed in separated cages (30 cm x 30 cm x 60 cm) and the number of eggs laid and the egg viability were recorded daily during 45 days. E. balteatus females had a pre-oviposition period of 10 days before mating happened. The fecundity increased steadily from day 11 to day 16 with an average of 30 eggs a day. During the following days (from day 23 to day 45), we found that the optimal fecundity was observed every second day and that 70.47% of the eggs laid during the entire life of the females were fertile. We also found that the fertility decreased significantly when the females were older than 38 days. As result, the age of hoverfly females influence significantly on their reproduction, with suggesting that hoverfly females from 2 to 5 weeks old are important agents for biological control programs.