The Neotropical mirid predator Macrolophus basicornis uses volatile cues to avoid contacting old, Trichogramma pretiosum parasitized eggs of Tuta absoluta

Polyphagous mirid predators are increasingly used in commercial, augmentative biological control. Information about their foraging behaviour is essential, especially if one intends to use several natural enemies to control one or more pests in a crop, to detect if negative intraguild effects occur. We studied a case of intraguild predation (IGP) involving the predator Macrolophus basicornis (Stal) (Hemiptera Miridae) of the worldwide invasive South American tomato leaf miner Tuta absoluta (Meyrick) (Lepidoptera Gelechiidae) and explored how this predator deals with prey parasitized by Trichogramma pretiosum (Riley) (Hymenoptera Trichogrammatidae). Behavioural observations show that M. basicornis predators contacted significantly fewer old, parasitized eggs of T. absoluta than recently parasitized eggs. Olfactometer tests revealed that predators could smell differences between vola-tiles of tomato leaves infested with eggs of different qualities to locate suitable prey. They preferred volatiles from leaflets with unparasitized eggs above control leaflets and, moreover, preferred volatiles from leaflets with recently parasitized eggs over volatiles of leaflets with 5-day-old parasitized eggs. When predators and parasitoids are used together to control T. absoluta, parasitoids should be introduced one week before predators are released to prevent high levels of IGP

Intensity of intraguild predation of parasitized eggs by mirid predators depends on time since parasitization: a case study with the parasitoid Trichogramma pretiosum and the predator Macrolophus basicornis attacking Tuta absoluta eggs

Concurrent releases of several species of natural enemies for pest control have been studied in various crops with either positive, neutral, or negative results. To control the pest Tuta absoluta (Meyrick) (Lepidoptera Gelechiidae), only the egg parasitoid Trichogramma pretiosum Riley (Hymenoptera Trichogrammatidae) is applied on many hectares with tomatoes in South America. Use of the mirid predator Macrolophus basicornis Stal (Hemiptera Miridae) is considered either alone or in combination with the parasitoid T. pretiosum. To determine if intraguild relationships between the two natural enemies negatively affect concurrent releases, unparasitized eggs and eggs parasitized by T. pretiosum were exposed to the predator. Knowing which stages of parasitized eggs are consumed or rejected by the predator is important for development of a release strategy resulting in highest pest mortality. M. basicornis consumed 1-2 day old parasitized eggs as well as unparasitized eggs, and, consequently, expressed strong intraguild predation (IGP). Five and 9-day old parasitized eggs were often not consumed, and, therefore, exerted the phenomenon of competitive exclusion (CE). Predation rates of old parasitized eggs were very low and similar in no-choice and choice tests, and in experiments with a large (100), medium (50) and very limited (10) number of preys offered, demonstrating a strong CE effect. Interestingly, in choice experiments with unparasitized and old parasitized eggs, predators started to consume unparasitized eggs significantly later than when only unparasitized or young parasitized eggs were offered. This suggests that old, parasitized eggs in some way reduce the foraging activity of M. basicornis. We expect that stronger pest reduction by concurrent releases of both natural enemies will only occur at the start of the tomato production season and when the egg parasitoid is introduced seven days before the mirid predator in order to reduce intraguild predation of parasitized eggs by the predator

Lessons from agriculture for the sustainable management of malaria vectors.

Willem Takken and colleagues argue for the expansion of insecticide monotherapy in malaria control by taking lessons from agriculture and including more sustainable integrated vector management strategies

Population dynamics of rice leaffolders(Lepidoptera: Pyralidae) and their natural enemies in irrigated rice in the Philippines

Populations of rice leaffolders and their natural enemies were studied in eight crops of irrigated rice in Laguna Province, the Philippines. The rice leaffolder complex consisted of three species: Cnaphalocrocis medinalis (Guenée), Marasmia patnalis Bradley and M. exigua Butler. Leaffolder population dynamics were characterized by an egg peak at maximum tillering and a broad larval peak around booting stage. Peak densities ranged from 0.2 to 2.0 larvae per hill. Most larvae originated from immigrant moths and there was no substantial second generation. The seasonal percentage egg parasitism by Trichogramma sp. ranged from 0 to 27°and percentage larval parasitism from 14 to 56ÐThe braconid Macrocentrus philippinensis Ashmead was the most commonly reared larval parasitoid. Forty natural enemy taxa that may attack rice leaffolders were identified from suction and sweepnet samples: 24 predator taxa and 16 parasitoid taxa. The estimated survival rates from leaffolder egg to larval stages and between larval stages showed large variation between rice crops, but were not clearly correlated with observed levels of parasitism, natural enemy abundance, or natural enemy to leaffolder ratios. It is suggested that the generally low densities of rice leaffolders in Philippine transplanted rice are caused by their ovipositional preference for crops at the maximum tillering stage, allowing for only one generation, and by high immature mortality caused by the abundant and diverse complex of natural enemies